1 /*
2 * Copyright (c) 1999, 2024, 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 "precompiled.hpp"
26 #include "c1/c1_Compilation.hpp"
27 #include "c1/c1_FrameMap.hpp"
28 #include "c1/c1_GraphBuilder.hpp"
29 #include "c1/c1_IR.hpp"
30 #include "c1/c1_InstructionPrinter.hpp"
31 #include "c1/c1_Optimizer.hpp"
32 #include "compiler/oopMap.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "utilities/bitMap.inline.hpp"
35
36
37 // Implementation of XHandlers
38 //
39 // Note: This code could eventually go away if we are
40 // just using the ciExceptionHandlerStream.
41
42 XHandlers::XHandlers(ciMethod* method) : _list(method->exception_table_length()) {
43 ciExceptionHandlerStream s(method);
44 while (!s.is_done()) {
45 _list.append(new XHandler(s.handler()));
46 s.next();
47 }
48 assert(s.count() == method->exception_table_length(), "exception table lengths inconsistent");
49 }
50
51 // deep copy of all XHandler contained in list
52 XHandlers::XHandlers(XHandlers* other) :
53 _list(other->length())
54 {
55 for (int i = 0; i < other->length(); i++) {
56 _list.append(new XHandler(other->handler_at(i)));
57 }
58 }
59
60 // Returns whether a particular exception type can be caught. Also
61 // returns true if klass is unloaded or any exception handler
62 // classes are unloaded. type_is_exact indicates whether the throw
63 // is known to be exactly that class or it might throw a subtype.
64 bool XHandlers::could_catch(ciInstanceKlass* klass, bool type_is_exact) const {
65 // the type is unknown so be conservative
66 if (!klass->is_loaded()) {
67 return true;
68 }
69
70 for (int i = 0; i < length(); i++) {
71 XHandler* handler = handler_at(i);
72 if (handler->is_catch_all()) {
73 // catch of ANY
74 return true;
75 }
76 ciInstanceKlass* handler_klass = handler->catch_klass();
77 // if it's unknown it might be catchable
78 if (!handler_klass->is_loaded()) {
79 return true;
80 }
81 // if the throw type is definitely a subtype of the catch type
82 // then it can be caught.
83 if (klass->is_subtype_of(handler_klass)) {
84 return true;
85 }
86 if (!type_is_exact) {
87 // If the type isn't exactly known then it can also be caught by
88 // catch statements where the inexact type is a subtype of the
89 // catch type.
90 // given: foo extends bar extends Exception
91 // throw bar can be caught by catch foo, catch bar, and catch
92 // Exception, however it can't be caught by any handlers without
93 // bar in its type hierarchy.
94 if (handler_klass->is_subtype_of(klass)) {
95 return true;
96 }
97 }
98 }
99
100 return false;
101 }
102
103
104 bool XHandlers::equals(XHandlers* others) const {
105 if (others == nullptr) return false;
106 if (length() != others->length()) return false;
107
108 for (int i = 0; i < length(); i++) {
109 if (!handler_at(i)->equals(others->handler_at(i))) return false;
110 }
111 return true;
112 }
113
114 bool XHandler::equals(XHandler* other) const {
115 assert(entry_pco() != -1 && other->entry_pco() != -1, "must have entry_pco");
116
117 if (entry_pco() != other->entry_pco()) return false;
118 if (scope_count() != other->scope_count()) return false;
119 if (_desc != other->_desc) return false;
120
121 assert(entry_block() == other->entry_block(), "entry_block must be equal when entry_pco is equal");
122 return true;
123 }
124
125
126 // Implementation of IRScope
127 BlockBegin* IRScope::build_graph(Compilation* compilation, int osr_bci) {
128 GraphBuilder gm(compilation, this);
129 NOT_PRODUCT(if (PrintValueNumbering && Verbose) gm.print_stats());
130 if (compilation->bailed_out()) return nullptr;
131 return gm.start();
132 }
133
134
135 IRScope::IRScope(Compilation* compilation, IRScope* caller, int caller_bci, ciMethod* method, int osr_bci, bool create_graph)
136 : _compilation(compilation)
137 , _callees(2)
138 , _requires_phi_function(method->max_locals())
139 {
140 _caller = caller;
141 _level = caller == nullptr ? 0 : caller->level() + 1;
142 _method = method;
143 _xhandlers = new XHandlers(method);
144 _number_of_locks = 0;
145 _monitor_pairing_ok = method->has_balanced_monitors();
146 _wrote_final = false;
147 _wrote_fields = false;
148 _wrote_volatile = false;
149 _start = nullptr;
150
151 if (osr_bci != -1) {
152 // selective creation of phi functions is not possibel in osr-methods
153 _requires_phi_function.set_range(0, method->max_locals());
154 }
155
156 assert(method->holder()->is_loaded() , "method holder must be loaded");
157
158 // build graph if monitor pairing is ok
159 if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci);
160 }
161
162
163 int IRScope::max_stack() const {
164 int my_max = method()->max_stack();
165 int callee_max = 0;
166 for (int i = 0; i < number_of_callees(); i++) {
167 callee_max = MAX2(callee_max, callee_no(i)->max_stack());
168 }
169 return my_max + callee_max;
170 }
171
172
173 bool IRScopeDebugInfo::should_reexecute() {
174 if (_should_reexecute) {
175 return true;
176 }
177 ciMethod* cur_method = scope()->method();
178 int cur_bci = bci();
179 if (cur_method != nullptr && cur_bci != SynchronizationEntryBCI) {
180 Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci);
181 return Interpreter::bytecode_should_reexecute(code);
182 } else
183 return false;
184 }
185
186 // Implementation of CodeEmitInfo
187
188 // Stack must be NON-null
189 CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers, bool deoptimize_on_exception)
190 : _scope_debug_info(nullptr)
191 , _scope(stack->scope())
192 , _exception_handlers(exception_handlers)
193 , _oop_map(nullptr)
194 , _stack(stack)
195 , _is_method_handle_invoke(false)
196 , _deoptimize_on_exception(deoptimize_on_exception)
197 , _force_reexecute(false) {
198 assert(_stack != nullptr, "must be non null");
199 }
200
201
202 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack)
203 : _scope_debug_info(nullptr)
204 , _scope(info->_scope)
205 , _exception_handlers(nullptr)
206 , _oop_map(nullptr)
207 , _stack(stack == nullptr ? info->_stack : stack)
208 , _is_method_handle_invoke(info->_is_method_handle_invoke)
209 , _deoptimize_on_exception(info->_deoptimize_on_exception)
210 , _force_reexecute(info->_force_reexecute) {
211
212 // deep copy of exception handlers
213 if (info->_exception_handlers != nullptr) {
214 _exception_handlers = new XHandlers(info->_exception_handlers);
215 }
216 }
217
218
219 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset, bool maybe_return_as_fields) {
220 // record the safepoint before recording the debug info for enclosing scopes
221 recorder->add_safepoint(pc_offset, _oop_map->deep_copy());
222 bool reexecute = _force_reexecute || _scope_debug_info->should_reexecute();
223 _scope_debug_info->record_debug_info(recorder, pc_offset, reexecute, _is_method_handle_invoke, maybe_return_as_fields);
224 recorder->end_safepoint(pc_offset);
225 }
226
227
228 void CodeEmitInfo::add_register_oop(LIR_Opr opr) {
229 assert(_oop_map != nullptr, "oop map must already exist");
230 assert(opr->is_single_cpu(), "should not call otherwise");
231
232 VMReg name = frame_map()->regname(opr);
233 _oop_map->set_oop(name);
234 }
235
236 // Mirror the stack size calculation in the deopt code
237 // How much stack space would we need at this point in the program in
238 // case of deoptimization?
