1 /*
2 * Copyright (c) 2018, 2021, Red Hat, Inc. All rights reserved.
3 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
28 #include "gc/shenandoah/shenandoahBarrierSetAssembler.hpp"
29 #include "gc/shenandoah/shenandoahForwarding.hpp"
30 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
31 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
32 #include "gc/shenandoah/shenandoahRuntime.hpp"
33 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
34 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
35 #include "gc/shenandoah/mode/shenandoahMode.hpp"
36 #include "interpreter/interpreter.hpp"
37 #include "runtime/javaThread.hpp"
38 #include "runtime/sharedRuntime.hpp"
39 #include "utilities/macros.hpp"
40 #ifdef COMPILER1
41 #include "c1/c1_LIRAssembler.hpp"
42 #include "c1/c1_MacroAssembler.hpp"
43 #include "gc/shenandoah/c1/shenandoahBarrierSetC1.hpp"
44 #endif
45
46 #define __ masm->
47
48 static void save_machine_state(MacroAssembler* masm, bool handle_gpr, bool handle_fp) {
49 if (handle_gpr) {
50 __ push_IU_state();
51 }
52
53 if (handle_fp) {
54 // Some paths can be reached from the c2i adapter with live fp arguments in registers.
55 LP64_ONLY(assert(Argument::n_float_register_parameters_j == 8, "8 fp registers to save at java call"));
56
57 if (UseSSE >= 2) {
58 const int xmm_size = wordSize * LP64_ONLY(2) NOT_LP64(4);
59 __ subptr(rsp, xmm_size * 8);
60 __ movdbl(Address(rsp, xmm_size * 0), xmm0);
61 __ movdbl(Address(rsp, xmm_size * 1), xmm1);
62 __ movdbl(Address(rsp, xmm_size * 2), xmm2);
63 __ movdbl(Address(rsp, xmm_size * 3), xmm3);
64 __ movdbl(Address(rsp, xmm_size * 4), xmm4);
65 __ movdbl(Address(rsp, xmm_size * 5), xmm5);
66 __ movdbl(Address(rsp, xmm_size * 6), xmm6);
67 __ movdbl(Address(rsp, xmm_size * 7), xmm7);
68 } else if (UseSSE >= 1) {
69 const int xmm_size = wordSize * LP64_ONLY(1) NOT_LP64(2);
70 __ subptr(rsp, xmm_size * 8);
71 __ movflt(Address(rsp, xmm_size * 0), xmm0);
72 __ movflt(Address(rsp, xmm_size * 1), xmm1);
73 __ movflt(Address(rsp, xmm_size * 2), xmm2);
74 __ movflt(Address(rsp, xmm_size * 3), xmm3);
75 __ movflt(Address(rsp, xmm_size * 4), xmm4);
76 __ movflt(Address(rsp, xmm_size * 5), xmm5);
77 __ movflt(Address(rsp, xmm_size * 6), xmm6);
78 __ movflt(Address(rsp, xmm_size * 7), xmm7);
79 } else {
80 __ push_FPU_state();
81 }
82 }
83 }
84
85 static void restore_machine_state(MacroAssembler* masm, bool handle_gpr, bool handle_fp) {
86 if (handle_fp) {
87 if (UseSSE >= 2) {
88 const int xmm_size = wordSize * LP64_ONLY(2) NOT_LP64(4);
89 __ movdbl(xmm0, Address(rsp, xmm_size * 0));
90 __ movdbl(xmm1, Address(rsp, xmm_size * 1));
91 __ movdbl(xmm2, Address(rsp, xmm_size * 2));
92 __ movdbl(xmm3, Address(rsp, xmm_size * 3));
93 __ movdbl(xmm4, Address(rsp, xmm_size * 4));
94 __ movdbl(xmm5, Address(rsp, xmm_size * 5));
95 __ movdbl(xmm6, Address(rsp, xmm_size * 6));
96 __ movdbl(xmm7, Address(rsp, xmm_size * 7));
97 __ addptr(rsp, xmm_size * 8);
98 } else if (UseSSE >= 1) {
99 const int xmm_size = wordSize * LP64_ONLY(1) NOT_LP64(2);
100 __ movflt(xmm0, Address(rsp, xmm_size * 0));
101 __ movflt(xmm1, Address(rsp, xmm_size * 1));
102 __ movflt(xmm2, Address(rsp, xmm_size * 2));
103 __ movflt(xmm3, Address(rsp, xmm_size * 3));
104 __ movflt(xmm4, Address(rsp, xmm_size * 4));
105 __ movflt(xmm5, Address(rsp, xmm_size * 5));
106 __ movflt(xmm6, Address(rsp, xmm_size * 6));
107 __ movflt(xmm7, Address(rsp, xmm_size * 7));
108 __ addptr(rsp, xmm_size * 8);
109 } else {
110 __ pop_FPU_state();
111 }
112 }
