1 /*
2 * Copyright (c) 2005, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "c1/c1_CFGPrinter.hpp"
26 #include "c1/c1_CodeStubs.hpp"
27 #include "c1/c1_Compilation.hpp"
28 #include "c1/c1_FrameMap.hpp"
29 #include "c1/c1_IR.hpp"
30 #include "c1/c1_LinearScan.hpp"
31 #include "c1/c1_LIRGenerator.hpp"
32 #include "c1/c1_ValueStack.hpp"
33 #include "code/vmreg.inline.hpp"
34 #include "runtime/timerTrace.hpp"
35 #include "utilities/bitMap.inline.hpp"
36
37 #ifndef PRODUCT
38
39 static LinearScanStatistic _stat_before_alloc;
40 static LinearScanStatistic _stat_after_asign;
41 static LinearScanStatistic _stat_final;
42
43 static LinearScanTimers _total_timer;
44
45 // helper macro for short definition of timer
46 #define TIME_LINEAR_SCAN(timer_name) TraceTime _block_timer("", _total_timer.timer(LinearScanTimers::timer_name), TimeLinearScan || TimeEachLinearScan, Verbose);
47
48 #else
49 #define TIME_LINEAR_SCAN(timer_name)
50 #endif
51
52 #ifdef ASSERT
53
54 // helper macro for short definition of trace-output inside code
55 #define TRACE_LINEAR_SCAN(level, code) \
56 if (TraceLinearScanLevel >= level) { \
57 code; \
58 }
59 #else
60 #define TRACE_LINEAR_SCAN(level, code)
61 #endif
62
63 // Map BasicType to spill size in 32-bit words, matching VMReg's notion of words
64 #ifdef _LP64
65 static int type2spill_size[T_CONFLICT+1]={ -1, 0, 0, 0, 1, 1, 1, 2, 1, 1, 1, 2, 2, 2, 2, 0, 2, 1, 2, 1, -1};
66 #else
67 static int type2spill_size[T_CONFLICT+1]={ -1, 0, 0, 0, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 0, 1, -1, 1, 1, -1};
68 #endif
69
70
71 // Implementation of LinearScan
72
73 LinearScan::LinearScan(IR* ir, LIRGenerator* gen, FrameMap* frame_map)
74 : _compilation(ir->compilation())
75 , _ir(ir)
76 , _gen(gen)
77 , _frame_map(frame_map)
78 , _cached_blocks(*ir->linear_scan_order())
79 , _num_virtual_regs(gen->max_virtual_register_number())
80 , _has_fpu_registers(false)
81 , _num_calls(-1)
82 , _max_spills(0)
83 , _unused_spill_slot(-1)
84 , _intervals(0) // initialized later with correct length
85 , _new_intervals_from_allocation(nullptr)
86 , _sorted_intervals(nullptr)
87 , _needs_full_resort(false)
88 , _lir_ops(0) // initialized later with correct length
89 , _block_of_op(0) // initialized later with correct length
90 , _has_info(0)
91 , _has_call(0)
92 , _interval_in_loop(0) // initialized later with correct length
93 , _scope_value_cache(0) // initialized later with correct length
94 {
95 assert(this->ir() != nullptr, "check if valid");
96 assert(this->compilation() != nullptr, "check if valid");
97 assert(this->gen() != nullptr, "check if valid");
98 assert(this->frame_map() != nullptr, "check if valid");
99 }
100
101
102 // ********** functions for converting LIR-Operands to register numbers
103 //
104 // Emulate a flat register file comprising physical integer registers,
105 // physical floating-point registers and virtual registers, in that order.
106 // Virtual registers already have appropriate numbers, since V0 is
107 // the number of physical registers.
108 // Returns -1 for hi word if opr is a single word operand.
109 //
110 // Note: the inverse operation (calculating an operand for register numbers)
111 // is done in calc_operand_for_interval()
112
113 int LinearScan::reg_num(LIR_Opr opr) {
114 assert(opr->is_register(), "should not call this otherwise");
115
116 if (opr->is_virtual_register()) {
117 assert(opr->vreg_number() >= nof_regs, "found a virtual register with a fixed-register number");
118 return opr->vreg_number();
119 } else if (opr->is_single_cpu()) {
120 return opr->cpu_regnr();
121 } else if (opr->is_double_cpu()) {
122 return opr->cpu_regnrLo();
123 #ifdef X86
124 } else if (opr->is_single_xmm()) {
125 return opr->fpu_regnr() + pd_first_xmm_reg;
126 } else if (opr->is_double_xmm()) {
127 return opr->fpu_regnrLo() + pd_first_xmm_reg;
128 #endif
129 } else if (opr->is_single_fpu()) {
130 return opr->fpu_regnr() + pd_first_fpu_reg;
131 } else if (opr->is_double_fpu()) {
132 return opr->fpu_regnrLo() + pd_first_fpu_reg;
133 } else {
134 ShouldNotReachHere();
135 return -1;
136 }
137 }
138
139 int LinearScan::reg_numHi(LIR_Opr opr) {
140 assert(opr->is_register(), "should not call this otherwise");
141
142 if (opr->is_virtual_register()) {
143 return -1;
144 } else if (opr->is_single_cpu()) {
145 return -1;
146 } else if (opr->is_double_cpu()) {
147 return opr->cpu_regnrHi();
148 #ifdef X86
149 } else if (opr->is_single_xmm()) {
150 return -1;
151 } else if (opr->is_double_xmm()) {
152 return -1;
153 #endif
154 } else if (opr->is_single_fpu()) {
155 return -1;
156 } else if (opr->is_double_fpu()) {
157 return opr->fpu_regnrHi() + pd_first_fpu_reg;
158 } else {
159 ShouldNotReachHere();
160 return -1;
161 }
162 }
163
164
165 // ********** functions for classification of intervals
166
167 bool LinearScan::is_precolored_interval(const Interval* i) {
168 return i->reg_num() < LinearScan::nof_regs;
169 }
170
171 bool LinearScan::is_virtual_interval(const Interval* i) {
172 return i->reg_num() >= LIR_Opr::vreg_base;
173 }
174
175 bool LinearScan::is_precolored_cpu_interval(const Interval* i) {
176 return i->reg_num() < LinearScan::nof_cpu_regs;
177 }
178
179 bool LinearScan::is_virtual_cpu_interval(const Interval* i) {
180 #if defined(__SOFTFP__) || defined(E500V2)
181 return i->reg_num() >= LIR_Opr::vreg_base;
182 #else
183 return i->reg_num() >= LIR_Opr::vreg_base && (i->type() != T_FLOAT && i->type() != T_DOUBLE);
184 #endif // __SOFTFP__ or E500V2
185 }
186
187 bool LinearScan::is_precolored_fpu_interval(const Interval* i) {
188 return i->reg_num() >= LinearScan::nof_cpu_regs && i->reg_num() < LinearScan::nof_regs;
189 }
190
191 bool LinearScan::is_virtual_fpu_interval(const Interval* i) {
192 #if defined(__SOFTFP__) || defined(E500V2)
193 return false;
194 #else
195 return i->reg_num() >= LIR_Opr::vreg_base && (i->type() == T_FLOAT || i->type() == T_DOUBLE);
196 #endif // __SOFTFP__ or E500V2
197 }
198
199 bool LinearScan::is_in_fpu_register(const Interval* i) {
200 // fixed intervals not needed for FPU stack allocation
201 return i->reg_num() >= nof_regs && pd_first_fpu_reg <= i->assigned_reg() && i->assigned_reg() <= pd_last_fpu_reg;
202 }
203
204 bool LinearScan::is_oop_interval(const Interval* i) {
205 // fixed intervals never contain oops
206 return i->reg_num() >= nof_regs && i->type() == T_OBJECT;
207 }
208
209
210 // ********** General helper functions
211
212 // compute next unused stack index that can be used for spilling
213 int LinearScan::allocate_spill_slot(bool double_word) {
214 int spill_slot;
215 if (double_word) {
216 if ((_max_spills & 1) == 1) {
217 // alignment of double-word values
218 // the hole because of the alignment is filled with the next single-word value
219 assert(_unused_spill_slot == -1, "wasting a spill slot");
220 _unused_spill_slot = _max_spills;
221 _max_spills++;
222 }
223 spill_slot = _max_spills;
224 _max_spills += 2;
225
226 } else if (_unused_spill_slot != -1) {
227 // re-use hole that was the result of a previous double-word alignment
228 spill_slot = _unused_spill_slot;
229 _unused_spill_slot = -1;
230
231 } else {
232 spill_slot = _max_spills;
233 _max_spills++;
234 }
235
236 int result = spill_slot + LinearScan::nof_regs + frame_map()->argcount();
237
238 // if too many slots used, bailout compilation.
239 if (result > 2000) {
240 bailout("too many stack slots used");
241 }
242
243 return result;
244 }
245
246 void LinearScan::assign_spill_slot(Interval* it) {
247 // assign the canonical spill slot of the parent (if a part of the interval
248 // is already spilled) or allocate a new spill slot
249 if (it->canonical_spill_slot() >= 0) {
250 it->assign_reg(it->canonical_spill_slot());
251 } else {
252 int spill = allocate_spill_slot(type2spill_size[it->type()] == 2);
253 it->set_canonical_spill_slot(spill);
254 it->assign_reg(spill);
255 }
256 }
257
258 void LinearScan::propagate_spill_slots() {
259 if (!frame_map()->finalize_frame(max_spills(), compilation()->needs_stack_repair())) {
260 bailout("frame too large");
261 }
262 }
263
264 // create a new interval with a predefined reg_num
265 // (only used for parent intervals that are created during the building phase)
266 Interval* LinearScan::create_interval(int reg_num) {
267 assert(_intervals.at(reg_num) == nullptr, "overwriting existing interval");
268
269 Interval* interval = new Interval(reg_num);
270 _intervals.at_put(reg_num, interval);
271
272 // assign register number for precolored intervals
273 if (reg_num < LIR_Opr::vreg_base) {
274 interval->assign_reg(reg_num);
275 }
276 return interval;
277 }
278
279 // assign a new reg_num to the interval and append it to the list of intervals
280 // (only used for child intervals that are created during register allocation)
281 void LinearScan::append_interval(Interval* it) {
282 it->set_reg_num(_intervals.length());
283 _intervals.append(it);
284 IntervalList* new_intervals = _new_intervals_from_allocation;
285 if (new_intervals == nullptr) {
286 new_intervals = _new_intervals_from_allocation = new IntervalList();
287 }
288 new_intervals->append(it);
289 }
290
291 // copy the vreg-flags if an interval is split
292 void LinearScan::copy_register_flags(Interval* from, Interval* to) {
293 if (gen()->is_vreg_flag_set(from->reg_num(), LIRGenerator::byte_reg)) {
294 gen()->set_vreg_flag(to->reg_num(), LIRGenerator::byte_reg);
295 }
296 if (gen()->is_vreg_flag_set(from->reg_num(), LIRGenerator::callee_saved)) {
297 gen()->set_vreg_flag(to->reg_num(), LIRGenerator::callee_saved);
298 }
299
300 // Note: do not copy the must_start_in_memory flag because it is not necessary for child
301 // intervals (only the very beginning of the interval must be in memory)
302 }
303
304
305 // ********** spill move optimization
306 // eliminate moves from register to stack if stack slot is known to be correct
307
308 // called during building of intervals
309 void LinearScan::change_spill_definition_pos(Interval* interval, int def_pos) {
310 assert(interval->is_split_parent(), "can only be called for split parents");
311
312 switch (interval->spill_state()) {
313 case noDefinitionFound:
314 assert(interval->spill_definition_pos() == -1, "must no be set before");
315 interval->set_spill_definition_pos(def_pos);
316 interval->set_spill_state(oneDefinitionFound);
317 break;
318
319 case oneDefinitionFound:
320 assert(def_pos <= interval->spill_definition_pos(), "positions are processed in reverse order when intervals are created");
321 if (def_pos < interval->spill_definition_pos() - 2) {
322 // second definition found, so no spill optimization possible for this interval
323 interval->set_spill_state(noOptimization);
324 } else {
325 // two consecutive definitions (because of two-operand LIR form)
326 assert(block_of_op_with_id(def_pos) == block_of_op_with_id(interval->spill_definition_pos()), "block must be equal");
327 }
328 break;
329
330 case noOptimization:
331 // nothing to do
332 break;
333
334 default:
335 assert(false, "other states not allowed at this time");
336 }
337 }
338
339 // called during register allocation
340 void LinearScan::change_spill_state(Interval* interval, int spill_pos) {
341 switch (interval->spill_state()) {
342 case oneDefinitionFound: {
343 int def_loop_depth = block_of_op_with_id(interval->spill_definition_pos())->loop_depth();
344 int spill_loop_depth = block_of_op_with_id(spill_pos)->loop_depth();
345
346 if (def_loop_depth < spill_loop_depth) {
347 // the loop depth of the spilling position is higher then the loop depth
348 // at the definition of the interval -> move write to memory out of loop
349 // by storing at definitin of the interval
350 interval->set_spill_state(storeAtDefinition);
351 } else {
352 // the interval is currently spilled only once, so for now there is no
353 // reason to store the interval at the definition
354 interval->set_spill_state(oneMoveInserted);
355 }
356 break;
357 }
358
359 case oneMoveInserted: {
360 // the interval is spilled more then once, so it is better to store it to
361 // memory at the definition
362 interval->set_spill_state(storeAtDefinition);
363 break;
364 }
365
366 case storeAtDefinition:
367 case startInMemory:
368 case noOptimization:
369 case noDefinitionFound:
370 // nothing to do
371 break;
372
373 default:
374 assert(false, "other states not allowed at this time");
375 }
376 }
377
378
379 bool LinearScan::must_store_at_definition(const Interval* i) {
380 return i->is_split_parent() && i->spill_state() == storeAtDefinition;
381 }
382
383 // called once before assignment of register numbers
384 void LinearScan::eliminate_spill_moves() {
385 TIME_LINEAR_SCAN(timer_eliminate_spill_moves);
386 TRACE_LINEAR_SCAN(3, tty->print_cr("***** Eliminating unnecessary spill moves"));
387
388 // collect all intervals that must be stored after their definion.
389 // the list is sorted by Interval::spill_definition_pos
390 Interval* interval;
391 Interval* temp_list;
392 create_unhandled_lists(&interval, &temp_list, must_store_at_definition, nullptr);
393
394 #ifdef ASSERT
395 Interval* prev = nullptr;
396 Interval* temp = interval;
397 while (temp != Interval::end()) {
398 assert(temp->spill_definition_pos() > 0, "invalid spill definition pos");
399 if (prev != nullptr) {
400 assert(temp->from() >= prev->from(), "intervals not sorted");
401 assert(temp->spill_definition_pos() >= prev->spill_definition_pos(), "when intervals are sorted by from, then they must also be sorted by spill_definition_pos");
402 }
403
404 assert(temp->canonical_spill_slot() >= LinearScan::nof_regs, "interval has no spill slot assigned");
405 assert(temp->spill_definition_pos() >= temp->from(), "invalid order");
406 assert(temp->spill_definition_pos() <= temp->from() + 2, "only intervals defined once at their start-pos can be optimized");
407
408 TRACE_LINEAR_SCAN(4, tty->print_cr("interval %d (from %d to %d) must be stored at %d", temp->reg_num(), temp->from(), temp->to(), temp->spill_definition_pos()));
409
410 temp = temp->next();
411 }
412 #endif
413
414 LIR_InsertionBuffer insertion_buffer;
415 int num_blocks = block_count();
416 for (int i = 0; i < num_blocks; i++) {
417 BlockBegin* block = block_at(i);
418 LIR_OpList* instructions = block->lir()->instructions_list();
419 int num_inst = instructions->length();
420 bool has_new = false;
421
422 // iterate all instructions of the block. skip the first because it is always a label
423 for (int j = 1; j < num_inst; j++) {
424 LIR_Op* op = instructions->at(j);
425 int op_id = op->id();
426
427 if (op_id == -1) {
428 // remove move from register to stack if the stack slot is guaranteed to be correct.
429 // only moves that have been inserted by LinearScan can be removed.
430 assert(op->code() == lir_move, "only moves can have a op_id of -1");
431 assert(op->as_Op1() != nullptr, "move must be LIR_Op1");
432 assert(op->as_Op1()->result_opr()->is_virtual(), "LinearScan inserts only moves to virtual registers");
433
434 LIR_Op1* op1 = (LIR_Op1*)op;
435 Interval* interval = interval_at(op1->result_opr()->vreg_number());
436
437 if (interval->assigned_reg() >= LinearScan::nof_regs && interval->always_in_memory()) {
438 // move target is a stack slot that is always correct, so eliminate instruction
439 TRACE_LINEAR_SCAN(4, tty->print_cr("eliminating move from interval %d to %d", op1->in_opr()->vreg_number(), op1->result_opr()->vreg_number()));
440 instructions->at_put(j, nullptr); // null-instructions are deleted by assign_reg_num
441 }
442
443 } else {
444 // insert move from register to stack just after the beginning of the interval
445 assert(interval == Interval::end() || interval->spill_definition_pos() >= op_id, "invalid order");
446 assert(interval == Interval::end() || (interval->is_split_parent() && interval->spill_state() == storeAtDefinition), "invalid interval");
447
448 while (interval != Interval::end() && interval->spill_definition_pos() == op_id) {
449 if (!has_new) {
450 // prepare insertion buffer (appended when all instructions of the block are processed)
451 insertion_buffer.init(block->lir());
452 has_new = true;
453 }
454
455 LIR_Opr from_opr = operand_for_interval(interval);
456 LIR_Opr to_opr = canonical_spill_opr(interval);
457 assert(from_opr->is_fixed_cpu() || from_opr->is_fixed_fpu(), "from operand must be a register");
458 assert(to_opr->is_stack(), "to operand must be a stack slot");
459
460 insertion_buffer.move(j, from_opr, to_opr);
461 TRACE_LINEAR_SCAN(4, tty->print_cr("inserting move after definition of interval %d to stack slot %d at op_id %d", interval->reg_num(), interval->canonical_spill_slot() - LinearScan::nof_regs, op_id));
462
463 interval = interval->next();
464 }
465 }
466 } // end of instruction iteration
467
468 if (has_new) {
469 block->lir()->append(&insertion_buffer);
470 }
471 } // end of block iteration
472
473 assert(interval == Interval::end(), "missed an interval");
474 }
475
476
477 // ********** Phase 1: number all instructions in all blocks
478 // Compute depth-first and linear scan block orders, and number LIR_Op nodes for linear scan.
479
480 void LinearScan::number_instructions() {
481 {
482 // dummy-timer to measure the cost of the timer itself
483 // (this time is then subtracted from all other timers to get the real value)
484 TIME_LINEAR_SCAN(timer_do_nothing);
485 }
486 TIME_LINEAR_SCAN(timer_number_instructions);
487
488 // Assign IDs to LIR nodes and build a mapping, lir_ops, from ID to LIR_Op node.
489 int num_blocks = block_count();
490 int num_instructions = 0;
491 int i;
492 for (i = 0; i < num_blocks; i++) {
493 num_instructions += block_at(i)->lir()->instructions_list()->length();
494 }
495
496 // initialize with correct length
497 _lir_ops = LIR_OpArray(num_instructions, num_instructions, nullptr);
498 _block_of_op = BlockBeginArray(num_instructions, num_instructions, nullptr);
499
500 int op_id = 0;
501 int idx = 0;
502
503 for (i = 0; i < num_blocks; i++) {
504 BlockBegin* block = block_at(i);
505 block->set_first_lir_instruction_id(op_id);
506 LIR_OpList* instructions = block->lir()->instructions_list();
507
508 int num_inst = instructions->length();
509 for (int j = 0; j < num_inst; j++) {
510 LIR_Op* op = instructions->at(j);
511 op->set_id(op_id);
512
513 _lir_ops.at_put(idx, op);
514 _block_of_op.at_put(idx, block);
515 assert(lir_op_with_id(op_id) == op, "must match");
516
517 idx++;
518 op_id += 2; // numbering of lir_ops by two
519 }
520 block->set_last_lir_instruction_id(op_id - 2);
521 }
522 assert(idx == num_instructions, "must match");
523 assert(idx * 2 == op_id, "must match");
524
525 _has_call.initialize(num_instructions);
526 _has_info.initialize(num_instructions);
527 }
528
529
530 // ********** Phase 2: compute local live sets separately for each block
531 // (sets live_gen and live_kill for each block)
532
533 void LinearScan::set_live_gen_kill(Value value, LIR_Op* op, BitMap& live_gen, BitMap& live_kill) {
534 LIR_Opr opr = value->operand();
535 Constant* con = value->as_Constant();
536
537 // check some asumptions about debug information
538 assert(!value->type()->is_illegal(), "if this local is used by the interpreter it shouldn't be of indeterminate type");
539 assert(con == nullptr || opr->is_virtual() || opr->is_constant() || opr->is_illegal(), "assumption: Constant instructions have only constant operands");
540 assert(con != nullptr || opr->is_virtual(), "assumption: non-Constant instructions have only virtual operands");
541
542 if ((con == nullptr || con->is_pinned()) && opr->is_register()) {
543 assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
544 int reg = opr->vreg_number();
545 if (!live_kill.at(reg)) {
546 live_gen.set_bit(reg);
547 TRACE_LINEAR_SCAN(4, tty->print_cr(" Setting live_gen for value %c%d, LIR op_id %d, register number %d", value->type()->tchar(), value->id(), op->id(), reg));
548 }
549 }
550 }
551
552
553 void LinearScan::compute_local_live_sets() {
554 TIME_LINEAR_SCAN(timer_compute_local_live_sets);
555
556 int num_blocks = block_count();
557 int live_size = live_set_size();
558 bool local_has_fpu_registers = false;
559 int local_num_calls = 0;
560 LIR_OpVisitState visitor;
561
562 BitMap2D local_interval_in_loop = BitMap2D(_num_virtual_regs, num_loops());
563
564 // iterate all blocks
565 for (int i = 0; i < num_blocks; i++) {
566 BlockBegin* block = block_at(i);
567
568 ResourceBitMap live_gen(live_size);
569 ResourceBitMap live_kill(live_size);
570
571 if (block->is_set(BlockBegin::exception_entry_flag)) {
572 // Phi functions at the begin of an exception handler are
573 // implicitly defined (= killed) at the beginning of the block.
574 for_each_phi_fun(block, phi,
575 if (!phi->is_illegal()) { live_kill.set_bit(phi->operand()->vreg_number()); }
576 );
577 }
578
579 LIR_OpList* instructions = block->lir()->instructions_list();
580 int num_inst = instructions->length();
581
582 // iterate all instructions of the block. skip the first because it is always a label
583 assert(visitor.no_operands(instructions->at(0)), "first operation must always be a label");
584 for (int j = 1; j < num_inst; j++) {
585 LIR_Op* op = instructions->at(j);
586
587 // visit operation to collect all operands
588 visitor.visit(op);
589
590 if (visitor.has_call()) {
591 _has_call.set_bit(op->id() >> 1);
592 local_num_calls++;
593 }
594 if (visitor.info_count() > 0) {
595 _has_info.set_bit(op->id() >> 1);
596 }
597
598 // iterate input operands of instruction
599 int k, n, reg;
600 n = visitor.opr_count(LIR_OpVisitState::inputMode);
601 for (k = 0; k < n; k++) {
602 LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::inputMode, k);
603 assert(opr->is_register(), "visitor should only return register operands");
604
605 if (opr->is_virtual_register()) {
606 assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
607 reg = opr->vreg_number();
608 if (!live_kill.at(reg)) {
609 live_gen.set_bit(reg);
610 TRACE_LINEAR_SCAN(4, tty->print_cr(" Setting live_gen for register %d at instruction %d", reg, op->id()));
611 }
612 if (block->loop_index() >= 0) {
613 local_interval_in_loop.set_bit(reg, block->loop_index());
614 }
615 local_has_fpu_registers = local_has_fpu_registers || opr->is_virtual_fpu();
616 }
617
618 #ifdef ASSERT
619 // fixed intervals are never live at block boundaries, so
620 // they need not be processed in live sets.
621 // this is checked by these assertions to be sure about it.
622 // the entry block may have incoming values in registers, which is ok.
623 if (!opr->is_virtual_register() && block != ir()->start()) {
624 reg = reg_num(opr);
625 if (is_processed_reg_num(reg)) {
626 assert(live_kill.at(reg), "using fixed register that is not defined in this block");
627 }
628 reg = reg_numHi(opr);
629 if (is_valid_reg_num(reg) && is_processed_reg_num(reg)) {
630 assert(live_kill.at(reg), "using fixed register that is not defined in this block");
631 }
632 }
633 #endif
634 }
635
636 // Add uses of live locals from interpreter's point of view for proper debug information generation
637 n = visitor.info_count();
638 for (k = 0; k < n; k++) {
639 CodeEmitInfo* info = visitor.info_at(k);
640 ValueStack* stack = info->stack();
641 for_each_state_value(stack, value,
642 set_live_gen_kill(value, op, live_gen, live_kill);
643 local_has_fpu_registers = local_has_fpu_registers || value->type()->is_float_kind();
644 );
645 }
646
647 // iterate temp operands of instruction
648 n = visitor.opr_count(LIR_OpVisitState::tempMode);
649 for (k = 0; k < n; k++) {
650 LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::tempMode, k);
651 assert(opr->is_register(), "visitor should only return register operands");
652
653 if (opr->is_virtual_register()) {
654 assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
655 reg = opr->vreg_number();
656 live_kill.set_bit(reg);
657 if (block->loop_index() >= 0) {
658 local_interval_in_loop.set_bit(reg, block->loop_index());
659 }
660 local_has_fpu_registers = local_has_fpu_registers || opr->is_virtual_fpu();
661 }
662
663 #ifdef ASSERT
664 // fixed intervals are never live at block boundaries, so
665 // they need not be processed in live sets
666 // process them only in debug mode so that this can be checked
667 if (!opr->is_virtual_register()) {
668 reg = reg_num(opr);
669 if (is_processed_reg_num(reg)) {
670 live_kill.set_bit(reg_num(opr));
671 }
672 reg = reg_numHi(opr);
673 if (is_valid_reg_num(reg) && is_processed_reg_num(reg)) {
674 live_kill.set_bit(reg);
675 }
676 }
677 #endif
678 }
679
680 // iterate output operands of instruction
681 n = visitor.opr_count(LIR_OpVisitState::outputMode);
682 for (k = 0; k < n; k++) {
683 LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::outputMode, k);
684 assert(opr->is_register(), "visitor should only return register operands");
685
686 if (opr->is_virtual_register()) {
687 assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
688 reg = opr->vreg_number();
689 live_kill.set_bit(reg);
690 if (block->loop_index() >= 0) {
691 local_interval_in_loop.set_bit(reg, block->loop_index());
692 }
693 local_has_fpu_registers = local_has_fpu_registers || opr->is_virtual_fpu();
694 }
695
696 #ifdef ASSERT
697 // fixed intervals are never live at block boundaries, so
698 // they need not be processed in live sets
699 // process them only in debug mode so that this can be checked
700 if (!opr->is_virtual_register()) {
701 reg = reg_num(opr);
702 if (is_processed_reg_num(reg)) {
703 live_kill.set_bit(reg_num(opr));
704 }
705 reg = reg_numHi(opr);
706 if (is_valid_reg_num(reg) && is_processed_reg_num(reg)) {
707 live_kill.set_bit(reg);
708 }
709 }
710 #endif
711 }
712 } // end of instruction iteration
713
714 block->set_live_gen (live_gen);
715 block->set_live_kill(live_kill);
716 block->set_live_in (ResourceBitMap(live_size));
717 block->set_live_out (ResourceBitMap(live_size));
718
719 TRACE_LINEAR_SCAN(4, tty->print("live_gen B%d ", block->block_id()); print_bitmap(block->live_gen()));
720 TRACE_LINEAR_SCAN(4, tty->print("live_kill B%d ", block->block_id()); print_bitmap(block->live_kill()));
721 } // end of block iteration
722
723 // propagate local calculated information into LinearScan object
724 _has_fpu_registers = local_has_fpu_registers;
725 compilation()->set_has_fpu_code(local_has_fpu_registers);
726
727 _num_calls = local_num_calls;
728 _interval_in_loop = local_interval_in_loop;
729 }
730
731
732 // ********** Phase 3: perform a backward dataflow analysis to compute global live sets
733 // (sets live_in and live_out for each block)
734
735 void LinearScan::compute_global_live_sets() {
736 TIME_LINEAR_SCAN(timer_compute_global_live_sets);
737
738 int num_blocks = block_count();
739 bool change_occurred;
740 bool change_occurred_in_block;
741 int iteration_count = 0;
742 ResourceBitMap live_out(live_set_size()); // scratch set for calculations
743
744 // Perform a backward dataflow analysis to compute live_out and live_in for each block.
745 // The loop is executed until a fixpoint is reached (no changes in an iteration)
746 // Exception handlers must be processed because not all live values are
747 // present in the state array, e.g. because of global value numbering
748 do {
749 change_occurred = false;
750
751 // iterate all blocks in reverse order
752 for (int i = num_blocks - 1; i >= 0; i--) {
753 BlockBegin* block = block_at(i);
754
755 change_occurred_in_block = false;
756
757 // live_out(block) is the union of live_in(sux), for successors sux of block
758 int n = block->number_of_sux();
759 int e = block->number_of_exception_handlers();
760 if (n + e > 0) {
761 // block has successors
762 if (n > 0) {
763 live_out.set_from(block->sux_at(0)->live_in());
764 for (int j = 1; j < n; j++) {
765 live_out.set_union(block->sux_at(j)->live_in());
766 }
767 } else {
768 live_out.clear();
769 }
770 for (int j = 0; j < e; j++) {
771 live_out.set_union(block->exception_handler_at(j)->live_in());
772 }
773
774 if (!block->live_out().is_same(live_out)) {
775 // A change occurred. Swap the old and new live out sets to avoid copying.
776 ResourceBitMap temp = block->live_out();
777 block->set_live_out(live_out);
778 live_out = temp;
779
780 change_occurred = true;
781 change_occurred_in_block = true;
782 }
783 }
784
785 if (iteration_count == 0 || change_occurred_in_block) {
786 // live_in(block) is the union of live_gen(block) with (live_out(block) & !live_kill(block))
787 // note: live_in has to be computed only in first iteration or if live_out has changed!
788 ResourceBitMap live_in = block->live_in();
789 live_in.set_from(block->live_out());
790 live_in.set_difference(block->live_kill());
791 live_in.set_union(block->live_gen());
792 }
793
794 #ifdef ASSERT
795 if (TraceLinearScanLevel >= 4) {
796 char c = ' ';
797 if (iteration_count == 0 || change_occurred_in_block) {
798 c = '*';
799 }
800 tty->print("(%d) live_in%c B%d ", iteration_count, c, block->block_id()); print_bitmap(block->live_in());
801 tty->print("(%d) live_out%c B%d ", iteration_count, c, block->block_id()); print_bitmap(block->live_out());
802 }
803 #endif
804 }
805 iteration_count++;
806
807 if (change_occurred && iteration_count > 50) {
808 BAILOUT("too many iterations in compute_global_live_sets");
809 }
810 } while (change_occurred);
811
812
813 #ifdef ASSERT
814 // check that fixed intervals are not live at block boundaries
815 // (live set must be empty at fixed intervals)
816 for (int i = 0; i < num_blocks; i++) {
817 BlockBegin* block = block_at(i);
818 for (int j = 0; j < LIR_Opr::vreg_base; j++) {
819 assert(block->live_in().at(j) == false, "live_in set of fixed register must be empty");
820 assert(block->live_out().at(j) == false, "live_out set of fixed register must be empty");
821 assert(block->live_gen().at(j) == false, "live_gen set of fixed register must be empty");
822 }
823 }
824 #endif
825
826 // check that the live_in set of the first block is empty
827 ResourceBitMap live_in_args(ir()->start()->live_in().size());
828 if (!ir()->start()->live_in().is_same(live_in_args)) {
829 #ifdef ASSERT
830 tty->print_cr("Error: live_in set of first block must be empty (when this fails, virtual registers are used before they are defined)");
831 tty->print_cr("affected registers:");
832 print_bitmap(ir()->start()->live_in());
833
834 // print some additional information to simplify debugging
835 for (unsigned int i = 0; i < ir()->start()->live_in().size(); i++) {
836 if (ir()->start()->live_in().at(i)) {
837 Instruction* instr = gen()->instruction_for_vreg(i);
838 tty->print_cr("* vreg %d (HIR instruction %c%d)", i, instr == nullptr ? ' ' : instr->type()->tchar(), instr == nullptr ? 0 : instr->id());
839
840 for (int j = 0; j < num_blocks; j++) {
841 BlockBegin* block = block_at(j);
842 if (block->live_gen().at(i)) {
843 tty->print_cr(" used in block B%d", block->block_id());
844 }
845 if (block->live_kill().at(i)) {
846 tty->print_cr(" defined in block B%d", block->block_id());
847 }
848 }
849 }
850 }
851
852 #endif
853 // when this fails, virtual registers are used before they are defined.
854 assert(false, "live_in set of first block must be empty");
855 // bailout of if this occurs in product mode.
856 bailout("live_in set of first block not empty");
857 }
858 }
859
860
861 // ********** Phase 4: build intervals
862 // (fills the list _intervals)
863
864 void LinearScan::add_use(Value value, int from, int to, IntervalUseKind use_kind) {
865 assert(!value->type()->is_illegal(), "if this value is used by the interpreter it shouldn't be of indeterminate type");
866 LIR_Opr opr = value->operand();
867 Constant* con = value->as_Constant();
868
869 if ((con == nullptr || con->is_pinned()) && opr->is_register()) {
870 assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
871 add_use(opr, from, to, use_kind);
872 }
873 }
874
875
876 void LinearScan::add_def(LIR_Opr opr, int def_pos, IntervalUseKind use_kind) {
877 TRACE_LINEAR_SCAN(2, tty->print(" def "); opr->print(tty); tty->print_cr(" def_pos %d (%d)", def_pos, use_kind));
878 assert(opr->is_register(), "should not be called otherwise");
879
880 if (opr->is_virtual_register()) {
881 assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
882 add_def(opr->vreg_number(), def_pos, use_kind, opr->type_register());
883
884 } else {
885 int reg = reg_num(opr);
886 if (is_processed_reg_num(reg)) {
887 add_def(reg, def_pos, use_kind, opr->type_register());
888 }
889 reg = reg_numHi(opr);
890 if (is_valid_reg_num(reg) && is_processed_reg_num(reg)) {
891 add_def(reg, def_pos, use_kind, opr->type_register());
892 }
893 }
894 }
895
896 void LinearScan::add_use(LIR_Opr opr, int from, int to, IntervalUseKind use_kind) {
897 TRACE_LINEAR_SCAN(2, tty->print(" use "); opr->print(tty); tty->print_cr(" from %d to %d (%d)", from, to, use_kind));
898 assert(opr->is_register(), "should not be called otherwise");
899
900 if (opr->is_virtual_register()) {
901 assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
902 add_use(opr->vreg_number(), from, to, use_kind, opr->type_register());
903
904 } else {
905 int reg = reg_num(opr);
906 if (is_processed_reg_num(reg)) {
907 add_use(reg, from, to, use_kind, opr->type_register());
908 }
909 reg = reg_numHi(opr);
910 if (is_valid_reg_num(reg) && is_processed_reg_num(reg)) {
911 add_use(reg, from, to, use_kind, opr->type_register());
912 }
913 }
914 }
915
916 void LinearScan::add_temp(LIR_Opr opr, int temp_pos, IntervalUseKind use_kind) {
917 TRACE_LINEAR_SCAN(2, tty->print(" temp "); opr->print(tty); tty->print_cr(" temp_pos %d (%d)", temp_pos, use_kind));
918 assert(opr->is_register(), "should not be called otherwise");
919
920 if (opr->is_virtual_register()) {
921 assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
922 add_temp(opr->vreg_number(), temp_pos, use_kind, opr->type_register());
923
924 } else {
925 int reg = reg_num(opr);
926 if (is_processed_reg_num(reg)) {
927 add_temp(reg, temp_pos, use_kind, opr->type_register());
928 }
929 reg = reg_numHi(opr);
930 if (is_valid_reg_num(reg) && is_processed_reg_num(reg)) {
931 add_temp(reg, temp_pos, use_kind, opr->type_register());
932 }
933 }
934 }
935
936
937 void LinearScan::add_def(int reg_num, int def_pos, IntervalUseKind use_kind, BasicType type) {
938 Interval* interval = interval_at(reg_num);
939 if (interval != nullptr) {
940 assert(interval->reg_num() == reg_num, "wrong interval");
941
942 if (type != T_ILLEGAL) {
943 interval->set_type(type);
944 }
945
946 Range* r = interval->first();
947 if (r->from() <= def_pos) {
948 // Update the starting point (when a range is first created for a use, its
949 // start is the beginning of the current block until a def is encountered.)