239 int CodeEmitInfo::interpreter_frame_size() const {
240 ValueStack* state = _stack;
241 int size = 0;
242 int callee_parameters = 0;
243 int callee_locals = 0;
244 int extra_args = state->scope()->method()->max_stack() - state->stack_size();
245
246 while (state != nullptr) {
247 int locks = state->locks_size();
248 int temps = state->stack_size();
249 bool is_top_frame = (state == _stack);
250 ciMethod* method = state->scope()->method();
251
252 int frame_size = BytesPerWord * Interpreter::size_activation(method->max_stack(),
253 temps + callee_parameters,
254 extra_args,
255 locks,
256 callee_parameters,
257 callee_locals,
258 is_top_frame);
259 size += frame_size;
260
261 callee_parameters = method->size_of_parameters();
262 callee_locals = method->max_locals();
263 extra_args = 0;
264 state = state->caller_state();
265 }
266 return size + Deoptimization::last_frame_adjust(0, callee_locals) * BytesPerWord;
267 }
268
269 // Implementation of IR
270
271 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) :
272 _num_loops(0) {
273 // setup IR fields
274 _compilation = compilation;
275 _top_scope = new IRScope(compilation, nullptr, -1, method, osr_bci, true);
276 _code = nullptr;
277 }
278
279
280 void IR::optimize_blocks() {
281 Optimizer opt(this);
282 if (!compilation()->profile_branches()) {
283 if (DoCEE) {
284 opt.eliminate_conditional_expressions();
285 #ifndef PRODUCT
286 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
287 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
288 #endif
289 }
290 if (EliminateBlocks) {
291 opt.eliminate_blocks();
292 #ifndef PRODUCT
293 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
294 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
295 #endif
296 }
297 }
298 }
299
300 void IR::eliminate_null_checks() {
301 Optimizer opt(this);
302 if (EliminateNullChecks) {
303 opt.eliminate_null_checks();
304 #ifndef PRODUCT
305 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
306 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
307 #endif
308 }
309 }
310
311 // The functionality of this class is to insert a new block between
312 // the 'from' and 'to' block of a critical edge.
313 // It first collects the block pairs, and then processes them.
314 //
315 // Some instructions may introduce more than one edge between two blocks.
316 // By checking if the current 'to' block sets critical_edge_split_flag
317 // (all new blocks set this flag) we can avoid repeated processing.
318 // This is why BlockPair contains the index rather than the original 'to' block.
319 class CriticalEdgeFinder: public BlockClosure {
320 BlockPairList blocks;
321
322 public:
323 CriticalEdgeFinder(IR* ir) {
324 ir->iterate_preorder(this);
325 }
326
327 void block_do(BlockBegin* bb) {
328 BlockEnd* be = bb->end();
329 int nos = be->number_of_sux();
330 if (nos >= 2) {
331 for (int i = 0; i < nos; i++) {
332 BlockBegin* sux = be->sux_at(i);
333 if (sux->number_of_preds() >= 2) {
334 blocks.append(new BlockPair(bb, i));
335 }
336 }
337 }
338 }
339
340 void split_edges() {
341 for (int i = 0; i < blocks.length(); i++) {
342 BlockPair* pair = blocks.at(i);
343 BlockBegin* from = pair->from();
344 int index = pair->index();
345 BlockBegin* to = from->end()->sux_at(index);
346 if (to->is_set(BlockBegin::critical_edge_split_flag)) {
347 // inserted
348 continue;
349 }
350 BlockBegin* split = from->insert_block_between(to);
351 #ifndef PRODUCT
352 if ((PrintIR || PrintIR1) && Verbose) {
353 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
354 from->block_id(), to->block_id(), split->block_id());
355 }
356 #endif
357 }
358 }
359 };
360
361 void IR::split_critical_edges() {
362 CriticalEdgeFinder cef(this);
363 cef.split_edges();
364 }
365
366
367 class UseCountComputer: public ValueVisitor, BlockClosure {
368 private:
369 void visit(Value* n) {
370 // Local instructions and Phis for expression stack values at the
371 // start of basic blocks are not added to the instruction list
372 if (!(*n)->is_linked() && (*n)->can_be_linked()) {
373 assert(false, "a node was not appended to the graph");
374 Compilation::current()->bailout("a node was not appended to the graph");
375 }
376 // use n's input if not visited before
377 if (!(*n)->is_pinned() && !(*n)->has_uses()) {
378 // note: a) if the instruction is pinned, it will be handled by compute_use_count
379 // b) if the instruction has uses, it was touched before
380 // => in both cases we don't need to update n's values
381 uses_do(n);
382 }
383 // use n
384 (*n)->_use_count++;
385 }
386
387 Values* worklist;
388 int depth;
389 enum {
390 max_recurse_depth = 20
391 };
392
393 void uses_do(Value* n) {
394 depth++;
395 if (depth > max_recurse_depth) {
396 // don't allow the traversal to recurse too deeply
397 worklist->push(*n);
398 } else {
399 (*n)->input_values_do(this);
400 // special handling for some instructions
401 if ((*n)->as_BlockEnd() != nullptr) {
402 // note on BlockEnd:
403 // must 'use' the stack only if the method doesn't
404 // terminate, however, in those cases stack is empty
405 (*n)->state_values_do(this);
406 }
407 }
408 depth--;
409 }
410
411 void block_do(BlockBegin* b) {
412 depth = 0;
413 // process all pinned nodes as the roots of expression trees
414 for (Instruction* n = b; n != nullptr; n = n->next()) {
415 if (n->is_pinned()) uses_do(&n);
416 }
417 assert(depth == 0, "should have counted back down");
418
419 // now process any unpinned nodes which recursed too deeply
420 while (worklist->length() > 0) {
421 Value t = worklist->pop();
422 if (!t->is_pinned()) {
423 // compute the use count
424 uses_do(&t);
425
426 // pin the instruction so that LIRGenerator doesn't recurse
427 // too deeply during it's evaluation.