113
114 if (handle_gpr) {
115 __ pop_IU_state();
116 }
117 }
118
119 void ShenandoahBarrierSetAssembler::arraycopy_prologue(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
120 Register src, Register dst, Register count) {
121
122 bool dest_uninitialized = (decorators & IS_DEST_UNINITIALIZED) != 0;
123
124 if (is_reference_type(type)) {
125 if (ShenandoahCardBarrier) {
126 bool checkcast = (decorators & ARRAYCOPY_CHECKCAST) != 0;
127 bool disjoint = (decorators & ARRAYCOPY_DISJOINT) != 0;
128 bool obj_int = type == T_OBJECT LP64_ONLY(&& UseCompressedOops);
129
130 // We need to save the original element count because the array copy stub
131 // will destroy the value and we need it for the card marking barrier.
132 #ifdef _LP64
133 if (!checkcast) {
134 if (!obj_int) {
135 // Save count for barrier
136 __ movptr(r11, count);
137 } else if (disjoint) {
138 // Save dst in r11 in the disjoint case
139 __ movq(r11, dst);
140 }
141 }
142 #else
143 if (disjoint) {
144 __ mov(rdx, dst); // save 'to'
145 }
146 #endif
147 }
148
149 if ((ShenandoahSATBBarrier && !dest_uninitialized) || ShenandoahIUBarrier || ShenandoahLoadRefBarrier) {
150 #ifdef _LP64
151 Register thread = r15_thread;
152 #else
153 Register thread = rax;
154 if (thread == src || thread == dst || thread == count) {
155 thread = rbx;
156 }
157 if (thread == src || thread == dst || thread == count) {
158 thread = rcx;
159 }
160 if (thread == src || thread == dst || thread == count) {
161 thread = rdx;
162 }
163 __ push(thread);
164 __ get_thread(thread);
165 #endif
166 assert_different_registers(src, dst, count, thread);
167
168 Label L_done;
169 // Short-circuit if count == 0.
170 __ testptr(count, count);
171 __ jcc(Assembler::zero, L_done);
172
173 // Avoid runtime call when not active.
174 Address gc_state(thread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
175 int flags;
176 if (ShenandoahSATBBarrier && dest_uninitialized) {
177 flags = ShenandoahHeap::HAS_FORWARDED;
178 } else {
179 flags = ShenandoahHeap::HAS_FORWARDED | ShenandoahHeap::MARKING;
180 }
181 __ testb(gc_state, flags);
182 __ jcc(Assembler::zero, L_done);
183
184 save_machine_state(masm, /* handle_gpr = */ true, /* handle_fp = */ false);
185
186 #ifdef _LP64
187 assert(src == rdi, "expected");
188 assert(dst == rsi, "expected");
189 assert(count == rdx, "expected");
190 if (UseCompressedOops) {
191 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::arraycopy_barrier_narrow_oop_entry),
192 src, dst, count);
193 } else
194 #endif
195 {
196 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::arraycopy_barrier_oop_entry),
197 src, dst, count);
198 }
199
200 restore_machine_state(masm, /* handle_gpr = */ true, /* handle_fp = */ false);
201
202 __ bind(L_done);
203 NOT_LP64(__ pop(thread);)
204 }
205 }
206
207 }
208
209 void ShenandoahBarrierSetAssembler::arraycopy_epilogue(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
210 Register src, Register dst, Register count) {
211
212 if (ShenandoahCardBarrier && is_reference_type(type)) {
213 bool checkcast = (decorators & ARRAYCOPY_CHECKCAST) != 0;
214 bool disjoint = (decorators & ARRAYCOPY_DISJOINT) != 0;
215 bool obj_int = type == T_OBJECT LP64_ONLY(&& UseCompressedOops);
216 Register tmp = rax;
217
218 #ifdef _LP64
219 if (!checkcast) {
220 if (!obj_int) {
221 // Save count for barrier
222 count = r11;
223 } else if (disjoint) {
224 // Use the saved dst in the disjoint case
225 dst = r11;
226 }
227 } else {
228 tmp = rscratch1;
229 }
230 #else
231 if (disjoint) {