950 r->set_from(def_pos);
951 interval->add_use_pos(def_pos, use_kind);
952
953 } else {
954 // Dead value - make vacuous interval
955 // also add use_kind for dead intervals
956 interval->add_range(def_pos, def_pos + 1);
957 interval->add_use_pos(def_pos, use_kind);
958 TRACE_LINEAR_SCAN(2, tty->print_cr("Warning: def of reg %d at %d occurs without use", reg_num, def_pos));
959 }
960
961 } else {
962 // Dead value - make vacuous interval
963 // also add use_kind for dead intervals
964 interval = create_interval(reg_num);
965 if (type != T_ILLEGAL) {
966 interval->set_type(type);
967 }
968
969 interval->add_range(def_pos, def_pos + 1);
970 interval->add_use_pos(def_pos, use_kind);
971 TRACE_LINEAR_SCAN(2, tty->print_cr("Warning: dead value %d at %d in live intervals", reg_num, def_pos));
972 }
973
974 change_spill_definition_pos(interval, def_pos);
975 if (use_kind == noUse && interval->spill_state() <= startInMemory) {
976 // detection of method-parameters and roundfp-results
977 // TODO: move this directly to position where use-kind is computed
978 interval->set_spill_state(startInMemory);
979 }
980 }
981
982 void LinearScan::add_use(int reg_num, int from, int to, IntervalUseKind use_kind, BasicType type) {
983 Interval* interval = interval_at(reg_num);
984 if (interval == nullptr) {
985 interval = create_interval(reg_num);
986 }
987 assert(interval->reg_num() == reg_num, "wrong interval");
988
989 if (type != T_ILLEGAL) {
990 interval->set_type(type);
991 }
992
993 interval->add_range(from, to);
994 interval->add_use_pos(to, use_kind);
995 }
996
997 void LinearScan::add_temp(int reg_num, int temp_pos, IntervalUseKind use_kind, BasicType type) {
998 Interval* interval = interval_at(reg_num);
999 if (interval == nullptr) {
1000 interval = create_interval(reg_num);
1001 }
1002 assert(interval->reg_num() == reg_num, "wrong interval");
1003
1004 if (type != T_ILLEGAL) {
1005 interval->set_type(type);
1006 }
1007
1008 interval->add_range(temp_pos, temp_pos + 1);
1009 interval->add_use_pos(temp_pos, use_kind);
1010 }
1011
1012
1013 // the results of this functions are used for optimizing spilling and reloading
1014 // if the functions return shouldHaveRegister and the interval is spilled,
1015 // it is not reloaded to a register.
1016 IntervalUseKind LinearScan::use_kind_of_output_operand(LIR_Op* op, LIR_Opr opr) {
1017 if (op->code() == lir_move) {
1018 assert(op->as_Op1() != nullptr, "lir_move must be LIR_Op1");
1019 LIR_Op1* move = (LIR_Op1*)op;
1020 LIR_Opr res = move->result_opr();
1021 bool result_in_memory = res->is_virtual() && gen()->is_vreg_flag_set(res->vreg_number(), LIRGenerator::must_start_in_memory);
1022
1023 if (result_in_memory) {
1024 // Begin of an interval with must_start_in_memory set.
1025 // This interval will always get a stack slot first, so return noUse.
1026 return noUse;
1027
1028 } else if (move->in_opr()->is_stack()) {
1029 // method argument (condition must be equal to handle_method_arguments)
1030 return noUse;
1031
1032 } else if (move->in_opr()->is_register() && move->result_opr()->is_register()) {
1033 // Move from register to register
1034 if (block_of_op_with_id(op->id())->is_set(BlockBegin::osr_entry_flag)) {
1035 // special handling of phi-function moves inside osr-entry blocks
1036 // input operand must have a register instead of output operand (leads to better register allocation)
1037 return shouldHaveRegister;
1038 }
1039 }
1040 }
1041
1042 if (opr->is_virtual() &&
1043 gen()->is_vreg_flag_set(opr->vreg_number(), LIRGenerator::must_start_in_memory)) {
1044 // result is a stack-slot, so prevent immediate reloading
1045 return noUse;
1046 }
1047
1048 // all other operands require a register
1049 return mustHaveRegister;
1050 }
1051
1052 IntervalUseKind LinearScan::use_kind_of_input_operand(LIR_Op* op, LIR_Opr opr) {
1053 if (op->code() == lir_move) {
1054 assert(op->as_Op1() != nullptr, "lir_move must be LIR_Op1");
1055 LIR_Op1* move = (LIR_Op1*)op;
1056 LIR_Opr res = move->result_opr();
1057 bool result_in_memory = res->is_virtual() && gen()->is_vreg_flag_set(res->vreg_number(), LIRGenerator::must_start_in_memory);
1058
1059 if (result_in_memory) {
1060 // Move to an interval with must_start_in_memory set.
1061 // To avoid moves from stack to stack (not allowed) force the input operand to a register
1062 return mustHaveRegister;
1063
1064 } else if (move->in_opr()->is_register() && move->result_opr()->is_register()) {
1065 // Move from register to register
1066 if (block_of_op_with_id(op->id())->is_set(BlockBegin::osr_entry_flag)) {
1067 // special handling of phi-function moves inside osr-entry blocks
1068 // input operand must have a register instead of output operand (leads to better register allocation)
1069 return mustHaveRegister;
1070 }
1071
1072 // The input operand is not forced to a register (moves from stack to register are allowed),
1073 // but it is faster if the input operand is in a register
1074 return shouldHaveRegister;
1075 }
1076 }
1077
1078
1079 #if defined(X86) || defined(S390)
1080 if (op->code() == lir_cmove) {
1081 // conditional moves can handle stack operands
1082 assert(op->result_opr()->is_register(), "result must always be in a register");
1083 return shouldHaveRegister;
1084 }
1085
1086 // optimizations for second input operand of arithmehtic operations on Intel
1087 // this operand is allowed to be on the stack in some cases
1088 BasicType opr_type = opr->type_register();
1089 if (opr_type == T_FLOAT || opr_type == T_DOUBLE) {
1090 // SSE float instruction
1091 switch (op->code()) {
1092 case lir_cmp:
1093 case lir_add:
1094 case lir_sub:
1095 case lir_mul:
1096 case lir_div:
1097 {
1098 assert(op->as_Op2() != nullptr, "must be LIR_Op2");
1099 LIR_Op2* op2 = (LIR_Op2*)op;
1100 if (op2->in_opr1() != op2->in_opr2() && op2->in_opr2() == opr) {
1101 assert((op2->result_opr()->is_register() || op->code() == lir_cmp) && op2->in_opr1()->is_register(), "cannot mark second operand as stack if others are not in register");
1102 return shouldHaveRegister;
1103 }
1104 }
1105 default:
1106 break;
1107 }
1108 // We want to sometimes use logical operations on pointers, in particular in GC barriers.
1109 // Since 64bit logical operations do not current support operands on stack, we have to make sure
1110 // T_OBJECT doesn't get spilled along with T_LONG.
1111 } else if (opr_type != T_LONG LP64_ONLY(&& opr_type != T_OBJECT)) {
1112 // integer instruction (note: long operands must always be in register)
1113 switch (op->code()) {
1114 case lir_cmp:
1115 case lir_add:
1116 case lir_sub:
1117 case lir_logic_and:
1118 case lir_logic_or:
1119 case lir_logic_xor:
1120 {
1121 assert(op->as_Op2() != nullptr, "must be LIR_Op2");
1122 LIR_Op2* op2 = (LIR_Op2*)op;
1123 if (op2->in_opr1() != op2->in_opr2() && op2->in_opr2() == opr) {
1124 assert((op2->result_opr()->is_register() || op->code() == lir_cmp) && op2->in_opr1()->is_register(), "cannot mark second operand as stack if others are not in register");
1125 return shouldHaveRegister;
1126 }
1127 }
1128 default:
1129 break;
1130 }
1131 }
1132 #endif // X86 || S390
1133
1134 // all other operands require a register
1135 return mustHaveRegister;
1136 }
1137
1138
1139 void LinearScan::handle_method_arguments(LIR_Op* op) {
1140 // special handling for method arguments (moves from stack to virtual register):
1141 // the interval gets no register assigned, but the stack slot.
1142 // it is split before the first use by the register allocator.
1143
1144 if (op->code() == lir_move) {
1145 assert(op->as_Op1() != nullptr, "must be LIR_Op1");
1146 LIR_Op1* move = (LIR_Op1*)op;
1147
1148 if (move->in_opr()->is_stack()) {
1149 #ifdef ASSERT
1150 int arg_size = compilation()->method()->arg_size();
1151 LIR_Opr o = move->in_opr();
1152 if (o->is_single_stack()) {
1153 assert(o->single_stack_ix() >= 0 && o->single_stack_ix() < arg_size, "out of range");
1154 } else if (o->is_double_stack()) {
1155 assert(o->double_stack_ix() >= 0 && o->double_stack_ix() < arg_size, "out of range");
1156 } else {
1157 ShouldNotReachHere();
1158 }
1159
1160 assert(move->id() > 0, "invalid id");
1161 assert(block_of_op_with_id(move->id())->number_of_preds() == 0, "move from stack must be in first block");
1162 assert(move->result_opr()->is_virtual(), "result of move must be a virtual register");
1163
1164 TRACE_LINEAR_SCAN(4, tty->print_cr("found move from stack slot %d to vreg %d", o->is_single_stack() ? o->single_stack_ix() : o->double_stack_ix(), reg_num(move->result_opr())));
1165 #endif
1166
1167 Interval* interval = interval_at(reg_num(move->result_opr()));
1168
1169 int stack_slot = LinearScan::nof_regs + (move->in_opr()->is_single_stack() ? move->in_opr()->single_stack_ix() : move->in_opr()->double_stack_ix());
1170 interval->set_canonical_spill_slot(stack_slot);
1171 interval->assign_reg(stack_slot);
1172 }
1173 }
1174 }
1175
1176 void LinearScan::handle_doubleword_moves(LIR_Op* op) {
1177 // special handling for doubleword move from memory to register:
1178 // in this case the registers of the input address and the result
1179 // registers must not overlap -> add a temp range for the input registers
1180 if (op->code() == lir_move) {
1181 assert(op->as_Op1() != nullptr, "must be LIR_Op1");
1182 LIR_Op1* move = (LIR_Op1*)op;
1183
1184 if (move->result_opr()->is_double_cpu() && move->in_opr()->is_pointer()) {
1185 LIR_Address* address = move->in_opr()->as_address_ptr();
1186 if (address != nullptr) {
1187 if (address->base()->is_valid()) {
1188 add_temp(address->base(), op->id(), noUse);
1189 }
1190 if (address->index()->is_valid()) {
1191 add_temp(address->index(), op->id(), noUse);
1192 }
1193 }
1194 }
1195 }
1196 }
1197
1198 void LinearScan::add_register_hints(LIR_Op* op) {
1199 switch (op->code()) {
1200 case lir_move: // fall through
1201 case lir_convert: {
1202 assert(op->as_Op1() != nullptr, "lir_move, lir_convert must be LIR_Op1");
1203 LIR_Op1* move = (LIR_Op1*)op;
1204
1205 LIR_Opr move_from = move->in_opr();
1206 LIR_Opr move_to = move->result_opr();
1207
1208 if (move_to->is_register() && move_from->is_register()) {
1209 Interval* from = interval_at(reg_num(move_from));
1210 Interval* to = interval_at(reg_num(move_to));
1211 if (from != nullptr && to != nullptr) {
1212 to->set_register_hint(from);
1213 TRACE_LINEAR_SCAN(4, tty->print_cr("operation at op_id %d: added hint from interval %d to %d", move->id(), from->reg_num(), to->reg_num()));
1214 }
1215 }
1216 break;
1217 }
1218 case lir_cmove: {
1219 assert(op->as_Op4() != nullptr, "lir_cmove must be LIR_Op4");
1220 LIR_Op4* cmove = (LIR_Op4*)op;
1221
1222 LIR_Opr move_from = cmove->in_opr1();
1223 LIR_Opr move_to = cmove->result_opr();
1224
1225 if (move_to->is_register() && move_from->is_register()) {
1226 Interval* from = interval_at(reg_num(move_from));
1227 Interval* to = interval_at(reg_num(move_to));
1228 if (from != nullptr && to != nullptr) {
1229 to->set_register_hint(from);
1230 TRACE_LINEAR_SCAN(4, tty->print_cr("operation at op_id %d: added hint from interval %d to %d", cmove->id(), from->reg_num(), to->reg_num()));
1231 }
1232 }
1233 break;
1234 }
1235 default:
1236 break;
1237 }
1238 }
1239
1240
1241 void LinearScan::build_intervals() {
1242 TIME_LINEAR_SCAN(timer_build_intervals);
1243
1244 // initialize interval list with expected number of intervals
1245 // (32 is added to have some space for split children without having to resize the list)
1246 _intervals = IntervalList(num_virtual_regs() + 32);
1247 // initialize all slots that are used by build_intervals
1248 _intervals.at_put_grow(num_virtual_regs() - 1, nullptr, nullptr);
1249
1250 // create a list with all caller-save registers (cpu, fpu, xmm)
1251 // when an instruction is a call, a temp range is created for all these registers
1252 int num_caller_save_registers = 0;
1253 int caller_save_registers[LinearScan::nof_regs];
1254
1255 int i;
1256 for (i = 0; i < FrameMap::nof_caller_save_cpu_regs(); i++) {
1257 LIR_Opr opr = FrameMap::caller_save_cpu_reg_at(i);
1258 assert(opr->is_valid() && opr->is_register(), "FrameMap should not return invalid operands");
1259 assert(reg_numHi(opr) == -1, "missing addition of range for hi-register");
1260 caller_save_registers[num_caller_save_registers++] = reg_num(opr);
1261 }
1262
1263 // temp ranges for fpu registers are only created when the method has
1264 // virtual fpu operands. Otherwise no allocation for fpu registers is
1265 // performed and so the temp ranges would be useless
1266 if (has_fpu_registers()) {
1267 #ifndef X86
1268 for (i = 0; i < FrameMap::nof_caller_save_fpu_regs; i++) {
1269 LIR_Opr opr = FrameMap::caller_save_fpu_reg_at(i);
1270 assert(opr->is_valid() && opr->is_register(), "FrameMap should not return invalid operands");
1271 assert(reg_numHi(opr) == -1, "missing addition of range for hi-register");
1272 caller_save_registers[num_caller_save_registers++] = reg_num(opr);
1273 }
1274 #else
1275 int num_caller_save_xmm_regs = FrameMap::get_num_caller_save_xmms();
1276 for (i = 0; i < num_caller_save_xmm_regs; i ++) {
1277 LIR_Opr opr = FrameMap::caller_save_xmm_reg_at(i);
1278 assert(opr->is_valid() && opr->is_register(), "FrameMap should not return invalid operands");
1279 assert(reg_numHi(opr) == -1, "missing addition of range for hi-register");
1280 caller_save_registers[num_caller_save_registers++] = reg_num(opr);
1281 }
1282 #endif // X86
1283 }
1284 assert(num_caller_save_registers <= LinearScan::nof_regs, "out of bounds");
1285
1286
1287 LIR_OpVisitState visitor;
1288
1289 // iterate all blocks in reverse order
1290 for (i = block_count() - 1; i >= 0; i--) {
1291 BlockBegin* block = block_at(i);
1292 LIR_OpList* instructions = block->lir()->instructions_list();
1293 int block_from = block->first_lir_instruction_id();
1294 int block_to = block->last_lir_instruction_id();
1295
1296 assert(block_from == instructions->at(0)->id(), "must be");
1297 assert(block_to == instructions->at(instructions->length() - 1)->id(), "must be");
1298
1299 // Update intervals for registers live at the end of this block;
1300 ResourceBitMap& live = block->live_out();
1301 auto updater = [&](BitMap::idx_t index) {
1302 int number = static_cast<int>(index);
1303 assert(number >= LIR_Opr::vreg_base, "fixed intervals must not be live on block bounds");
1304 TRACE_LINEAR_SCAN(2, tty->print_cr("live in %d to %d", number, block_to + 2));
1305
1306 add_use(number, block_from, block_to + 2, noUse, T_ILLEGAL);
1307
1308 // add special use positions for loop-end blocks when the
1309 // interval is used anywhere inside this loop. It's possible
1310 // that the block was part of a non-natural loop, so it might
1311 // have an invalid loop index.
1312 if (block->is_set(BlockBegin::linear_scan_loop_end_flag) &&
1313 block->loop_index() != -1 &&
1314 is_interval_in_loop(number, block->loop_index())) {
1315 interval_at(number)->add_use_pos(block_to + 1, loopEndMarker);
1316 }
1317 };
1318 live.iterate(updater);
1319
1320 // iterate all instructions of the block in reverse order.
1321 // skip the first instruction because it is always a label
1322 // definitions of intervals are processed before uses
1323 assert(visitor.no_operands(instructions->at(0)), "first operation must always be a label");
1324 for (int j = instructions->length() - 1; j >= 1; j--) {
1325 LIR_Op* op = instructions->at(j);
1326 int op_id = op->id();
1327
1328 // visit operation to collect all operands
1329 visitor.visit(op);
1330
1331 // add a temp range for each register if operation destroys caller-save registers
1332 if (visitor.has_call()) {
1333 for (int k = 0; k < num_caller_save_registers; k++) {
1334 add_temp(caller_save_registers[k], op_id, noUse, T_ILLEGAL);
1335 }
1336 TRACE_LINEAR_SCAN(4, tty->print_cr("operation destroys all caller-save registers"));
1337 }
1338
1339 // Add any platform dependent temps
1340 pd_add_temps(op);
1341
1342 // visit definitions (output and temp operands)
1343 int k, n;
1344 n = visitor.opr_count(LIR_OpVisitState::outputMode);
1345 for (k = 0; k < n; k++) {
1346 LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::outputMode, k);
1347 assert(opr->is_register(), "visitor should only return register operands");
1348 add_def(opr, op_id, use_kind_of_output_operand(op, opr));
1349 }
1350
1351 n = visitor.opr_count(LIR_OpVisitState::tempMode);
1352 for (k = 0; k < n; k++) {
1353 LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::tempMode, k);
1354 assert(opr->is_register(), "visitor should only return register operands");
1355 add_temp(opr, op_id, mustHaveRegister);
1356 }
1357
1358 // visit uses (input operands)
1359 n = visitor.opr_count(LIR_OpVisitState::inputMode);
1360 for (k = 0; k < n; k++) {
1361 LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::inputMode, k);
1362 assert(opr->is_register(), "visitor should only return register operands");
1363 add_use(opr, block_from, op_id, use_kind_of_input_operand(op, opr));
1364 }
1365
1366 // Add uses of live locals from interpreter's point of view for proper
1367 // debug information generation
1368 // Treat these operands as temp values (if the life range is extended
1369 // to a call site, the value would be in a register at the call otherwise)
1370 n = visitor.info_count();
1371 for (k = 0; k < n; k++) {
1372 CodeEmitInfo* info = visitor.info_at(k);
1373 ValueStack* stack = info->stack();
1374 for_each_state_value(stack, value,
1375 add_use(value, block_from, op_id + 1, noUse);
1376 );
1377 }
1378
1379 // special steps for some instructions (especially moves)
1380 handle_method_arguments(op);
1381 handle_doubleword_moves(op);
1382 add_register_hints(op);
1383
1384 } // end of instruction iteration
1385 } // end of block iteration
1386
1387
1388 // add the range [0, 1[ to all fixed intervals
1389 // -> the register allocator need not handle unhandled fixed intervals
1390 for (int n = 0; n < LinearScan::nof_regs; n++) {
1391 Interval* interval = interval_at(n);
1392 if (interval != nullptr) {
1393 interval->add_range(0, 1);
1394 }
1395 }
1396 }
1397
1398
1399 // ********** Phase 5: actual register allocation
1400
1401 int LinearScan::interval_cmp(Interval** a, Interval** b) {
1402 if (*a != nullptr) {
1403 if (*b != nullptr) {
1404 return (*a)->from() - (*b)->from();
1405 } else {
1406 return -1;
1407 }
1408 } else {
1409 if (*b != nullptr) {
1410 return 1;
1411 } else {
1412 return 0;
1413 }
1414 }
1415 }
1416
1417 #ifdef ASSERT
1418 static int interval_cmp(Interval* const& l, Interval* const& r) {
1419 return l->from() - r->from();
1420 }
1421
1422 static bool find_interval(Interval* interval, IntervalArray* intervals) {
1423 bool found;
1424 int idx = intervals->find_sorted<Interval*, interval_cmp>(interval, found);
1425
1426 if (!found) {
1427 return false;
1428 }
1429
1430 int from = interval->from();
1431
1432 // The index we've found using binary search is pointing to an interval
1433 // that is defined in the same place as the interval we were looking for.
1434 // So now we have to look around that index and find exact interval.
1435 for (int i = idx; i >= 0; i--) {
1436 if (intervals->at(i) == interval) {
1437 return true;
1438 }
1439 if (intervals->at(i)->from() != from) {
1440 break;
1441 }
1442 }
1443
1444 for (int i = idx + 1; i < intervals->length(); i++) {
1445 if (intervals->at(i) == interval) {
1446 return true;
1447 }
1448 if (intervals->at(i)->from() != from) {
1449 break;
1450 }
1451 }
1452
1453 return false;
1454 }
1455
1456 bool LinearScan::is_sorted(IntervalArray* intervals) {
1457 int from = -1;
1458 int null_count = 0;
1459
1460 for (int i = 0; i < intervals->length(); i++) {
1461 Interval* it = intervals->at(i);
1462 if (it != nullptr) {
1463 assert(from <= it->from(), "Intervals are unordered");
1464 from = it->from();
1465 } else {
1466 null_count++;
1467 }
1468 }
1469
1470 assert(null_count == 0, "Sorted intervals should not contain nulls");
1471
1472 null_count = 0;
1473
1474 for (int i = 0; i < interval_count(); i++) {
1475 Interval* interval = interval_at(i);
1476 if (interval != nullptr) {
1477 assert(find_interval(interval, intervals), "Lists do not contain same intervals");
1478 } else {
1479 null_count++;
1480 }
1481 }
1482
1483 assert(interval_count() - null_count == intervals->length(),
1484 "Sorted list should contain the same amount of non-null intervals as unsorted list");
1485
1486 return true;
1487 }
1488 #endif
1489
1490 void LinearScan::add_to_list(Interval** first, Interval** prev, Interval* interval) {
1491 if (*prev != nullptr) {
1492 (*prev)->set_next(interval);
1493 } else {
1494 *first = interval;
1495 }
1496 *prev = interval;
1497 }
1498
1499 void LinearScan::create_unhandled_lists(Interval** list1, Interval** list2, bool (is_list1)(const Interval* i), bool (is_list2)(const Interval* i)) {
1500 assert(is_sorted(_sorted_intervals), "interval list is not sorted");
1501
1502 *list1 = *list2 = Interval::end();
1503
1504 Interval* list1_prev = nullptr;
1505 Interval* list2_prev = nullptr;
1506 Interval* v;
1507
1508 const int n = _sorted_intervals->length();
1509 for (int i = 0; i < n; i++) {
1510 v = _sorted_intervals->at(i);
1511 if (v == nullptr) continue;
1512
1513 if (is_list1(v)) {
1514 add_to_list(list1, &list1_prev, v);
1515 } else if (is_list2 == nullptr || is_list2(v)) {
1516 add_to_list(list2, &list2_prev, v);
1517 }
1518 }
1519
1520 if (list1_prev != nullptr) list1_prev->set_next(Interval::end());
1521 if (list2_prev != nullptr) list2_prev->set_next(Interval::end());
1522
1523 assert(list1_prev == nullptr || list1_prev->next() == Interval::end(), "linear list ends not with sentinel");
1524 assert(list2_prev == nullptr || list2_prev->next() == Interval::end(), "linear list ends not with sentinel");
1525 }
1526
1527
1528 void LinearScan::sort_intervals_before_allocation() {
1529 TIME_LINEAR_SCAN(timer_sort_intervals_before);
1530
1531 if (_needs_full_resort) {
1532 // There is no known reason why this should occur but just in case...
1533 assert(false, "should never occur");
1534 // Re-sort existing interval list because an Interval::from() has changed
1535 _sorted_intervals->sort(interval_cmp);
1536 _needs_full_resort = false;
1537 }
1538
1539 IntervalList* unsorted_list = &_intervals;
1540 int unsorted_len = unsorted_list->length();
1541 int sorted_len = 0;
1542 int unsorted_idx;
1543 int sorted_idx = 0;
1544 int sorted_from_max = -1;
1545
1546 // calc number of items for sorted list (sorted list must not contain null values)
1547 for (unsorted_idx = 0; unsorted_idx < unsorted_len; unsorted_idx++) {
1548 if (unsorted_list->at(unsorted_idx) != nullptr) {
1549 sorted_len++;
1550 }
1551 }
1552 IntervalArray* sorted_list = new IntervalArray(sorted_len, sorted_len, nullptr);
1553
1554 // special sorting algorithm: the original interval-list is almost sorted,
1555 // only some intervals are swapped. So this is much faster than a complete QuickSort
1556 for (unsorted_idx = 0; unsorted_idx < unsorted_len; unsorted_idx++) {
1557 Interval* cur_interval = unsorted_list->at(unsorted_idx);
1558
1559 if (cur_interval != nullptr) {
1560 int cur_from = cur_interval->from();
1561
1562 if (sorted_from_max <= cur_from) {
1563 sorted_list->at_put(sorted_idx++, cur_interval);
1564 sorted_from_max = cur_interval->from();
1565 } else {
1566 // the assumption that the intervals are already sorted failed,
1567 // so this interval must be sorted in manually
1568 int j;
1569 for (j = sorted_idx - 1; j >= 0 && cur_from < sorted_list->at(j)->from(); j--) {
1570 sorted_list->at_put(j + 1, sorted_list->at(j));
1571 }
1572 sorted_list->at_put(j + 1, cur_interval);
1573 sorted_idx++;
1574 }
1575 }
1576 }
1577 _sorted_intervals = sorted_list;
1578 assert(is_sorted(_sorted_intervals), "intervals unsorted");
1579 }
1580
1581 void LinearScan::sort_intervals_after_allocation() {
1582 TIME_LINEAR_SCAN(timer_sort_intervals_after);
1583
1584 if (_needs_full_resort) {
1585 // Re-sort existing interval list because an Interval::from() has changed
1586 _sorted_intervals->sort(interval_cmp);
1587 _needs_full_resort = false;
1588 }
1589
1590 IntervalArray* old_list = _sorted_intervals;
1591 IntervalList* new_list = _new_intervals_from_allocation;
1592 int old_len = old_list->length();
1593 int new_len = new_list == nullptr ? 0 : new_list->length();
1594
1595 if (new_len == 0) {
1596 // no intervals have been added during allocation, so sorted list is already up to date
1597 assert(is_sorted(_sorted_intervals), "intervals unsorted");
1598 return;
1599 }
1600
1601 // conventional sort-algorithm for new intervals
1602 new_list->sort(interval_cmp);
1603
1604 // merge old and new list (both already sorted) into one combined list
1605 int combined_list_len = old_len + new_len;
1606 IntervalArray* combined_list = new IntervalArray(combined_list_len, combined_list_len, nullptr);
1607 int old_idx = 0;
1608 int new_idx = 0;
1609
1610 while (old_idx + new_idx < old_len + new_len) {
1611 if (new_idx >= new_len || (old_idx < old_len && old_list->at(old_idx)->from() <= new_list->at(new_idx)->from())) {
1612 combined_list->at_put(old_idx + new_idx, old_list->at(old_idx));
1613 old_idx++;
1614 } else {
1615 combined_list->at_put(old_idx + new_idx, new_list->at(new_idx));
1616 new_idx++;
1617 }
1618 }
1619
1620 _sorted_intervals = combined_list;
1621 assert(is_sorted(_sorted_intervals), "intervals unsorted");
1622 }
1623
1624
1625 void LinearScan::allocate_registers() {
1626 TIME_LINEAR_SCAN(timer_allocate_registers);
1627
1628 Interval* precolored_cpu_intervals, *not_precolored_cpu_intervals;
1629 Interval* precolored_fpu_intervals, *not_precolored_fpu_intervals;
1630
1631 // collect cpu intervals
1632 create_unhandled_lists(&precolored_cpu_intervals, ¬_precolored_cpu_intervals,
1633 is_precolored_cpu_interval, is_virtual_cpu_interval);
1634
1635 // collect fpu intervals
1636 create_unhandled_lists(&precolored_fpu_intervals, ¬_precolored_fpu_intervals,
1637 is_precolored_fpu_interval, is_virtual_fpu_interval);
1638 // this fpu interval collection cannot be moved down below with the allocation section as
1639 // the cpu_lsw.walk() changes interval positions.
1640
1641 if (!has_fpu_registers()) {
1642 #ifdef ASSERT
1643 assert(not_precolored_fpu_intervals == Interval::end(), "missed an uncolored fpu interval");
1644 #else
1645 if (not_precolored_fpu_intervals != Interval::end()) {
1646 BAILOUT("missed an uncolored fpu interval");
1647 }
1648 #endif
1649 }
1650
1651 // allocate cpu registers
1652 LinearScanWalker cpu_lsw(this, precolored_cpu_intervals, not_precolored_cpu_intervals);
1653 cpu_lsw.walk();
1654 cpu_lsw.finish_allocation();
1655
1656 if (has_fpu_registers()) {
1657 // allocate fpu registers
1658 LinearScanWalker fpu_lsw(this, precolored_fpu_intervals, not_precolored_fpu_intervals);
1659 fpu_lsw.walk();
1660 fpu_lsw.finish_allocation();
1661 }
1662 }
1663
1664
1665 // ********** Phase 6: resolve data flow
1666 // (insert moves at edges between blocks if intervals have been split)
1667
1668 // wrapper for Interval::split_child_at_op_id that performs a bailout in product mode
1669 // instead of returning null
1670 Interval* LinearScan::split_child_at_op_id(Interval* interval, int op_id, LIR_OpVisitState::OprMode mode) {
1671 Interval* result = interval->split_child_at_op_id(op_id, mode);
1672 if (result != nullptr) {
1673 return result;
1674 }
1675
1676 assert(false, "must find an interval, but do a clean bailout in product mode");
1677 result = new Interval(LIR_Opr::vreg_base);
1678 result->assign_reg(0);
1679 result->set_type(T_INT);
1680 BAILOUT_("LinearScan: interval is null", result);
1681 }
1682
1683
1684 Interval* LinearScan::interval_at_block_begin(BlockBegin* block, int reg_num) {
1685 assert(LinearScan::nof_regs <= reg_num && reg_num < num_virtual_regs(), "register number out of bounds");
1686 assert(interval_at(reg_num) != nullptr, "no interval found");
1687
1688 return split_child_at_op_id(interval_at(reg_num), block->first_lir_instruction_id(), LIR_OpVisitState::outputMode);
1689 }
1690
1691 Interval* LinearScan::interval_at_block_end(BlockBegin* block, int reg_num) {
1692 assert(LinearScan::nof_regs <= reg_num && reg_num < num_virtual_regs(), "register number out of bounds");
1693 assert(interval_at(reg_num) != nullptr, "no interval found");
1694
1695 return split_child_at_op_id(interval_at(reg_num), block->last_lir_instruction_id() + 1, LIR_OpVisitState::outputMode);
1696 }
1697
1698 Interval* LinearScan::interval_at_op_id(int reg_num, int op_id) {
1699 assert(LinearScan::nof_regs <= reg_num && reg_num < num_virtual_regs(), "register number out of bounds");
1700 assert(interval_at(reg_num) != nullptr, "no interval found");
1701
1702 return split_child_at_op_id(interval_at(reg_num), op_id, LIR_OpVisitState::inputMode);
1703 }
1704
1705
1706 void LinearScan::resolve_collect_mappings(BlockBegin* from_block, BlockBegin* to_block, MoveResolver &move_resolver) {
1707 DEBUG_ONLY(move_resolver.check_empty());
1708
1709 // visit all registers where the live_at_edge bit is set
1710 const ResourceBitMap& live_at_edge = to_block->live_in();
1711 auto visitor = [&](BitMap::idx_t index) {
1712 int r = static_cast<int>(index);
1713 assert(r < num_virtual_regs(), "live information set for not existing interval");
1714 assert(from_block->live_out().at(r) && to_block->live_in().at(r), "interval not live at this edge");
1715
1716 Interval* from_interval = interval_at_block_end(from_block, r);
1717 Interval* to_interval = interval_at_block_begin(to_block, r);
1718
1719 if (from_interval != to_interval && (from_interval->assigned_reg() != to_interval->assigned_reg() || from_interval->assigned_regHi() != to_interval->assigned_regHi())) {
1720 // need to insert move instruction
1721 move_resolver.add_mapping(from_interval, to_interval);
1722 }
1723 };
1724 live_at_edge.iterate(visitor, 0, live_set_size());
1725 }
1726
1727
1728 void LinearScan::resolve_find_insert_pos(BlockBegin* from_block, BlockBegin* to_block, MoveResolver &move_resolver) {
1729 if (from_block->number_of_sux() <= 1) {
1730 TRACE_LINEAR_SCAN(4, tty->print_cr("inserting moves at end of from_block B%d", from_block->block_id()));
1731
1732 LIR_OpList* instructions = from_block->lir()->instructions_list();
1733 LIR_OpBranch* branch = instructions->last()->as_OpBranch();
1734 if (branch != nullptr) {
1735 // insert moves before branch
1736 assert(branch->cond() == lir_cond_always, "block does not end with an unconditional jump");
1737 move_resolver.set_insert_position(from_block->lir(), instructions->length() - 2);
1738 } else {
1739 move_resolver.set_insert_position(from_block->lir(), instructions->length() - 1);
1740 }
1741
1742 } else {
1743 TRACE_LINEAR_SCAN(4, tty->print_cr("inserting moves at beginning of to_block B%d", to_block->block_id()));
1744 #ifdef ASSERT
1745 assert(from_block->lir()->instructions_list()->at(0)->as_OpLabel() != nullptr, "block does not start with a label");
1746
1747 // because the number of predecessor edges matches the number of
1748 // successor edges, blocks which are reached by switch statements
1749 // may have be more than one predecessor but it will be guaranteed
1750 // that all predecessors will be the same.