428 t->pin();
429 }
430 }
431 assert(depth == 0, "should have counted back down");
432 }
433
434 UseCountComputer() {
435 worklist = new Values();
436 depth = 0;
437 }
438
439 public:
440 static void compute(BlockList* blocks) {
441 UseCountComputer ucc;
442 blocks->iterate_backward(&ucc);
443 }
444 };
445
446
447 // helper macro for short definition of trace-output inside code
448 #ifdef ASSERT
449 #define TRACE_LINEAR_SCAN(level, code) \
450 if (TraceLinearScanLevel >= level) { \
451 code; \
452 }
453 #else
454 #define TRACE_LINEAR_SCAN(level, code)
455 #endif
456
457 class ComputeLinearScanOrder : public StackObj {
458 private:
459 int _max_block_id; // the highest block_id of a block
460 int _num_blocks; // total number of blocks (smaller than _max_block_id)
461 int _num_loops; // total number of loops
462 bool _iterative_dominators;// method requires iterative computation of dominatiors
463
464 BlockList* _linear_scan_order; // the resulting list of blocks in correct order
465
466 ResourceBitMap _visited_blocks; // used for recursive processing of blocks
467 ResourceBitMap _active_blocks; // used for recursive processing of blocks
468 ResourceBitMap _dominator_blocks; // temporary BitMap used for computation of dominator
469 intArray _forward_branches; // number of incoming forward branches for each block
470 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges
471 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop
472 BlockList _work_list; // temporary list (used in mark_loops and compute_order)
473 BlockList _loop_headers;
474
475 Compilation* _compilation;
476
477 // accessors for _visited_blocks and _active_blocks
478 void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); }
479 bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); }
480 bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); }
481 void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); }
482 void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); }
483 void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); }
484
485 // accessors for _forward_branches
486 void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); }
487 int dec_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) - 1); return _forward_branches.at(b->block_id()); }
488
489 // accessors for _loop_map
490 bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); }
491 void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); }
492 void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); }
493
494 // count edges between blocks
495 void count_edges(BlockBegin* cur, BlockBegin* parent);
496
497 // loop detection
498 void mark_loops();
499 void clear_non_natural_loops(BlockBegin* start_block);
500 void assign_loop_depth(BlockBegin* start_block);
501
502 // computation of final block order
503 BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b);
504 void compute_dominator(BlockBegin* cur, BlockBegin* parent);
505 void compute_dominator_impl(BlockBegin* cur, BlockBegin* parent);
506 int compute_weight(BlockBegin* cur);
507 bool ready_for_processing(BlockBegin* cur);
508 void sort_into_work_list(BlockBegin* b);
509 void append_block(BlockBegin* cur);
510 void compute_order(BlockBegin* start_block);
511
512 // fixup of dominators for non-natural loops
513 bool compute_dominators_iter();
514 void compute_dominators();
515
516 // debug functions
517 DEBUG_ONLY(void print_blocks();)
518 DEBUG_ONLY(void verify();)
519
520 Compilation* compilation() const { return _compilation; }
521 public:
522 ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block);
523
524 // accessors for final result
525 BlockList* linear_scan_order() const { return _linear_scan_order; }
526 int num_loops() const { return _num_loops; }
527 };
528
529
530 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) :
531 _max_block_id(BlockBegin::number_of_blocks()),
532 _num_blocks(0),
533 _num_loops(0),
534 _iterative_dominators(false),
535 _linear_scan_order(nullptr), // initialized later with correct size
536 _visited_blocks(_max_block_id),
537 _active_blocks(_max_block_id),
538 _dominator_blocks(_max_block_id),
539 _forward_branches(_max_block_id, _max_block_id, 0),
540 _loop_end_blocks(8),
541 _loop_map(0), // initialized later with correct size
542 _work_list(8),
543 _compilation(c)
544 {
545 TRACE_LINEAR_SCAN(2, tty->print_cr("***** computing linear-scan block order"));
546
547 count_edges(start_block, nullptr);
548
549 if (compilation()->is_profiling()) {
550 ciMethod *method = compilation()->method();
551 if (!method->is_accessor()) {
552 ciMethodData* md = method->method_data_or_null();
553 assert(md != nullptr, "Sanity");
554 md->set_compilation_stats(_num_loops, _num_blocks);
555 }
556 }
557
558 if (_num_loops > 0) {
559 mark_loops();
560 clear_non_natural_loops(start_block);
561 assign_loop_depth(start_block);
562 }
563
564 compute_order(start_block);
565 compute_dominators();
566
567 DEBUG_ONLY(print_blocks());
568 DEBUG_ONLY(verify());
569 }
570
571
572 // Traverse the CFG:
573 // * count total number of blocks
574 // * count all incoming edges and backward incoming edges
575 // * number loop header blocks
576 // * create a list with all loop end blocks
577 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
578 TRACE_LINEAR_SCAN(3, tty->print_cr("Enter count_edges for block B%d coming from B%d", cur->block_id(), parent != nullptr ? parent->block_id() : -1));
579 assert(cur->dominator() == nullptr, "dominator already initialized");
580
581 if (is_active(cur)) {
582 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
583 assert(is_visited(cur), "block must be visisted when block is active");
584 assert(parent != nullptr, "must have parent");
585
586 cur->set(BlockBegin::backward_branch_target_flag);
587
588 // When a loop header is also the start of an exception handler, then the backward branch is
589 // an exception edge. Because such edges are usually critical edges which cannot be split, the
590 // loop must be excluded here from processing.