232 __ mov(dst, rdx); // restore 'to'
233 }
234 #endif
235 gen_write_ref_array_post_barrier(masm, decorators, dst, count, tmp);
236 }
237 }
238
239 void ShenandoahBarrierSetAssembler::shenandoah_write_barrier_pre(MacroAssembler* masm,
240 Register obj,
241 Register pre_val,
242 Register thread,
243 Register tmp,
244 bool tosca_live,
245 bool expand_call) {
246
247 if (ShenandoahSATBBarrier) {
248 satb_write_barrier_pre(masm, obj, pre_val, thread, tmp, tosca_live, expand_call);
249 }
250 }
251
252 void ShenandoahBarrierSetAssembler::satb_write_barrier_pre(MacroAssembler* masm,
253 Register obj,
254 Register pre_val,
255 Register thread,
256 Register tmp,
257 bool tosca_live,
258 bool expand_call) {
259 // If expand_call is true then we expand the call_VM_leaf macro
260 // directly to skip generating the check by
261 // InterpreterMacroAssembler::call_VM_leaf_base that checks _last_sp.
262
263 #ifdef _LP64
264 assert(thread == r15_thread, "must be");
265 #endif // _LP64
266
267 Label done;
268 Label runtime;
269
270 assert(pre_val != noreg, "check this code");
271
272 if (obj != noreg) {
273 assert_different_registers(obj, pre_val, tmp);
274 assert(pre_val != rax, "check this code");
275 }
276
277 Address in_progress(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_active_offset()));
278 Address index(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset()));
279 Address buffer(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset()));
280
281 Address gc_state(thread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
282 __ testb(gc_state, ShenandoahHeap::MARKING);
283 __ jcc(Assembler::zero, done);
284
285 // Do we need to load the previous value?
286 if (obj != noreg) {
287 __ load_heap_oop(pre_val, Address(obj, 0), noreg, noreg, AS_RAW);
288 }
289
290 // Is the previous value null?
291 __ cmpptr(pre_val, NULL_WORD);
292 __ jcc(Assembler::equal, done);
293
294 // Can we store original value in the thread's buffer?
295 // Is index == 0?
296 // (The index field is typed as size_t.)
297
298 __ movptr(tmp, index); // tmp := *index_adr
299 __ cmpptr(tmp, 0); // tmp == 0?
300 __ jcc(Assembler::equal, runtime); // If yes, goto runtime
301
302 __ subptr(tmp, wordSize); // tmp := tmp - wordSize
303 __ movptr(index, tmp); // *index_adr := tmp
304 __ addptr(tmp, buffer); // tmp := tmp + *buffer_adr
305
306 // Record the previous value
307 __ movptr(Address(tmp, 0), pre_val);
308 __ jmp(done);
309
310 __ bind(runtime);
311 // save the live input values
312 if(tosca_live) __ push(rax);
313
314 if (obj != noreg && obj != rax)
315 __ push(obj);
316
317 if (pre_val != rax)
318 __ push(pre_val);
319
320 // Calling the runtime using the regular call_VM_leaf mechanism generates
321 // code (generated by InterpreterMacroAssember::call_VM_leaf_base)
322 // that checks that the *(ebp+frame::interpreter_frame_last_sp) == nullptr.
323 //
324 // If we care generating the pre-barrier without a frame (e.g. in the
325 // intrinsified Reference.get() routine) then ebp might be pointing to
326 // the caller frame and so this check will most likely fail at runtime.
327 //
328 // Expanding the call directly bypasses the generation of the check.
329 // So when we do not have have a full interpreter frame on the stack
330 // expand_call should be passed true.
331
332 NOT_LP64( __ push(thread); )
333
334 #ifdef _LP64
335 // We move pre_val into c_rarg0 early, in order to avoid smashing it, should
336 // pre_val be c_rarg1 (where the call prologue would copy thread argument).