1751 for (int i = 0; i < to_block->number_of_preds(); i++) {
1752 assert(from_block == to_block->pred_at(i), "all critical edges must be broken");
1753 }
1754 #endif
1755
1756 move_resolver.set_insert_position(to_block->lir(), 0);
1757 }
1758 }
1759
1760
1761 // insert necessary moves (spilling or reloading) at edges between blocks if interval has been split
1762 void LinearScan::resolve_data_flow() {
1763 TIME_LINEAR_SCAN(timer_resolve_data_flow);
1764
1765 int num_blocks = block_count();
1766 MoveResolver move_resolver(this);
1767 ResourceBitMap block_completed(num_blocks);
1768 ResourceBitMap already_resolved(num_blocks);
1769
1770 int i;
1771 for (i = 0; i < num_blocks; i++) {
1772 BlockBegin* block = block_at(i);
1773
1774 // check if block has only one predecessor and only one successor
1775 if (block->number_of_preds() == 1 && block->number_of_sux() == 1 && block->number_of_exception_handlers() == 0) {
1776 LIR_OpList* instructions = block->lir()->instructions_list();
1777 assert(instructions->at(0)->code() == lir_label, "block must start with label");
1778 assert(instructions->last()->code() == lir_branch, "block with successors must end with branch");
1779 assert(instructions->last()->as_OpBranch()->cond() == lir_cond_always, "block with successor must end with unconditional branch");
1780
1781 // check if block is empty (only label and branch)
1782 if (instructions->length() == 2) {
1783 BlockBegin* pred = block->pred_at(0);
1784 BlockBegin* sux = block->sux_at(0);
1785
1786 // prevent optimization of two consecutive blocks
1787 if (!block_completed.at(pred->linear_scan_number()) && !block_completed.at(sux->linear_scan_number())) {
1788 TRACE_LINEAR_SCAN(3, tty->print_cr("**** optimizing empty block B%d (pred: B%d, sux: B%d)", block->block_id(), pred->block_id(), sux->block_id()));
1789 block_completed.set_bit(block->linear_scan_number());
1790
1791 // directly resolve between pred and sux (without looking at the empty block between)
1792 resolve_collect_mappings(pred, sux, move_resolver);
1793 if (move_resolver.has_mappings()) {
1794 move_resolver.set_insert_position(block->lir(), 0);
1795 move_resolver.resolve_and_append_moves();
1796 }
1797 }
1798 }
1799 }
1800 }
1801
1802
1803 for (i = 0; i < num_blocks; i++) {
1804 if (!block_completed.at(i)) {
1805 BlockBegin* from_block = block_at(i);
1806 already_resolved.set_from(block_completed);
1807
1808 int num_sux = from_block->number_of_sux();
1809 for (int s = 0; s < num_sux; s++) {
1810 BlockBegin* to_block = from_block->sux_at(s);
1811
1812 // check for duplicate edges between the same blocks (can happen with switch blocks)
1813 if (!already_resolved.at(to_block->linear_scan_number())) {
1814 TRACE_LINEAR_SCAN(3, tty->print_cr("**** processing edge between B%d and B%d", from_block->block_id(), to_block->block_id()));
1815 already_resolved.set_bit(to_block->linear_scan_number());
1816
1817 // collect all intervals that have been split between from_block and to_block
1818 resolve_collect_mappings(from_block, to_block, move_resolver);
1819 if (move_resolver.has_mappings()) {
1820 resolve_find_insert_pos(from_block, to_block, move_resolver);
1821 move_resolver.resolve_and_append_moves();
1822 }
1823 }
1824 }
1825 }
1826 }
1827 }
1828
1829
1830 void LinearScan::resolve_exception_entry(BlockBegin* block, int reg_num, MoveResolver &move_resolver) {
1831 if (interval_at(reg_num) == nullptr) {
1832 // if a phi function is never used, no interval is created -> ignore this
1833 return;
1834 }
1835
1836 Interval* interval = interval_at_block_begin(block, reg_num);
1837 int reg = interval->assigned_reg();
1838 int regHi = interval->assigned_regHi();
1839
1840 if ((reg < nof_regs && interval->always_in_memory())) {
1841 // the interval is split to get a short range that is located on the stack
1842 // in the following case:
1843 // * the interval started in memory (e.g. method parameter), but is currently in a register
1844 // this is an optimization for exception handling that reduces the number of moves that
1845 // are necessary for resolving the states when an exception uses this exception handler
1846
1847 // range that will be spilled to memory
1848 int from_op_id = block->first_lir_instruction_id();
1849 int to_op_id = from_op_id + 1; // short live range of length 1
1850 assert(interval->from() <= from_op_id && interval->to() >= to_op_id,
1851 "no split allowed between exception entry and first instruction");
1852
1853 if (interval->from() != from_op_id) {
1854 // the part before from_op_id is unchanged
1855 interval = interval->split(from_op_id);
1856 interval->assign_reg(reg, regHi);
1857 append_interval(interval);
1858 } else {
1859 _needs_full_resort = true;
1860 }
1861 assert(interval->from() == from_op_id, "must be true now");
1862
1863 Interval* spilled_part = interval;
1864 if (interval->to() != to_op_id) {
1865 // the part after to_op_id is unchanged
1866 spilled_part = interval->split_from_start(to_op_id);
1867 append_interval(spilled_part);
1868 move_resolver.add_mapping(spilled_part, interval);
1869 }
1870 assign_spill_slot(spilled_part);
1871
1872 assert(spilled_part->from() == from_op_id && spilled_part->to() == to_op_id, "just checking");
1873 }
1874 }
1875
1876 void LinearScan::resolve_exception_entry(BlockBegin* block, MoveResolver &move_resolver) {
1877 assert(block->is_set(BlockBegin::exception_entry_flag), "should not call otherwise");
1878 DEBUG_ONLY(move_resolver.check_empty());
1879
1880 // visit all registers where the live_in bit is set
1881 auto resolver = [&](BitMap::idx_t index) {
1882 int r = static_cast<int>(index);
1883 resolve_exception_entry(block, r, move_resolver);
1884 };
1885 block->live_in().iterate(resolver, 0, live_set_size());
1886
1887 // the live_in bits are not set for phi functions of the xhandler entry, so iterate them separately
1888 for_each_phi_fun(block, phi,
1889 if (!phi->is_illegal()) { resolve_exception_entry(block, phi->operand()->vreg_number(), move_resolver); }
1890 );
1891
1892 if (move_resolver.has_mappings()) {
1893 // insert moves after first instruction
1894 move_resolver.set_insert_position(block->lir(), 0);
1895 move_resolver.resolve_and_append_moves();
1896 }
1897 }
1898
1899
1900 void LinearScan::resolve_exception_edge(XHandler* handler, int throwing_op_id, int reg_num, Phi* phi, MoveResolver &move_resolver) {
1901 if (interval_at(reg_num) == nullptr) {
1902 // if a phi function is never used, no interval is created -> ignore this
1903 return;
1904 }
1905
1906 // the computation of to_interval is equal to resolve_collect_mappings,
1907 // but from_interval is more complicated because of phi functions
1908 BlockBegin* to_block = handler->entry_block();
1909 Interval* to_interval = interval_at_block_begin(to_block, reg_num);
1910
1911 if (phi != nullptr) {
1912 // phi function of the exception entry block
1913 // no moves are created for this phi function in the LIR_Generator, so the
1914 // interval at the throwing instruction must be searched using the operands
1915 // of the phi function
1916 Value from_value = phi->operand_at(handler->phi_operand());
1917 if (from_value == nullptr) {
1918 // We have reached here in a kotlin application running with JVMTI
1919 // capability "can_access_local_variables".
1920 // The illegal state is not yet propagated to this phi. Do it here.
1921 phi->make_illegal();
1922 // We can skip the illegal phi edge.
1923 return;
1924 }
1925
1926 // with phi functions it can happen that the same from_value is used in
1927 // multiple mappings, so notify move-resolver that this is allowed
1928 move_resolver.set_multiple_reads_allowed();
1929
1930 Constant* con = from_value->as_Constant();
1931 if (con != nullptr && (!con->is_pinned() || con->operand()->is_constant())) {
1932 // Need a mapping from constant to interval if unpinned (may have no register) or if the operand is a constant (no register).
1933 move_resolver.add_mapping(LIR_OprFact::value_type(con->type()), to_interval);
1934 } else {
1935 // search split child at the throwing op_id
1936 Interval* from_interval = interval_at_op_id(from_value->operand()->vreg_number(), throwing_op_id);
1937 move_resolver.add_mapping(from_interval, to_interval);
1938 }
1939 } else {
1940 // no phi function, so use reg_num also for from_interval
1941 // search split child at the throwing op_id
1942 Interval* from_interval = interval_at_op_id(reg_num, throwing_op_id);
1943 if (from_interval != to_interval) {
1944 // optimization to reduce number of moves: when to_interval is on stack and
1945 // the stack slot is known to be always correct, then no move is necessary
1946 if (!from_interval->always_in_memory() || from_interval->canonical_spill_slot() != to_interval->assigned_reg()) {
1947 move_resolver.add_mapping(from_interval, to_interval);
1948 }
1949 }
1950 }
1951 }
1952
1953 void LinearScan::resolve_exception_edge(XHandler* handler, int throwing_op_id, MoveResolver &move_resolver) {
1954 TRACE_LINEAR_SCAN(4, tty->print_cr("resolving exception handler B%d: throwing_op_id=%d", handler->entry_block()->block_id(), throwing_op_id));
1955
1956 DEBUG_ONLY(move_resolver.check_empty());
1957 assert(handler->lir_op_id() == -1, "already processed this xhandler");
1958 DEBUG_ONLY(handler->set_lir_op_id(throwing_op_id));
1959 assert(handler->entry_code() == nullptr, "code already present");
1960
1961 // visit all registers where the live_in bit is set
1962 BlockBegin* block = handler->entry_block();
1963 auto resolver = [&](BitMap::idx_t index) {
1964 int r = static_cast<int>(index);
1965 resolve_exception_edge(handler, throwing_op_id, r, nullptr, move_resolver);
1966 };
1967 block->live_in().iterate(resolver, 0, live_set_size());
1968
1969 // the live_in bits are not set for phi functions of the xhandler entry, so iterate them separately
1970 for_each_phi_fun(block, phi,
1971 if (!phi->is_illegal()) { resolve_exception_edge(handler, throwing_op_id, phi->operand()->vreg_number(), phi, move_resolver); }
1972 );
1973
1974 if (move_resolver.has_mappings()) {
1975 LIR_List* entry_code = new LIR_List(compilation());
1976 move_resolver.set_insert_position(entry_code, 0);
1977 move_resolver.resolve_and_append_moves();
1978
1979 entry_code->jump(handler->entry_block());
1980 handler->set_entry_code(entry_code);
1981 }
1982 }
1983
1984
1985 void LinearScan::resolve_exception_handlers() {
1986 MoveResolver move_resolver(this);
1987 LIR_OpVisitState visitor;
1988 int num_blocks = block_count();
1989
1990 int i;
1991 for (i = 0; i < num_blocks; i++) {
1992 BlockBegin* block = block_at(i);
1993 if (block->is_set(BlockBegin::exception_entry_flag)) {
1994 resolve_exception_entry(block, move_resolver);
1995 }
1996 }
1997
1998 for (i = 0; i < num_blocks; i++) {
1999 BlockBegin* block = block_at(i);
2000 LIR_List* ops = block->lir();
2001 int num_ops = ops->length();
2002
2003 // iterate all instructions of the block. skip the first because it is always a label
2004 assert(visitor.no_operands(ops->at(0)), "first operation must always be a label");
2005 for (int j = 1; j < num_ops; j++) {
2006 LIR_Op* op = ops->at(j);
2007 int op_id = op->id();
2008
2009 if (op_id != -1 && has_info(op_id)) {
2010 // visit operation to collect all operands
2011 visitor.visit(op);
2012 assert(visitor.info_count() > 0, "should not visit otherwise");
2013
2014 XHandlers* xhandlers = visitor.all_xhandler();
2015 int n = xhandlers->length();
2016 for (int k = 0; k < n; k++) {
2017 resolve_exception_edge(xhandlers->handler_at(k), op_id, move_resolver);
2018 }
2019
2020 #ifdef ASSERT
2021 } else {
2022 visitor.visit(op);
2023 assert(visitor.all_xhandler()->length() == 0, "missed exception handler");
2024 #endif
2025 }
2026 }
2027 }
2028 }
2029
2030
2031 // ********** Phase 7: assign register numbers back to LIR
2032 // (includes computation of debug information and oop maps)
2033
2034 VMReg LinearScan::vm_reg_for_interval(Interval* interval) {
2035 VMReg reg = interval->cached_vm_reg();
2036 if (!reg->is_valid() ) {
2037 reg = vm_reg_for_operand(operand_for_interval(interval));
2038 interval->set_cached_vm_reg(reg);
2039 }
2040 assert(reg == vm_reg_for_operand(operand_for_interval(interval)), "wrong cached value");
2041 return reg;
2042 }
2043
2044 VMReg LinearScan::vm_reg_for_operand(LIR_Opr opr) {
2045 assert(opr->is_oop(), "currently only implemented for oop operands");
2046 return frame_map()->regname(opr);
2047 }
2048
2049
2050 LIR_Opr LinearScan::operand_for_interval(Interval* interval) {
2051 LIR_Opr opr = interval->cached_opr();
2052 if (opr->is_illegal()) {
2053 opr = calc_operand_for_interval(interval);
2054 interval->set_cached_opr(opr);
2055 }
2056
2057 assert(opr == calc_operand_for_interval(interval), "wrong cached value");
2058 return opr;
2059 }
2060
2061 LIR_Opr LinearScan::calc_operand_for_interval(const Interval* interval) {
2062 int assigned_reg = interval->assigned_reg();
2063 BasicType type = interval->type();
2064
2065 if (assigned_reg >= nof_regs) {
2066 // stack slot
2067 assert(interval->assigned_regHi() == any_reg, "must not have hi register");
2068 return LIR_OprFact::stack(assigned_reg - nof_regs, type);
2069
2070 } else {
2071 // register
2072 switch (type) {
2073 case T_OBJECT: {
2074 assert(assigned_reg >= pd_first_cpu_reg && assigned_reg <= pd_last_cpu_reg, "no cpu register");
2075 assert(interval->assigned_regHi() == any_reg, "must not have hi register");
2076 return LIR_OprFact::single_cpu_oop(assigned_reg);
2077 }
2078
2079 case T_ADDRESS: {
2080 assert(assigned_reg >= pd_first_cpu_reg && assigned_reg <= pd_last_cpu_reg, "no cpu register");
2081 assert(interval->assigned_regHi() == any_reg, "must not have hi register");
2082 return LIR_OprFact::single_cpu_address(assigned_reg);
2083 }
2084
2085 case T_METADATA: {
2086 assert(assigned_reg >= pd_first_cpu_reg && assigned_reg <= pd_last_cpu_reg, "no cpu register");
2087 assert(interval->assigned_regHi() == any_reg, "must not have hi register");
2088 return LIR_OprFact::single_cpu_metadata(assigned_reg);
2089 }
2090
2091 #ifdef __SOFTFP__
2092 case T_FLOAT: // fall through
2093 #endif // __SOFTFP__
2094 case T_INT: {
2095 assert(assigned_reg >= pd_first_cpu_reg && assigned_reg <= pd_last_cpu_reg, "no cpu register");
2096 assert(interval->assigned_regHi() == any_reg, "must not have hi register");
2097 return LIR_OprFact::single_cpu(assigned_reg);
2098 }
2099
2100 #ifdef __SOFTFP__
2101 case T_DOUBLE: // fall through
2102 #endif // __SOFTFP__
2103 case T_LONG: {
2104 int assigned_regHi = interval->assigned_regHi();
2105 assert(assigned_reg >= pd_first_cpu_reg && assigned_reg <= pd_last_cpu_reg, "no cpu register");
2106 assert(num_physical_regs(T_LONG) == 1 ||
2107 (assigned_regHi >= pd_first_cpu_reg && assigned_regHi <= pd_last_cpu_reg), "no cpu register");
2108
2109 assert(assigned_reg != assigned_regHi, "invalid allocation");
2110 assert(num_physical_regs(T_LONG) == 1 || assigned_reg < assigned_regHi,
2111 "register numbers must be sorted (ensure that e.g. a move from eax,ebx to ebx,eax can not occur)");
2112 assert((assigned_regHi != any_reg) ^ (num_physical_regs(T_LONG) == 1), "must be match");
2113 if (requires_adjacent_regs(T_LONG)) {
2114 assert(assigned_reg % 2 == 0 && assigned_reg + 1 == assigned_regHi, "must be sequential and even");
2115 }
2116
2117 #ifdef _LP64
2118 return LIR_OprFact::double_cpu(assigned_reg, assigned_reg);
2119 #else
2120 return LIR_OprFact::double_cpu(assigned_reg, assigned_regHi);
2121 #endif // LP64
2122 }
2123
2124 #ifndef __SOFTFP__
2125 case T_FLOAT: {
2126 #ifdef X86
2127 int last_xmm_reg = pd_last_xmm_reg;
2128 if (UseAVX < 3) {
2129 last_xmm_reg = pd_first_xmm_reg + (pd_nof_xmm_regs_frame_map / 2) - 1;
2130 }
2131 assert(assigned_reg >= pd_first_xmm_reg && assigned_reg <= last_xmm_reg, "no xmm register");
2132 assert(interval->assigned_regHi() == any_reg, "must not have hi register");
2133 return LIR_OprFact::single_xmm(assigned_reg - pd_first_xmm_reg);
2134 #else
2135 assert(assigned_reg >= pd_first_fpu_reg && assigned_reg <= pd_last_fpu_reg, "no fpu register");
2136 assert(interval->assigned_regHi() == any_reg, "must not have hi register");
2137 return LIR_OprFact::single_fpu(assigned_reg - pd_first_fpu_reg);
2138 #endif // !X86
2139 }
2140
2141 case T_DOUBLE: {
2142 #if defined(X86)
2143 int last_xmm_reg = pd_last_xmm_reg;
2144 if (UseAVX < 3) {
2145 last_xmm_reg = pd_first_xmm_reg + (pd_nof_xmm_regs_frame_map / 2) - 1;
2146 }
2147 assert(assigned_reg >= pd_first_xmm_reg && assigned_reg <= last_xmm_reg, "no xmm register");
2148 assert(interval->assigned_regHi() == any_reg, "must not have hi register (double xmm values are stored in one register)");
2149 LIR_Opr result = LIR_OprFact::double_xmm(assigned_reg - pd_first_xmm_reg);
2150 #elif defined(ARM32)
2151 assert(assigned_reg >= pd_first_fpu_reg && assigned_reg <= pd_last_fpu_reg, "no fpu register");
2152 assert(interval->assigned_regHi() >= pd_first_fpu_reg && interval->assigned_regHi() <= pd_last_fpu_reg, "no fpu register");
2153 assert(assigned_reg % 2 == 0 && assigned_reg + 1 == interval->assigned_regHi(), "must be sequential and even");
2154 LIR_Opr result = LIR_OprFact::double_fpu(assigned_reg - pd_first_fpu_reg, interval->assigned_regHi() - pd_first_fpu_reg);
2155 #else
2156 assert(assigned_reg >= pd_first_fpu_reg && assigned_reg <= pd_last_fpu_reg, "no fpu register");
2157 assert(interval->assigned_regHi() == any_reg, "must not have hi register (double fpu values are stored in one register on Intel)");
2158 LIR_Opr result = LIR_OprFact::double_fpu(assigned_reg - pd_first_fpu_reg);
2159 #endif
2160 return result;
2161 }
2162 #endif // __SOFTFP__
2163
2164 default: {
2165 ShouldNotReachHere();
2166 return LIR_OprFact::illegalOpr;
2167 }
2168 }
2169 }
2170 }
2171
2172 LIR_Opr LinearScan::canonical_spill_opr(Interval* interval) {
2173 assert(interval->canonical_spill_slot() >= nof_regs, "canonical spill slot not set");
2174 return LIR_OprFact::stack(interval->canonical_spill_slot() - nof_regs, interval->type());
2175 }
2176
2177 LIR_Opr LinearScan::color_lir_opr(LIR_Opr opr, int op_id, LIR_OpVisitState::OprMode mode) {
2178 assert(opr->is_virtual(), "should not call this otherwise");
2179
2180 Interval* interval = interval_at(opr->vreg_number());
2181 assert(interval != nullptr, "interval must exist");
2182
2183 if (op_id != -1) {
2184 #ifdef ASSERT
2185 BlockBegin* block = block_of_op_with_id(op_id);
2186 if (block->number_of_sux() <= 1 && op_id == block->last_lir_instruction_id()) {
2187 // check if spill moves could have been appended at the end of this block, but
2188 // before the branch instruction. So the split child information for this branch would
2189 // be incorrect.
2190 LIR_OpBranch* branch = block->lir()->instructions_list()->last()->as_OpBranch();
2191 if (branch != nullptr) {
2192 if (block->live_out().at(opr->vreg_number())) {
2193 assert(branch->cond() == lir_cond_always, "block does not end with an unconditional jump");
2194 assert(false, "can't get split child for the last branch of a block because the information would be incorrect (moves are inserted before the branch in resolve_data_flow)");
2195 }
2196 }
2197 }
2198 #endif
2199
2200 // operands are not changed when an interval is split during allocation,
2201 // so search the right interval here
2202 interval = split_child_at_op_id(interval, op_id, mode);
2203 }
2204
2205 LIR_Opr res = operand_for_interval(interval);
2206
2207 #ifdef X86
2208 // new semantic for is_last_use: not only set on definite end of interval,
2209 // but also before hole
2210 // This may still miss some cases (e.g. for dead values), but it is not necessary that the
2211 // last use information is completely correct
2212 // information is only needed for fpu stack allocation
2213 if (res->is_fpu_register()) {
2214 if (opr->is_last_use() || op_id == interval->to() || (op_id != -1 && interval->has_hole_between(op_id, op_id + 1))) {
2215 assert(op_id == -1 || !is_block_begin(op_id), "holes at begin of block may also result from control flow");
2216 res = res->make_last_use();
2217 }
2218 }
2219 #endif
2220
2221 assert(!gen()->is_vreg_flag_set(opr->vreg_number(), LIRGenerator::callee_saved) || !FrameMap::is_caller_save_register(res), "bad allocation");
2222
2223 return res;
2224 }
2225
2226
2227 #ifdef ASSERT
2228 // some methods used to check correctness of debug information
2229
2230 void assert_no_register_values(GrowableArray<ScopeValue*>* values) {
2231 if (values == nullptr) {
2232 return;
2233 }
2234
2235 for (int i = 0; i < values->length(); i++) {
2236 ScopeValue* value = values->at(i);
2237
2238 if (value->is_location()) {
2239 Location location = ((LocationValue*)value)->location();
2240 assert(location.where() == Location::on_stack, "value is in register");
2241 }
2242 }
2243 }
2244
2245 void assert_no_register_values(GrowableArray<MonitorValue*>* values) {
2246 if (values == nullptr) {
2247 return;
2248 }
2249
2250 for (int i = 0; i < values->length(); i++) {
2251 MonitorValue* value = values->at(i);
2252
2253 if (value->owner()->is_location()) {
2254 Location location = ((LocationValue*)value->owner())->location();
2255 assert(location.where() == Location::on_stack, "owner is in register");
2256 }
2257 assert(value->basic_lock().where() == Location::on_stack, "basic_lock is in register");
2258 }
2259 }
2260
2261 static void assert_equal(Location l1, Location l2) {
2262 assert(l1.where() == l2.where() && l1.type() == l2.type() && l1.offset() == l2.offset(), "");
2263 }
2264
2265 static void assert_equal(ScopeValue* v1, ScopeValue* v2) {
2266 if (v1->is_location()) {
2267 assert(v2->is_location(), "");
2268 assert_equal(((LocationValue*)v1)->location(), ((LocationValue*)v2)->location());
2269 } else if (v1->is_constant_int()) {
2270 assert(v2->is_constant_int(), "");
2271 assert(((ConstantIntValue*)v1)->value() == ((ConstantIntValue*)v2)->value(), "");
2272 } else if (v1->is_constant_double()) {
2273 assert(v2->is_constant_double(), "");
2274 assert(((ConstantDoubleValue*)v1)->value() == ((ConstantDoubleValue*)v2)->value(), "");
2275 } else if (v1->is_constant_long()) {
2276 assert(v2->is_constant_long(), "");
2277 assert(((ConstantLongValue*)v1)->value() == ((ConstantLongValue*)v2)->value(), "");
2278 } else if (v1->is_constant_oop()) {
2279 assert(v2->is_constant_oop(), "");
2280 assert(((ConstantOopWriteValue*)v1)->value() == ((ConstantOopWriteValue*)v2)->value(), "");
2281 } else {
2282 ShouldNotReachHere();
2283 }
2284 }
2285
2286 static void assert_equal(MonitorValue* m1, MonitorValue* m2) {
2287 assert_equal(m1->owner(), m2->owner());
2288 assert_equal(m1->basic_lock(), m2->basic_lock());
2289 }
2290
2291 static void assert_equal(IRScopeDebugInfo* d1, IRScopeDebugInfo* d2) {
2292 assert(d1->scope() == d2->scope(), "not equal");
2293 assert(d1->bci() == d2->bci(), "not equal");
2294
2295 if (d1->locals() != nullptr) {
2296 assert(d1->locals() != nullptr && d2->locals() != nullptr, "not equal");
2297 assert(d1->locals()->length() == d2->locals()->length(), "not equal");
2298 for (int i = 0; i < d1->locals()->length(); i++) {
2299 assert_equal(d1->locals()->at(i), d2->locals()->at(i));
2300 }
2301 } else {
2302 assert(d1->locals() == nullptr && d2->locals() == nullptr, "not equal");
2303 }
2304
2305 if (d1->expressions() != nullptr) {
2306 assert(d1->expressions() != nullptr && d2->expressions() != nullptr, "not equal");
2307 assert(d1->expressions()->length() == d2->expressions()->length(), "not equal");
2308 for (int i = 0; i < d1->expressions()->length(); i++) {
2309 assert_equal(d1->expressions()->at(i), d2->expressions()->at(i));
2310 }
2311 } else {
2312 assert(d1->expressions() == nullptr && d2->expressions() == nullptr, "not equal");
2313 }
2314
2315 if (d1->monitors() != nullptr) {
2316 assert(d1->monitors() != nullptr && d2->monitors() != nullptr, "not equal");
2317 assert(d1->monitors()->length() == d2->monitors()->length(), "not equal");
2318 for (int i = 0; i < d1->monitors()->length(); i++) {
2319 assert_equal(d1->monitors()->at(i), d2->monitors()->at(i));
2320 }
2321 } else {
2322 assert(d1->monitors() == nullptr && d2->monitors() == nullptr, "not equal");
2323 }
2324
2325 if (d1->caller() != nullptr) {
2326 assert(d1->caller() != nullptr && d2->caller() != nullptr, "not equal");
2327 assert_equal(d1->caller(), d2->caller());
2328 } else {
2329 assert(d1->caller() == nullptr && d2->caller() == nullptr, "not equal");
2330 }
2331 }
2332
2333 static void check_stack_depth(CodeEmitInfo* info, int stack_end) {
2334 if (info->stack()->bci() != SynchronizationEntryBCI && !info->scope()->method()->is_native()) {
2335 Bytecodes::Code code = info->scope()->method()->java_code_at_bci(info->stack()->bci());
2336 switch (code) {
2337 case Bytecodes::_ifnull : // fall through
2338 case Bytecodes::_ifnonnull : // fall through
2339 case Bytecodes::_ifeq : // fall through
2340 case Bytecodes::_ifne : // fall through
2341 case Bytecodes::_iflt : // fall through
2342 case Bytecodes::_ifge : // fall through
2343 case Bytecodes::_ifgt : // fall through
2344 case Bytecodes::_ifle : // fall through
2345 case Bytecodes::_if_icmpeq : // fall through
2346 case Bytecodes::_if_icmpne : // fall through
2347 case Bytecodes::_if_icmplt : // fall through
2348 case Bytecodes::_if_icmpge : // fall through
2349 case Bytecodes::_if_icmpgt : // fall through
2350 case Bytecodes::_if_icmple : // fall through
2351 case Bytecodes::_if_acmpeq : // fall through
2352 case Bytecodes::_if_acmpne :
2353 assert(stack_end >= -Bytecodes::depth(code), "must have non-empty expression stack at if bytecode");
2354 break;
2355 default:
2356 break;
2357 }
2358 }
2359 }
2360
2361 #endif // ASSERT
2362
2363
2364 IntervalWalker* LinearScan::init_compute_oop_maps() {
2365 // setup lists of potential oops for walking
2366 Interval* oop_intervals;
2367 Interval* non_oop_intervals;
2368
2369 create_unhandled_lists(&oop_intervals, &non_oop_intervals, is_oop_interval, nullptr);
2370
2371 // intervals that have no oops inside need not to be processed
2372 // to ensure a walking until the last instruction id, add a dummy interval
2373 // with a high operation id
2374 non_oop_intervals = new Interval(any_reg);
2375 non_oop_intervals->add_range(max_jint - 2, max_jint - 1);
2376
2377 return new IntervalWalker(this, oop_intervals, non_oop_intervals);
2378 }
2379
2380
2381 OopMap* LinearScan::compute_oop_map(IntervalWalker* iw, LIR_Op* op, CodeEmitInfo* info, bool is_call_site) {
2382 TRACE_LINEAR_SCAN(3, tty->print_cr("creating oop map at op_id %d", op->id()));
2383
2384 // walk before the current operation -> intervals that start at
2385 // the operation (= output operands of the operation) are not
2386 // included in the oop map
2387 iw->walk_before(op->id());
2388
2389 int frame_size = frame_map()->framesize();
2390 int arg_count = frame_map()->oop_map_arg_count();
2391 OopMap* map = new OopMap(frame_size, arg_count);
2392
2393 // Iterate through active intervals
2394 for (Interval* interval = iw->active_first(fixedKind); interval != Interval::end(); interval = interval->next()) {
2395 int assigned_reg = interval->assigned_reg();
2396
2397 assert(interval->current_from() <= op->id() && op->id() <= interval->current_to(), "interval should not be active otherwise");
2398 assert(interval->assigned_regHi() == any_reg, "oop must be single word");
2399 assert(interval->reg_num() >= LIR_Opr::vreg_base, "fixed interval found");
2400
2401 // Check if this range covers the instruction. Intervals that
2402 // start or end at the current operation are not included in the
2403 // oop map, except in the case of patching moves. For patching
2404 // moves, any intervals which end at this instruction are included
2405 // in the oop map since we may safepoint while doing the patch
2406 // before we've consumed the inputs.
2407 if (op->is_patching() || op->id() < interval->current_to()) {
2408
2409 // caller-save registers must not be included into oop-maps at calls
2410 assert(!is_call_site || assigned_reg >= nof_regs || !is_caller_save(assigned_reg), "interval is in a caller-save register at a call -> register will be overwritten");
2411
2412 VMReg name = vm_reg_for_interval(interval);
2413 set_oop(map, name);
2414
2415 // Spill optimization: when the stack value is guaranteed to be always correct,
2416 // then it must be added to the oop map even if the interval is currently in a register
2417 if (interval->always_in_memory() &&
2418 op->id() > interval->spill_definition_pos() &&
2419 interval->assigned_reg() != interval->canonical_spill_slot()) {
2420 assert(interval->spill_definition_pos() > 0, "position not set correctly");
2421 assert(interval->canonical_spill_slot() >= LinearScan::nof_regs, "no spill slot assigned");
2422 assert(interval->assigned_reg() < LinearScan::nof_regs, "interval is on stack, so stack slot is registered twice");
2423
2424 set_oop(map, frame_map()->slot_regname(interval->canonical_spill_slot() - LinearScan::nof_regs));
2425 }
2426 }
2427 }
2428
2429 // add oops from lock stack
2430 assert(info->stack() != nullptr, "CodeEmitInfo must always have a stack");
2431 int locks_count = info->stack()->total_locks_size();
2432 for (int i = 0; i < locks_count; i++) {
2433 set_oop(map, frame_map()->monitor_object_regname(i));
2434 }
2435
2436 return map;
2437 }
2438
2439
2440 void LinearScan::compute_oop_map(IntervalWalker* iw, const LIR_OpVisitState &visitor, LIR_Op* op) {
2441 assert(visitor.info_count() > 0, "no oop map needed");
2442
2443 // compute oop_map only for first CodeEmitInfo
2444 // because it is (in most cases) equal for all other infos of the same operation
2445 CodeEmitInfo* first_info = visitor.info_at(0);
2446 OopMap* first_oop_map = compute_oop_map(iw, op, first_info, visitor.has_call());
2447
2448 for (int i = 0; i < visitor.info_count(); i++) {
2449 CodeEmitInfo* info = visitor.info_at(i);
2450 OopMap* oop_map = first_oop_map;
2451
2452 // compute worst case interpreter size in case of a deoptimization
2453 _compilation->update_interpreter_frame_size(info->interpreter_frame_size());
2454
2455 if (info->stack()->locks_size() != first_info->stack()->locks_size()) {
2456 // this info has a different number of locks then the precomputed oop map
2457 // (possible for lock and unlock instructions) -> compute oop map with
2458 // correct lock information
2459 oop_map = compute_oop_map(iw, op, info, visitor.has_call());
2460 }
2461
2462 if (info->_oop_map == nullptr) {
2463 info->_oop_map = oop_map;
2464 } else {
2465 // a CodeEmitInfo can not be shared between different LIR-instructions
2466 // because interval splitting can occur anywhere between two instructions
2467 // and so the oop maps must be different
2468 // -> check if the already set oop_map is exactly the one calculated for this operation
2469 assert(info->_oop_map == oop_map, "same CodeEmitInfo used for multiple LIR instructions");
2470 }
2471 }
2472 }
2473
2474
2475 // frequently used constants
2476 // Allocate them with new so they are never destroyed (otherwise, a
2477 // forced exit could destroy these objects while they are still in
2478 // use).