591 if (cur->is_set(BlockBegin::exception_entry_flag)) {
592 // Make sure that dominators are correct in this weird situation
593 _iterative_dominators = true;
594 return;
595 }
596
597 cur->set(BlockBegin::linear_scan_loop_header_flag);
598 parent->set(BlockBegin::linear_scan_loop_end_flag);
599
600 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
601 "loop end blocks must have one successor (critical edges are split)");
602
603 _loop_end_blocks.append(parent);
604 return;
605 }
606
607 // increment number of incoming forward branches
608 inc_forward_branches(cur);
609
610 if (is_visited(cur)) {
611 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
612 return;
613 }
614
615 _num_blocks++;
616 set_visited(cur);
617 set_active(cur);
618
619 // recursive call for all successors
620 int i;
621 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
622 count_edges(cur->sux_at(i), cur);
623 }
624 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
625 count_edges(cur->exception_handler_at(i), cur);
626 }
627
628 clear_active(cur);
629
630 // Each loop has a unique number.
631 // When multiple loops are nested, assign_loop_depth assumes that the
632 // innermost loop has the lowest number. This is guaranteed by setting
633 // the loop number after the recursive calls for the successors above
634 // have returned.
635 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
636 assert(cur->loop_index() == -1, "cannot set loop-index twice");
637 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
638
639 cur->set_loop_index(_num_loops);
640 _loop_headers.append(cur);
641 _num_loops++;
642 }
643
644 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
645 }
646
647
648 void ComputeLinearScanOrder::mark_loops() {
649 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
650
651 _loop_map = BitMap2D(_num_loops, _max_block_id);
652
653 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
654 BlockBegin* loop_end = _loop_end_blocks.at(i);
655 BlockBegin* loop_start = loop_end->sux_at(0);
656 int loop_idx = loop_start->loop_index();
657
658 TRACE_LINEAR_SCAN(3, tty->print_cr("Processing loop from B%d to B%d (loop %d):", loop_start->block_id(), loop_end->block_id(), loop_idx));
659 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
660 assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
661 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
662 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
663 assert(_work_list.is_empty(), "work list must be empty before processing");
664
665 // add the end-block of the loop to the working list
666 _work_list.push(loop_end);
667 set_block_in_loop(loop_idx, loop_end);
668 do {
669 BlockBegin* cur = _work_list.pop();
670
671 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id()));
672 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
673
674 // recursive processing of all predecessors ends when start block of loop is reached
675 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
676 for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
677 BlockBegin* pred = cur->pred_at(j);
678
679 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
680 // this predecessor has not been processed yet, so add it to work list
681 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id()));
682 _work_list.push(pred);
683 set_block_in_loop(loop_idx, pred);
684 }
685 }
686 }
687 } while (!_work_list.is_empty());
688 }
689 }
690
691
692 // check for non-natural loops (loops where the loop header does not dominate
693 // all other loop blocks = loops with multiple entries).
694 // such loops are ignored
695 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
696 for (int i = _num_loops - 1; i >= 0; i--) {
697 if (is_block_in_loop(i, start_block)) {
698 // loop i contains the entry block of the method
699 // -> this is not a natural loop, so ignore it
700 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
701
702 BlockBegin *loop_header = _loop_headers.at(i);
703 assert(loop_header->is_set(BlockBegin::linear_scan_loop_header_flag), "Must be loop header");
704
705 for (int j = 0; j < loop_header->number_of_preds(); j++) {
706 BlockBegin *pred = loop_header->pred_at(j);
707 pred->clear(BlockBegin::linear_scan_loop_end_flag);
708 }
709
710 loop_header->clear(BlockBegin::linear_scan_loop_header_flag);
711
712 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
713 clear_block_in_loop(i, block_id);
714 }
715 _iterative_dominators = true;
716 }
717 }
718 }
719
720 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
721 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing loop-depth and weight"));
722 init_visited();
723
724 assert(_work_list.is_empty(), "work list must be empty before processing");
725 _work_list.append(start_block);
726
727 do {
728 BlockBegin* cur = _work_list.pop();
729
730 if (!is_visited(cur)) {
731 set_visited(cur);
732 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
733
734 // compute loop-depth and loop-index for the block
735 assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
736 int i;
737 int loop_depth = 0;
738 int min_loop_idx = -1;
739 for (i = _num_loops - 1; i >= 0; i--) {
740 if (is_block_in_loop(i, cur)) {
741 loop_depth++;
742 min_loop_idx = i;
743 }
744 }
745 cur->set_loop_depth(loop_depth);
746 cur->set_loop_index(min_loop_idx);
747
748 // append all unvisited successors to work list
749 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
750 _work_list.append(cur->sux_at(i));
751 }
752 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
753 _work_list.append(cur->exception_handler_at(i));
754 }
755 }
756 } while (!_work_list.is_empty());
757 }
758
759
760 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
761 assert(a != nullptr && b != nullptr, "must have input blocks");
762
763 _dominator_blocks.clear();
764 while (a != nullptr) {
765 _dominator_blocks.set_bit(a->block_id());
766 assert(a->dominator() != nullptr || a == _linear_scan_order->at(0), "dominator must be initialized");
767 a = a->dominator();
768 }
769 while (b != nullptr && !_dominator_blocks.at(b->block_id())) {
770 assert(b->dominator() != nullptr || b == _linear_scan_order->at(0), "dominator must be initialized");
771 b = b->dominator();
772 }
773
774 assert(b != nullptr, "could not find dominator");
775 return b;
776 }
777
778 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
779 init_visited();
780 compute_dominator_impl(cur, parent);
781 }
782
783 void ComputeLinearScanOrder::compute_dominator_impl(BlockBegin* cur, BlockBegin* parent) {
784 // Mark as visited to avoid recursive calls with same parent
785 set_visited(cur);
786
787 if (cur->dominator() == nullptr) {
788 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
789 cur->set_dominator(parent);
790
791 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
792 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: computing dominator of B%d: common dominator of B%d and B%d is B%d", cur->block_id(), parent->block_id(), cur->dominator()->block_id(), common_dominator(cur->dominator(), parent)->block_id()));
793 // Does not hold for exception blocks
794 assert(cur->number_of_preds() > 1 || cur->is_set(BlockBegin::exception_entry_flag), "");
795 cur->set_dominator(common_dominator(cur->dominator(), parent));
796 }
797
798 // Additional edge to xhandler of all our successors
799 // range check elimination needs that the state at the end of a
800 // block be valid in every block it dominates so cur must dominate
801 // the exception handlers of its successors.