2479 ConstantOopWriteValue* LinearScan::_oop_null_scope_value = new (mtCompiler) ConstantOopWriteValue(nullptr);
2480 ConstantIntValue* LinearScan::_int_m1_scope_value = new (mtCompiler) ConstantIntValue(-1);
2481 ConstantIntValue* LinearScan::_int_0_scope_value = new (mtCompiler) ConstantIntValue((jint)0);
2482 ConstantIntValue* LinearScan::_int_1_scope_value = new (mtCompiler) ConstantIntValue(1);
2483 ConstantIntValue* LinearScan::_int_2_scope_value = new (mtCompiler) ConstantIntValue(2);
2484 LocationValue* _illegal_value = new (mtCompiler) LocationValue(Location());
2485
2486 void LinearScan::init_compute_debug_info() {
2487 // cache for frequently used scope values
2488 // (cpu registers and stack slots)
2489 int cache_size = (LinearScan::nof_cpu_regs + frame_map()->argcount() + max_spills()) * 2;
2490 _scope_value_cache = ScopeValueArray(cache_size, cache_size, nullptr);
2491 }
2492
2493 MonitorValue* LinearScan::location_for_monitor_index(int monitor_index) {
2494 Location loc;
2495 if (!frame_map()->location_for_monitor_object(monitor_index, &loc)) {
2496 bailout("too large frame");
2497 }
2498 ScopeValue* object_scope_value = new LocationValue(loc);
2499
2500 if (!frame_map()->location_for_monitor_lock(monitor_index, &loc)) {
2501 bailout("too large frame");
2502 }
2503 return new MonitorValue(object_scope_value, loc);
2504 }
2505
2506 LocationValue* LinearScan::location_for_name(int name, Location::Type loc_type) {
2507 Location loc;
2508 if (!frame_map()->locations_for_slot(name, loc_type, &loc)) {
2509 bailout("too large frame");
2510 }
2511 return new LocationValue(loc);
2512 }
2513
2514
2515 int LinearScan::append_scope_value_for_constant(LIR_Opr opr, GrowableArray<ScopeValue*>* scope_values) {
2516 assert(opr->is_constant(), "should not be called otherwise");
2517
2518 LIR_Const* c = opr->as_constant_ptr();
2519 BasicType t = c->type();
2520 switch (t) {
2521 case T_OBJECT: {
2522 jobject value = c->as_jobject();
2523 if (value == nullptr) {
2524 scope_values->append(_oop_null_scope_value);
2525 } else {
2526 scope_values->append(new ConstantOopWriteValue(c->as_jobject()));
2527 }
2528 return 1;
2529 }
2530
2531 case T_INT: // fall through
2532 case T_FLOAT: {
2533 int value = c->as_jint_bits();
2534 switch (value) {
2535 case -1: scope_values->append(_int_m1_scope_value); break;
2536 case 0: scope_values->append(_int_0_scope_value); break;
2537 case 1: scope_values->append(_int_1_scope_value); break;
2538 case 2: scope_values->append(_int_2_scope_value); break;
2539 default: scope_values->append(new ConstantIntValue(c->as_jint_bits())); break;
2540 }
2541 return 1;
2542 }
2543
2544 case T_LONG: // fall through
2545 case T_DOUBLE: {
2546 #ifdef _LP64
2547 scope_values->append(_int_0_scope_value);
2548 scope_values->append(new ConstantLongValue(c->as_jlong_bits()));
2549 #else
2550 if (hi_word_offset_in_bytes > lo_word_offset_in_bytes) {
2551 scope_values->append(new ConstantIntValue(c->as_jint_hi_bits()));
2552 scope_values->append(new ConstantIntValue(c->as_jint_lo_bits()));
2553 } else {
2554 scope_values->append(new ConstantIntValue(c->as_jint_lo_bits()));
2555 scope_values->append(new ConstantIntValue(c->as_jint_hi_bits()));
2556 }
2557 #endif
2558 return 2;
2559 }
2560
2561 case T_ADDRESS: {
2562 #ifdef _LP64
2563 scope_values->append(new ConstantLongValue(c->as_jint()));
2564 #else
2565 scope_values->append(new ConstantIntValue(c->as_jint()));
2566 #endif
2567 return 1;
2568 }
2569
2570 default:
2571 ShouldNotReachHere();
2572 return -1;
2573 }
2574 }
2575
2576 int LinearScan::append_scope_value_for_operand(LIR_Opr opr, GrowableArray<ScopeValue*>* scope_values) {
2577 if (opr->is_single_stack()) {
2578 int stack_idx = opr->single_stack_ix();
2579 bool is_oop = opr->is_oop_register();
2580 int cache_idx = (stack_idx + LinearScan::nof_cpu_regs) * 2 + (is_oop ? 1 : 0);
2581
2582 ScopeValue* sv = _scope_value_cache.at(cache_idx);
2583 if (sv == nullptr) {
2584 Location::Type loc_type = is_oop ? Location::oop : Location::normal;
2585 sv = location_for_name(stack_idx, loc_type);
2586 _scope_value_cache.at_put(cache_idx, sv);
2587 }
2588
2589 // check if cached value is correct
2590 DEBUG_ONLY(assert_equal(sv, location_for_name(stack_idx, is_oop ? Location::oop : Location::normal)));
2591
2592 scope_values->append(sv);
2593 return 1;
2594
2595 } else if (opr->is_single_cpu()) {
2596 bool is_oop = opr->is_oop_register();
2597 int cache_idx = opr->cpu_regnr() * 2 + (is_oop ? 1 : 0);
2598 Location::Type int_loc_type = NOT_LP64(Location::normal) LP64_ONLY(Location::int_in_long);
2599
2600 ScopeValue* sv = _scope_value_cache.at(cache_idx);
2601 if (sv == nullptr) {
2602 Location::Type loc_type = is_oop ? Location::oop : int_loc_type;
2603 VMReg rname = frame_map()->regname(opr);
2604 sv = new LocationValue(Location::new_reg_loc(loc_type, rname));
2605 _scope_value_cache.at_put(cache_idx, sv);
2606 }
2607
2608 // check if cached value is correct
2609 DEBUG_ONLY(assert_equal(sv, new LocationValue(Location::new_reg_loc(is_oop ? Location::oop : int_loc_type, frame_map()->regname(opr)))));
2610
2611 scope_values->append(sv);
2612 return 1;
2613
2614 #ifdef X86
2615 } else if (opr->is_single_xmm()) {
2616 VMReg rname = opr->as_xmm_float_reg()->as_VMReg();
2617 LocationValue* sv = new LocationValue(Location::new_reg_loc(Location::normal, rname));
2618
2619 scope_values->append(sv);
2620 return 1;
2621 #endif
2622
2623 } else if (opr->is_single_fpu()) {
2624 #if defined(AMD64)
2625 assert(false, "FPU not used on x86-64");
2626 #endif
2627 Location::Type loc_type = float_saved_as_double ? Location::float_in_dbl : Location::normal;
2628 VMReg rname = frame_map()->fpu_regname(opr->fpu_regnr());
2629 #ifndef __SOFTFP__
2630 #ifndef VM_LITTLE_ENDIAN
2631 // On S390 a (single precision) float value occupies only the high
2632 // word of the full double register. So when the double register is
2633 // stored to memory (e.g. by the RegisterSaver), then the float value
2634 // is found at offset 0. I.e. the code below is not needed on S390.
2635 #ifndef S390
2636 if (! float_saved_as_double) {
2637 // On big endian system, we may have an issue if float registers use only
2638 // the low half of the (same) double registers.
2639 // Both the float and the double could have the same regnr but would correspond
2640 // to two different addresses once saved.
2641
2642 // get next safely (no assertion checks)
2643 VMReg next = VMRegImpl::as_VMReg(1+rname->value());
2644 if (next->is_reg() &&
2645 (next->as_FloatRegister() == rname->as_FloatRegister())) {
2646 // the back-end does use the same numbering for the double and the float
2647 rname = next; // VMReg for the low bits, e.g. the real VMReg for the float
2648 }
2649 }
2650 #endif // !S390
2651 #endif
2652 #endif
2653 LocationValue* sv = new LocationValue(Location::new_reg_loc(loc_type, rname));
2654
2655 scope_values->append(sv);
2656 return 1;
2657
2658 } else {
2659 // double-size operands
2660
2661 ScopeValue* first;
2662 ScopeValue* second;
2663
2664 if (opr->is_double_stack()) {
2665 #ifdef _LP64
2666 Location loc1;
2667 Location::Type loc_type = opr->type() == T_LONG ? Location::lng : Location::dbl;
2668 if (!frame_map()->locations_for_slot(opr->double_stack_ix(), loc_type, &loc1, nullptr)) {
2669 bailout("too large frame");
2670 }
2671
2672 first = new LocationValue(loc1);
2673 second = _int_0_scope_value;
2674 #else
2675 Location loc1, loc2;
2676 if (!frame_map()->locations_for_slot(opr->double_stack_ix(), Location::normal, &loc1, &loc2)) {
2677 bailout("too large frame");
2678 }
2679 first = new LocationValue(loc1);
2680 second = new LocationValue(loc2);
2681 #endif // _LP64
2682
2683 } else if (opr->is_double_cpu()) {
2684 #ifdef _LP64
2685 VMReg rname_first = opr->as_register_lo()->as_VMReg();
2686 first = new LocationValue(Location::new_reg_loc(Location::lng, rname_first));
2687 second = _int_0_scope_value;
2688 #else
2689 VMReg rname_first = opr->as_register_lo()->as_VMReg();
2690 VMReg rname_second = opr->as_register_hi()->as_VMReg();
2691
2692 if (hi_word_offset_in_bytes < lo_word_offset_in_bytes) {
2693 // lo/hi and swapped relative to first and second, so swap them
2694 VMReg tmp = rname_first;
2695 rname_first = rname_second;
2696 rname_second = tmp;
2697 }
2698
2699 first = new LocationValue(Location::new_reg_loc(Location::normal, rname_first));
2700 second = new LocationValue(Location::new_reg_loc(Location::normal, rname_second));
2701 #endif //_LP64
2702
2703
2704 #ifdef X86
2705 } else if (opr->is_double_xmm()) {
2706 assert(opr->fpu_regnrLo() == opr->fpu_regnrHi(), "assumed in calculation");
2707 VMReg rname_first = opr->as_xmm_double_reg()->as_VMReg();
2708 # ifdef _LP64
2709 first = new LocationValue(Location::new_reg_loc(Location::dbl, rname_first));
2710 second = _int_0_scope_value;
2711 # else
2712 first = new LocationValue(Location::new_reg_loc(Location::normal, rname_first));
2713 // %%% This is probably a waste but we'll keep things as they were for now
2714 if (true) {
2715 VMReg rname_second = rname_first->next();
2716 second = new LocationValue(Location::new_reg_loc(Location::normal, rname_second));
2717 }
2718 # endif
2719 #endif
2720
2721 } else if (opr->is_double_fpu()) {
2722 // On SPARC, fpu_regnrLo/fpu_regnrHi represents the two halves of
2723 // the double as float registers in the native ordering. On X86,
2724 // fpu_regnrLo is a FPU stack slot whose VMReg represents
2725 // the low-order word of the double and fpu_regnrLo + 1 is the
2726 // name for the other half. *first and *second must represent the
2727 // least and most significant words, respectively.
2728
2729 #ifdef AMD64
2730 assert(false, "FPU not used on x86-64");
2731 #endif
2732 #ifdef ARM32
2733 assert(opr->fpu_regnrHi() == opr->fpu_regnrLo() + 1, "assumed in calculation (only fpu_regnrLo is used)");
2734 #endif
2735
2736 #ifdef VM_LITTLE_ENDIAN
2737 VMReg rname_first = frame_map()->fpu_regname(opr->fpu_regnrLo());
2738 #else
2739 VMReg rname_first = frame_map()->fpu_regname(opr->fpu_regnrHi());
2740 #endif
2741
2742 #ifdef _LP64
2743 first = new LocationValue(Location::new_reg_loc(Location::dbl, rname_first));
2744 second = _int_0_scope_value;
2745 #else
2746 first = new LocationValue(Location::new_reg_loc(Location::normal, rname_first));
2747 // %%% This is probably a waste but we'll keep things as they were for now
2748 if (true) {
2749 VMReg rname_second = rname_first->next();
2750 second = new LocationValue(Location::new_reg_loc(Location::normal, rname_second));
2751 }
2752 #endif
2753
2754 } else {
2755 ShouldNotReachHere();
2756 first = nullptr;
2757 second = nullptr;
2758 }
2759
2760 assert(first != nullptr && second != nullptr, "must be set");
2761 // The convention the interpreter uses is that the second local
2762 // holds the first raw word of the native double representation.
2763 // This is actually reasonable, since locals and stack arrays
2764 // grow downwards in all implementations.
2765 // (If, on some machine, the interpreter's Java locals or stack
2766 // were to grow upwards, the embedded doubles would be word-swapped.)
2767 scope_values->append(second);
2768 scope_values->append(first);
2769 return 2;
2770 }
2771 }
2772
2773
2774 int LinearScan::append_scope_value(int op_id, Value value, GrowableArray<ScopeValue*>* scope_values) {
2775 if (value != nullptr) {
2776 LIR_Opr opr = value->operand();
2777 Constant* con = value->as_Constant();
2778
2779 assert(con == nullptr || opr->is_virtual() || opr->is_constant() || opr->is_illegal(), "assumption: Constant instructions have only constant operands (or illegal if constant is optimized away)");
2780 assert(con != nullptr || opr->is_virtual(), "assumption: non-Constant instructions have only virtual operands");
2781
2782 if (con != nullptr && !con->is_pinned() && !opr->is_constant()) {
2783 // Unpinned constants may have a virtual operand for a part of the lifetime
2784 // or may be illegal when it was optimized away,
2785 // so always use a constant operand
2786 opr = LIR_OprFact::value_type(con->type());
2787 }
2788 assert(opr->is_virtual() || opr->is_constant(), "other cases not allowed here");
2789
2790 if (opr->is_virtual()) {
2791 LIR_OpVisitState::OprMode mode = LIR_OpVisitState::inputMode;
2792
2793 BlockBegin* block = block_of_op_with_id(op_id);
2794 if (block->number_of_sux() == 1 && op_id == block->last_lir_instruction_id()) {
2795 // generating debug information for the last instruction of a block.
2796 // if this instruction is a branch, spill moves are inserted before this branch
2797 // and so the wrong operand would be returned (spill moves at block boundaries are not
2798 // considered in the live ranges of intervals)
2799 // Solution: use the first op_id of the branch target block instead.
2800 if (block->lir()->instructions_list()->last()->as_OpBranch() != nullptr) {
2801 if (block->live_out().at(opr->vreg_number())) {
2802 op_id = block->sux_at(0)->first_lir_instruction_id();
2803 mode = LIR_OpVisitState::outputMode;
2804 }
2805 }
2806 }
2807
2808 // Get current location of operand
2809 // The operand must be live because debug information is considered when building the intervals
2810 // if the interval is not live, color_lir_opr will cause an assertion failure
2811 opr = color_lir_opr(opr, op_id, mode);
2812 assert(!has_call(op_id) || opr->is_stack() || !is_caller_save(reg_num(opr)), "can not have caller-save register operands at calls");
2813
2814 // Append to ScopeValue array
2815 return append_scope_value_for_operand(opr, scope_values);
2816
2817 } else {
2818 assert(value->as_Constant() != nullptr, "all other instructions have only virtual operands");
2819 assert(opr->is_constant(), "operand must be constant");
2820
2821 return append_scope_value_for_constant(opr, scope_values);
2822 }
2823 } else {
2824 // append a dummy value because real value not needed
2825 scope_values->append(_illegal_value);
2826 return 1;
2827 }
2828 }
2829
2830
2831 IRScopeDebugInfo* LinearScan::compute_debug_info_for_scope(int op_id, IRScope* cur_scope, ValueStack* cur_state, ValueStack* innermost_state) {
2832 IRScopeDebugInfo* caller_debug_info = nullptr;
2833
2834 ValueStack* caller_state = cur_state->caller_state();
2835 if (caller_state != nullptr) {
2836 // process recursively to compute outermost scope first
2837 caller_debug_info = compute_debug_info_for_scope(op_id, cur_scope->caller(), caller_state, innermost_state);
2838 }
2839
2840 // initialize these to null.
2841 // If we don't need deopt info or there are no locals, expressions or monitors,
2842 // then these get recorded as no information and avoids the allocation of 0 length arrays.
2843 GrowableArray<ScopeValue*>* locals = nullptr;
2844 GrowableArray<ScopeValue*>* expressions = nullptr;
2845 GrowableArray<MonitorValue*>* monitors = nullptr;
2846
2847 // describe local variable values
2848 int nof_locals = cur_state->locals_size();
2849 if (nof_locals > 0) {
2850 locals = new GrowableArray<ScopeValue*>(nof_locals);
2851
2852 int pos = 0;
2853 while (pos < nof_locals) {
2854 assert(pos < cur_state->locals_size(), "why not?");
2855
2856 Value local = cur_state->local_at(pos);
2857 pos += append_scope_value(op_id, local, locals);
2858
2859 assert(locals->length() == pos, "must match");
2860 }
2861 assert(locals->length() == nof_locals, "wrong number of locals");
2862 }
2863 assert(nof_locals == cur_scope->method()->max_locals(), "wrong number of locals");
2864 assert(nof_locals == cur_state->locals_size(), "wrong number of locals");
2865
2866 // describe expression stack
2867 int nof_stack = cur_state->stack_size();
2868 if (nof_stack > 0) {
2869 expressions = new GrowableArray<ScopeValue*>(nof_stack);
2870
2871 int pos = 0;
2872 while (pos < nof_stack) {
2873 Value expression = cur_state->stack_at(pos);
2874 pos += append_scope_value(op_id, expression, expressions);
2875
2876 assert(expressions->length() == pos, "must match");
2877 }
2878 assert(expressions->length() == cur_state->stack_size(), "wrong number of stack entries");
2879 }
2880
2881 // describe monitors
2882 int nof_locks = cur_state->locks_size();
2883 if (nof_locks > 0) {
2884 int lock_offset = cur_state->caller_state() != nullptr ? cur_state->caller_state()->total_locks_size() : 0;
2885 monitors = new GrowableArray<MonitorValue*>(nof_locks);
2886 for (int i = 0; i < nof_locks; i++) {
2887 monitors->append(location_for_monitor_index(lock_offset + i));
2888 }
2889 }
2890
2891 return new IRScopeDebugInfo(cur_scope, cur_state->bci(), locals, expressions, monitors, caller_debug_info, cur_state->should_reexecute());
2892 }
2893
2894
2895 void LinearScan::compute_debug_info(CodeEmitInfo* info, int op_id) {
2896 TRACE_LINEAR_SCAN(3, tty->print_cr("creating debug information at op_id %d", op_id));
2897
2898 IRScope* innermost_scope = info->scope();
2899 ValueStack* innermost_state = info->stack();
2900
2901 assert(innermost_scope != nullptr && innermost_state != nullptr, "why is it missing?");
2902
2903 DEBUG_ONLY(check_stack_depth(info, innermost_state->stack_size()));
2904
2905 if (info->_scope_debug_info == nullptr) {
2906 // compute debug information
2907 info->_scope_debug_info = compute_debug_info_for_scope(op_id, innermost_scope, innermost_state, innermost_state);
2908 } else {
2909 // debug information already set. Check that it is correct from the current point of view
2910 DEBUG_ONLY(assert_equal(info->_scope_debug_info, compute_debug_info_for_scope(op_id, innermost_scope, innermost_state, innermost_state)));
2911 }
2912 }
2913
2914
2915 void LinearScan::assign_reg_num(LIR_OpList* instructions, IntervalWalker* iw) {
2916 LIR_OpVisitState visitor;
2917 int num_inst = instructions->length();
2918 bool has_dead = false;
2919
2920 for (int j = 0; j < num_inst; j++) {
2921 LIR_Op* op = instructions->at(j);
2922 if (op == nullptr) { // this can happen when spill-moves are removed in eliminate_spill_moves
2923 has_dead = true;
2924 continue;
2925 }
2926 int op_id = op->id();
2927
2928 // visit instruction to get list of operands
2929 visitor.visit(op);
2930
2931 // iterate all modes of the visitor and process all virtual operands
2932 for_each_visitor_mode(mode) {
2933 int n = visitor.opr_count(mode);
2934 for (int k = 0; k < n; k++) {
2935 LIR_Opr opr = visitor.opr_at(mode, k);
2936 if (opr->is_virtual_register()) {
2937 visitor.set_opr_at(mode, k, color_lir_opr(opr, op_id, mode));
2938 }
2939 }
2940 }
2941
2942 if (visitor.info_count() > 0) {
2943 // exception handling
2944 if (compilation()->has_exception_handlers()) {
2945 XHandlers* xhandlers = visitor.all_xhandler();
2946 int n = xhandlers->length();
2947 for (int k = 0; k < n; k++) {
2948 XHandler* handler = xhandlers->handler_at(k);
2949 if (handler->entry_code() != nullptr) {
2950 assign_reg_num(handler->entry_code()->instructions_list(), nullptr);
2951 }
2952 }
2953 } else {
2954 assert(visitor.all_xhandler()->length() == 0, "missed exception handler");
2955 }
2956
2957 // compute oop map
2958 assert(iw != nullptr, "needed for compute_oop_map");
2959 compute_oop_map(iw, visitor, op);
2960
2961 // compute debug information
2962 int n = visitor.info_count();
2963 for (int k = 0; k < n; k++) {
2964 compute_debug_info(visitor.info_at(k), op_id);
2965 }
2966 }
2967
2968 #ifdef ASSERT
2969 // make sure we haven't made the op invalid.
2970 op->verify();
2971 #endif
2972
2973 // remove useless moves
2974 if (op->code() == lir_move) {
2975 assert(op->as_Op1() != nullptr, "move must be LIR_Op1");
2976 LIR_Op1* move = (LIR_Op1*)op;
2977 LIR_Opr src = move->in_opr();
2978 LIR_Opr dst = move->result_opr();
2979 if (dst == src ||
2980 (!dst->is_pointer() && !src->is_pointer() &&
2981 src->is_same_register(dst))) {
2982 instructions->at_put(j, nullptr);
2983 has_dead = true;
2984 }
2985 }
2986 }
2987
2988 if (has_dead) {
2989 // iterate all instructions of the block and remove all null-values.
2990 int insert_point = 0;
2991 for (int j = 0; j < num_inst; j++) {
2992 LIR_Op* op = instructions->at(j);
2993 if (op != nullptr) {
2994 if (insert_point != j) {
2995 instructions->at_put(insert_point, op);
2996 }
2997 insert_point++;
2998 }
2999 }
3000 instructions->trunc_to(insert_point);
3001 }
3002 }
3003
3004 void LinearScan::assign_reg_num() {
3005 TIME_LINEAR_SCAN(timer_assign_reg_num);
3006
3007 init_compute_debug_info();
3008 IntervalWalker* iw = init_compute_oop_maps();
3009
3010 int num_blocks = block_count();
3011 for (int i = 0; i < num_blocks; i++) {
3012 BlockBegin* block = block_at(i);
3013 assign_reg_num(block->lir()->instructions_list(), iw);
3014 }
3015 }
3016
3017
3018 void LinearScan::do_linear_scan() {
3019 NOT_PRODUCT(_total_timer.begin_method());
3020
3021 number_instructions();
3022
3023 NOT_PRODUCT(print_lir(1, "Before Register Allocation"));
3024
3025 compute_local_live_sets();
3026 compute_global_live_sets();
3027 CHECK_BAILOUT();
3028
3029 build_intervals();
3030 CHECK_BAILOUT();
3031 sort_intervals_before_allocation();
3032
3033 NOT_PRODUCT(print_intervals("Before Register Allocation"));
3034 NOT_PRODUCT(LinearScanStatistic::compute(this, _stat_before_alloc));
3035
3036 allocate_registers();
3037 CHECK_BAILOUT();
3038
3039 resolve_data_flow();
3040 if (compilation()->has_exception_handlers()) {
3041 resolve_exception_handlers();
3042 }
3043 // fill in number of spill slots into frame_map
3044 propagate_spill_slots();
3045 CHECK_BAILOUT();
3046
3047 NOT_PRODUCT(print_intervals("After Register Allocation"));
3048 NOT_PRODUCT(print_lir(2, "LIR after register allocation:"));
3049
3050 sort_intervals_after_allocation();
3051
3052 DEBUG_ONLY(verify());
3053
3054 eliminate_spill_moves();
3055 assign_reg_num();
3056 CHECK_BAILOUT();
3057
3058 NOT_PRODUCT(print_lir(2, "LIR after assignment of register numbers:"));
3059 NOT_PRODUCT(LinearScanStatistic::compute(this, _stat_after_asign));
3060
3061 #ifndef RISCV
3062 // Disable these optimizations on riscv temporarily, because it does not
3063 // work when the comparison operands are bound to branches or cmoves.
3064 { TIME_LINEAR_SCAN(timer_optimize_lir);
3065
3066 EdgeMoveOptimizer::optimize(ir()->code());
3067 ControlFlowOptimizer::optimize(ir()->code());
3068 // check that cfg is still correct after optimizations
3069 ir()->verify();
3070 }
3071 #endif
3072
3073 NOT_PRODUCT(print_lir(1, "Before Code Generation", false));
3074 NOT_PRODUCT(LinearScanStatistic::compute(this, _stat_final));
3075 NOT_PRODUCT(_total_timer.end_method(this));
3076 }
3077
3078
3079 // ********** Printing functions
3080
3081 #ifndef PRODUCT
3082
3083 void LinearScan::print_timers(double total) {
3084 _total_timer.print(total);
3085 }
3086
3087 void LinearScan::print_statistics() {
3088 _stat_before_alloc.print("before allocation");
3089 _stat_after_asign.print("after assignment of register");
3090 _stat_final.print("after optimization");
3091 }
3092
3093 void LinearScan::print_bitmap(BitMap& b) {
3094 for (unsigned int i = 0; i < b.size(); i++) {
3095 if (b.at(i)) tty->print("%d ", i);
3096 }
3097 tty->cr();
3098 }
3099
3100 void LinearScan::print_intervals(const char* label) {
3101 if (TraceLinearScanLevel >= 1) {
3102 int i;
3103 tty->cr();
3104 tty->print_cr("%s", label);
3105
3106 for (i = 0; i < interval_count(); i++) {
3107 Interval* interval = interval_at(i);
3108 if (interval != nullptr) {
3109 interval->print();
3110 }
3111 }
3112
3113 tty->cr();
3114 tty->print_cr("--- Basic Blocks ---");
3115 for (i = 0; i < block_count(); i++) {
3116 BlockBegin* block = block_at(i);
3117 tty->print("B%d [%d, %d, %d, %d] ", block->block_id(), block->first_lir_instruction_id(), block->last_lir_instruction_id(), block->loop_index(), block->loop_depth());
3118 }
3119 tty->cr();
3120 tty->cr();
3121 }
3122
3123 if (PrintCFGToFile) {
3124 CFGPrinter::print_intervals(&_intervals, label);
3125 }
3126 }
3127
3128 void LinearScan::print_lir(int level, const char* label, bool hir_valid) {
3129 if (TraceLinearScanLevel >= level) {
3130 tty->cr();
3131 tty->print_cr("%s", label);
3132 print_LIR(ir()->linear_scan_order());
3133 tty->cr();
3134 }
3135
3136 if (level == 1 && PrintCFGToFile) {
3137 CFGPrinter::print_cfg(ir()->linear_scan_order(), label, hir_valid, true);
3138 }
3139 }
3140
3141 void LinearScan::print_reg_num(outputStream* out, int reg_num) {
3142 if (reg_num == -1) {
3143 out->print("[ANY]");
3144 return;
3145 } else if (reg_num >= LIR_Opr::vreg_base) {
3146 out->print("[VREG %d]", reg_num);
3147 return;
3148 }
3149
3150 LIR_Opr opr = get_operand(reg_num);
3151 assert(opr->is_valid(), "unknown register");
3152 opr->print(out);
3153 }
3154
3155 LIR_Opr LinearScan::get_operand(int reg_num) {
3156 LIR_Opr opr = LIR_OprFact::illegal();
3157
3158 #ifdef X86
3159 int last_xmm_reg = pd_last_xmm_reg;
3160 #ifdef _LP64
3161 if (UseAVX < 3) {
3162 last_xmm_reg = pd_first_xmm_reg + (pd_nof_xmm_regs_frame_map / 2) - 1;
3163 }
3164 #endif
3165 #endif
3166 if (reg_num >= pd_first_cpu_reg && reg_num <= pd_last_cpu_reg) {
3167 opr = LIR_OprFact::single_cpu(reg_num);
3168 } else if (reg_num >= pd_first_fpu_reg && reg_num <= pd_last_fpu_reg) {
3169 opr = LIR_OprFact::single_fpu(reg_num - pd_first_fpu_reg);
3170 #ifdef X86
3171 } else if (reg_num >= pd_first_xmm_reg && reg_num <= last_xmm_reg) {
3172 opr = LIR_OprFact::single_xmm(reg_num - pd_first_xmm_reg);
3173 #endif
3174 } else {
3175 // reg_num == -1 or a virtual register, return the illegal operand
3176 }
3177 return opr;
3178 }
3179
3180 Interval* LinearScan::find_interval_at(int reg_num) const {
3181 if (reg_num < 0 || reg_num >= _intervals.length()) {
3182 return nullptr;
3183 }
3184 return interval_at(reg_num);
3185 }
3186
3187 #endif // PRODUCT
3188
3189
3190 // ********** verification functions for allocation
3191 // (check that all intervals have a correct register and that no registers are overwritten)
3192 #ifdef ASSERT
3193
3194 void LinearScan::verify() {
3195 TRACE_LINEAR_SCAN(2, tty->print_cr("********* verifying intervals ******************************************"));
3196 verify_intervals();
3197
3198 TRACE_LINEAR_SCAN(2, tty->print_cr("********* verifying that no oops are in fixed intervals ****************"));
3199 verify_no_oops_in_fixed_intervals();
3200
3201 TRACE_LINEAR_SCAN(2, tty->print_cr("********* verifying that unpinned constants are not alive across block boundaries"));
3202 verify_constants();
3203
3204 TRACE_LINEAR_SCAN(2, tty->print_cr("********* verifying register allocation ********************************"));
3205 verify_registers();
3206
3207 TRACE_LINEAR_SCAN(2, tty->print_cr("********* no errors found **********************************************"));
3208 }
3209
3210 void LinearScan::verify_intervals() {
3211 int len = interval_count();
3212 bool has_error = false;
3213
3214 for (int i = 0; i < len; i++) {
3215 Interval* i1 = interval_at(i);
3216 if (i1 == nullptr) continue;
3217
3218 i1->check_split_children();
3219
3220 if (i1->reg_num() != i) {
3221 tty->print_cr("Interval %d is on position %d in list", i1->reg_num(), i); i1->print(); tty->cr();
3222 has_error = true;
3223 }
3224
3225 if (i1->reg_num() >= LIR_Opr::vreg_base && i1->type() == T_ILLEGAL) {
3226 tty->print_cr("Interval %d has no type assigned", i1->reg_num()); i1->print(); tty->cr();
3227 has_error = true;
3228 }
3229
3230 if (i1->assigned_reg() == any_reg) {
3231 tty->print_cr("Interval %d has no register assigned", i1->reg_num()); i1->print(); tty->cr();
3232 has_error = true;
3233 }
3234
3235 if (i1->assigned_reg() == i1->assigned_regHi()) {
3236 tty->print_cr("Interval %d: low and high register equal", i1->reg_num()); i1->print(); tty->cr();
3237 has_error = true;
3238 }
3239
3240 if (!is_processed_reg_num(i1->assigned_reg())) {
3241 tty->print_cr("Can not have an Interval for an ignored register"); i1->print(); tty->cr();
3242 has_error = true;
3243 }
3244
3245 // special intervals that are created in MoveResolver
3246 // -> ignore them because the range information has no meaning there
3247 if (i1->from() == 1 && i1->to() == 2) continue;
3248
3249 if (i1->first() == Range::end()) {
3250 tty->print_cr("Interval %d has no Range", i1->reg_num()); i1->print(); tty->cr();
3251 has_error = true;
3252 }
3253
3254 for (Range* r = i1->first(); r != Range::end(); r = r->next()) {
3255 if (r->from() >= r->to()) {
3256 tty->print_cr("Interval %d has zero length range", i1->reg_num()); i1->print(); tty->cr();
3257 has_error = true;
3258 }
3259 }
3260
3261 for (int j = i + 1; j < len; j++) {
3262 Interval* i2 = interval_at(j);
3263 if (i2 == nullptr || (i2->from() == 1 && i2->to() == 2)) continue;
3264
3265 int r1 = i1->assigned_reg();
3266 int r1Hi = i1->assigned_regHi();
3267 int r2 = i2->assigned_reg();
3268 int r2Hi = i2->assigned_regHi();
3269 if ((r1 == r2 || r1 == r2Hi || (r1Hi != any_reg && (r1Hi == r2 || r1Hi == r2Hi))) && i1->intersects(i2)) {
3270 tty->print_cr("Intervals %d and %d overlap and have the same register assigned", i1->reg_num(), i2->reg_num());
3271 i1->print(); tty->cr();
3272 i2->print(); tty->cr();
3273 has_error = true;
3274 }
3275 }
3276 }
3277
3278 assert(has_error == false, "register allocation invalid");
3279 }
3280
3281
3282 void LinearScan::verify_no_oops_in_fixed_intervals() {
3283 Interval* fixed_intervals;
3284 Interval* other_intervals;
3285 create_unhandled_lists(&fixed_intervals, &other_intervals, is_precolored_cpu_interval, nullptr);
3286
3287 // to ensure a walking until the last instruction id, add a dummy interval
3288 // with a high operation id
3289 other_intervals = new Interval(any_reg);
3290 other_intervals->add_range(max_jint - 2, max_jint - 1);
3291 IntervalWalker* iw = new IntervalWalker(this, fixed_intervals, other_intervals);
3292
3293 LIR_OpVisitState visitor;
3294 for (int i = 0; i < block_count(); i++) {
3295 BlockBegin* block = block_at(i);
3296
3297 LIR_OpList* instructions = block->lir()->instructions_list();
3298
3299 for (int j = 0; j < instructions->length(); j++) {
3300 LIR_Op* op = instructions->at(j);
3301 int op_id = op->id();
3302
3303 visitor.visit(op);
3304
3305 if (visitor.info_count() > 0) {
3306 iw->walk_before(op->id());
3307 bool check_live = true;
3308 if (op->code() == lir_move) {
3309 LIR_Op1* move = (LIR_Op1*)op;
3310 check_live = (move->patch_code() == lir_patch_none);
3311 }
3312 LIR_OpBranch* branch = op->as_OpBranch();
3313 if (branch != nullptr && branch->stub() != nullptr && branch->stub()->is_exception_throw_stub()) {
3314 // Don't bother checking the stub in this case since the
3315 // exception stub will never return to normal control flow.
3316 check_live = false;
3317 }
3318
3319 // Make sure none of the fixed registers is live across an
3320 // oopmap since we can't handle that correctly.
3321 if (check_live) {
3322 for (Interval* interval = iw->active_first(fixedKind);
3323 interval != Interval::end();
3324 interval = interval->next()) {
3325 if (interval->current_to() > op->id() + 1) {
3326 // This interval is live out of this op so make sure
3327 // that this interval represents some value that's
3328 // referenced by this op either as an input or output.
3329 bool ok = false;
3330 for_each_visitor_mode(mode) {
3331 int n = visitor.opr_count(mode);
3332 for (int k = 0; k < n; k++) {
3333 LIR_Opr opr = visitor.opr_at(mode, k);
3334 if (opr->is_fixed_cpu()) {
3335 if (interval_at(reg_num(opr)) == interval) {
3336 ok = true;
3337 break;
3338 }
3339 int hi = reg_numHi(opr);
3340 if (hi != -1 && interval_at(hi) == interval) {
3341 ok = true;
3342 break;
3343 }
3344 }
3345 }
3346 }
3347 assert(ok, "fixed intervals should never be live across an oopmap point");
3348 }
3349 }
3350 }
3351 }
3352
3353 // oop-maps at calls do not contain registers, so check is not needed
3354 if (!visitor.has_call()) {
3355
3356 for_each_visitor_mode(mode) {
3357 int n = visitor.opr_count(mode);
3358 for (int k = 0; k < n; k++) {
3359 LIR_Opr opr = visitor.opr_at(mode, k);
3360
3361 if (opr->is_fixed_cpu() && opr->is_oop()) {
3362 // operand is a non-virtual cpu register and contains an oop
3363 TRACE_LINEAR_SCAN(4, op->print_on(tty); tty->print("checking operand "); opr->print(); tty->cr());
3364
3365 Interval* interval = interval_at(reg_num(opr));
3366 assert(interval != nullptr, "no interval");
3367
3368 if (mode == LIR_OpVisitState::inputMode) {
3369 if (interval->to() >= op_id + 1) {
3370 assert(interval->to() < op_id + 2 ||
3371 interval->has_hole_between(op_id, op_id + 2),
3372 "oop input operand live after instruction");
3373 }
3374 } else if (mode == LIR_OpVisitState::outputMode) {
3375 if (interval->from() <= op_id - 1) {
3376 assert(interval->has_hole_between(op_id - 1, op_id),
3377 "oop input operand live after instruction");
3378 }
3379 }
3380 }
3381 }
3382 }
3383 }
3384 }
3385 }
3386 }
3387
3388
3389 void LinearScan::verify_constants() {
3390 int num_regs = num_virtual_regs();
3391 int size = live_set_size();
3392 int num_blocks = block_count();
3393
3394 for (int i = 0; i < num_blocks; i++) {
3395 BlockBegin* block = block_at(i);
3396 ResourceBitMap& live_at_edge = block->live_in();
3397
3398 // visit all registers where the live_at_edge bit is set
3399 auto visitor = [&](BitMap::idx_t index) {
3400 int r = static_cast<int>(index);
3401 TRACE_LINEAR_SCAN(4, tty->print("checking interval %d of block B%d", r, block->block_id()));
3402
3403 Value value = gen()->instruction_for_vreg(r);
3404
3405 assert(value != nullptr, "all intervals live across block boundaries must have Value");
3406 assert(value->operand()->is_register() && value->operand()->is_virtual(), "value must have virtual operand");
3407 assert(value->operand()->vreg_number() == r, "register number must match");
3408 // TKR assert(value->as_Constant() == nullptr || value->is_pinned(), "only pinned constants can be alive across block boundaries");
3409 };
3410 live_at_edge.iterate(visitor, 0, size);
3411 }
3412 }
3413
3414
3415 class RegisterVerifier: public StackObj {
3416 private:
3417 LinearScan* _allocator;
3418 BlockList _work_list; // all blocks that must be processed
3419 IntervalsList _saved_states; // saved information of previous check
3420
3421 // simplified access to methods of LinearScan
3422 Compilation* compilation() const { return _allocator->compilation(); }
3423 Interval* interval_at(int reg_num) const { return _allocator->interval_at(reg_num); }
3424 int reg_num(LIR_Opr opr) const { return _allocator->reg_num(opr); }
3425
3426 // currently, only registers are processed
3427 int state_size() { return LinearScan::nof_regs; }
3428
3429 // accessors
3430 IntervalList* state_for_block(BlockBegin* block) { return _saved_states.at(block->block_id()); }
3431 void set_state_for_block(BlockBegin* block, IntervalList* saved_state) { _saved_states.at_put(block->block_id(), saved_state); }
3432 void add_to_work_list(BlockBegin* block) { if (!_work_list.contains(block)) _work_list.append(block); }
3433
3434 // helper functions
3435 IntervalList* copy(IntervalList* input_state);
3436 void state_put(IntervalList* input_state, int reg, Interval* interval);
3437 bool check_state(IntervalList* input_state, int reg, Interval* interval);
3438
3439 void process_block(BlockBegin* block);
3440 void process_xhandler(XHandler* xhandler, IntervalList* input_state);
3441 void process_successor(BlockBegin* block, IntervalList* input_state);
3442 void process_operations(LIR_List* ops, IntervalList* input_state);
3443
3444 public:
3445 RegisterVerifier(LinearScan* allocator)
3446 : _allocator(allocator)
3447 , _work_list(16)
3448 , _saved_states(BlockBegin::number_of_blocks(), BlockBegin::number_of_blocks(), nullptr)
3449 { }
3450
3451 void verify(BlockBegin* start);
3452 };
3453
3454
3455 // entry function from LinearScan that starts the verification
3456 void LinearScan::verify_registers() {
3457 RegisterVerifier verifier(this);
3458 verifier.verify(block_at(0));
3459 }
3460
3461
3462 void RegisterVerifier::verify(BlockBegin* start) {
3463 // setup input registers (method arguments) for first block
3464 int input_state_len = state_size();
3465 IntervalList* input_state = new IntervalList(input_state_len, input_state_len, nullptr);
3466 CallingConvention* args = compilation()->frame_map()->incoming_arguments();
3467 for (int n = 0; n < args->length(); n++) {
3468 LIR_Opr opr = args->at(n);
3469 if (opr->is_register()) {
3470 Interval* interval = interval_at(reg_num(opr));
3471
3472 if (interval->assigned_reg() < state_size()) {
3473 input_state->at_put(interval->assigned_reg(), interval);
3474 }
3475 if (interval->assigned_regHi() != LinearScan::any_reg && interval->assigned_regHi() < state_size()) {
3476 input_state->at_put(interval->assigned_regHi(), interval);
3477 }
3478 }
3479 }
3480
3481 set_state_for_block(start, input_state);
3482 add_to_work_list(start);
3483
3484 // main loop for verification
3485 do {
3486 BlockBegin* block = _work_list.at(0);
3487 _work_list.remove_at(0);
3488
3489 process_block(block);
3490 } while (!_work_list.is_empty());
3491 }
3492
3493 void RegisterVerifier::process_block(BlockBegin* block) {
3494 TRACE_LINEAR_SCAN(2, tty->cr(); tty->print_cr("process_block B%d", block->block_id()));
3495
3496 // must copy state because it is modified
3497 IntervalList* input_state = copy(state_for_block(block));
3498
3499 if (TraceLinearScanLevel >= 4) {
3500 tty->print_cr("Input-State of intervals:");
3501 tty->print(" ");
3502 for (int i = 0; i < state_size(); i++) {
3503 if (input_state->at(i) != nullptr) {
3504 tty->print(" %4d", input_state->at(i)->reg_num());
3505 } else {
3506 tty->print(" __");
3507 }
3508 }
3509 tty->cr();
3510 tty->cr();
3511 }
3512
3513 // process all operations of the block
3514 process_operations(block->lir(), input_state);
3515
3516 // iterate all successors
3517 for (int i = 0; i < block->number_of_sux(); i++) {
3518 process_successor(block->sux_at(i), input_state);
3519 }
3520 }
3521
3522 void RegisterVerifier::process_xhandler(XHandler* xhandler, IntervalList* input_state) {
3523 TRACE_LINEAR_SCAN(2, tty->print_cr("process_xhandler B%d", xhandler->entry_block()->block_id()));
3524
3525 // must copy state because it is modified
3526 input_state = copy(input_state);
3527
3528 if (xhandler->entry_code() != nullptr) {
3529 process_operations(xhandler->entry_code(), input_state);
3530 }
3531 process_successor(xhandler->entry_block(), input_state);
3532 }
3533
3534 void RegisterVerifier::process_successor(BlockBegin* block, IntervalList* input_state) {
3535 IntervalList* saved_state = state_for_block(block);
3536
3537 if (saved_state != nullptr) {
3538 // this block was already processed before.
3539 // check if new input_state is consistent with saved_state
3540
3541 bool saved_state_correct = true;
3542 for (int i = 0; i < state_size(); i++) {
3543 if (input_state->at(i) != saved_state->at(i)) {
3544 // current input_state and previous saved_state assume a different
3545 // interval in this register -> assume that this register is invalid
3546 if (saved_state->at(i) != nullptr) {
3547 // invalidate old calculation only if it assumed that
3548 // register was valid. when the register was already invalid,
3549 // then the old calculation was correct.
3550 saved_state_correct = false;
3551 saved_state->at_put(i, nullptr);
3552
3553 TRACE_LINEAR_SCAN(4, tty->print_cr("process_successor B%d: invalidating slot %d", block->block_id(), i));
3554 }
3555 }
3556 }
3557
3558 if (saved_state_correct) {
3559 // already processed block with correct input_state
3560 TRACE_LINEAR_SCAN(2, tty->print_cr("process_successor B%d: previous visit already correct", block->block_id()));
3561 } else {
3562 // must re-visit this block
3563 TRACE_LINEAR_SCAN(2, tty->print_cr("process_successor B%d: must re-visit because input state changed", block->block_id()));
3564 add_to_work_list(block);
3565 }
3566
3567 } else {
3568 // block was not processed before, so set initial input_state
3569 TRACE_LINEAR_SCAN(2, tty->print_cr("process_successor B%d: initial visit", block->block_id()));
3570
3571 set_state_for_block(block, copy(input_state));
3572 add_to_work_list(block);
3573 }
3574 }
3575
3576
3577 IntervalList* RegisterVerifier::copy(IntervalList* input_state) {
3578 IntervalList* copy_state = new IntervalList(input_state->length());
3579 copy_state->appendAll(input_state);
3580 return copy_state;
3581 }
3582
3583 void RegisterVerifier::state_put(IntervalList* input_state, int reg, Interval* interval) {
3584 if (reg != LinearScan::any_reg && reg < state_size()) {
3585 if (interval != nullptr) {
3586 TRACE_LINEAR_SCAN(4, tty->print_cr(" reg[%d] = %d", reg, interval->reg_num()));
3587 } else if (input_state->at(reg) != nullptr) {
3588 TRACE_LINEAR_SCAN(4, tty->print_cr(" reg[%d] = null", reg));
3589 }
3590
3591 input_state->at_put(reg, interval);
3592 }
3593 }
3594
3595 bool RegisterVerifier::check_state(IntervalList* input_state, int reg, Interval* interval) {
3596 if (reg != LinearScan::any_reg && reg < state_size()) {
3597 if (input_state->at(reg) != interval) {
3598 tty->print_cr("!! Error in register allocation: register %d does not contain interval %d", reg, interval->reg_num());
3599 return true;
3600 }
3601 }
3602 return false;
3603 }
3604
3605 void RegisterVerifier::process_operations(LIR_List* ops, IntervalList* input_state) {
3606 // visit all instructions of the block
3607 LIR_OpVisitState visitor;
3608 bool has_error = false;
3609
3610 for (int i = 0; i < ops->length(); i++) {
3611 LIR_Op* op = ops->at(i);
3612 visitor.visit(op);
3613
3614 TRACE_LINEAR_SCAN(4, op->print_on(tty));
3615
3616 // check if input operands are correct
3617 int j;
3618 int n = visitor.opr_count(LIR_OpVisitState::inputMode);
3619 for (j = 0; j < n; j++) {
3620 LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::inputMode, j);
3621 if (opr->is_register() && LinearScan::is_processed_reg_num(reg_num(opr))) {
3622 Interval* interval = interval_at(reg_num(opr));
3623 if (op->id() != -1) {
3624 interval = interval->split_child_at_op_id(op->id(), LIR_OpVisitState::inputMode);
3625 }
3626
3627 has_error |= check_state(input_state, interval->assigned_reg(), interval->split_parent());
3628 has_error |= check_state(input_state, interval->assigned_regHi(), interval->split_parent());
3629
3630 // When an operand is marked with is_last_use, then the fpu stack allocator
3631 // removes the register from the fpu stack -> the register contains no value
3632 if (opr->is_last_use()) {
3633 state_put(input_state, interval->assigned_reg(), nullptr);
3634 state_put(input_state, interval->assigned_regHi(), nullptr);
3635 }
3636 }
3637 }
3638
3639 // invalidate all caller save registers at calls
3640 if (visitor.has_call()) {
3641 for (j = 0; j < FrameMap::nof_caller_save_cpu_regs(); j++) {
3642 state_put(input_state, reg_num(FrameMap::caller_save_cpu_reg_at(j)), nullptr);
3643 }
3644 for (j = 0; j < FrameMap::nof_caller_save_fpu_regs; j++) {
3645 state_put(input_state, reg_num(FrameMap::caller_save_fpu_reg_at(j)), nullptr);
3646 }
3647
3648 #ifdef X86
3649 int num_caller_save_xmm_regs = FrameMap::get_num_caller_save_xmms();
3650 for (j = 0; j < num_caller_save_xmm_regs; j++) {
3651 state_put(input_state, reg_num(FrameMap::caller_save_xmm_reg_at(j)), nullptr);
3652 }
3653 #endif
3654 }
3655
3656 // process xhandler before output and temp operands
3657 XHandlers* xhandlers = visitor.all_xhandler();
3658 n = xhandlers->length();
3659 for (int k = 0; k < n; k++) {
3660 process_xhandler(xhandlers->handler_at(k), input_state);
3661 }
3662
3663 // set temp operands (some operations use temp operands also as output operands, so can't set them null)
3664 n = visitor.opr_count(LIR_OpVisitState::tempMode);
3665 for (j = 0; j < n; j++) {
3666 LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::tempMode, j);
3667 if (opr->is_register() && LinearScan::is_processed_reg_num(reg_num(opr))) {
3668 Interval* interval = interval_at(reg_num(opr));
3669 if (op->id() != -1) {
3670 interval = interval->split_child_at_op_id(op->id(), LIR_OpVisitState::tempMode);
3671 }
3672
3673 state_put(input_state, interval->assigned_reg(), interval->split_parent());
3674 state_put(input_state, interval->assigned_regHi(), interval->split_parent());
3675 }
3676 }
3677
3678 // set output operands
3679 n = visitor.opr_count(LIR_OpVisitState::outputMode);
3680 for (j = 0; j < n; j++) {
3681 LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::outputMode, j);
3682 if (opr->is_register() && LinearScan::is_processed_reg_num(reg_num(opr))) {
3683 Interval* interval = interval_at(reg_num(opr));
3684 if (op->id() != -1) {
3685 interval = interval->split_child_at_op_id(op->id(), LIR_OpVisitState::outputMode);
3686 }
3687
3688 state_put(input_state, interval->assigned_reg(), interval->split_parent());
3689 state_put(input_state, interval->assigned_regHi(), interval->split_parent());
3690 }
3691 }
3692 }
3693 assert(has_error == false, "Error in register allocation");
3694 }
3695
3696 #endif // ASSERT
3697
3698
3699
3700 // **** Implementation of MoveResolver ******************************
3701
3702 MoveResolver::MoveResolver(LinearScan* allocator) :
3703 _allocator(allocator),
3704 _insert_list(nullptr),
3705 _insert_idx(-1),
3706 _insertion_buffer(),
3707 _mapping_from(8),
3708 _mapping_from_opr(8),
3709 _mapping_to(8),
3710 _multiple_reads_allowed(false)
3711 {
3712 for (int i = 0; i < LinearScan::nof_regs; i++) {
3713 _register_blocked[i] = 0;
3714 }
3715 DEBUG_ONLY(check_empty());
3716 }
3717
3718
3719 #ifdef ASSERT
3720
3721 void MoveResolver::check_empty() {
3722 assert(_mapping_from.length() == 0 && _mapping_from_opr.length() == 0 && _mapping_to.length() == 0, "list must be empty before and after processing");
3723 for (int i = 0; i < LinearScan::nof_regs; i++) {
3724 assert(register_blocked(i) == 0, "register map must be empty before and after processing");
3725 }
3726 assert(_multiple_reads_allowed == false, "must have default value");
3727 }
3728
3729 void MoveResolver::verify_before_resolve() {
3730 assert(_mapping_from.length() == _mapping_from_opr.length(), "length must be equal");
3731 assert(_mapping_from.length() == _mapping_to.length(), "length must be equal");
3732 assert(_insert_list != nullptr && _insert_idx != -1, "insert position not set");
3733
3734 int i, j;
3735 if (!_multiple_reads_allowed) {
3736 for (i = 0; i < _mapping_from.length(); i++) {
3737 for (j = i + 1; j < _mapping_from.length(); j++) {
3738 assert(_mapping_from.at(i) == nullptr || _mapping_from.at(i) != _mapping_from.at(j), "cannot read from same interval twice");
3739 }
3740 }
3741 }
3742
3743 for (i = 0; i < _mapping_to.length(); i++) {
3744 for (j = i + 1; j < _mapping_to.length(); j++) {
3745 assert(_mapping_to.at(i) != _mapping_to.at(j), "cannot write to same interval twice");
3746 }
3747 }
3748
3749
3750 ResourceBitMap used_regs(LinearScan::nof_regs + allocator()->frame_map()->argcount() + allocator()->max_spills());
3751 if (!_multiple_reads_allowed) {
3752 for (i = 0; i < _mapping_from.length(); i++) {
3753 Interval* it = _mapping_from.at(i);
3754 if (it != nullptr) {
3755 assert(!used_regs.at(it->assigned_reg()), "cannot read from same register twice");
3756 used_regs.set_bit(it->assigned_reg());
3757
3758 if (it->assigned_regHi() != LinearScan::any_reg) {
3759 assert(!used_regs.at(it->assigned_regHi()), "cannot read from same register twice");
3760 used_regs.set_bit(it->assigned_regHi());
3761 }
3762 }
3763 }
3764 }
3765
3766 used_regs.clear();
3767 for (i = 0; i < _mapping_to.length(); i++) {
3768 Interval* it = _mapping_to.at(i);
3769 assert(!used_regs.at(it->assigned_reg()), "cannot write to same register twice");
3770 used_regs.set_bit(it->assigned_reg());
3771
3772 if (it->assigned_regHi() != LinearScan::any_reg) {
3773 assert(!used_regs.at(it->assigned_regHi()), "cannot write to same register twice");
3774 used_regs.set_bit(it->assigned_regHi());
3775 }
3776 }
3777
3778 used_regs.clear();
3779 for (i = 0; i < _mapping_from.length(); i++) {
3780 Interval* it = _mapping_from.at(i);
3781 if (it != nullptr && it->assigned_reg() >= LinearScan::nof_regs) {
3782 used_regs.set_bit(it->assigned_reg());
3783 }
3784 }
3785 for (i = 0; i < _mapping_to.length(); i++) {
3786 Interval* it = _mapping_to.at(i);
3787 assert(!used_regs.at(it->assigned_reg()) || it->assigned_reg() == _mapping_from.at(i)->assigned_reg(), "stack slots used in _mapping_from must be disjoint to _mapping_to");
3788 }
3789 }
3790
3791 #endif // ASSERT
3792
3793
3794 // mark assigned_reg and assigned_regHi of the interval as blocked
3795 void MoveResolver::block_registers(Interval* it) {
3796 int reg = it->assigned_reg();
3797 if (reg < LinearScan::nof_regs) {
3798 assert(_multiple_reads_allowed || register_blocked(reg) == 0, "register already marked as used");
3799 set_register_blocked(reg, 1);
3800 }
3801 reg = it->assigned_regHi();
3802 if (reg != LinearScan::any_reg && reg < LinearScan::nof_regs) {
3803 assert(_multiple_reads_allowed || register_blocked(reg) == 0, "register already marked as used");
3804 set_register_blocked(reg, 1);
3805 }
3806 }
3807
3808 // mark assigned_reg and assigned_regHi of the interval as unblocked
3809 void MoveResolver::unblock_registers(Interval* it) {
3810 int reg = it->assigned_reg();
3811 if (reg < LinearScan::nof_regs) {
3812 assert(register_blocked(reg) > 0, "register already marked as unused");
3813 set_register_blocked(reg, -1);
3814 }
3815 reg = it->assigned_regHi();
3816 if (reg != LinearScan::any_reg && reg < LinearScan::nof_regs) {
3817 assert(register_blocked(reg) > 0, "register already marked as unused");
3818 set_register_blocked(reg, -1);
3819 }
3820 }
3821
3822 // check if assigned_reg and assigned_regHi of the to-interval are not blocked (or only blocked by from)
3823 bool MoveResolver::save_to_process_move(Interval* from, Interval* to) {
3824 int from_reg = -1;
3825 int from_regHi = -1;
3826 if (from != nullptr) {
3827 from_reg = from->assigned_reg();
3828 from_regHi = from->assigned_regHi();
3829 }
3830
3831 int reg = to->assigned_reg();
3832 if (reg < LinearScan::nof_regs) {
3833 if (register_blocked(reg) > 1 || (register_blocked(reg) == 1 && reg != from_reg && reg != from_regHi)) {
3834 return false;
3835 }
3836 }
3837 reg = to->assigned_regHi();
3838 if (reg != LinearScan::any_reg && reg < LinearScan::nof_regs) {
3839 if (register_blocked(reg) > 1 || (register_blocked(reg) == 1 && reg != from_reg && reg != from_regHi)) {
3840 return false;
3841 }
3842 }
3843
3844 return true;
3845 }
3846
3847
3848 void MoveResolver::create_insertion_buffer(LIR_List* list) {
3849 assert(!_insertion_buffer.initialized(), "overwriting existing buffer");
3850 _insertion_buffer.init(list);
3851 }
3852
3853 void MoveResolver::append_insertion_buffer() {
3854 if (_insertion_buffer.initialized()) {
3855 _insertion_buffer.lir_list()->append(&_insertion_buffer);
3856 }
3857 assert(!_insertion_buffer.initialized(), "must be uninitialized now");
3858
3859 _insert_list = nullptr;
3860 _insert_idx = -1;
3861 }
3862
3863 void MoveResolver::insert_move(Interval* from_interval, Interval* to_interval) {
3864 assert(from_interval->reg_num() != to_interval->reg_num(), "from and to interval equal");
3865 assert(from_interval->type() == to_interval->type(), "move between different types");
3866 assert(_insert_list != nullptr && _insert_idx != -1, "must setup insert position first");
3867 assert(_insertion_buffer.lir_list() == _insert_list, "wrong insertion buffer");
3868
3869 LIR_Opr from_opr = get_virtual_register(from_interval);
3870 LIR_Opr to_opr = get_virtual_register(to_interval);
3871
3872 if (!_multiple_reads_allowed) {
3873 // the last_use flag is an optimization for FPU stack allocation. When the same
3874 // input interval is used in more than one move, then it is too difficult to determine
3875 // if this move is really the last use.
3876 from_opr = from_opr->make_last_use();
3877 }
3878 _insertion_buffer.move(_insert_idx, from_opr, to_opr);
3879
3880 TRACE_LINEAR_SCAN(4, tty->print_cr("MoveResolver: inserted move from register %d (%d, %d) to %d (%d, %d)", from_interval->reg_num(), from_interval->assigned_reg(), from_interval->assigned_regHi(), to_interval->reg_num(), to_interval->assigned_reg(), to_interval->assigned_regHi()));
3881 }
3882
3883 void MoveResolver::insert_move(LIR_Opr from_opr, Interval* to_interval) {
3884 assert(from_opr->type() == to_interval->type(), "move between different types");
3885 assert(_insert_list != nullptr && _insert_idx != -1, "must setup insert position first");
3886 assert(_insertion_buffer.lir_list() == _insert_list, "wrong insertion buffer");
3887
3888 LIR_Opr to_opr = get_virtual_register(to_interval);
3889 _insertion_buffer.move(_insert_idx, from_opr, to_opr);
3890
3891 TRACE_LINEAR_SCAN(4, tty->print("MoveResolver: inserted move from constant "); from_opr->print(); tty->print_cr(" to %d (%d, %d)", to_interval->reg_num(), to_interval->assigned_reg(), to_interval->assigned_regHi()));
3892 }
3893
3894 LIR_Opr MoveResolver::get_virtual_register(Interval* interval) {
3895 // Add a little fudge factor for the bailout since the bailout is only checked periodically. This allows us to hand out
3896 // a few extra registers before we really run out which helps to avoid to trip over assertions.
3897 int reg_num = interval->reg_num();
3898 if (reg_num + 20 >= LIR_Opr::vreg_max) {
3899 _allocator->bailout("out of virtual registers in linear scan");
3900 if (reg_num + 2 >= LIR_Opr::vreg_max) {
3901 // Wrap it around and continue until bailout really happens to avoid hitting assertions.
3902 reg_num = LIR_Opr::vreg_base;
3903 }
3904 }
3905 LIR_Opr vreg = LIR_OprFact::virtual_register(reg_num, interval->type());
3906 assert(vreg != LIR_OprFact::illegal(), "ran out of virtual registers");
3907 return vreg;
3908 }
3909
3910 void MoveResolver::resolve_mappings() {
3911 TRACE_LINEAR_SCAN(4, tty->print_cr("MoveResolver: resolving mappings for Block B%d, index %d", _insert_list->block() != nullptr ? _insert_list->block()->block_id() : -1, _insert_idx));
3912 DEBUG_ONLY(verify_before_resolve());
3913
3914 // Block all registers that are used as input operands of a move.
3915 // When a register is blocked, no move to this register is emitted.
3916 // This is necessary for detecting cycles in moves.
3917 int i;
3918 for (i = _mapping_from.length() - 1; i >= 0; i--) {
3919 Interval* from_interval = _mapping_from.at(i);
3920 if (from_interval != nullptr) {
3921 block_registers(from_interval);
3922 }
3923 }
3924
3925 int spill_candidate = -1;
3926 while (_mapping_from.length() > 0) {
3927 bool processed_interval = false;
3928
3929 for (i = _mapping_from.length() - 1; i >= 0; i--) {
3930 Interval* from_interval = _mapping_from.at(i);
3931 Interval* to_interval = _mapping_to.at(i);
3932
3933 if (save_to_process_move(from_interval, to_interval)) {
3934 // this interval can be processed because target is free
3935 if (from_interval != nullptr) {
3936 insert_move(from_interval, to_interval);
3937 unblock_registers(from_interval);
3938 } else {
3939 insert_move(_mapping_from_opr.at(i), to_interval);
3940 }
3941 _mapping_from.remove_at(i);
3942 _mapping_from_opr.remove_at(i);
3943 _mapping_to.remove_at(i);
3944
3945 processed_interval = true;
3946 } else if (from_interval != nullptr && from_interval->assigned_reg() < LinearScan::nof_regs) {
3947 // this interval cannot be processed now because target is not free
3948 // it starts in a register, so it is a possible candidate for spilling
3949 spill_candidate = i;
3950 }
3951 }
3952
3953 if (!processed_interval) {
3954 // no move could be processed because there is a cycle in the move list
3955 // (e.g. r1 -> r2, r2 -> r1), so one interval must be spilled to memory
3956 guarantee(spill_candidate != -1, "no interval in register for spilling found");
3957
3958 // create a new spill interval and assign a stack slot to it
3959 Interval* from_interval = _mapping_from.at(spill_candidate);
3960 Interval* spill_interval = new Interval(-1);
3961 spill_interval->set_type(from_interval->type());
3962
3963 // add a dummy range because real position is difficult to calculate
3964 // Note: this range is a special case when the integrity of the allocation is checked
3965 spill_interval->add_range(1, 2);
3966
3967 // do not allocate a new spill slot for temporary interval, but
3968 // use spill slot assigned to from_interval. Otherwise moves from
3969 // one stack slot to another can happen (not allowed by LIR_Assembler
3970 int spill_slot = from_interval->canonical_spill_slot();
3971 if (spill_slot < 0) {
3972 spill_slot = allocator()->allocate_spill_slot(type2spill_size[spill_interval->type()] == 2);
3973 from_interval->set_canonical_spill_slot(spill_slot);
3974 }
3975 spill_interval->assign_reg(spill_slot);
3976 allocator()->append_interval(spill_interval);
3977
3978 TRACE_LINEAR_SCAN(4, tty->print_cr("created new Interval %d for spilling", spill_interval->reg_num()));
3979
3980 // insert a move from register to stack and update the mapping
3981 insert_move(from_interval, spill_interval);
3982 _mapping_from.at_put(spill_candidate, spill_interval);
3983 unblock_registers(from_interval);
3984 }
3985 }
3986
3987 // reset to default value
3988 _multiple_reads_allowed = false;
3989
3990 // check that all intervals have been processed
3991 DEBUG_ONLY(check_empty());
3992 }
3993
3994
3995 void MoveResolver::set_insert_position(LIR_List* insert_list, int insert_idx) {
3996 TRACE_LINEAR_SCAN(4, tty->print_cr("MoveResolver: setting insert position to Block B%d, index %d", insert_list->block() != nullptr ? insert_list->block()->block_id() : -1, insert_idx));
3997 assert(_insert_list == nullptr && _insert_idx == -1, "use move_insert_position instead of set_insert_position when data already set");
3998
3999 create_insertion_buffer(insert_list);
4000 _insert_list = insert_list;
4001 _insert_idx = insert_idx;
4002 }
4003
4004 void MoveResolver::move_insert_position(LIR_List* insert_list, int insert_idx) {
4005 TRACE_LINEAR_SCAN(4, tty->print_cr("MoveResolver: moving insert position to Block B%d, index %d", insert_list->block() != nullptr ? insert_list->block()->block_id() : -1, insert_idx));
4006
4007 if (_insert_list != nullptr && (insert_list != _insert_list || insert_idx != _insert_idx)) {
4008 // insert position changed -> resolve current mappings
4009 resolve_mappings();
4010 }
4011
4012 if (insert_list != _insert_list) {
4013 // block changed -> append insertion_buffer because it is
4014 // bound to a specific block and create a new insertion_buffer
4015 append_insertion_buffer();
4016 create_insertion_buffer(insert_list);
4017 }
4018
4019 _insert_list = insert_list;
4020 _insert_idx = insert_idx;
4021 }
4022
4023 void MoveResolver::add_mapping(Interval* from_interval, Interval* to_interval) {
4024 TRACE_LINEAR_SCAN(4, tty->print_cr("MoveResolver: adding mapping from %d (%d, %d) to %d (%d, %d)", from_interval->reg_num(), from_interval->assigned_reg(), from_interval->assigned_regHi(), to_interval->reg_num(), to_interval->assigned_reg(), to_interval->assigned_regHi()));
4025
4026 _mapping_from.append(from_interval);
4027 _mapping_from_opr.append(LIR_OprFact::illegalOpr);
4028 _mapping_to.append(to_interval);
4029 }
4030
4031
4032 void MoveResolver::add_mapping(LIR_Opr from_opr, Interval* to_interval) {
4033 TRACE_LINEAR_SCAN(4, tty->print("MoveResolver: adding mapping from "); from_opr->print(); tty->print_cr(" to %d (%d, %d)", to_interval->reg_num(), to_interval->assigned_reg(), to_interval->assigned_regHi()));
4034 assert(from_opr->is_constant(), "only for constants");
4035
4036 _mapping_from.append(nullptr);
4037 _mapping_from_opr.append(from_opr);
4038 _mapping_to.append(to_interval);
4039 }
4040
4041 void MoveResolver::resolve_and_append_moves() {
4042 if (has_mappings()) {
4043 resolve_mappings();
4044 }
4045 append_insertion_buffer();
4046 }
4047
4048
4049
4050 // **** Implementation of Range *************************************
4051
4052 Range::Range(int from, int to, Range* next) :
4053 _from(from),
4054 _to(to),
4055 _next(next)
4056 {
4057 }
4058
4059 // initialize sentinel
4060 Range* Range::_end = nullptr;
4061 void Range::initialize() {
4062 assert(_end == nullptr, "Range initialized more than once");
4063 alignas(Range) static uint8_t end_storage[sizeof(Range)];
4064 _end = ::new(static_cast<void*>(end_storage)) Range(max_jint, max_jint, nullptr);
4065 }
4066
4067 int Range::intersects_at(Range* r2) const {
4068 const Range* r1 = this;
4069
4070 assert(r1 != nullptr && r2 != nullptr, "null ranges not allowed");
4071 assert(r1 != _end && r2 != _end, "empty ranges not allowed");
4072
4073 do {
4074 if (r1->from() < r2->from()) {
4075 if (r1->to() <= r2->from()) {
4076 r1 = r1->next(); if (r1 == _end) return -1;
4077 } else {
4078 return r2->from();
4079 }
4080 } else if (r2->from() < r1->from()) {
4081 if (r2->to() <= r1->from()) {
4082 r2 = r2->next(); if (r2 == _end) return -1;
4083 } else {
4084 return r1->from();
4085 }
4086 } else { // r1->from() == r2->from()
4087 if (r1->from() == r1->to()) {
4088 r1 = r1->next(); if (r1 == _end) return -1;
4089 } else if (r2->from() == r2->to()) {
4090 r2 = r2->next(); if (r2 == _end) return -1;
4091 } else {
4092 return r1->from();
4093 }
4094 }
4095 } while (true);
4096 }
4097
4098 #ifndef PRODUCT
4099 void Range::print(outputStream* out) const {
4100 out->print("[%d, %d[ ", _from, _to);
4101 }
4102 #endif
4103
4104
4105
4106 // **** Implementation of Interval **********************************
4107
4108 // initialize sentinel
4109 Interval* Interval::_end = nullptr;
4110 void Interval::initialize() {
4111 Range::initialize();
4112 assert(_end == nullptr, "Interval initialized more than once");
4113 alignas(Interval) static uint8_t end_storage[sizeof(Interval)];
4114 _end = ::new(static_cast<void*>(end_storage)) Interval(-1);
4115 }
4116
4117 Interval::Interval(int reg_num) :
4118 _reg_num(reg_num),
4119 _type(T_ILLEGAL),
4120 _first(Range::end()),
4121 _use_pos_and_kinds(12),
4122 _current(Range::end()),
4123 _next(_end),
4124 _state(invalidState),
4125 _assigned_reg(LinearScan::any_reg),
4126 _assigned_regHi(LinearScan::any_reg),
4127 _cached_to(-1),
4128 _cached_opr(LIR_OprFact::illegalOpr),
4129 _cached_vm_reg(VMRegImpl::Bad()),
4130 _split_children(nullptr),
4131 _canonical_spill_slot(-1),
4132 _insert_move_when_activated(false),
4133 _spill_state(noDefinitionFound),
4134 _spill_definition_pos(-1),
4135 _register_hint(nullptr)
4136 {
4137 _split_parent = this;
4138 _current_split_child = this;
4139 }
4140
4141 int Interval::calc_to() {
4142 assert(_first != Range::end(), "interval has no range");
4143
4144 Range* r = _first;
4145 while (r->next() != Range::end()) {
4146 r = r->next();
4147 }
4148 return r->to();
4149 }
4150
4151
4152 #ifdef ASSERT
4153 // consistency check of split-children
4154 void Interval::check_split_children() {
4155 if (_split_children != nullptr && _split_children->length() > 0) {
4156 assert(is_split_parent(), "only split parents can have children");
4157
4158 for (int i = 0; i < _split_children->length(); i++) {
4159 Interval* i1 = _split_children->at(i);
4160
4161 assert(i1->split_parent() == this, "not a split child of this interval");
4162 assert(i1->type() == type(), "must be equal for all split children");
4163 assert(i1->canonical_spill_slot() == canonical_spill_slot(), "must be equal for all split children");
4164
4165 for (int j = i + 1; j < _split_children->length(); j++) {
4166 Interval* i2 = _split_children->at(j);
4167
4168 assert(i1->reg_num() != i2->reg_num(), "same register number");
4169
4170 if (i1->from() < i2->from()) {
4171 assert(i1->to() <= i2->from() && i1->to() < i2->to(), "intervals overlapping");
4172 } else {
4173 assert(i2->from() < i1->from(), "intervals start at same op_id");
4174 assert(i2->to() <= i1->from() && i2->to() < i1->to(), "intervals overlapping");
4175 }
4176 }
4177 }
4178 }
4179 }
4180 #endif // ASSERT
4181
4182 Interval* Interval::register_hint(bool search_split_child) const {
4183 if (!search_split_child) {
4184 return _register_hint;
4185 }
4186
4187 if (_register_hint != nullptr) {
4188 assert(_register_hint->is_split_parent(), "only split parents are valid hint registers");
4189
4190 if (_register_hint->assigned_reg() >= 0 && _register_hint->assigned_reg() < LinearScan::nof_regs) {
4191 return _register_hint;
4192
4193 } else if (_register_hint->_split_children != nullptr && _register_hint->_split_children->length() > 0) {
4194 // search the first split child that has a register assigned
4195 int len = _register_hint->_split_children->length();
4196 for (int i = 0; i < len; i++) {
4197 Interval* cur = _register_hint->_split_children->at(i);
4198
4199 if (cur->assigned_reg() >= 0 && cur->assigned_reg() < LinearScan::nof_regs) {
4200 return cur;
4201 }
4202 }
4203 }
4204 }
4205
4206 // no hint interval found that has a register assigned
4207 return nullptr;
4208 }
4209
4210
4211 Interval* Interval::split_child_at_op_id(int op_id, LIR_OpVisitState::OprMode mode) {
4212 assert(is_split_parent(), "can only be called for split parents");
4213 assert(op_id >= 0, "invalid op_id (method can not be called for spill moves)");
4214
4215 Interval* result;
4216 if (_split_children == nullptr || _split_children->length() == 0) {
4217 result = this;
4218 } else {
4219 result = nullptr;
4220 int len = _split_children->length();
4221
4222 // in outputMode, the end of the interval (op_id == cur->to()) is not valid
4223 int to_offset = (mode == LIR_OpVisitState::outputMode ? 0 : 1);
4224
4225 int i;
4226 for (i = 0; i < len; i++) {
4227 Interval* cur = _split_children->at(i);
4228 if (cur->from() <= op_id && op_id < cur->to() + to_offset) {
4229 if (i > 0) {
4230 // exchange current split child to start of list (faster access for next call)
4231 _split_children->at_put(i, _split_children->at(0));
4232 _split_children->at_put(0, cur);
4233 }
4234
4235 // interval found
4236 result = cur;
4237 break;
4238 }
4239 }
4240
4241 #ifdef ASSERT
4242 for (i = 0; i < len; i++) {
4243 Interval* tmp = _split_children->at(i);
4244 if (tmp != result && tmp->from() <= op_id && op_id < tmp->to() + to_offset) {
4245 tty->print_cr("two valid result intervals found for op_id %d: %d and %d", op_id, result->reg_num(), tmp->reg_num());
4246 result->print();
4247 tmp->print();
4248 assert(false, "two valid result intervals found");
4249 }
4250 }
4251 #endif
4252 }
4253
4254 assert(result != nullptr, "no matching interval found");
4255 assert(result->covers(op_id, mode), "op_id not covered by interval");
4256
4257 return result;
4258 }
4259
4260
4261 // returns the last split child that ends before the given op_id
4262 Interval* Interval::split_child_before_op_id(int op_id) {
4263 assert(op_id >= 0, "invalid op_id");
4264
4265 Interval* parent = split_parent();
4266 Interval* result = nullptr;
4267
4268 assert(parent->_split_children != nullptr, "no split children available");
4269 int len = parent->_split_children->length();
4270 assert(len > 0, "no split children available");
4271
4272 for (int i = len - 1; i >= 0; i--) {
4273 Interval* cur = parent->_split_children->at(i);
4274 if (cur->to() <= op_id && (result == nullptr || result->to() < cur->to())) {
4275 result = cur;
4276 }
4277 }
4278
4279 assert(result != nullptr, "no split child found");
4280 return result;
4281 }
4282
4283
4284 // Note: use positions are sorted descending -> first use has highest index
4285 int Interval::first_usage(IntervalUseKind min_use_kind) const {
4286 assert(LinearScan::is_virtual_interval(this), "cannot access use positions for fixed intervals");
4287
4288 for (int i = _use_pos_and_kinds.length() - 2; i >= 0; i -= 2) {
4289 if (_use_pos_and_kinds.at(i + 1) >= min_use_kind) {
4290 return _use_pos_and_kinds.at(i);
4291 }
4292 }
4293 return max_jint;
4294 }
4295
4296 int Interval::next_usage(IntervalUseKind min_use_kind, int from) const {
4297 assert(LinearScan::is_virtual_interval(this), "cannot access use positions for fixed intervals");
4298
4299 for (int i = _use_pos_and_kinds.length() - 2; i >= 0; i -= 2) {
4300 if (_use_pos_and_kinds.at(i) >= from && _use_pos_and_kinds.at(i + 1) >= min_use_kind) {
4301 return _use_pos_and_kinds.at(i);
4302 }
4303 }
4304 return max_jint;
4305 }
4306
4307 int Interval::next_usage_exact(IntervalUseKind exact_use_kind, int from) const {
4308 assert(LinearScan::is_virtual_interval(this), "cannot access use positions for fixed intervals");
4309
4310 for (int i = _use_pos_and_kinds.length() - 2; i >= 0; i -= 2) {
4311 if (_use_pos_and_kinds.at(i) >= from && _use_pos_and_kinds.at(i + 1) == exact_use_kind) {
4312 return _use_pos_and_kinds.at(i);
4313 }
4314 }
4315 return max_jint;
4316 }
4317
4318 int Interval::previous_usage(IntervalUseKind min_use_kind, int from) const {
4319 assert(LinearScan::is_virtual_interval(this), "cannot access use positions for fixed intervals");
4320
4321 int prev = 0;
4322 for (int i = _use_pos_and_kinds.length() - 2; i >= 0; i -= 2) {
4323 if (_use_pos_and_kinds.at(i) > from) {
4324 return prev;
4325 }
4326 if (_use_pos_and_kinds.at(i + 1) >= min_use_kind) {
4327 prev = _use_pos_and_kinds.at(i);
4328 }
4329 }
4330 return prev;
4331 }
4332
4333 void Interval::add_use_pos(int pos, IntervalUseKind use_kind) {
4334 assert(covers(pos, LIR_OpVisitState::inputMode), "use position not covered by live range");
4335
4336 // do not add use positions for precolored intervals because
4337 // they are never used
4338 if (use_kind != noUse && reg_num() >= LIR_Opr::vreg_base) {
4339 #ifdef ASSERT
4340 assert(_use_pos_and_kinds.length() % 2 == 0, "must be");
4341 for (int i = 0; i < _use_pos_and_kinds.length(); i += 2) {
4342 assert(pos <= _use_pos_and_kinds.at(i), "already added a use-position with lower position");
4343 assert(_use_pos_and_kinds.at(i + 1) >= firstValidKind && _use_pos_and_kinds.at(i + 1) <= lastValidKind, "invalid use kind");
4344 if (i > 0) {
4345 assert(_use_pos_and_kinds.at(i) < _use_pos_and_kinds.at(i - 2), "not sorted descending");
4346 }
4347 }
4348 #endif
4349
4350 // Note: add_use is called in descending order, so list gets sorted
4351 // automatically by just appending new use positions
4352 int len = _use_pos_and_kinds.length();
4353 if (len == 0 || _use_pos_and_kinds.at(len - 2) > pos) {
4354 _use_pos_and_kinds.append(pos);
4355 _use_pos_and_kinds.append(use_kind);
4356 } else if (_use_pos_and_kinds.at(len - 1) < use_kind) {
4357 assert(_use_pos_and_kinds.at(len - 2) == pos, "list not sorted correctly");
4358 _use_pos_and_kinds.at_put(len - 1, use_kind);
4359 }
4360 }
4361 }
4362
4363 void Interval::add_range(int from, int to) {
4364 assert(from < to, "invalid range");
4365 assert(first() == Range::end() || to < first()->next()->from(), "not inserting at begin of interval");
4366 assert(from <= first()->to(), "not inserting at begin of interval");
4367
4368 if (first()->from() <= to) {
4369 // join intersecting ranges
4370 first()->set_from(MIN2(from, first()->from()));
4371 first()->set_to (MAX2(to, first()->to()));
4372 } else {
4373 // insert new range
4374 _first = new Range(from, to, first());
4375 }
4376 }
4377
4378 Interval* Interval::new_split_child() {
4379 // allocate new interval
4380 Interval* result = new Interval(-1);
4381 result->set_type(type());
4382
4383 Interval* parent = split_parent();
4384 result->_split_parent = parent;
4385 result->set_register_hint(parent);
4386
4387 // insert new interval in children-list of parent
4388 if (parent->_split_children == nullptr) {
4389 assert(is_split_parent(), "list must be initialized at first split");
4390
4391 parent->_split_children = new IntervalList(4);
4392 parent->_split_children->append(this);
4393 }
4394 parent->_split_children->append(result);
4395
4396 return result;
4397 }
4398
4399 // split this interval at the specified position and return
4400 // the remainder as a new interval.