802 int num_cur_xhandler = cur->number_of_exception_handlers();
803 for (int j = 0; j < num_cur_xhandler; j++) {
804 BlockBegin* xhandler = cur->exception_handler_at(j);
805 if (!is_visited(xhandler)) {
806 compute_dominator_impl(xhandler, parent);
807 }
808 }
809 }
810
811
812 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
813 BlockBegin* single_sux = nullptr;
814 if (cur->number_of_sux() == 1) {
815 single_sux = cur->sux_at(0);
816 }
817
818 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
819 int weight = (cur->loop_depth() & 0x7FFF) << 16;
820
821 // general macro for short definition of weight flags
822 // the first instance of INC_WEIGHT_IF has the highest priority
823 int cur_bit = 15;
824 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
825
826 // this is necessary for the (very rare) case that two successive blocks have
827 // the same loop depth, but a different loop index (can happen for endless loops
828 // with exception handlers)
829 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
830
831 // loop end blocks (blocks that end with a backward branch) are added
832 // after all other blocks of the loop.
833 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
834
835 // critical edge split blocks are preferred because than they have a bigger
836 // proability to be completely empty
837 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
838
839 // exceptions should not be thrown in normal control flow, so these blocks
840 // are added as late as possible
841 INC_WEIGHT_IF(cur->end()->as_Throw() == nullptr && (single_sux == nullptr || single_sux->end()->as_Throw() == nullptr));
842 INC_WEIGHT_IF(cur->end()->as_Return() == nullptr && (single_sux == nullptr || single_sux->end()->as_Return() == nullptr));
843
844 // exceptions handlers are added as late as possible
845 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
846
847 // guarantee that weight is > 0
848 weight |= 1;
849
850 #undef INC_WEIGHT_IF
851 assert(cur_bit >= 0, "too many flags");
852 assert(weight > 0, "weight cannot become negative");
853
854 return weight;
855 }
856
857 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
858 // Discount the edge just traveled.
859 // When the number drops to zero, all forward branches were processed
860 if (dec_forward_branches(cur) != 0) {
861 return false;
862 }
863
864 assert(_linear_scan_order->find(cur) == -1, "block already processed (block can be ready only once)");
865 assert(_work_list.find(cur) == -1, "block already in work-list (block can be ready only once)");
866 return true;
867 }
868
869 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
870 assert(_work_list.find(cur) == -1, "block already in work list");
871
872 int cur_weight = compute_weight(cur);
873
874 // the linear_scan_number is used to cache the weight of a block
875 cur->set_linear_scan_number(cur_weight);
876
877 #ifndef PRODUCT
878 if (StressLinearScan) {
879 _work_list.insert_before(0, cur);
880 return;
881 }
882 #endif
883
884 _work_list.append(nullptr); // provide space for new element
885
886 int insert_idx = _work_list.length() - 1;
887 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
888 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
889 insert_idx--;
890 }
891 _work_list.at_put(insert_idx, cur);
892
893 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
894 TRACE_LINEAR_SCAN(3, for (int i = 0; i < _work_list.length(); i++) tty->print_cr("%8d B%2d weight:%6x", i, _work_list.at(i)->block_id(), _work_list.at(i)->linear_scan_number()));
895
896 #ifdef ASSERT
897 for (int i = 0; i < _work_list.length(); i++) {
898 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
899 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
900 }
901 #endif
902 }
903
904 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
905 TRACE_LINEAR_SCAN(3, tty->print_cr("appending block B%d (weight 0x%6x) to linear-scan order", cur->block_id(), cur->linear_scan_number()));
906 assert(_linear_scan_order->find(cur) == -1, "cannot add the same block twice");
907
908 // currently, the linear scan order and code emit order are equal.
909 // therefore the linear_scan_number and the weight of a block must also
910 // be equal.
911 cur->set_linear_scan_number(_linear_scan_order->length());
912 _linear_scan_order->append(cur);
913 }
914
915 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
916 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing final block order"));
917
918 // the start block is always the first block in the linear scan order
919 _linear_scan_order = new BlockList(_num_blocks);
920 append_block(start_block);
921
922 assert(start_block->end()->as_Base() != nullptr, "start block must end with Base-instruction");
923 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
924 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
925
926 BlockBegin* sux_of_osr_entry = nullptr;
927 if (osr_entry != nullptr) {
928 // special handling for osr entry:
929 // ignore the edge between the osr entry and its successor for processing
930 // the osr entry block is added manually below
931 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
932 assert(osr_entry->sux_at(0)->number_of_preds() >= 2, "successor of osr entry must have two predecessors (otherwise it is not present in normal control flow");
933
934 sux_of_osr_entry = osr_entry->sux_at(0);
935 dec_forward_branches(sux_of_osr_entry);
936
937 compute_dominator(osr_entry, start_block);
938 _iterative_dominators = true;
939 }
940 compute_dominator(std_entry, start_block);
941
942 // start processing with standard entry block
943 assert(_work_list.is_empty(), "list must be empty before processing");
944
945 if (ready_for_processing(std_entry)) {
946 sort_into_work_list(std_entry);
947 } else {
948 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
949 }
950
951 do {
952 BlockBegin* cur = _work_list.pop();
953
954 if (cur == sux_of_osr_entry) {
955 // the osr entry block is ignored in normal processing, it is never added to the
956 // work list. Instead, it is added as late as possible manually here.