4401 //
4402 // when an interval is split, a bi-directional link is established between the original interval
4403 // (the split parent) and the intervals that are split off this interval (the split children)
4404 // When a split child is split again, the new created interval is also a direct child
4405 // of the original parent (there is no tree of split children stored, but a flat list)
4406 // All split children are spilled to the same stack slot (stored in _canonical_spill_slot)
4407 //
4408 // Note: The new interval has no valid reg_num
4409 Interval* Interval::split(int split_pos) {
4410 assert(LinearScan::is_virtual_interval(this), "cannot split fixed intervals");
4411
4412 // allocate new interval
4413 Interval* result = new_split_child();
4414
4415 // split the ranges
4416 Range* prev = nullptr;
4417 Range* cur = _first;
4418 while (cur != Range::end() && cur->to() <= split_pos) {
4419 prev = cur;
4420 cur = cur->next();
4421 }
4422 assert(cur != Range::end(), "split interval after end of last range");
4423
4424 if (cur->from() < split_pos) {
4425 result->_first = new Range(split_pos, cur->to(), cur->next());
4426 cur->set_to(split_pos);
4427 cur->set_next(Range::end());
4428
4429 } else {
4430 assert(prev != nullptr, "split before start of first range");
4431 result->_first = cur;
4432 prev->set_next(Range::end());
4433 }
4434 result->_current = result->_first;
4435 _cached_to = -1; // clear cached value
4436
4437 // split list of use positions
4438 int total_len = _use_pos_and_kinds.length();
4439 int start_idx = total_len - 2;
4440 while (start_idx >= 0 && _use_pos_and_kinds.at(start_idx) < split_pos) {
4441 start_idx -= 2;
4442 }
4443
4444 intStack new_use_pos_and_kinds(total_len - start_idx);
4445 int i;
4446 for (i = start_idx + 2; i < total_len; i++) {
4447 new_use_pos_and_kinds.append(_use_pos_and_kinds.at(i));
4448 }
4449
4450 _use_pos_and_kinds.trunc_to(start_idx + 2);
4451 result->_use_pos_and_kinds = _use_pos_and_kinds;
4452 _use_pos_and_kinds = new_use_pos_and_kinds;
4453
4454 #ifdef ASSERT
4455 assert(_use_pos_and_kinds.length() % 2 == 0, "must have use kind for each use pos");
4456 assert(result->_use_pos_and_kinds.length() % 2 == 0, "must have use kind for each use pos");
4457 assert(_use_pos_and_kinds.length() + result->_use_pos_and_kinds.length() == total_len, "missed some entries");
4458
4459 for (i = 0; i < _use_pos_and_kinds.length(); i += 2) {
4460 assert(_use_pos_and_kinds.at(i) < split_pos, "must be");
4461 assert(_use_pos_and_kinds.at(i + 1) >= firstValidKind && _use_pos_and_kinds.at(i + 1) <= lastValidKind, "invalid use kind");
4462 }
4463 for (i = 0; i < result->_use_pos_and_kinds.length(); i += 2) {
4464 assert(result->_use_pos_and_kinds.at(i) >= split_pos, "must be");
4465 assert(result->_use_pos_and_kinds.at(i + 1) >= firstValidKind && result->_use_pos_and_kinds.at(i + 1) <= lastValidKind, "invalid use kind");
4466 }
4467 #endif
4468
4469 return result;
4470 }
4471
4472 // split this interval at the specified position and return
4473 // the head as a new interval (the original interval is the tail)
4474 //
4475 // Currently, only the first range can be split, and the new interval
4476 // must not have split positions
4477 Interval* Interval::split_from_start(int split_pos) {
4478 assert(LinearScan::is_virtual_interval(this), "cannot split fixed intervals");
4479 assert(split_pos > from() && split_pos < to(), "can only split inside interval");
4480 assert(split_pos > _first->from() && split_pos <= _first->to(), "can only split inside first range");
4481 assert(first_usage(noUse) > split_pos, "can not split when use positions are present");
4482
4483 // allocate new interval
4484 Interval* result = new_split_child();
4485
4486 // the new created interval has only one range (checked by assertion above),
4487 // so the splitting of the ranges is very simple
4488 result->add_range(_first->from(), split_pos);
4489
4490 if (split_pos == _first->to()) {
4491 assert(_first->next() != Range::end(), "must not be at end");
4492 _first = _first->next();
4493 } else {
4494 _first->set_from(split_pos);
4495 }
4496
4497 return result;
4498 }
4499
4500
4501 // returns true if the op_id is inside the interval
4502 bool Interval::covers(int op_id, LIR_OpVisitState::OprMode mode) const {
4503 Range* cur = _first;
4504
4505 while (cur != Range::end() && cur->to() < op_id) {
4506 cur = cur->next();
4507 }
4508 if (cur != Range::end()) {
4509 assert(cur->to() != cur->next()->from(), "ranges not separated");
4510
4511 if (mode == LIR_OpVisitState::outputMode) {
4512 return cur->from() <= op_id && op_id < cur->to();
4513 } else {
4514 return cur->from() <= op_id && op_id <= cur->to();
4515 }
4516 }
4517 return false;
4518 }
4519
4520 // returns true if the interval has any hole between hole_from and hole_to
4521 // (even if the hole has only the length 1)
4522 bool Interval::has_hole_between(int hole_from, int hole_to) {
4523 assert(hole_from < hole_to, "check");
4524 assert(from() <= hole_from && hole_to <= to(), "index out of interval");
4525
4526 Range* cur = _first;
4527 while (cur != Range::end()) {
4528 assert(cur->to() < cur->next()->from(), "no space between ranges");
4529
4530 // hole-range starts before this range -> hole
4531 if (hole_from < cur->from()) {
4532 return true;
4533
4534 // hole-range completely inside this range -> no hole
4535 } else if (hole_to <= cur->to()) {
4536 return false;
4537
4538 // overlapping of hole-range with this range -> hole
4539 } else if (hole_from <= cur->to()) {
4540 return true;
4541 }
4542
4543 cur = cur->next();
4544 }
4545
4546 return false;
4547 }
4548
4549 // Check if there is an intersection with any of the split children of 'interval'
4550 bool Interval::intersects_any_children_of(Interval* interval) const {
4551 if (interval->_split_children != nullptr) {
4552 for (int i = 0; i < interval->_split_children->length(); i++) {
4553 if (intersects(interval->_split_children->at(i))) {
4554 return true;
4555 }
4556 }
4557 }
4558 return false;
4559 }
4560
4561
4562 #ifndef PRODUCT
4563 void Interval::print_on(outputStream* out, bool is_cfg_printer) const {
4564 const char* SpillState2Name[] = { "no definition", "no spill store", "one spill store", "store at definition", "start in memory", "no optimization" };
4565 const char* UseKind2Name[] = { "N", "L", "S", "M" };
4566
4567 const char* type_name;
4568 if (reg_num() < LIR_Opr::vreg_base) {
4569 type_name = "fixed";
4570 } else {
4571 type_name = type2name(type());
4572 }
4573 out->print("%d %s ", reg_num(), type_name);
4574
4575 if (is_cfg_printer) {
4576 // Special version for compatibility with C1 Visualizer.
4577 LIR_Opr opr = LinearScan::get_operand(reg_num());
4578 if (opr->is_valid()) {
4579 out->print("\"");
4580 opr->print(out);
4581 out->print("\" ");
4582 }
4583 } else {
4584 // Improved output for normal debugging.
4585 if (reg_num() < LIR_Opr::vreg_base) {
4586 LinearScan::print_reg_num(out, assigned_reg());
4587 } else if (assigned_reg() != -1 && (LinearScan::num_physical_regs(type()) == 1 || assigned_regHi() != -1)) {
4588 LinearScan::calc_operand_for_interval(this)->print(out);
4589 } else {
4590 // Virtual register that has no assigned register yet.
4591 out->print("[ANY]");
4592 }
4593 out->print(" ");
4594 }
4595 out->print("%d %d ", split_parent()->reg_num(), (register_hint(false) != nullptr ? register_hint(false)->reg_num() : -1));
4596
4597 // print ranges
4598 Range* cur = _first;
4599 while (cur != Range::end()) {
4600 cur->print(out);
4601 cur = cur->next();
4602 assert(cur != nullptr, "range list not closed with range sentinel");
4603 }
4604
4605 // print use positions
4606 int prev = 0;
4607 assert(_use_pos_and_kinds.length() % 2 == 0, "must be");
4608 for (int i =_use_pos_and_kinds.length() - 2; i >= 0; i -= 2) {
4609 assert(_use_pos_and_kinds.at(i + 1) >= firstValidKind && _use_pos_and_kinds.at(i + 1) <= lastValidKind, "invalid use kind");
4610 assert(prev < _use_pos_and_kinds.at(i), "use positions not sorted");
4611
4612 out->print("%d %s ", _use_pos_and_kinds.at(i), UseKind2Name[_use_pos_and_kinds.at(i + 1)]);
4613 prev = _use_pos_and_kinds.at(i);
4614 }
4615
4616 out->print(" \"%s\"", SpillState2Name[spill_state()]);
4617 out->cr();
4618 }
4619
4620 void Interval::print_parent() const {
4621 if (_split_parent != this) {
4622 _split_parent->print_on(tty);
4623 } else {
4624 tty->print_cr("Parent: this");
4625 }
4626 }
4627
4628 void Interval::print_children() const {
4629 if (_split_children == nullptr) {
4630 tty->print_cr("Children: []");
4631 } else {
4632 tty->print_cr("Children:");
4633 for (int i = 0; i < _split_children->length(); i++) {
4634 tty->print("%d: ", i);
4635 _split_children->at(i)->print_on(tty);
4636 }
4637 }
4638 }
4639 #endif // NOT PRODUCT
4640
4641
4642
4643
4644 // **** Implementation of IntervalWalker ****************************
4645
4646 IntervalWalker::IntervalWalker(LinearScan* allocator, Interval* unhandled_fixed_first, Interval* unhandled_any_first)
4647 : _compilation(allocator->compilation())
4648 , _allocator(allocator)
4649 {
4650 _unhandled_first[fixedKind] = unhandled_fixed_first;
4651 _unhandled_first[anyKind] = unhandled_any_first;
4652 _active_first[fixedKind] = Interval::end();
4653 _inactive_first[fixedKind] = Interval::end();
4654 _active_first[anyKind] = Interval::end();
4655 _inactive_first[anyKind] = Interval::end();
4656 _current_position = -1;
4657 _current = nullptr;
4658 next_interval();
4659 }
4660
4661
4662 // append interval in order of current range from()
4663 void IntervalWalker::append_sorted(Interval** list, Interval* interval) {
4664 Interval* prev = nullptr;
4665 Interval* cur = *list;
4666 while (cur->current_from() < interval->current_from()) {
4667 prev = cur; cur = cur->next();
4668 }
4669 if (prev == nullptr) {
4670 *list = interval;
4671 } else {
4672 prev->set_next(interval);
4673 }
4674 interval->set_next(cur);
4675 }
4676
4677 void IntervalWalker::append_to_unhandled(Interval** list, Interval* interval) {
4678 assert(interval->from() >= current()->current_from(), "cannot append new interval before current walk position");
4679
4680 Interval* prev = nullptr;
4681 Interval* cur = *list;
4682 while (cur->from() < interval->from() || (cur->from() == interval->from() && cur->first_usage(noUse) < interval->first_usage(noUse))) {
4683 prev = cur; cur = cur->next();
4684 }
4685 if (prev == nullptr) {
4686 *list = interval;
4687 } else {
4688 prev->set_next(interval);
4689 }
4690 interval->set_next(cur);
4691 }
4692
4693
4694 inline bool IntervalWalker::remove_from_list(Interval** list, Interval* i) {
4695 while (*list != Interval::end() && *list != i) {
4696 list = (*list)->next_addr();
4697 }
4698 if (*list != Interval::end()) {
4699 assert(*list == i, "check");
4700 *list = (*list)->next();
4701 return true;
4702 } else {
4703 return false;
4704 }
4705 }
4706
4707 void IntervalWalker::remove_from_list(Interval* i) {
4708 bool deleted;
4709
4710 if (i->state() == activeState) {
4711 deleted = remove_from_list(active_first_addr(anyKind), i);
4712 } else {
4713 assert(i->state() == inactiveState, "invalid state");
4714 deleted = remove_from_list(inactive_first_addr(anyKind), i);
4715 }
4716
4717 assert(deleted, "interval has not been found in list");
4718 }
4719
4720
4721 void IntervalWalker::walk_to(IntervalState state, int from) {
4722 assert (state == activeState || state == inactiveState, "wrong state");
4723 for_each_interval_kind(kind) {
4724 Interval** prev = state == activeState ? active_first_addr(kind) : inactive_first_addr(kind);
4725 Interval* next = *prev;
4726 while (next->current_from() <= from) {
4727 Interval* cur = next;
4728 next = cur->next();
4729
4730 bool range_has_changed = false;
4731 while (cur->current_to() <= from) {
4732 cur->next_range();
4733 range_has_changed = true;
4734 }
4735
4736 // also handle move from inactive list to active list
4737 range_has_changed = range_has_changed || (state == inactiveState && cur->current_from() <= from);
4738
4739 if (range_has_changed) {
4740 // remove cur from list
4741 *prev = next;
4742 if (cur->current_at_end()) {
4743 // move to handled state (not maintained as a list)
4744 cur->set_state(handledState);
4745 DEBUG_ONLY(interval_moved(cur, kind, state, handledState);)
4746 } else if (cur->current_from() <= from){
4747 // sort into active list
4748 append_sorted(active_first_addr(kind), cur);
4749 cur->set_state(activeState);
4750 if (*prev == cur) {
4751 assert(state == activeState, "check");
4752 prev = cur->next_addr();
4753 }
4754 DEBUG_ONLY(interval_moved(cur, kind, state, activeState);)
4755 } else {
4756 // sort into inactive list
4757 append_sorted(inactive_first_addr(kind), cur);
4758 cur->set_state(inactiveState);
4759 if (*prev == cur) {
4760 assert(state == inactiveState, "check");
4761 prev = cur->next_addr();
4762 }
4763 DEBUG_ONLY(interval_moved(cur, kind, state, inactiveState);)
4764 }
4765 } else {
4766 prev = cur->next_addr();
4767 continue;
4768 }
4769 }
4770 }
4771 }
4772
4773
4774 void IntervalWalker::next_interval() {
4775 IntervalKind kind;
4776 Interval* any = _unhandled_first[anyKind];
4777 Interval* fixed = _unhandled_first[fixedKind];
4778
4779 if (any != Interval::end()) {
4780 // intervals may start at same position -> prefer fixed interval
4781 kind = fixed != Interval::end() && fixed->from() <= any->from() ? fixedKind : anyKind;
4782
4783 assert((kind == fixedKind && fixed->from() <= any->from()) ||
4784 (kind == anyKind && any->from() <= fixed->from()), "wrong interval!!!");
4785 assert(any == Interval::end() || fixed == Interval::end() || any->from() != fixed->from() || kind == fixedKind, "if fixed and any-Interval start at same position, fixed must be processed first");
4786
4787 } else if (fixed != Interval::end()) {
4788 kind = fixedKind;
4789 } else {
4790 _current = nullptr; return;
4791 }
4792 _current_kind = kind;
4793 _current = _unhandled_first[kind];
4794 _unhandled_first[kind] = _current->next();
4795 _current->set_next(Interval::end());
4796 _current->rewind_range();
4797 }
4798
4799
4800 void IntervalWalker::walk_to(int lir_op_id) {
4801 assert(_current_position <= lir_op_id, "can not walk backwards");
4802 while (current() != nullptr) {
4803 bool is_active = current()->from() <= lir_op_id;
4804 int id = is_active ? current()->from() : lir_op_id;
4805
4806 TRACE_LINEAR_SCAN(2, if (_current_position < id) { tty->cr(); tty->print_cr("walk_to(%d) **************************************************************", id); })
4807
4808 // set _current_position prior to call of walk_to
4809 _current_position = id;
4810
4811 // call walk_to even if _current_position == id
4812 walk_to(activeState, id);
4813 walk_to(inactiveState, id);
4814
4815 if (is_active) {
4816 current()->set_state(activeState);
4817 if (activate_current()) {
4818 append_sorted(active_first_addr(current_kind()), current());
4819 DEBUG_ONLY(interval_moved(current(), current_kind(), unhandledState, activeState);)
4820 }
4821
4822 next_interval();
4823 } else {
4824 return;
4825 }
4826 }
4827 }
4828
4829 #ifdef ASSERT
4830 void IntervalWalker::interval_moved(Interval* interval, IntervalKind kind, IntervalState from, IntervalState to) {
4831 if (TraceLinearScanLevel >= 4) {
4832 #define print_state(state) \
4833 switch(state) {\
4834 case unhandledState: tty->print("unhandled"); break;\
4835 case activeState: tty->print("active"); break;\
4836 case inactiveState: tty->print("inactive"); break;\
4837 case handledState: tty->print("handled"); break;\
4838 default: ShouldNotReachHere(); \
4839 }
4840
4841 print_state(from); tty->print(" to "); print_state(to);
4842 tty->fill_to(23);
4843 interval->print();
4844
4845 #undef print_state
4846 }
4847 }
4848 #endif // ASSERT
4849
4850 // **** Implementation of LinearScanWalker **************************
4851
4852 LinearScanWalker::LinearScanWalker(LinearScan* allocator, Interval* unhandled_fixed_first, Interval* unhandled_any_first)
4853 : IntervalWalker(allocator, unhandled_fixed_first, unhandled_any_first)
4854 , _move_resolver(allocator)
4855 {
4856 for (int i = 0; i < LinearScan::nof_regs; i++) {
4857 _spill_intervals[i] = new IntervalList(2);
4858 }
4859 }
4860
4861
4862 inline void LinearScanWalker::init_use_lists(bool only_process_use_pos) {
4863 for (int i = _first_reg; i <= _last_reg; i++) {
4864 _use_pos[i] = max_jint;
4865
4866 if (!only_process_use_pos) {
4867 _block_pos[i] = max_jint;
4868 _spill_intervals[i]->clear();
4869 }
4870 }
4871 }
4872
4873 inline void LinearScanWalker::exclude_from_use(int reg) {
4874 assert(reg < LinearScan::nof_regs, "interval must have a register assigned (stack slots not allowed)");
4875 if (reg >= _first_reg && reg <= _last_reg) {
4876 _use_pos[reg] = 0;
4877 }
4878 }
4879 inline void LinearScanWalker::exclude_from_use(Interval* i) {
4880 assert(i->assigned_reg() != any_reg, "interval has no register assigned");
4881
4882 exclude_from_use(i->assigned_reg());
4883 exclude_from_use(i->assigned_regHi());
4884 }
4885
4886 inline void LinearScanWalker::set_use_pos(int reg, Interval* i, int use_pos, bool only_process_use_pos) {
4887 assert(use_pos != 0, "must use exclude_from_use to set use_pos to 0");
4888
4889 if (reg >= _first_reg && reg <= _last_reg) {
4890 if (_use_pos[reg] > use_pos) {
4891 _use_pos[reg] = use_pos;
4892 }
4893 if (!only_process_use_pos) {
4894 _spill_intervals[reg]->append(i);
4895 }
4896 }
4897 }
4898 inline void LinearScanWalker::set_use_pos(Interval* i, int use_pos, bool only_process_use_pos) {
4899 assert(i->assigned_reg() != any_reg, "interval has no register assigned");
4900 if (use_pos != -1) {
4901 set_use_pos(i->assigned_reg(), i, use_pos, only_process_use_pos);
4902 set_use_pos(i->assigned_regHi(), i, use_pos, only_process_use_pos);
4903 }
4904 }
4905
4906 inline void LinearScanWalker::set_block_pos(int reg, Interval* i, int block_pos) {
4907 if (reg >= _first_reg && reg <= _last_reg) {
4908 if (_block_pos[reg] > block_pos) {
4909 _block_pos[reg] = block_pos;
4910 }
4911 if (_use_pos[reg] > block_pos) {
4912 _use_pos[reg] = block_pos;
4913 }
4914 }
4915 }
4916 inline void LinearScanWalker::set_block_pos(Interval* i, int block_pos) {
4917 assert(i->assigned_reg() != any_reg, "interval has no register assigned");
4918 if (block_pos != -1) {
4919 set_block_pos(i->assigned_reg(), i, block_pos);
4920 set_block_pos(i->assigned_regHi(), i, block_pos);
4921 }
4922 }
4923
4924
4925 void LinearScanWalker::free_exclude_active_fixed() {
4926 Interval* list = active_first(fixedKind);
4927 while (list != Interval::end()) {
4928 assert(list->assigned_reg() < LinearScan::nof_regs, "active interval must have a register assigned");
4929 exclude_from_use(list);
4930 list = list->next();
4931 }
4932 }
4933
4934 void LinearScanWalker::free_exclude_active_any() {
4935 Interval* list = active_first(anyKind);
4936 while (list != Interval::end()) {
4937 exclude_from_use(list);
4938 list = list->next();
4939 }
4940 }
4941
4942 void LinearScanWalker::free_collect_inactive_fixed(Interval* cur) {
4943 Interval* list = inactive_first(fixedKind);
4944 while (list != Interval::end()) {
4945 if (cur->to() <= list->current_from()) {
4946 assert(list->current_intersects_at(cur) == -1, "must not intersect");
4947 set_use_pos(list, list->current_from(), true);
4948 } else {
4949 set_use_pos(list, list->current_intersects_at(cur), true);
4950 }
4951 list = list->next();
4952 }
4953 }
4954
4955 void LinearScanWalker::free_collect_inactive_any(Interval* cur) {
4956 Interval* list = inactive_first(anyKind);
4957 while (list != Interval::end()) {
4958 set_use_pos(list, list->current_intersects_at(cur), true);
4959 list = list->next();
4960 }
4961 }
4962
4963 void LinearScanWalker::spill_exclude_active_fixed() {
4964 Interval* list = active_first(fixedKind);
4965 while (list != Interval::end()) {
4966 exclude_from_use(list);
4967 list = list->next();
4968 }
4969 }
4970
4971 void LinearScanWalker::spill_block_inactive_fixed(Interval* cur) {
4972 Interval* list = inactive_first(fixedKind);
4973 while (list != Interval::end()) {
4974 if (cur->to() > list->current_from()) {
4975 set_block_pos(list, list->current_intersects_at(cur));
4976 } else {
4977 assert(list->current_intersects_at(cur) == -1, "invalid optimization: intervals intersect");
4978 }
4979
4980 list = list->next();
4981 }
4982 }
4983
4984 void LinearScanWalker::spill_collect_active_any() {
4985 Interval* list = active_first(anyKind);
4986 while (list != Interval::end()) {
4987 set_use_pos(list, MIN2(list->next_usage(loopEndMarker, _current_position), list->to()), false);
4988 list = list->next();
4989 }
4990 }
4991
4992 void LinearScanWalker::spill_collect_inactive_any(Interval* cur) {
4993 Interval* list = inactive_first(anyKind);
4994 while (list != Interval::end()) {
4995 if (list->current_intersects(cur)) {
4996 set_use_pos(list, MIN2(list->next_usage(loopEndMarker, _current_position), list->to()), false);
4997 }
4998 list = list->next();
4999 }
5000 }
5001
5002
5003 void LinearScanWalker::insert_move(int op_id, Interval* src_it, Interval* dst_it) {
5004 // output all moves here. When source and target are equal, the move is
5005 // optimized away later in assign_reg_nums
5006
5007 op_id = (op_id + 1) & ~1;
5008 BlockBegin* op_block = allocator()->block_of_op_with_id(op_id);
5009 assert(op_id > 0 && allocator()->block_of_op_with_id(op_id - 2) == op_block, "cannot insert move at block boundary");
5010
5011 // calculate index of instruction inside instruction list of current block
5012 // the minimal index (for a block with no spill moves) can be calculated because the
5013 // numbering of instructions is known.
5014 // When the block already contains spill moves, the index must be increased until the
5015 // correct index is reached.
5016 LIR_OpList* list = op_block->lir()->instructions_list();
5017 int index = (op_id - list->at(0)->id()) / 2;
5018 assert(list->at(index)->id() <= op_id, "error in calculation");
5019
5020 while (list->at(index)->id() != op_id) {
5021 index++;
5022 assert(0 <= index && index < list->length(), "index out of bounds");
5023 }
5024 assert(1 <= index && index < list->length(), "index out of bounds");
5025 assert(list->at(index)->id() == op_id, "error in calculation");
5026
5027 // insert new instruction before instruction at position index
5028 _move_resolver.move_insert_position(op_block->lir(), index - 1);
5029 _move_resolver.add_mapping(src_it, dst_it);
5030 }
5031
5032
5033 int LinearScanWalker::find_optimal_split_pos(BlockBegin* min_block, BlockBegin* max_block, int max_split_pos) {
5034 int from_block_nr = min_block->linear_scan_number();
5035 int to_block_nr = max_block->linear_scan_number();
5036
5037 assert(0 <= from_block_nr && from_block_nr < block_count(), "out of range");
5038 assert(0 <= to_block_nr && to_block_nr < block_count(), "out of range");
5039 assert(from_block_nr < to_block_nr, "must cross block boundary");
5040
5041 // Try to split at end of max_block. If this would be after
5042 // max_split_pos, then use the begin of max_block
5043 int optimal_split_pos = max_block->last_lir_instruction_id() + 2;
5044 if (optimal_split_pos > max_split_pos) {
5045 optimal_split_pos = max_block->first_lir_instruction_id();
5046 }
5047
5048 int min_loop_depth = max_block->loop_depth();
5049 for (int i = to_block_nr - 1; i >= from_block_nr; i--) {
5050 BlockBegin* cur = block_at(i);
5051
5052 if (cur->loop_depth() < min_loop_depth) {
5053 // block with lower loop-depth found -> split at the end of this block
5054 min_loop_depth = cur->loop_depth();
5055 optimal_split_pos = cur->last_lir_instruction_id() + 2;
5056 }
5057 }
5058 assert(optimal_split_pos > allocator()->max_lir_op_id() || allocator()->is_block_begin(optimal_split_pos), "algorithm must move split pos to block boundary");
5059
5060 return optimal_split_pos;
5061 }
5062
5063
5064 int LinearScanWalker::find_optimal_split_pos(Interval* it, int min_split_pos, int max_split_pos, bool do_loop_optimization) {
5065 int optimal_split_pos = -1;
5066 if (min_split_pos == max_split_pos) {
5067 // trivial case, no optimization of split position possible
5068 TRACE_LINEAR_SCAN(4, tty->print_cr(" min-pos and max-pos are equal, no optimization possible"));
5069 optimal_split_pos = min_split_pos;
5070
5071 } else {
5072 assert(min_split_pos < max_split_pos, "must be true then");
5073 assert(min_split_pos > 0, "cannot access min_split_pos - 1 otherwise");
5074
5075 // reason for using min_split_pos - 1: when the minimal split pos is exactly at the
5076 // beginning of a block, then min_split_pos is also a possible split position.
5077 // Use the block before as min_block, because then min_block->last_lir_instruction_id() + 2 == min_split_pos
5078 BlockBegin* min_block = allocator()->block_of_op_with_id(min_split_pos - 1);
5079
5080 // reason for using max_split_pos - 1: otherwise there would be an assertion failure
5081 // when an interval ends at the end of the last block of the method
5082 // (in this case, max_split_pos == allocator()->max_lir_op_id() + 2, and there is no
5083 // block at this op_id)
5084 BlockBegin* max_block = allocator()->block_of_op_with_id(max_split_pos - 1);
5085
5086 assert(min_block->linear_scan_number() <= max_block->linear_scan_number(), "invalid order");
5087 if (min_block == max_block) {
5088 // split position cannot be moved to block boundary, so split as late as possible
5089 TRACE_LINEAR_SCAN(4, tty->print_cr(" cannot move split pos to block boundary because min_pos and max_pos are in same block"));
5090 optimal_split_pos = max_split_pos;
5091
5092 } else if (it->has_hole_between(max_split_pos - 1, max_split_pos) && !allocator()->is_block_begin(max_split_pos)) {
5093 // Do not move split position if the interval has a hole before max_split_pos.
5094 // Intervals resulting from Phi-Functions have more than one definition (marked
5095 // as mustHaveRegister) with a hole before each definition. When the register is needed
5096 // for the second definition, an earlier reloading is unnecessary.
5097 TRACE_LINEAR_SCAN(4, tty->print_cr(" interval has hole just before max_split_pos, so splitting at max_split_pos"));
5098 optimal_split_pos = max_split_pos;
5099
5100 } else {
5101 // search optimal block boundary between min_split_pos and max_split_pos
5102 TRACE_LINEAR_SCAN(4, tty->print_cr(" moving split pos to optimal block boundary between block B%d and B%d", min_block->block_id(), max_block->block_id()));
5103
5104 if (do_loop_optimization) {
5105 // Loop optimization: if a loop-end marker is found between min- and max-position,
5106 // then split before this loop
5107 int loop_end_pos = it->next_usage_exact(loopEndMarker, min_block->last_lir_instruction_id() + 2);
5108 TRACE_LINEAR_SCAN(4, tty->print_cr(" loop optimization: loop end found at pos %d", loop_end_pos));
5109
5110 assert(loop_end_pos > min_split_pos, "invalid order");
5111 if (loop_end_pos < max_split_pos) {
5112 // loop-end marker found between min- and max-position
5113 // if it is not the end marker for the same loop as the min-position, then move
5114 // the max-position to this loop block.