957 append_block(osr_entry);
958 compute_dominator(cur, osr_entry);
959 }
960 append_block(cur);
961
962 int i;
963 int num_sux = cur->number_of_sux();
964 // changed loop order to get "intuitive" order of if- and else-blocks
965 for (i = 0; i < num_sux; i++) {
966 BlockBegin* sux = cur->sux_at(i);
967 compute_dominator(sux, cur);
968 if (ready_for_processing(sux)) {
969 sort_into_work_list(sux);
970 }
971 }
972 num_sux = cur->number_of_exception_handlers();
973 for (i = 0; i < num_sux; i++) {
974 BlockBegin* sux = cur->exception_handler_at(i);
975 if (ready_for_processing(sux)) {
976 sort_into_work_list(sux);
977 }
978 }
979 } while (_work_list.length() > 0);
980 }
981
982
983 bool ComputeLinearScanOrder::compute_dominators_iter() {
984 bool changed = false;
985 int num_blocks = _linear_scan_order->length();
986
987 assert(_linear_scan_order->at(0)->dominator() == nullptr, "must not have dominator");
988 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
989 for (int i = 1; i < num_blocks; i++) {
990 BlockBegin* block = _linear_scan_order->at(i);
991
992 BlockBegin* dominator = block->pred_at(0);
993 int num_preds = block->number_of_preds();
994
995 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: Processing B%d", block->block_id()));
996
997 for (int j = 0; j < num_preds; j++) {
998
999 BlockBegin *pred = block->pred_at(j);
1000 TRACE_LINEAR_SCAN(4, tty->print_cr(" DOM: Subrocessing B%d", pred->block_id()));
1001
1002 if (block->is_set(BlockBegin::exception_entry_flag)) {
1003 dominator = common_dominator(dominator, pred);
1004 int num_pred_preds = pred->number_of_preds();
1005 for (int k = 0; k < num_pred_preds; k++) {
1006 dominator = common_dominator(dominator, pred->pred_at(k));
1007 }
1008 } else {
1009 dominator = common_dominator(dominator, pred);
1010 }
1011 }
1012
1013 if (dominator != block->dominator()) {
1014 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: updating dominator of B%d from B%d to B%d", block->block_id(), block->dominator()->block_id(), dominator->block_id()));
1015
1016 block->set_dominator(dominator);
1017 changed = true;
1018 }
1019 }
1020 return changed;
1021 }
1022
1023 void ComputeLinearScanOrder::compute_dominators() {
1024 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
1025
1026 // iterative computation of dominators is only required for methods with non-natural loops
1027 // and OSR-methods. For all other methods, the dominators computed when generating the
1028 // linear scan block order are correct.
1029 if (_iterative_dominators) {
1030 do {
1031 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
1032 } while (compute_dominators_iter());
1033 }
1034
1035 // check that dominators are correct
1036 assert(!compute_dominators_iter(), "fix point not reached");
1037
1038 // Add Blocks to dominates-Array
1039 int num_blocks = _linear_scan_order->length();
1040 for (int i = 0; i < num_blocks; i++) {
1041 BlockBegin* block = _linear_scan_order->at(i);
1042
1043 BlockBegin *dom = block->dominator();
1044 if (dom) {
1045 assert(dom->dominator_depth() != -1, "Dominator must have been visited before");
1046 dom->dominates()->append(block);
1047 block->set_dominator_depth(dom->dominator_depth() + 1);
1048 } else {
1049 block->set_dominator_depth(0);
1050 }
1051 }
1052 }
1053
1054
1055 #ifdef ASSERT
1056 void ComputeLinearScanOrder::print_blocks() {
1057 if (TraceLinearScanLevel >= 2) {
1058 tty->print_cr("----- loop information:");
1059 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1060 BlockBegin* cur = _linear_scan_order->at(block_idx);
1061
1062 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
1063 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1064 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
1065 }
1066 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
1067 }
1068 }
1069
1070 if (TraceLinearScanLevel >= 1) {
1071 tty->print_cr("----- linear-scan block order:");
1072 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1073 BlockBegin* cur = _linear_scan_order->at(block_idx);
1074 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
1075
1076 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
1077 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
1078 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
1079 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
1080
1081 if (cur->dominator() != nullptr) {
1082 tty->print(" dom: B%d ", cur->dominator()->block_id());
1083 } else {
1084 tty->print(" dom: null ");
1085 }
1086
1087 if (cur->number_of_preds() > 0) {
1088 tty->print(" preds: ");
1089 for (int j = 0; j < cur->number_of_preds(); j++) {
1090 BlockBegin* pred = cur->pred_at(j);
1091 tty->print("B%d ", pred->block_id());
1092 }
1093 }
1094 if (cur->number_of_sux() > 0) {
1095 tty->print(" sux: ");
1096 for (int j = 0; j < cur->number_of_sux(); j++) {
1097 BlockBegin* sux = cur->sux_at(j);
1098 tty->print("B%d ", sux->block_id());
1099 }
1100 }
1101 if (cur->number_of_exception_handlers() > 0) {
1102 tty->print(" ex: ");
1103 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1104 BlockBegin* ex = cur->exception_handler_at(j);
1105 tty->print("B%d ", ex->block_id());
1106 }
1107 }
1108 tty->cr();
1109 }
1110 }
1111 }
1112
1113 void ComputeLinearScanOrder::verify() {
1114 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1115
1116 if (StressLinearScan) {
1117 // blocks are scrambled when StressLinearScan is used
1118 return;
1119 }
1120
1121 // check that all successors of a block have a higher linear-scan-number
1122 // and that all predecessors of a block have a lower linear-scan-number
1123 // (only backward branches of loops are ignored)
1124 int i;
1125 for (i = 0; i < _linear_scan_order->length(); i++) {
1126 BlockBegin* cur = _linear_scan_order->at(i);
1127
1128 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1129 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->find(cur), "incorrect linear_scan_number");