5115 // Desired result: uses tagged as shouldHaveRegister inside a loop cause a reloading
5116 // of the interval (normally, only mustHaveRegister causes a reloading)
5117 BlockBegin* loop_block = allocator()->block_of_op_with_id(loop_end_pos);
5118
5119 TRACE_LINEAR_SCAN(4, tty->print_cr(" interval is used in loop that ends in block B%d, so trying to move max_block back from B%d to B%d", loop_block->block_id(), max_block->block_id(), loop_block->block_id()));
5120 assert(loop_block != min_block, "loop_block and min_block must be different because block boundary is needed between");
5121
5122 optimal_split_pos = find_optimal_split_pos(min_block, loop_block, loop_block->last_lir_instruction_id() + 2);
5123 if (optimal_split_pos == loop_block->last_lir_instruction_id() + 2) {
5124 optimal_split_pos = -1;
5125 TRACE_LINEAR_SCAN(4, tty->print_cr(" loop optimization not necessary"));
5126 } else {
5127 TRACE_LINEAR_SCAN(4, tty->print_cr(" loop optimization successful"));
5128 }
5129 }
5130 }
5131
5132 if (optimal_split_pos == -1) {
5133 // not calculated by loop optimization
5134 optimal_split_pos = find_optimal_split_pos(min_block, max_block, max_split_pos);
5135 }
5136 }
5137 }
5138 TRACE_LINEAR_SCAN(4, tty->print_cr(" optimal split position: %d", optimal_split_pos));
5139
5140 return optimal_split_pos;
5141 }
5142
5143
5144 /*
5145 split an interval at the optimal position between min_split_pos and
5146 max_split_pos in two parts:
5147 1) the left part has already a location assigned
5148 2) the right part is sorted into to the unhandled-list
5149 */
5150 void LinearScanWalker::split_before_usage(Interval* it, int min_split_pos, int max_split_pos) {
5151 TRACE_LINEAR_SCAN(2, tty->print ("----- splitting interval: "); it->print());
5152 TRACE_LINEAR_SCAN(2, tty->print_cr(" between %d and %d", min_split_pos, max_split_pos));
5153
5154 assert(it->from() < min_split_pos, "cannot split at start of interval");
5155 assert(current_position() < min_split_pos, "cannot split before current position");
5156 assert(min_split_pos <= max_split_pos, "invalid order");
5157 assert(max_split_pos <= it->to(), "cannot split after end of interval");
5158
5159 int optimal_split_pos = find_optimal_split_pos(it, min_split_pos, max_split_pos, true);
5160
5161 assert(min_split_pos <= optimal_split_pos && optimal_split_pos <= max_split_pos, "out of range");
5162 assert(optimal_split_pos <= it->to(), "cannot split after end of interval");
5163 assert(optimal_split_pos > it->from(), "cannot split at start of interval");
5164
5165 if (optimal_split_pos == it->to() && it->next_usage(mustHaveRegister, min_split_pos) == max_jint) {
5166 // the split position would be just before the end of the interval
5167 // -> no split at all necessary
5168 TRACE_LINEAR_SCAN(4, tty->print_cr(" no split necessary because optimal split position is at end of interval"));
5169 return;
5170 }
5171
5172 // must calculate this before the actual split is performed and before split position is moved to odd op_id
5173 bool move_necessary = !allocator()->is_block_begin(optimal_split_pos) && !it->has_hole_between(optimal_split_pos - 1, optimal_split_pos);
5174
5175 if (!allocator()->is_block_begin(optimal_split_pos)) {
5176 // move position before actual instruction (odd op_id)
5177 optimal_split_pos = (optimal_split_pos - 1) | 1;
5178 }
5179
5180 TRACE_LINEAR_SCAN(4, tty->print_cr(" splitting at position %d", optimal_split_pos));
5181 assert(allocator()->is_block_begin(optimal_split_pos) || (optimal_split_pos % 2 == 1), "split pos must be odd when not on block boundary");
5182 assert(!allocator()->is_block_begin(optimal_split_pos) || (optimal_split_pos % 2 == 0), "split pos must be even on block boundary");
5183
5184 Interval* split_part = it->split(optimal_split_pos);
5185
5186 allocator()->append_interval(split_part);
5187 allocator()->copy_register_flags(it, split_part);
5188 split_part->set_insert_move_when_activated(move_necessary);
5189 append_to_unhandled(unhandled_first_addr(anyKind), split_part);
5190
5191 TRACE_LINEAR_SCAN(2, tty->print_cr(" split interval in two parts (insert_move_when_activated: %d)", move_necessary));
5192 TRACE_LINEAR_SCAN(2, tty->print (" "); it->print());
5193 TRACE_LINEAR_SCAN(2, tty->print (" "); split_part->print());
5194 }
5195
5196 /*
5197 split an interval at the optimal position between min_split_pos and
5198 max_split_pos in two parts:
5199 1) the left part has already a location assigned
5200 2) the right part is always on the stack and therefore ignored in further processing
5201 */
5202 void LinearScanWalker::split_for_spilling(Interval* it) {
5203 // calculate allowed range of splitting position
5204 int max_split_pos = current_position();
5205 int min_split_pos = MAX2(it->previous_usage(shouldHaveRegister, max_split_pos) + 1, it->from());
5206
5207 TRACE_LINEAR_SCAN(2, tty->print ("----- splitting and spilling interval: "); it->print());
5208 TRACE_LINEAR_SCAN(2, tty->print_cr(" between %d and %d", min_split_pos, max_split_pos));
5209
5210 assert(it->state() == activeState, "why spill interval that is not active?");
5211 assert(it->from() <= min_split_pos, "cannot split before start of interval");
5212 assert(min_split_pos <= max_split_pos, "invalid order");
5213 assert(max_split_pos < it->to(), "cannot split at end end of interval");
5214 assert(current_position() < it->to(), "interval must not end before current position");
5215
5216 if (min_split_pos == it->from()) {
5217 // the whole interval is never used, so spill it entirely to memory
5218 TRACE_LINEAR_SCAN(2, tty->print_cr(" spilling entire interval because split pos is at beginning of interval"));
5219 assert(it->first_usage(shouldHaveRegister) > current_position(), "interval must not have use position before current_position");
5220
5221 allocator()->assign_spill_slot(it);
5222 allocator()->change_spill_state(it, min_split_pos);
5223
5224 // Also kick parent intervals out of register to memory when they have no use
5225 // position. This avoids short interval in register surrounded by intervals in
5226 // memory -> avoid useless moves from memory to register and back
5227 Interval* parent = it;
5228 while (parent != nullptr && parent->is_split_child()) {
5229 parent = parent->split_child_before_op_id(parent->from());
5230
5231 if (parent->assigned_reg() < LinearScan::nof_regs) {
5232 if (parent->first_usage(shouldHaveRegister) == max_jint) {
5233 // parent is never used, so kick it out of its assigned register
5234 TRACE_LINEAR_SCAN(4, tty->print_cr(" kicking out interval %d out of its register because it is never used", parent->reg_num()));
5235 allocator()->assign_spill_slot(parent);
5236 } else {
5237 // do not go further back because the register is actually used by the interval
5238 parent = nullptr;
5239 }
5240 }
5241 }
5242
5243 } else {
5244 // search optimal split pos, split interval and spill only the right hand part
5245 int optimal_split_pos = find_optimal_split_pos(it, min_split_pos, max_split_pos, false);
5246
5247 assert(min_split_pos <= optimal_split_pos && optimal_split_pos <= max_split_pos, "out of range");
5248 assert(optimal_split_pos < it->to(), "cannot split at end of interval");
5249 assert(optimal_split_pos >= it->from(), "cannot split before start of interval");
5250
5251 if (!allocator()->is_block_begin(optimal_split_pos)) {
5252 // move position before actual instruction (odd op_id)
5253 optimal_split_pos = (optimal_split_pos - 1) | 1;
5254 }
5255
5256 TRACE_LINEAR_SCAN(4, tty->print_cr(" splitting at position %d", optimal_split_pos));
5257 assert(allocator()->is_block_begin(optimal_split_pos) || (optimal_split_pos % 2 == 1), "split pos must be odd when not on block boundary");
5258 assert(!allocator()->is_block_begin(optimal_split_pos) || (optimal_split_pos % 2 == 0), "split pos must be even on block boundary");
5259
5260 Interval* spilled_part = it->split(optimal_split_pos);
5261 allocator()->append_interval(spilled_part);
5262 allocator()->assign_spill_slot(spilled_part);
5263 allocator()->change_spill_state(spilled_part, optimal_split_pos);
5264
5265 if (!allocator()->is_block_begin(optimal_split_pos)) {
5266 TRACE_LINEAR_SCAN(4, tty->print_cr(" inserting move from interval %d to %d", it->reg_num(), spilled_part->reg_num()));
5267 insert_move(optimal_split_pos, it, spilled_part);
5268 }
5269
5270 // the current_split_child is needed later when moves are inserted for reloading
5271 assert(spilled_part->current_split_child() == it, "overwriting wrong current_split_child");
5272 spilled_part->make_current_split_child();
5273
5274 TRACE_LINEAR_SCAN(2, tty->print_cr(" split interval in two parts"));
5275 TRACE_LINEAR_SCAN(2, tty->print (" "); it->print());
5276 TRACE_LINEAR_SCAN(2, tty->print (" "); spilled_part->print());
5277 }
5278 }
5279
5280
5281 void LinearScanWalker::split_stack_interval(Interval* it) {
5282 int min_split_pos = current_position() + 1;
5283 int max_split_pos = MIN2(it->first_usage(shouldHaveRegister), it->to());
5284
5285 split_before_usage(it, min_split_pos, max_split_pos);
5286 }
5287
5288 void LinearScanWalker::split_when_partial_register_available(Interval* it, int register_available_until) {
5289 int min_split_pos = MAX2(it->previous_usage(shouldHaveRegister, register_available_until), it->from() + 1);
5290 int max_split_pos = register_available_until;
5291
5292 split_before_usage(it, min_split_pos, max_split_pos);
5293 }
5294
5295 void LinearScanWalker::split_and_spill_interval(Interval* it) {
5296 assert(it->state() == activeState || it->state() == inactiveState, "other states not allowed");
5297
5298 int current_pos = current_position();
5299 if (it->state() == inactiveState) {
5300 // the interval is currently inactive, so no spill slot is needed for now.
5301 // when the split part is activated, the interval has a new chance to get a register,
5302 // so in the best case no stack slot is necessary
5303 assert(it->has_hole_between(current_pos - 1, current_pos + 1), "interval can not be inactive otherwise");
5304 split_before_usage(it, current_pos + 1, current_pos + 1);
5305
5306 } else {
5307 // search the position where the interval must have a register and split
5308 // at the optimal position before.
5309 // The new created part is added to the unhandled list and will get a register
5310 // when it is activated
5311 int min_split_pos = current_pos + 1;
5312 int max_split_pos = MIN2(it->next_usage(mustHaveRegister, min_split_pos), it->to());
5313
5314 split_before_usage(it, min_split_pos, max_split_pos);
5315
5316 assert(it->next_usage(mustHaveRegister, current_pos) == max_jint, "the remaining part is spilled to stack and therefore has no register");
5317 split_for_spilling(it);
5318 }
5319 }
5320
5321 int LinearScanWalker::find_free_reg(int reg_needed_until, int interval_to, int hint_reg, int ignore_reg, bool* need_split) {
5322 int min_full_reg = any_reg;
5323 int max_partial_reg = any_reg;
5324
5325 for (int i = _first_reg; i <= _last_reg; i++) {
5326 if (i == ignore_reg) {
5327 // this register must be ignored
5328
5329 } else if (_use_pos[i] >= interval_to) {
5330 // this register is free for the full interval
5331 if (min_full_reg == any_reg || i == hint_reg || (_use_pos[i] < _use_pos[min_full_reg] && min_full_reg != hint_reg)) {
5332 min_full_reg = i;
5333 }
5334 } else if (_use_pos[i] > reg_needed_until) {
5335 // this register is at least free until reg_needed_until
5336 if (max_partial_reg == any_reg || i == hint_reg || (_use_pos[i] > _use_pos[max_partial_reg] && max_partial_reg != hint_reg)) {
5337 max_partial_reg = i;
5338 }
5339 }
5340 }
5341
5342 if (min_full_reg != any_reg) {
5343 return min_full_reg;
5344 } else if (max_partial_reg != any_reg) {
5345 *need_split = true;
5346 return max_partial_reg;
5347 } else {
5348 return any_reg;
5349 }
5350 }
5351
5352 int LinearScanWalker::find_free_double_reg(int reg_needed_until, int interval_to, int hint_reg, bool* need_split) {
5353 assert((_last_reg - _first_reg + 1) % 2 == 0, "adjust algorithm");
5354
5355 int min_full_reg = any_reg;
5356 int max_partial_reg = any_reg;
5357
5358 for (int i = _first_reg; i < _last_reg; i+=2) {
5359 if (_use_pos[i] >= interval_to && _use_pos[i + 1] >= interval_to) {
5360 // this register is free for the full interval
5361 if (min_full_reg == any_reg || i == hint_reg || (_use_pos[i] < _use_pos[min_full_reg] && min_full_reg != hint_reg)) {
5362 min_full_reg = i;
5363 }
5364 } else if (_use_pos[i] > reg_needed_until && _use_pos[i + 1] > reg_needed_until) {
5365 // this register is at least free until reg_needed_until
5366 if (max_partial_reg == any_reg || i == hint_reg || (_use_pos[i] > _use_pos[max_partial_reg] && max_partial_reg != hint_reg)) {
5367 max_partial_reg = i;
5368 }
5369 }
5370 }
5371
5372 if (min_full_reg != any_reg) {
5373 return min_full_reg;
5374 } else if (max_partial_reg != any_reg) {
5375 *need_split = true;
5376 return max_partial_reg;
5377 } else {
5378 return any_reg;
5379 }
5380 }
5381
5382 bool LinearScanWalker::alloc_free_reg(Interval* cur) {
5383 TRACE_LINEAR_SCAN(2, tty->print("trying to find free register for "); cur->print());
5384
5385 init_use_lists(true);
5386 free_exclude_active_fixed();
5387 free_exclude_active_any();
5388 free_collect_inactive_fixed(cur);
5389 free_collect_inactive_any(cur);
5390 assert(unhandled_first(fixedKind) == Interval::end(), "must not have unhandled fixed intervals because all fixed intervals have a use at position 0");
5391
5392 // _use_pos contains the start of the next interval that has this register assigned
5393 // (either as a fixed register or a normal allocated register in the past)
5394 // only intervals overlapping with cur are processed, non-overlapping invervals can be ignored safely
5395 #ifdef ASSERT
5396 if (TraceLinearScanLevel >= 4) {
5397 tty->print_cr(" state of registers:");
5398 for (int i = _first_reg; i <= _last_reg; i++) {
5399 tty->print(" reg %d (", i);
5400 LinearScan::print_reg_num(i);
5401 tty->print_cr("): use_pos: %d", _use_pos[i]);
5402 }
5403 }
5404 #endif
5405
5406 int hint_reg, hint_regHi;
5407 Interval* register_hint = cur->register_hint();
5408 if (register_hint != nullptr) {
5409 hint_reg = register_hint->assigned_reg();
5410 hint_regHi = register_hint->assigned_regHi();
5411
5412 if (_num_phys_regs == 2 && allocator()->is_precolored_cpu_interval(register_hint)) {
5413 assert(hint_reg != any_reg && hint_regHi == any_reg, "must be for fixed intervals");
5414 hint_regHi = hint_reg + 1; // connect e.g. eax-edx
5415 }
5416 #ifdef ASSERT
5417 if (TraceLinearScanLevel >= 4) {
5418 tty->print(" hint registers %d (", hint_reg);
5419 LinearScan::print_reg_num(hint_reg);
5420 tty->print("), %d (", hint_regHi);
5421 LinearScan::print_reg_num(hint_regHi);
5422 tty->print(") from interval ");
5423 register_hint->print();
5424 }
5425 #endif
5426 } else {
5427 hint_reg = any_reg;
5428 hint_regHi = any_reg;
5429 }
5430 assert(hint_reg == any_reg || hint_reg != hint_regHi, "hint reg and regHi equal");
5431 assert(cur->assigned_reg() == any_reg && cur->assigned_regHi() == any_reg, "register already assigned to interval");
5432
5433 // the register must be free at least until this position
5434 int reg_needed_until = cur->from() + 1;
5435 int interval_to = cur->to();
5436
5437 bool need_split = false;
5438 int split_pos;
5439 int reg;
5440 int regHi = any_reg;
5441
5442 if (_adjacent_regs) {
5443 reg = find_free_double_reg(reg_needed_until, interval_to, hint_reg, &need_split);
5444 regHi = reg + 1;
5445 if (reg == any_reg) {
5446 return false;
5447 }
5448 split_pos = MIN2(_use_pos[reg], _use_pos[regHi]);
5449
5450 } else {
5451 reg = find_free_reg(reg_needed_until, interval_to, hint_reg, any_reg, &need_split);
5452 if (reg == any_reg) {
5453 return false;
5454 }
5455 split_pos = _use_pos[reg];
5456
5457 if (_num_phys_regs == 2) {
5458 regHi = find_free_reg(reg_needed_until, interval_to, hint_regHi, reg, &need_split);
5459
5460 if (_use_pos[reg] < interval_to && regHi == any_reg) {
5461 // do not split interval if only one register can be assigned until the split pos
5462 // (when one register is found for the whole interval, split&spill is only
5463 // performed for the hi register)
5464 return false;
5465
5466 } else if (regHi != any_reg) {
5467 split_pos = MIN2(split_pos, _use_pos[regHi]);
5468
5469 // sort register numbers to prevent e.g. a move from eax,ebx to ebx,eax
5470 if (reg > regHi) {
5471 int temp = reg;
5472 reg = regHi;
5473 regHi = temp;
5474 }
5475 }
5476 }
5477 }
5478
5479 cur->assign_reg(reg, regHi);
5480 #ifdef ASSERT
5481 if (TraceLinearScanLevel >= 2) {
5482 tty->print(" selected registers %d (", reg);
5483 LinearScan::print_reg_num(reg);
5484 tty->print("), %d (", regHi);
5485 LinearScan::print_reg_num(regHi);
5486 tty->print_cr(")");
5487 }
5488 #endif
5489 assert(split_pos > 0, "invalid split_pos");
5490 if (need_split) {
5491 // register not available for full interval, so split it
5492 split_when_partial_register_available(cur, split_pos);
5493 }
5494
5495 // only return true if interval is completely assigned
5496 return _num_phys_regs == 1 || regHi != any_reg;
5497 }
5498
5499
5500 int LinearScanWalker::find_locked_reg(int reg_needed_until, int interval_to, int ignore_reg, bool* need_split) {
5501 int max_reg = any_reg;
5502
5503 for (int i = _first_reg; i <= _last_reg; i++) {
5504 if (i == ignore_reg) {
5505 // this register must be ignored
5506
5507 } else if (_use_pos[i] > reg_needed_until) {
5508 if (max_reg == any_reg || _use_pos[i] > _use_pos[max_reg]) {
5509 max_reg = i;
5510 }
5511 }
5512 }
5513
5514 if (max_reg != any_reg && _block_pos[max_reg] <= interval_to) {
5515 *need_split = true;
5516 }
5517
5518 return max_reg;
5519 }
5520
5521 int LinearScanWalker::find_locked_double_reg(int reg_needed_until, int interval_to, bool* need_split) {
5522 assert((_last_reg - _first_reg + 1) % 2 == 0, "adjust algorithm");
5523
5524 int max_reg = any_reg;
5525
5526 for (int i = _first_reg; i < _last_reg; i+=2) {
5527 if (_use_pos[i] > reg_needed_until && _use_pos[i + 1] > reg_needed_until) {
5528 if (max_reg == any_reg || _use_pos[i] > _use_pos[max_reg]) {
5529 max_reg = i;
5530 }
5531 }
5532 }
5533
5534 if (max_reg != any_reg &&
5535 (_block_pos[max_reg] <= interval_to || _block_pos[max_reg + 1] <= interval_to)) {
5536 *need_split = true;
5537 }
5538
5539 return max_reg;
5540 }
5541
5542 void LinearScanWalker::split_and_spill_intersecting_intervals(int reg, int regHi) {
5543 assert(reg != any_reg, "no register assigned");
5544
5545 for (int i = 0; i < _spill_intervals[reg]->length(); i++) {
5546 Interval* it = _spill_intervals[reg]->at(i);
5547 remove_from_list(it);
5548 split_and_spill_interval(it);
5549 }
5550
5551 if (regHi != any_reg) {
5552 IntervalList* processed = _spill_intervals[reg];
5553 for (int i = 0; i < _spill_intervals[regHi]->length(); i++) {
5554 Interval* it = _spill_intervals[regHi]->at(i);
5555 if (processed->find(it) == -1) {
5556 remove_from_list(it);
5557 split_and_spill_interval(it);
5558 }
5559 }
5560 }
5561 }
5562
5563
5564 // Split an Interval and spill it to memory so that cur can be placed in a register
5565 void LinearScanWalker::alloc_locked_reg(Interval* cur) {
5566 TRACE_LINEAR_SCAN(2, tty->print("need to split and spill to get register for "); cur->print());
5567
5568 // collect current usage of registers
5569 init_use_lists(false);
5570 spill_exclude_active_fixed();
5571 assert(unhandled_first(fixedKind) == Interval::end(), "must not have unhandled fixed intervals because all fixed intervals have a use at position 0");
5572 spill_block_inactive_fixed(cur);
5573 spill_collect_active_any();
5574 spill_collect_inactive_any(cur);
5575
5576 #ifdef ASSERT
5577 if (TraceLinearScanLevel >= 4) {
5578 tty->print_cr(" state of registers:");
5579 for (int i = _first_reg; i <= _last_reg; i++) {
5580 tty->print(" reg %d(", i);
5581 LinearScan::print_reg_num(i);
5582 tty->print("): use_pos: %d, block_pos: %d, intervals: ", _use_pos[i], _block_pos[i]);
5583 for (int j = 0; j < _spill_intervals[i]->length(); j++) {
5584 tty->print("%d ", _spill_intervals[i]->at(j)->reg_num());
5585 }
5586 tty->cr();
5587 }
5588 }
5589 #endif
5590
5591 // the register must be free at least until this position
5592 int reg_needed_until = MIN2(cur->first_usage(mustHaveRegister), cur->from() + 1);
5593 int interval_to = cur->to();
5594 assert (reg_needed_until > 0 && reg_needed_until < max_jint, "interval has no use");
5595
5596 int split_pos = 0;
5597 int use_pos = 0;
5598 bool need_split = false;
5599 int reg, regHi;
5600
5601 if (_adjacent_regs) {
5602 reg = find_locked_double_reg(reg_needed_until, interval_to, &need_split);
5603 regHi = reg + 1;
5604
5605 if (reg != any_reg) {
5606 use_pos = MIN2(_use_pos[reg], _use_pos[regHi]);
5607 split_pos = MIN2(_block_pos[reg], _block_pos[regHi]);
5608 }
5609 } else {
5610 reg = find_locked_reg(reg_needed_until, interval_to, cur->assigned_reg(), &need_split);
5611 regHi = any_reg;
5612
5613 if (reg != any_reg) {
5614 use_pos = _use_pos[reg];
5615 split_pos = _block_pos[reg];
5616
5617 if (_num_phys_regs == 2) {
5618 if (cur->assigned_reg() != any_reg) {
5619 regHi = reg;
5620 reg = cur->assigned_reg();
5621 } else {
5622 regHi = find_locked_reg(reg_needed_until, interval_to, reg, &need_split);
5623 if (regHi != any_reg) {
5624 use_pos = MIN2(use_pos, _use_pos[regHi]);
5625 split_pos = MIN2(split_pos, _block_pos[regHi]);
5626 }
5627 }
5628
5629 if (regHi != any_reg && reg > regHi) {
5630 // sort register numbers to prevent e.g. a move from eax,ebx to ebx,eax
5631 int temp = reg;
5632 reg = regHi;
5633 regHi = temp;
5634 }
5635 }
5636 }
5637 }
5638
5639 if (reg == any_reg || (_num_phys_regs == 2 && regHi == any_reg) || use_pos <= cur->first_usage(mustHaveRegister)) {
5640 // the first use of cur is later than the spilling position -> spill cur
5641 TRACE_LINEAR_SCAN(4, tty->print_cr("able to spill current interval. first_usage(register): %d, use_pos: %d", cur->first_usage(mustHaveRegister), use_pos));
5642
5643 if (cur->first_usage(mustHaveRegister) <= cur->from() + 1) {
5644 assert(false, "cannot spill interval that is used in first instruction (possible reason: no register found)");
5645 // assign a reasonable register and do a bailout in product mode to avoid errors
5646 allocator()->assign_spill_slot(cur);
5647 BAILOUT("LinearScan: no register found");
5648 }
5649
5650 split_and_spill_interval(cur);
5651 } else {
5652 #ifdef ASSERT
5653 if (TraceLinearScanLevel >= 4) {
5654 tty->print("decided to use register %d (", reg);
5655 LinearScan::print_reg_num(reg);
5656 tty->print("), %d (", regHi);
5657 LinearScan::print_reg_num(regHi);
5658 tty->print_cr(")");
5659 }
5660 #endif
5661 assert(reg != any_reg && (_num_phys_regs == 1 || regHi != any_reg), "no register found");
5662 assert(split_pos > 0, "invalid split_pos");
5663 assert(need_split == false || split_pos > cur->from(), "splitting interval at from");
5664
5665 cur->assign_reg(reg, regHi);
5666 if (need_split) {
5667 // register not available for full interval, so split it
5668 split_when_partial_register_available(cur, split_pos);
5669 }
5670
5671 // perform splitting and spilling for all affected intervals
5672 split_and_spill_intersecting_intervals(reg, regHi);
5673 }
5674 }
5675
5676 bool LinearScanWalker::no_allocation_possible(Interval* cur) {
5677 #ifdef X86
5678 // fast calculation of intervals that can never get a register because the
5679 // the next instruction is a call that blocks all registers
5680 // Note: this does not work if callee-saved registers are available (e.g. on Sparc)
5681
5682 // check if this interval is the result of a split operation
5683 // (an interval got a register until this position)
5684 int pos = cur->from();
5685 if ((pos & 1) == 1) {
5686 // the current instruction is a call that blocks all registers
5687 if (pos < allocator()->max_lir_op_id() && allocator()->has_call(pos + 1)) {
5688 TRACE_LINEAR_SCAN(4, tty->print_cr(" free register cannot be available because all registers blocked by following call"));
5689
5690 // safety check that there is really no register available
5691 assert(alloc_free_reg(cur) == false, "found a register for this interval");
5692 return true;
5693 }
5694
5695 }
5696 #endif
5697 return false;
5698 }
5699
5700 void LinearScanWalker::init_vars_for_alloc(Interval* cur) {
5701 BasicType type = cur->type();
5702 _num_phys_regs = LinearScan::num_physical_regs(type);
5703 _adjacent_regs = LinearScan::requires_adjacent_regs(type);
5704
5705 if (pd_init_regs_for_alloc(cur)) {
5706 // the appropriate register range was selected.
5707 } else if (type == T_FLOAT || type == T_DOUBLE) {
5708 _first_reg = pd_first_fpu_reg;
5709 _last_reg = pd_last_fpu_reg;
5710 } else {
5711 _first_reg = pd_first_cpu_reg;
5712 _last_reg = FrameMap::last_cpu_reg();
5713 }
5714
5715 assert(0 <= _first_reg && _first_reg < LinearScan::nof_regs, "out of range");
5716 assert(0 <= _last_reg && _last_reg < LinearScan::nof_regs, "out of range");
5717 }
5718
5719
5720 bool LinearScanWalker::is_move(LIR_Op* op, Interval* from, Interval* to) {
5721 if (op->code() != lir_move) {
5722 return false;
5723 }
5724 assert(op->as_Op1() != nullptr, "move must be LIR_Op1");
5725
5726 LIR_Opr in = ((LIR_Op1*)op)->in_opr();
5727 LIR_Opr res = ((LIR_Op1*)op)->result_opr();
5728 return in->is_virtual() && res->is_virtual() && in->vreg_number() == from->reg_num() && res->vreg_number() == to->reg_num();
5729 }
5730
5731 // optimization (especially for phi functions of nested loops):
5732 // assign same spill slot to non-intersecting intervals
5733 void LinearScanWalker::combine_spilled_intervals(Interval* cur) {
5734 if (cur->is_split_child()) {
5735 // optimization is only suitable for split parents
5736 return;
5737 }
5738
5739 Interval* register_hint = cur->register_hint(false);
5740 if (register_hint == nullptr) {
5741 // cur is not the target of a move, otherwise register_hint would be set
5742 return;
5743 }
5744 assert(register_hint->is_split_parent(), "register hint must be split parent");
5745
5746 if (cur->spill_state() != noOptimization || register_hint->spill_state() != noOptimization) {
5747 // combining the stack slots for intervals where spill move optimization is applied
5748 // is not benefitial and would cause problems
5749 return;
5750 }
5751
5752 int begin_pos = cur->from();
5753 int end_pos = cur->to();
5754 if (end_pos > allocator()->max_lir_op_id() || (begin_pos & 1) != 0 || (end_pos & 1) != 0) {
5755 // safety check that lir_op_with_id is allowed
5756 return;
5757 }
5758
5759 if (!is_move(allocator()->lir_op_with_id(begin_pos), register_hint, cur) || !is_move(allocator()->lir_op_with_id(end_pos), cur, register_hint)) {
5760 // cur and register_hint are not connected with two moves
5761 return;
5762 }
5763
5764 Interval* begin_hint = register_hint->split_child_at_op_id(begin_pos, LIR_OpVisitState::inputMode);
5765 Interval* end_hint = register_hint->split_child_at_op_id(end_pos, LIR_OpVisitState::outputMode);
5766 if (begin_hint == end_hint || begin_hint->to() != begin_pos || end_hint->from() != end_pos) {
5767 // register_hint must be split, otherwise the re-writing of use positions does not work
5768 return;
5769 }
5770
5771 assert(begin_hint->assigned_reg() != any_reg, "must have register assigned");
5772 assert(end_hint->assigned_reg() == any_reg, "must not have register assigned");
5773 assert(cur->first_usage(mustHaveRegister) == begin_pos, "must have use position at begin of interval because of move");
5774 assert(end_hint->first_usage(mustHaveRegister) == end_pos, "must have use position at begin of interval because of move");
5775
5776 if (begin_hint->assigned_reg() < LinearScan::nof_regs) {
5777 // register_hint is not spilled at begin_pos, so it would not be benefitial to immediately spill cur
5778 return;
5779 }
5780 assert(register_hint->canonical_spill_slot() != -1, "must be set when part of interval was spilled");
5781 assert(!cur->intersects(register_hint), "cur should not intersect register_hint");
5782
5783 if (cur->intersects_any_children_of(register_hint)) {
5784 // Bail out if cur intersects any split children of register_hint, which have the same spill slot as their parent. An overlap of two intervals with
5785 // the same spill slot could result in a situation where both intervals are spilled at the same time to the same stack location which is not correct.
5786 return;
5787 }
5788
5789 // modify intervals such that cur gets the same stack slot as register_hint
5790 // delete use positions to prevent the intervals to get a register at beginning
5791 cur->set_canonical_spill_slot(register_hint->canonical_spill_slot());
5792 cur->remove_first_use_pos();
5793 end_hint->remove_first_use_pos();
5794 }
5795
5796
5797 // allocate a physical register or memory location to an interval
5798 bool LinearScanWalker::activate_current() {
5799 Interval* cur = current();
5800 bool result = true;
5801
5802 TRACE_LINEAR_SCAN(2, tty->print ("+++++ activating interval "); cur->print());
5803 TRACE_LINEAR_SCAN(4, tty->print_cr(" split_parent: %d, insert_move_when_activated: %d", cur->split_parent()->reg_num(), cur->insert_move_when_activated()));
5804
5805 if (cur->assigned_reg() >= LinearScan::nof_regs) {
5806 // activating an interval that has a stack slot assigned -> split it at first use position
5807 // used for method parameters
5808 TRACE_LINEAR_SCAN(4, tty->print_cr(" interval has spill slot assigned (method parameter) -> split it before first use"));
5809
5810 split_stack_interval(cur);
5811 result = false;
5812
5813 } else if (allocator()->gen()->is_vreg_flag_set(cur->reg_num(), LIRGenerator::must_start_in_memory)) {
5814 // activating an interval that must start in a stack slot, but may get a register later
5815 TRACE_LINEAR_SCAN(4, tty->print_cr(" interval must start in stack slot -> split it before first use"));
5816 assert(cur->assigned_reg() == any_reg && cur->assigned_regHi() == any_reg, "register already assigned");
5817
5818 allocator()->assign_spill_slot(cur);
5819 split_stack_interval(cur);
5820 result = false;
5821
5822 } else if (cur->assigned_reg() == any_reg) {
5823 // interval has not assigned register -> normal allocation
5824 // (this is the normal case for most intervals)
5825 TRACE_LINEAR_SCAN(4, tty->print_cr(" normal allocation of register"));
5826
5827 // assign same spill slot to non-intersecting intervals
5828 combine_spilled_intervals(cur);
5829
5830 init_vars_for_alloc(cur);
5831 if (no_allocation_possible(cur) || !alloc_free_reg(cur)) {
5832 // no empty register available.
5833 // split and spill another interval so that this interval gets a register
5834 alloc_locked_reg(cur);
5835 }
5836
5837 // spilled intervals need not be move to active-list
5838 if (cur->assigned_reg() >= LinearScan::nof_regs) {
5839 result = false;
5840 }
5841 }
5842
5843 // load spilled values that become active from stack slot to register
5844 if (cur->insert_move_when_activated()) {
5845 assert(cur->is_split_child(), "must be");
5846 assert(cur->current_split_child() != nullptr, "must be");
5847 assert(cur->current_split_child()->reg_num() != cur->reg_num(), "cannot insert move between same interval");
5848 TRACE_LINEAR_SCAN(4, tty->print_cr("Inserting move from interval %d to %d because insert_move_when_activated is set", cur->current_split_child()->reg_num(), cur->reg_num()));
5849
5850 insert_move(cur->from(), cur->current_split_child(), cur);
5851 }
5852 cur->make_current_split_child();
5853
5854 return result; // true = interval is moved to active list
5855 }
5856
5857
5858 // Implementation of EdgeMoveOptimizer
5859
5860 EdgeMoveOptimizer::EdgeMoveOptimizer() :
5861 _edge_instructions(4),
5862 _edge_instructions_idx(4)
5863 {
5864 }
5865
5866 void EdgeMoveOptimizer::optimize(BlockList* code) {
5867 EdgeMoveOptimizer optimizer = EdgeMoveOptimizer();
5868
5869 // ignore the first block in the list (index 0 is not processed)
5870 for (int i = code->length() - 1; i >= 1; i--) {
5871 BlockBegin* block = code->at(i);
5872
5873 if (block->number_of_preds() > 1 && !block->is_set(BlockBegin::exception_entry_flag)) {
5874 optimizer.optimize_moves_at_block_end(block);
5875 }
5876 if (block->number_of_sux() == 2) {
5877 optimizer.optimize_moves_at_block_begin(block);
5878 }
5879 }
5880 }
5881
5882
5883 // clear all internal data structures
5884 void EdgeMoveOptimizer::init_instructions() {
5885 _edge_instructions.clear();
5886 _edge_instructions_idx.clear();
5887 }
5888
5889 // append a lir-instruction-list and the index of the current operation in to the list
5890 void EdgeMoveOptimizer::append_instructions(LIR_OpList* instructions, int instructions_idx) {
5891 _edge_instructions.append(instructions);
5892 _edge_instructions_idx.append(instructions_idx);
5893 }
5894
5895 // return the current operation of the given edge (predecessor or successor)
5896 LIR_Op* EdgeMoveOptimizer::instruction_at(int edge) {
5897 LIR_OpList* instructions = _edge_instructions.at(edge);
5898 int idx = _edge_instructions_idx.at(edge);
5899
5900 if (idx < instructions->length()) {
5901 return instructions->at(idx);
5902 } else {
5903 return nullptr;
5904 }
5905 }
5906
5907 // removes the current operation of the given edge (predecessor or successor)
5908 void EdgeMoveOptimizer::remove_cur_instruction(int edge, bool decrement_index) {
5909 LIR_OpList* instructions = _edge_instructions.at(edge);
5910 int idx = _edge_instructions_idx.at(edge);
5911 instructions->remove_at(idx);
5912
5913 if (decrement_index) {
5914 _edge_instructions_idx.at_put(edge, idx - 1);
5915 }
5916 }
5917
5918
5919 bool EdgeMoveOptimizer::operations_different(LIR_Op* op1, LIR_Op* op2) {
5920 if (op1 == nullptr || op2 == nullptr) {
5921 // at least one block is already empty -> no optimization possible
5922 return true;
5923 }
5924
5925 if (op1->code() == lir_move && op2->code() == lir_move) {
5926 assert(op1->as_Op1() != nullptr, "move must be LIR_Op1");
5927 assert(op2->as_Op1() != nullptr, "move must be LIR_Op1");
5928 LIR_Op1* move1 = (LIR_Op1*)op1;
5929 LIR_Op1* move2 = (LIR_Op1*)op2;
5930 if (move1->info() == move2->info() && move1->in_opr() == move2->in_opr() && move1->result_opr() == move2->result_opr()) {
5931 // these moves are exactly equal and can be optimized
5932 return false;
5933 }
5934 }
5935
5936 // no optimization possible
5937 return true;
5938 }
5939
5940 void EdgeMoveOptimizer::optimize_moves_at_block_end(BlockBegin* block) {
5941 TRACE_LINEAR_SCAN(4, tty->print_cr("optimizing moves at end of block B%d", block->block_id()));
5942
5943 if (block->is_predecessor(block)) {
5944 // currently we can't handle this correctly.