1130
1131 int j;
1132 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1133 BlockBegin* sux = cur->sux_at(j);
1134
1135 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->find(sux), "incorrect linear_scan_number");
1136 if (!sux->is_set(BlockBegin::backward_branch_target_flag)) {
1137 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1138 }
1139 if (cur->loop_depth() == sux->loop_depth()) {
1140 assert(cur->loop_index() == sux->loop_index() || sux->is_set(BlockBegin::linear_scan_loop_header_flag), "successive blocks with same loop depth must have same loop index");
1141 }
1142 }
1143
1144 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1145 BlockBegin* pred = cur->pred_at(j);
1146
1147 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->find(pred), "incorrect linear_scan_number");
1148 if (!cur->is_set(BlockBegin::backward_branch_target_flag)) {
1149 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1150 }
1151 if (cur->loop_depth() == pred->loop_depth()) {
1152 assert(cur->loop_index() == pred->loop_index() || cur->is_set(BlockBegin::linear_scan_loop_header_flag), "successive blocks with same loop depth must have same loop index");
1153 }
1154
1155 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1156 }
1157
1158 // check dominator
1159 if (i == 0) {
1160 assert(cur->dominator() == nullptr, "first block has no dominator");
1161 } else {
1162 assert(cur->dominator() != nullptr, "all but first block must have dominator");
1163 }
1164 // Assertion does not hold for exception handlers
1165 assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0) || cur->is_set(BlockBegin::exception_entry_flag), "Single predecessor must also be dominator");
1166 }
1167
1168 // check that all loops are continuous
1169 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1170 int block_idx = 0;
1171 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1172
1173 // skip blocks before the loop
1174 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1175 block_idx++;
1176 }
1177 // skip blocks of loop
1178 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1179 block_idx++;
1180 }
1181 // after the first non-loop block, there must not be another loop-block
1182 while (block_idx < _num_blocks) {
1183 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1184 block_idx++;
1185 }
1186 }
1187 }
1188 #endif // ASSERT
1189
1190
1191 void IR::compute_code() {
1192 assert(is_valid(), "IR must be valid");
1193
1194 ComputeLinearScanOrder compute_order(compilation(), start());
1195 _num_loops = compute_order.num_loops();
1196 _code = compute_order.linear_scan_order();
1197 }
1198
1199
1200 void IR::compute_use_counts() {
1201 // make sure all values coming out of this block get evaluated.
1202 int num_blocks = _code->length();
1203 for (int i = 0; i < num_blocks; i++) {
1204 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1205 }
1206
1207 // compute use counts
1208 UseCountComputer::compute(_code);
1209 }
1210
1211
1212 void IR::iterate_preorder(BlockClosure* closure) {
1213 assert(is_valid(), "IR must be valid");
1214 start()->iterate_preorder(closure);
1215 }
1216
1217
1218 void IR::iterate_postorder(BlockClosure* closure) {
1219 assert(is_valid(), "IR must be valid");
1220 start()->iterate_postorder(closure);
1221 }
1222
1223 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1224 linear_scan_order()->iterate_forward(closure);
1225 }
1226
1227
1228 #ifndef PRODUCT
1229 class BlockPrinter: public BlockClosure {
1230 private:
1231 InstructionPrinter* _ip;
1232 bool _cfg_only;
1233 bool _live_only;
1234
1235 public:
1236 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1237 _ip = ip;
1238 _cfg_only = cfg_only;
1239 _live_only = live_only;
1240 }
1241
1242 virtual void block_do(BlockBegin* block) {
1243 if (_cfg_only) {
1244 _ip->print_instr(block); tty->cr();
1245 } else {
1246 block->print_block(*_ip, _live_only);
1247 }
1248 }
1249 };
1250
1251
1252 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1253 ttyLocker ttyl;
1254 InstructionPrinter ip(!cfg_only);
1255 BlockPrinter bp(&ip, cfg_only, live_only);
1256 start->iterate_preorder(&bp);
1257 tty->cr();
1258 }
1259
1260 void IR::print(bool cfg_only, bool live_only) {
1261 if (is_valid()) {
1262 print(start(), cfg_only, live_only);
1263 } else {
1264 tty->print_cr("invalid IR");
1265 }
1266 }
1267 #endif // PRODUCT
1268
1269 #ifdef ASSERT
1270 class EndNotNullValidator : public BlockClosure {
1271 public:
1272 virtual void block_do(BlockBegin* block) {
1273 assert(block->end() != nullptr, "Expect block end to exist.");
1274 }
1275 };
1276
1277 class XentryFlagValidator : public BlockClosure {
1278 public:
1279 virtual void block_do(BlockBegin* block) {
1280 for (int i = 0; i < block->end()->number_of_sux(); i++) {
1281 assert(!block->end()->sux_at(i)->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1282 }
1283 for (int i = 0; i < block->number_of_exception_handlers(); i++) {
1284 assert(block->exception_handler_at(i)->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1285 }
1286 }
1287 };
1288
1289 typedef GrowableArray<BlockList*> BlockListList;
1290
1291 // Validation goals:
1292 // - code() length == blocks length
1293 // - code() contents == blocks content
1294 // - Each block's computed predecessors match sux lists (length)
1295 // - Each block's computed predecessors match sux lists (set content)
1296 class PredecessorAndCodeValidator : public BlockClosure {
1297 private:
1298 BlockListList* _predecessors; // Each index i will hold predecessors of block with id i
1299 BlockList* _blocks;
1300
1301 static int cmp(BlockBegin** a, BlockBegin** b) {
1302 return (*a)->block_id() - (*b)->block_id();
1303 }
1304
1305 public:
1306 PredecessorAndCodeValidator(IR* hir) {
1307 ResourceMark rm;
1308 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), BlockBegin::number_of_blocks(), nullptr);
1309 _blocks = new BlockList(BlockBegin::number_of_blocks());
1310
1311 hir->start()->iterate_preorder(this);
1312 if (hir->code() != nullptr) {
1313 assert(hir->code()->length() == _blocks->length(), "must match");
1314 for (int i = 0; i < _blocks->length(); i++) {
1315 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1316 }
1317 }
1318
1319 for (int i = 0; i < _blocks->length(); i++) {
1320 BlockBegin* block = _blocks->at(i);
1321 verify_block_preds_against_collected_preds(block);
1322 }
1323 }
1324
1325 virtual void block_do(BlockBegin* block) {
1326 _blocks->append(block);
1327 collect_predecessors(block);
1328 }
1329
1330 private:
1331 void collect_predecessors(BlockBegin* block) {
1332 for (int i = 0; i < block->end()->number_of_sux(); i++) {
1333 collect_predecessor(block, block->end()->sux_at(i));
1334 }
1335 for (int i = 0; i < block->number_of_exception_handlers(); i++) {
1336 collect_predecessor(block, block->exception_handler_at(i));
1337 }
1338 }
1339
1340 void collect_predecessor(BlockBegin* const pred, const BlockBegin* sux) {
1341 BlockList* preds = _predecessors->at_grow(sux->block_id(), nullptr);
1342 if (preds == nullptr) {
1343 preds = new BlockList();
1344 _predecessors->at_put(sux->block_id(), preds);
1345 }
1346 preds->append(pred);
1347 }
1348
1349 void verify_block_preds_against_collected_preds(const BlockBegin* block) const {
1350 BlockList* preds = _predecessors->at(block->block_id());
1351 if (preds == nullptr) {
1352 assert(block->number_of_preds() == 0, "should be the same");
1353 return;
1354 }
1355 assert(preds->length() == block->number_of_preds(), "should be the same");
1356
1357 // clone the pred list so we can mutate it
1358 BlockList* pred_copy = new BlockList();
1359 for (int j = 0; j < block->number_of_preds(); j++) {
1360 pred_copy->append(block->pred_at(j));
1361 }
1362 // sort them in the same order
1363 preds->sort(cmp);
1364 pred_copy->sort(cmp);
1365 for (int j = 0; j < block->number_of_preds(); j++) {
1366 assert(preds->at(j) == pred_copy->at(j), "must match");
1367 }
1368 }
1369 };
1370
1371 class VerifyBlockBeginField : public BlockClosure {
1372 public:
1373 virtual void block_do(BlockBegin* block) {
1374 for (Instruction* cur = block; cur != nullptr; cur = cur->next()) {
1375 assert(cur->block() == block, "Block begin is not correct");
1376 }
1377 }
1378 };
1379
1380 class ValidateEdgeMutuality : public BlockClosure {
1381 public:
1382 virtual void block_do(BlockBegin* block) {
1383 for (int i = 0; i < block->end()->number_of_sux(); i++) {
1384 assert(block->end()->sux_at(i)->is_predecessor(block), "Block's successor should have it as predecessor");
1385 }
1386
1387 for (int i = 0; i < block->number_of_exception_handlers(); i++) {
1388 assert(block->exception_handler_at(i)->is_predecessor(block), "Block's exception handler should have it as predecessor");
1389 }
1390
1391 for (int i = 0; i < block->number_of_preds(); i++) {
1392 assert(block->pred_at(i) != nullptr, "Predecessor must exist");
1393 assert(block->pred_at(i)->end() != nullptr, "Predecessor end must exist");
1394 bool is_sux = block->pred_at(i)->end()->is_sux(block);
1395 bool is_xhandler = block->pred_at(i)->is_exception_handler(block);
1396 assert(is_sux || is_xhandler, "Block's predecessor should have it as successor or xhandler");
1397 }
1398 }
1399 };
1400
1401 void IR::expand_with_neighborhood(BlockList& blocks) {
1402 int original_size = blocks.length();
1403 for (int h = 0; h < original_size; h++) {
1404 BlockBegin* block = blocks.at(h);
1405
1406 for (int i = 0; i < block->end()->number_of_sux(); i++) {
1407 if (!blocks.contains(block->end()->sux_at(i))) {
1408 blocks.append(block->end()->sux_at(i));
1409 }
1410 }
1411
1412 for (int i = 0; i < block->number_of_preds(); i++) {
1413 if (!blocks.contains(block->pred_at(i))) {
1414 blocks.append(block->pred_at(i));
1415 }
1416 }
1417
1418 for (int i = 0; i < block->number_of_exception_handlers(); i++) {
1419 if (!blocks.contains(block->exception_handler_at(i))) {
1420 blocks.append(block->exception_handler_at(i));
1421 }
1422 }
1423 }
1424 }
1425
1426 void IR::verify_local(BlockList& blocks) {
1427 EndNotNullValidator ennv;
1428 blocks.iterate_forward(&ennv);
1429
1430 ValidateEdgeMutuality vem;
1431 blocks.iterate_forward(&vem);
1432
1433 VerifyBlockBeginField verifier;
1434 blocks.iterate_forward(&verifier);
1435 }
1436
1437 void IR::verify() {
1438 XentryFlagValidator xe;
1439 iterate_postorder(&xe);
1440
1441 PredecessorAndCodeValidator pv(this);
1442
1443 EndNotNullValidator ennv;
1444 iterate_postorder(&ennv);
1445
1446 ValidateEdgeMutuality vem;
1447 iterate_postorder(&vem);
1448
1449 VerifyBlockBeginField verifier;
1450 iterate_postorder(&verifier);
1451 }
1452 #endif // ASSERT
1453
1454 void SubstitutionResolver::visit(Value* v) {
1455 Value v0 = *v;
1456 if (v0) {
1457 Value vs = v0->subst();
1458 if (vs != v0) {
1459 *v = v0->subst();
1460 }
1461 }
1462 }
1463
1464 #ifdef ASSERT
1465 class SubstitutionChecker: public ValueVisitor {
1466 void visit(Value* v) {
1467 Value v0 = *v;
1468 if (v0) {
1469 Value vs = v0->subst();
1470 assert(vs == v0, "missed substitution");
1471 }
1472 }
1473 };
1474 #endif
1475
1476
1477 void SubstitutionResolver::block_do(BlockBegin* block) {
1478 Instruction* last = nullptr;
1479 for (Instruction* n = block; n != nullptr;) {
1480 n->values_do(this);
1481 // need to remove this instruction from the instruction stream
1482 if (n->subst() != n) {
1483 guarantee(last != nullptr, "must have last");
1484 last->set_next(n->next());
1485 } else {
1486 last = n;
1487 }
1488 n = last->next();
1489 }
1490
1491 #ifdef ASSERT
1492 SubstitutionChecker check_substitute;
1493 if (block->state()) block->state()->values_do(&check_substitute);
1494 block->block_values_do(&check_substitute);
1495 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
1496 #endif
1497 }