5945 return;
5946 }
5947
5948 init_instructions();
5949 int num_preds = block->number_of_preds();
5950 assert(num_preds > 1, "do not call otherwise");
5951 assert(!block->is_set(BlockBegin::exception_entry_flag), "exception handlers not allowed");
5952
5953 // setup a list with the lir-instructions of all predecessors
5954 int i;
5955 for (i = 0; i < num_preds; i++) {
5956 BlockBegin* pred = block->pred_at(i);
5957 LIR_OpList* pred_instructions = pred->lir()->instructions_list();
5958
5959 if (pred->number_of_sux() != 1) {
5960 // this can happen with switch-statements where multiple edges are between
5961 // the same blocks.
5962 return;
5963 }
5964
5965 assert(pred->number_of_sux() == 1, "can handle only one successor");
5966 assert(pred->sux_at(0) == block, "invalid control flow");
5967 assert(pred_instructions->last()->code() == lir_branch, "block with successor must end with branch");
5968 assert(pred_instructions->last()->as_OpBranch() != nullptr, "branch must be LIR_OpBranch");
5969 assert(pred_instructions->last()->as_OpBranch()->cond() == lir_cond_always, "block must end with unconditional branch");
5970
5971 if (pred_instructions->last()->info() != nullptr) {
5972 // can not optimize instructions when debug info is needed
5973 return;
5974 }
5975
5976 // ignore the unconditional branch at the end of the block
5977 append_instructions(pred_instructions, pred_instructions->length() - 2);
5978 }
5979
5980
5981 // process lir-instructions while all predecessors end with the same instruction
5982 while (true) {
5983 LIR_Op* op = instruction_at(0);
5984 for (i = 1; i < num_preds; i++) {
5985 if (operations_different(op, instruction_at(i))) {
5986 // these instructions are different and cannot be optimized ->
5987 // no further optimization possible
5988 return;
5989 }
5990 }
5991
5992 TRACE_LINEAR_SCAN(4, tty->print("found instruction that is equal in all %d predecessors: ", num_preds); op->print());
5993
5994 // insert the instruction at the beginning of the current block
5995 block->lir()->insert_before(1, op);
5996
5997 // delete the instruction at the end of all predecessors
5998 for (i = 0; i < num_preds; i++) {
5999 remove_cur_instruction(i, true);
6000 }
6001 }
6002 }
6003
6004
6005 void EdgeMoveOptimizer::optimize_moves_at_block_begin(BlockBegin* block) {
6006 TRACE_LINEAR_SCAN(4, tty->print_cr("optimization moves at begin of block B%d", block->block_id()));
6007
6008 init_instructions();
6009 int num_sux = block->number_of_sux();
6010
6011 LIR_OpList* cur_instructions = block->lir()->instructions_list();
6012
6013 assert(num_sux == 2, "method should not be called otherwise");
6014 assert(cur_instructions->last()->code() == lir_branch, "block with successor must end with branch");
6015 assert(cur_instructions->last()->as_OpBranch() != nullptr, "branch must be LIR_OpBranch");
6016 assert(cur_instructions->last()->as_OpBranch()->cond() == lir_cond_always, "block must end with unconditional branch");
6017
6018 if (cur_instructions->last()->info() != nullptr) {
6019 // can no optimize instructions when debug info is needed
6020 return;
6021 }
6022
6023 LIR_Op* branch = cur_instructions->at(cur_instructions->length() - 2);
6024 if (branch->info() != nullptr || (branch->code() != lir_branch && branch->code() != lir_cond_float_branch)) {
6025 // not a valid case for optimization
6026 // currently, only blocks that end with two branches (conditional branch followed
6027 // by unconditional branch) are optimized
6028 return;
6029 }
6030
6031 // now it is guaranteed that the block ends with two branch instructions.
6032 // the instructions are inserted at the end of the block before these two branches
6033 int insert_idx = cur_instructions->length() - 2;
6034
6035 int i;
6036 #ifdef ASSERT
6037 for (i = insert_idx - 1; i >= 0; i--) {
6038 LIR_Op* op = cur_instructions->at(i);
6039 if ((op->code() == lir_branch || op->code() == lir_cond_float_branch) && ((LIR_OpBranch*)op)->block() != nullptr) {
6040 assert(false, "block with two successors can have only two branch instructions");
6041 }
6042 }
6043 #endif
6044
6045 // setup a list with the lir-instructions of all successors
6046 for (i = 0; i < num_sux; i++) {
6047 BlockBegin* sux = block->sux_at(i);
6048 LIR_OpList* sux_instructions = sux->lir()->instructions_list();
6049
6050 assert(sux_instructions->at(0)->code() == lir_label, "block must start with label");
6051
6052 if (sux->number_of_preds() != 1) {
6053 // this can happen with switch-statements where multiple edges are between
6054 // the same blocks.
6055 return;
6056 }
6057 assert(sux->pred_at(0) == block, "invalid control flow");
6058 assert(!sux->is_set(BlockBegin::exception_entry_flag), "exception handlers not allowed");
6059
6060 // ignore the label at the beginning of the block
6061 append_instructions(sux_instructions, 1);
6062 }
6063
6064 // process lir-instructions while all successors begin with the same instruction
6065 while (true) {
6066 LIR_Op* op = instruction_at(0);
6067 for (i = 1; i < num_sux; i++) {
6068 if (operations_different(op, instruction_at(i))) {
6069 // these instructions are different and cannot be optimized ->
6070 // no further optimization possible
6071 return;
6072 }
6073 }
6074
6075 TRACE_LINEAR_SCAN(4, tty->print("----- found instruction that is equal in all %d successors: ", num_sux); op->print());
6076
6077 // insert instruction at end of current block
6078 block->lir()->insert_before(insert_idx, op);
6079 insert_idx++;
6080
6081 // delete the instructions at the beginning of all successors
6082 for (i = 0; i < num_sux; i++) {
6083 remove_cur_instruction(i, false);
6084 }
6085 }
6086 }
6087
6088
6089 // Implementation of ControlFlowOptimizer
6090
6091 ControlFlowOptimizer::ControlFlowOptimizer() :
6092 _original_preds(4)
6093 {
6094 }
6095
6096 void ControlFlowOptimizer::optimize(BlockList* code) {
6097 ControlFlowOptimizer optimizer = ControlFlowOptimizer();
6098
6099 // push the OSR entry block to the end so that we're not jumping over it.
6100 BlockBegin* osr_entry = code->at(0)->end()->as_Base()->osr_entry();
6101 if (osr_entry) {
6102 int index = osr_entry->linear_scan_number();
6103 assert(code->at(index) == osr_entry, "wrong index");
6104 code->remove_at(index);
6105 code->append(osr_entry);
6106 }
6107
6108 optimizer.reorder_short_loops(code);
6109 optimizer.delete_empty_blocks(code);
6110 optimizer.delete_unnecessary_jumps(code);
6111 optimizer.delete_jumps_to_return(code);
6112 }
6113
6114 void ControlFlowOptimizer::reorder_short_loop(BlockList* code, BlockBegin* header_block, int header_idx) {
6115 int i = header_idx + 1;
6116 int max_end = MIN2(header_idx + ShortLoopSize, code->length());
6117 while (i < max_end && code->at(i)->loop_depth() >= header_block->loop_depth()) {
6118 i++;
6119 }
6120
6121 if (i == code->length() || code->at(i)->loop_depth() < header_block->loop_depth()) {
6122 int end_idx = i - 1;
6123 BlockBegin* end_block = code->at(end_idx);
6124
6125 if (end_block->number_of_sux() == 1 && end_block->sux_at(0) == header_block) {
6126 // short loop from header_idx to end_idx found -> reorder blocks such that
6127 // the header_block is the last block instead of the first block of the loop
6128 TRACE_LINEAR_SCAN(1, tty->print_cr("Reordering short loop: length %d, header B%d, end B%d",
6129 end_idx - header_idx + 1,
6130 header_block->block_id(), end_block->block_id()));
6131
6132 for (int j = header_idx; j < end_idx; j++) {
6133 code->at_put(j, code->at(j + 1));
6134 }
6135 code->at_put(end_idx, header_block);
6136
6137 // correct the flags so that any loop alignment occurs in the right place.
6138 assert(code->at(end_idx)->is_set(BlockBegin::backward_branch_target_flag), "must be backward branch target");
6139 code->at(end_idx)->clear(BlockBegin::backward_branch_target_flag);
6140 code->at(header_idx)->set(BlockBegin::backward_branch_target_flag);
6141 }
6142 }
6143 }
6144
6145 void ControlFlowOptimizer::reorder_short_loops(BlockList* code) {
6146 for (int i = code->length() - 1; i >= 0; i--) {
6147 BlockBegin* block = code->at(i);
6148
6149 if (block->is_set(BlockBegin::linear_scan_loop_header_flag)) {
6150 reorder_short_loop(code, block, i);
6151 }
6152 }
6153
6154 DEBUG_ONLY(verify(code));
6155 }
6156
6157 // only blocks with exactly one successor can be deleted. Such blocks
6158 // must always end with an unconditional branch to this successor
6159 bool ControlFlowOptimizer::can_delete_block(BlockBegin* block) {
6160 if (block->number_of_sux() != 1 || block->number_of_exception_handlers() != 0 || block->is_entry_block()) {
6161 return false;
6162 }
6163
6164 LIR_OpList* instructions = block->lir()->instructions_list();
6165
6166 assert(instructions->length() >= 2, "block must have label and branch");
6167 assert(instructions->at(0)->code() == lir_label, "first instruction must always be a label");
6168 assert(instructions->last()->as_OpBranch() != nullptr, "last instruction must always be a branch");
6169 assert(instructions->last()->as_OpBranch()->cond() == lir_cond_always, "branch must be unconditional");
6170 assert(instructions->last()->as_OpBranch()->block() == block->sux_at(0), "branch target must be the successor");
6171
6172 // block must have exactly one successor
6173
6174 if (instructions->length() == 2 && instructions->last()->info() == nullptr) {
6175 return true;
6176 }
6177 return false;
6178 }
6179
6180 // substitute branch targets in all branch-instructions of this blocks
6181 void ControlFlowOptimizer::substitute_branch_target(BlockBegin* block, BlockBegin* target_from, BlockBegin* target_to) {
6182 TRACE_LINEAR_SCAN(3, tty->print_cr("Deleting empty block: substituting from B%d to B%d inside B%d", target_from->block_id(), target_to->block_id(), block->block_id()));
6183
6184 LIR_OpList* instructions = block->lir()->instructions_list();
6185
6186 assert(instructions->at(0)->code() == lir_label, "first instruction must always be a label");
6187 for (int i = instructions->length() - 1; i >= 1; i--) {
6188 LIR_Op* op = instructions->at(i);
6189
6190 if (op->code() == lir_branch || op->code() == lir_cond_float_branch) {
6191 assert(op->as_OpBranch() != nullptr, "branch must be of type LIR_OpBranch");
6192 LIR_OpBranch* branch = (LIR_OpBranch*)op;
6193
6194 if (branch->block() == target_from) {
6195 branch->change_block(target_to);
6196 }
6197 if (branch->ublock() == target_from) {
6198 branch->change_ublock(target_to);
6199 }
6200 }
6201 }
6202 }
6203
6204 void ControlFlowOptimizer::delete_empty_blocks(BlockList* code) {
6205 int old_pos = 0;
6206 int new_pos = 0;
6207 int num_blocks = code->length();
6208
6209 while (old_pos < num_blocks) {
6210 BlockBegin* block = code->at(old_pos);
6211
6212 if (can_delete_block(block)) {
6213 BlockBegin* new_target = block->sux_at(0);
6214
6215 // propagate backward branch target flag for correct code alignment
6216 if (block->is_set(BlockBegin::backward_branch_target_flag)) {
6217 new_target->set(BlockBegin::backward_branch_target_flag);
6218 }
6219
6220 // collect a list with all predecessors that contains each predecessor only once
6221 // the predecessors of cur are changed during the substitution, so a copy of the
6222 // predecessor list is necessary
6223 int j;
6224 _original_preds.clear();
6225 for (j = block->number_of_preds() - 1; j >= 0; j--) {
6226 BlockBegin* pred = block->pred_at(j);
6227 if (_original_preds.find(pred) == -1) {
6228 _original_preds.append(pred);
6229 }
6230 }
6231
6232 for (j = _original_preds.length() - 1; j >= 0; j--) {
6233 BlockBegin* pred = _original_preds.at(j);
6234 substitute_branch_target(pred, block, new_target);
6235 pred->substitute_sux(block, new_target);
6236 }
6237 } else {
6238 // adjust position of this block in the block list if blocks before
6239 // have been deleted
6240 if (new_pos != old_pos) {
6241 code->at_put(new_pos, code->at(old_pos));
6242 }
6243 new_pos++;
6244 }
6245 old_pos++;
6246 }
6247 code->trunc_to(new_pos);
6248
6249 DEBUG_ONLY(verify(code));
6250 }
6251
6252 void ControlFlowOptimizer::delete_unnecessary_jumps(BlockList* code) {
6253 // skip the last block because there a branch is always necessary
6254 for (int i = code->length() - 2; i >= 0; i--) {
6255 BlockBegin* block = code->at(i);
6256 LIR_OpList* instructions = block->lir()->instructions_list();
6257
6258 LIR_Op* last_op = instructions->last();
6259 if (last_op->code() == lir_branch) {
6260 assert(last_op->as_OpBranch() != nullptr, "branch must be of type LIR_OpBranch");
6261 LIR_OpBranch* last_branch = (LIR_OpBranch*)last_op;
6262
6263 assert(last_branch->block() != nullptr, "last branch must always have a block as target");
6264 assert(last_branch->label() == last_branch->block()->label(), "must be equal");
6265
6266 if (last_branch->info() == nullptr) {
6267 if (last_branch->block() == code->at(i + 1)) {
6268
6269 TRACE_LINEAR_SCAN(3, tty->print_cr("Deleting unconditional branch at end of block B%d", block->block_id()));
6270
6271 // delete last branch instruction
6272 instructions->trunc_to(instructions->length() - 1);
6273
6274 } else {
6275 LIR_Op* prev_op = instructions->at(instructions->length() - 2);
6276 if (prev_op->code() == lir_branch || prev_op->code() == lir_cond_float_branch) {
6277 assert(prev_op->as_OpBranch() != nullptr, "branch must be of type LIR_OpBranch");
6278 LIR_OpBranch* prev_branch = (LIR_OpBranch*)prev_op;
6279
6280 if (prev_branch->stub() == nullptr) {
6281
6282 LIR_Op2* prev_cmp = nullptr;
6283 // There might be a cmove inserted for profiling which depends on the same
6284 // compare. If we change the condition of the respective compare, we have
6285 // to take care of this cmove as well.
6286 LIR_Op4* prev_cmove = nullptr;
6287
6288 for(int j = instructions->length() - 3; j >= 0 && prev_cmp == nullptr; j--) {
6289 prev_op = instructions->at(j);
6290 // check for the cmove
6291 if (prev_op->code() == lir_cmove) {
6292 assert(prev_op->as_Op4() != nullptr, "cmove must be of type LIR_Op4");
6293 prev_cmove = (LIR_Op4*)prev_op;
6294 assert(prev_branch->cond() == prev_cmove->condition(), "should be the same");
6295 }
6296 if (prev_op->code() == lir_cmp) {
6297 assert(prev_op->as_Op2() != nullptr, "branch must be of type LIR_Op2");
6298 prev_cmp = (LIR_Op2*)prev_op;
6299 assert(prev_branch->cond() == prev_cmp->condition(), "should be the same");
6300 }
6301 }
6302 // Guarantee because it is dereferenced below.
6303 guarantee(prev_cmp != nullptr, "should have found comp instruction for branch");
6304 if (prev_branch->block() == code->at(i + 1) && prev_branch->info() == nullptr) {
6305
6306 TRACE_LINEAR_SCAN(3, tty->print_cr("Negating conditional branch and deleting unconditional branch at end of block B%d", block->block_id()));
6307
6308 // eliminate a conditional branch to the immediate successor
6309 prev_branch->change_block(last_branch->block());
6310 prev_branch->negate_cond();
6311 prev_cmp->set_condition(prev_branch->cond());
6312 instructions->trunc_to(instructions->length() - 1);
6313 // if we do change the condition, we have to change the cmove as well
6314 if (prev_cmove != nullptr) {
6315 prev_cmove->set_condition(prev_branch->cond());
6316 LIR_Opr t = prev_cmove->in_opr1();
6317 prev_cmove->set_in_opr1(prev_cmove->in_opr2());
6318 prev_cmove->set_in_opr2(t);
6319 }
6320 }
6321 }
6322 }
6323 }
6324 }
6325 }
6326 }
6327
6328 DEBUG_ONLY(verify(code));
6329 }
6330
6331 void ControlFlowOptimizer::delete_jumps_to_return(BlockList* code) {
6332 #ifdef ASSERT
6333 ResourceBitMap return_converted(BlockBegin::number_of_blocks());
6334 #endif
6335
6336 for (int i = code->length() - 1; i >= 0; i--) {
6337 BlockBegin* block = code->at(i);
6338 LIR_OpList* cur_instructions = block->lir()->instructions_list();
6339 LIR_Op* cur_last_op = cur_instructions->last();
6340
6341 assert(cur_instructions->at(0)->code() == lir_label, "first instruction must always be a label");
6342 if (cur_instructions->length() == 2 && cur_last_op->code() == lir_return) {
6343 // the block contains only a label and a return
6344 // if a predecessor ends with an unconditional jump to this block, then the jump
6345 // can be replaced with a return instruction
6346 //
6347 // Note: the original block with only a return statement cannot be deleted completely
6348 // because the predecessors might have other (conditional) jumps to this block
6349 // -> this may lead to unnecessary return instructions in the final code
6350
6351 assert(cur_last_op->info() == nullptr, "return instructions do not have debug information");
6352 assert(block->number_of_sux() == 0 ||
6353 (return_converted.at(block->block_id()) && block->number_of_sux() == 1),
6354 "blocks that end with return must not have successors");
6355
6356 assert(cur_last_op->as_Op1() != nullptr, "return must be LIR_Op1");
6357 LIR_Opr return_opr = ((LIR_Op1*)cur_last_op)->in_opr();
6358
6359 for (int j = block->number_of_preds() - 1; j >= 0; j--) {
6360 BlockBegin* pred = block->pred_at(j);
6361 LIR_OpList* pred_instructions = pred->lir()->instructions_list();
6362 LIR_Op* pred_last_op = pred_instructions->last();
6363
6364 if (pred_last_op->code() == lir_branch) {
6365 assert(pred_last_op->as_OpBranch() != nullptr, "branch must be LIR_OpBranch");
6366 LIR_OpBranch* pred_last_branch = (LIR_OpBranch*)pred_last_op;
6367
6368 if (pred_last_branch->block() == block && pred_last_branch->cond() == lir_cond_always && pred_last_branch->info() == nullptr) {
6369 // replace the jump to a return with a direct return
6370 // Note: currently the edge between the blocks is not deleted
6371 pred_instructions->at_put(pred_instructions->length() - 1, new LIR_OpReturn(return_opr));
6372 #ifdef ASSERT
6373 return_converted.set_bit(pred->block_id());
6374 #endif
6375 }
6376 }
6377 }
6378 }
6379 }
6380 }
6381
6382
6383 #ifdef ASSERT
6384 void ControlFlowOptimizer::verify(BlockList* code) {
6385 for (int i = 0; i < code->length(); i++) {
6386 BlockBegin* block = code->at(i);
6387 LIR_OpList* instructions = block->lir()->instructions_list();
6388
6389 int j;
6390 for (j = 0; j < instructions->length(); j++) {
6391 LIR_OpBranch* op_branch = instructions->at(j)->as_OpBranch();
6392
6393 if (op_branch != nullptr) {
6394 assert(op_branch->block() == nullptr || code->find(op_branch->block()) != -1, "branch target not valid");
6395 assert(op_branch->ublock() == nullptr || code->find(op_branch->ublock()) != -1, "branch target not valid");
6396 }
6397 }
6398
6399 for (j = 0; j < block->number_of_sux() - 1; j++) {
6400 BlockBegin* sux = block->sux_at(j);
6401 assert(code->find(sux) != -1, "successor not valid");
6402 }
6403
6404 for (j = 0; j < block->number_of_preds() - 1; j++) {
6405 BlockBegin* pred = block->pred_at(j);
6406 assert(code->find(pred) != -1, "successor not valid");
6407 }
6408 }
6409 }
6410 #endif
6411
6412
6413 #ifndef PRODUCT
6414
6415 // Implementation of LinearStatistic
6416
6417 const char* LinearScanStatistic::counter_name(int counter_idx) {
6418 switch (counter_idx) {
6419 case counter_method: return "compiled methods";
6420 case counter_fpu_method: return "methods using fpu";
6421 case counter_loop_method: return "methods with loops";
6422 case counter_exception_method:return "methods with xhandler";
6423
6424 case counter_loop: return "loops";
6425 case counter_block: return "blocks";
6426 case counter_loop_block: return "blocks inside loop";
6427 case counter_exception_block: return "exception handler entries";
6428 case counter_interval: return "intervals";
6429 case counter_fixed_interval: return "fixed intervals";
6430 case counter_range: return "ranges";
6431 case counter_fixed_range: return "fixed ranges";
6432 case counter_use_pos: return "use positions";
6433 case counter_fixed_use_pos: return "fixed use positions";
6434 case counter_spill_slots: return "spill slots";
6435
6436 // counter for classes of lir instructions
6437 case counter_instruction: return "total instructions";
6438 case counter_label: return "labels";
6439 case counter_entry: return "method entries";
6440 case counter_return: return "method returns";
6441 case counter_call: return "method calls";
6442 case counter_move: return "moves";
6443 case counter_cmp: return "compare";
6444 case counter_cond_branch: return "conditional branches";
6445 case counter_uncond_branch: return "unconditional branches";
6446 case counter_stub_branch: return "branches to stub";
6447 case counter_alu: return "artithmetic + logic";
6448 case counter_alloc: return "allocations";
6449 case counter_sync: return "synchronisation";
6450 case counter_throw: return "throw";
6451 case counter_unwind: return "unwind";
6452 case counter_typecheck: return "type+null-checks";
6453 case counter_misc_inst: return "other instructions";
6454 case counter_other_inst: return "misc. instructions";
6455
6456 // counter for different types of moves
6457 case counter_move_total: return "total moves";
6458 case counter_move_reg_reg: return "register->register";
6459 case counter_move_reg_stack: return "register->stack";
6460 case counter_move_stack_reg: return "stack->register";
6461 case counter_move_stack_stack:return "stack->stack";
6462 case counter_move_reg_mem: return "register->memory";
6463 case counter_move_mem_reg: return "memory->register";
6464 case counter_move_const_any: return "constant->any";
6465
6466 case blank_line_1: return "";
6467 case blank_line_2: return "";
6468
6469 default: ShouldNotReachHere(); return "";
6470 }
6471 }
6472
6473 LinearScanStatistic::Counter LinearScanStatistic::base_counter(int counter_idx) {
6474 if (counter_idx == counter_fpu_method || counter_idx == counter_loop_method || counter_idx == counter_exception_method) {
6475 return counter_method;
6476 } else if (counter_idx == counter_loop_block || counter_idx == counter_exception_block) {
6477 return counter_block;
6478 } else if (counter_idx >= counter_instruction && counter_idx <= counter_other_inst) {
6479 return counter_instruction;
6480 } else if (counter_idx >= counter_move_total && counter_idx <= counter_move_const_any) {
6481 return counter_move_total;
6482 }
6483 return invalid_counter;
6484 }
6485
6486 LinearScanStatistic::LinearScanStatistic() {
6487 for (int i = 0; i < number_of_counters; i++) {
6488 _counters_sum[i] = 0;
6489 _counters_max[i] = -1;
6490 }
6491
6492 }
6493
6494 // add the method-local numbers to the total sum
6495 void LinearScanStatistic::sum_up(LinearScanStatistic &method_statistic) {
6496 for (int i = 0; i < number_of_counters; i++) {
6497 _counters_sum[i] += method_statistic._counters_sum[i];
6498 _counters_max[i] = MAX2(_counters_max[i], method_statistic._counters_sum[i]);
6499 }
6500 }
6501
6502 void LinearScanStatistic::print(const char* title) {
6503 if (CountLinearScan || TraceLinearScanLevel > 0) {
6504 tty->cr();
6505 tty->print_cr("***** LinearScan statistic - %s *****", title);
6506
6507 for (int i = 0; i < number_of_counters; i++) {
6508 if (_counters_sum[i] > 0 || _counters_max[i] >= 0) {
6509 tty->print("%25s: %8d", counter_name(i), _counters_sum[i]);
6510
6511 LinearScanStatistic::Counter cntr = base_counter(i);
6512 if (cntr != invalid_counter) {
6513 tty->print(" (%5.1f%%) ", _counters_sum[i] * 100.0 / _counters_sum[cntr]);
6514 } else {
6515 tty->print(" ");
6516 }
6517
6518 if (_counters_max[i] >= 0) {
6519 tty->print("%8d", _counters_max[i]);
6520 }
6521 }
6522 tty->cr();
6523 }
6524 }
6525 }
6526
6527 void LinearScanStatistic::collect(LinearScan* allocator) {
6528 inc_counter(counter_method);
6529 if (allocator->has_fpu_registers()) {
6530 inc_counter(counter_fpu_method);
6531 }
6532 if (allocator->num_loops() > 0) {
6533 inc_counter(counter_loop_method);
6534 }
6535 inc_counter(counter_loop, allocator->num_loops());
6536 inc_counter(counter_spill_slots, allocator->max_spills());
6537
6538 int i;
6539 for (i = 0; i < allocator->interval_count(); i++) {
6540 Interval* cur = allocator->interval_at(i);
6541
6542 if (cur != nullptr) {
6543 inc_counter(counter_interval);
6544 inc_counter(counter_use_pos, cur->num_use_positions());
6545 if (LinearScan::is_precolored_interval(cur)) {
6546 inc_counter(counter_fixed_interval);
6547 inc_counter(counter_fixed_use_pos, cur->num_use_positions());
6548 }
6549
6550 Range* range = cur->first();
6551 while (range != Range::end()) {
6552 inc_counter(counter_range);
6553 if (LinearScan::is_precolored_interval(cur)) {
6554 inc_counter(counter_fixed_range);
6555 }
6556 range = range->next();
6557 }
6558 }
6559 }
6560
6561 bool has_xhandlers = false;
6562 // Note: only count blocks that are in code-emit order
6563 for (i = 0; i < allocator->ir()->code()->length(); i++) {
6564 BlockBegin* cur = allocator->ir()->code()->at(i);
6565
6566 inc_counter(counter_block);
6567 if (cur->loop_depth() > 0) {
6568 inc_counter(counter_loop_block);
6569 }
6570 if (cur->is_set(BlockBegin::exception_entry_flag)) {
6571 inc_counter(counter_exception_block);
6572 has_xhandlers = true;
6573 }
6574
6575 LIR_OpList* instructions = cur->lir()->instructions_list();
6576 for (int j = 0; j < instructions->length(); j++) {
6577 LIR_Op* op = instructions->at(j);
6578
6579 inc_counter(counter_instruction);
6580
6581 switch (op->code()) {
6582 case lir_label: inc_counter(counter_label); break;
6583 case lir_std_entry:
6584 case lir_osr_entry: inc_counter(counter_entry); break;
6585 case lir_return: inc_counter(counter_return); break;
6586
6587 case lir_rtcall:
6588 case lir_static_call:
6589 case lir_optvirtual_call: inc_counter(counter_call); break;
6590
6591 case lir_move: {
6592 inc_counter(counter_move);
6593 inc_counter(counter_move_total);
6594
6595 LIR_Opr in = op->as_Op1()->in_opr();
6596 LIR_Opr res = op->as_Op1()->result_opr();
6597 if (in->is_register()) {
6598 if (res->is_register()) {
6599 inc_counter(counter_move_reg_reg);
6600 } else if (res->is_stack()) {
6601 inc_counter(counter_move_reg_stack);
6602 } else if (res->is_address()) {
6603 inc_counter(counter_move_reg_mem);
6604 } else {
6605 ShouldNotReachHere();
6606 }
6607 } else if (in->is_stack()) {
6608 if (res->is_register()) {
6609 inc_counter(counter_move_stack_reg);
6610 } else {
6611 inc_counter(counter_move_stack_stack);
6612 }
6613 } else if (in->is_address()) {
6614 assert(res->is_register(), "must be");
6615 inc_counter(counter_move_mem_reg);
6616 } else if (in->is_constant()) {
6617 inc_counter(counter_move_const_any);
6618 } else {
6619 ShouldNotReachHere();
6620 }
6621 break;
6622 }
6623
6624 case lir_cmp: inc_counter(counter_cmp); break;
6625
6626 case lir_branch:
6627 case lir_cond_float_branch: {
6628 LIR_OpBranch* branch = op->as_OpBranch();
6629 if (branch->block() == nullptr) {
6630 inc_counter(counter_stub_branch);
6631 } else if (branch->cond() == lir_cond_always) {
6632 inc_counter(counter_uncond_branch);
6633 } else {
6634 inc_counter(counter_cond_branch);
6635 }
6636 break;
6637 }
6638
6639 case lir_neg:
6640 case lir_add:
6641 case lir_sub:
6642 case lir_mul:
6643 case lir_div:
6644 case lir_rem:
6645 case lir_sqrt:
6646 case lir_abs:
6647 case lir_f2hf:
6648 case lir_hf2f:
6649 case lir_logic_and:
6650 case lir_logic_or:
6651 case lir_logic_xor:
6652 case lir_shl:
6653 case lir_shr:
6654 case lir_ushr: inc_counter(counter_alu); break;
6655
6656 case lir_alloc_object:
6657 case lir_alloc_array: inc_counter(counter_alloc); break;
6658
6659 case lir_monaddr:
6660 case lir_lock:
6661 case lir_unlock: inc_counter(counter_sync); break;
6662
6663 case lir_throw: inc_counter(counter_throw); break;
6664
6665 case lir_unwind: inc_counter(counter_unwind); break;
6666
6667 case lir_null_check:
6668 case lir_leal:
6669 case lir_instanceof:
6670 case lir_checkcast:
6671 case lir_store_check: inc_counter(counter_typecheck); break;
6672
6673 case lir_nop:
6674 case lir_push:
6675 case lir_pop:
6676 case lir_convert:
6677 case lir_cmove: inc_counter(counter_misc_inst); break;
6678
6679 default: inc_counter(counter_other_inst); break;
6680 }
6681 }
6682 }
6683
6684 if (has_xhandlers) {
6685 inc_counter(counter_exception_method);
6686 }
6687 }
6688
6689 void LinearScanStatistic::compute(LinearScan* allocator, LinearScanStatistic &global_statistic) {
6690 if (CountLinearScan || TraceLinearScanLevel > 0) {
6691
6692 LinearScanStatistic local_statistic = LinearScanStatistic();
6693
6694 local_statistic.collect(allocator);
6695 global_statistic.sum_up(local_statistic);
6696
6697 if (TraceLinearScanLevel > 2) {
6698 local_statistic.print("current local statistic");
6699 }
6700 }
6701 }
6702
6703
6704 // Implementation of LinearTimers
6705
6706 LinearScanTimers::LinearScanTimers() {
6707 for (int i = 0; i < number_of_timers; i++) {
6708 timer(i)->reset();
6709 }
6710 }
6711
6712 const char* LinearScanTimers::timer_name(int idx) {
6713 switch (idx) {
6714 case timer_do_nothing: return "Nothing (Time Check)";
6715 case timer_number_instructions: return "Number Instructions";
6716 case timer_compute_local_live_sets: return "Local Live Sets";
6717 case timer_compute_global_live_sets: return "Global Live Sets";
6718 case timer_build_intervals: return "Build Intervals";
6719 case timer_sort_intervals_before: return "Sort Intervals Before";
6720 case timer_allocate_registers: return "Allocate Registers";
6721 case timer_resolve_data_flow: return "Resolve Data Flow";
6722 case timer_sort_intervals_after: return "Sort Intervals After";
6723 case timer_eliminate_spill_moves: return "Spill optimization";
6724 case timer_assign_reg_num: return "Assign Reg Num";
6725 case timer_optimize_lir: return "Optimize LIR";
6726 default: ShouldNotReachHere(); return "";
6727 }
6728 }
6729
6730 void LinearScanTimers::begin_method() {
6731 if (TimeEachLinearScan) {
6732 // reset all timers to measure only current method
6733 for (int i = 0; i < number_of_timers; i++) {
6734 timer(i)->reset();
6735 }
6736 }
6737 }
6738
6739 void LinearScanTimers::end_method(LinearScan* allocator) {
6740 if (TimeEachLinearScan) {
6741
6742 double c = timer(timer_do_nothing)->seconds();
6743 double total = 0;
6744 for (int i = 1; i < number_of_timers; i++) {
6745 total += timer(i)->seconds() - c;
6746 }
6747
6748 if (total >= 0.0005) {
6749 // print all information in one line for automatic processing
6750 tty->print("@"); allocator->compilation()->method()->print_name();
6751
6752 tty->print("@ %d ", allocator->compilation()->method()->code_size());
6753 tty->print("@ %d ", allocator->block_at(allocator->block_count() - 1)->last_lir_instruction_id() / 2);
6754 tty->print("@ %d ", allocator->block_count());
6755 tty->print("@ %d ", allocator->num_virtual_regs());
6756 tty->print("@ %d ", allocator->interval_count());
6757 tty->print("@ %d ", allocator->_num_calls);
6758 tty->print("@ %d ", allocator->num_loops());
6759
6760 tty->print("@ %6.6f ", total);
6761 for (int i = 1; i < number_of_timers; i++) {
6762 tty->print("@ %4.1f ", ((timer(i)->seconds() - c) / total) * 100);
6763 }
6764 tty->cr();
6765 }
6766 }
6767 }
6768
6769 void LinearScanTimers::print(double total_time) {
6770 if (TimeLinearScan) {
6771 // correction value: sum of dummy-timer that only measures the time that
6772 // is necessary to start and stop itself
6773 double c = timer(timer_do_nothing)->seconds();
6774
6775 for (int i = 0; i < number_of_timers; i++) {
6776 double t = timer(i)->seconds();
6777 tty->print_cr(" %25s: %6.3f s (%4.1f%%) corrected: %6.3f s (%4.1f%%)", timer_name(i), t, (t / total_time) * 100.0, t - c, (t - c) / (total_time - 2 * number_of_timers * c) * 100);
6778 }
6779 }
6780 }
6781
6782 #endif // #ifndef PRODUCT