337 // Note: this should not accidentally smash thread, because thread is always r15.
338 assert(thread != c_rarg0, "smashed arg");
339 if (c_rarg0 != pre_val) {
340 __ mov(c_rarg0, pre_val);
341 }
342 #endif
343
344 if (expand_call) {
345 LP64_ONLY( assert(pre_val != c_rarg1, "smashed arg"); )
346 #ifdef _LP64
347 if (c_rarg1 != thread) {
348 __ mov(c_rarg1, thread);
349 }
350 // Already moved pre_val into c_rarg0 above
351 #else
352 __ push(thread);
353 __ push(pre_val);
354 #endif
355 __ MacroAssembler::call_VM_leaf_base(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry), 2);
356 } else {
357 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry), LP64_ONLY(c_rarg0) NOT_LP64(pre_val), thread);
358 }
359
360 NOT_LP64( __ pop(thread); )
361
362 // save the live input values
363 if (pre_val != rax)
364 __ pop(pre_val);
365
366 if (obj != noreg && obj != rax)
367 __ pop(obj);
368
369 if(tosca_live) __ pop(rax);
370
371 __ bind(done);
372 }
373
374 void ShenandoahBarrierSetAssembler::load_reference_barrier(MacroAssembler* masm, Register dst, Address src, DecoratorSet decorators) {
375 assert(ShenandoahLoadRefBarrier, "Should be enabled");
376
377 bool is_strong = ShenandoahBarrierSet::is_strong_access(decorators);
378 bool is_weak = ShenandoahBarrierSet::is_weak_access(decorators);
379 bool is_phantom = ShenandoahBarrierSet::is_phantom_access(decorators);
380 bool is_native = ShenandoahBarrierSet::is_native_access(decorators);
381 bool is_narrow = UseCompressedOops && !is_native;
382
383 Label heap_stable, not_cset;
384
385 __ block_comment("load_reference_barrier { ");
386
387 // Check if GC is active
388 #ifdef _LP64
389 Register thread = r15_thread;
390 #else
391 Register thread = rcx;
392 if (thread == dst) {
393 thread = rbx;
394 }
395 __ push(thread);
396 __ get_thread(thread);
397 #endif
398
399 Address gc_state(thread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
400 int flags = ShenandoahHeap::HAS_FORWARDED;
401 if (!is_strong) {
402 flags |= ShenandoahHeap::WEAK_ROOTS;
403 }
404 __ testb(gc_state, flags);
405 __ jcc(Assembler::zero, heap_stable);
406
407 Register tmp1 = noreg, tmp2 = noreg;
408 if (is_strong) {
409 // Test for object in cset
410 // Allocate temporary registers
411 for (int i = 0; i < 8; i++) {
412 Register r = as_Register(i);
413 if (r != rsp && r != rbp && r != dst && r != src.base() && r != src.index()) {
414 if (tmp1 == noreg) {
415 tmp1 = r;
416 } else {
417 tmp2 = r;
418 break;
419 }
420 }
421 }
422 assert(tmp1 != noreg, "tmp1 allocated");
423 assert(tmp2 != noreg, "tmp2 allocated");
424 assert_different_registers(tmp1, tmp2, src.base(), src.index());
425 assert_different_registers(tmp1, tmp2, dst);
426
427 __ push(tmp1);
428 __ push(tmp2);
429
430 // Optimized cset-test
431 __ movptr(tmp1, dst);
432 __ shrptr(tmp1, ShenandoahHeapRegion::region_size_bytes_shift_jint());
433 __ movptr(tmp2, (intptr_t) ShenandoahHeap::in_cset_fast_test_addr());
434 __ movbool(tmp1, Address(tmp1, tmp2, Address::times_1));
435 __ testbool(tmp1);
436 __ jcc(Assembler::zero, not_cset);
437 }
438
439 save_machine_state(masm, /* handle_gpr = */ false, /* handle_fp = */ true);
440
441 // The rest is saved with the optimized path
442
443 uint num_saved_regs = 4 + (dst != rax ? 1 : 0) LP64_ONLY(+4);
444 __ subptr(rsp, num_saved_regs * wordSize);
445 uint slot = num_saved_regs;
446 if (dst != rax) {
447 __ movptr(Address(rsp, (--slot) * wordSize), rax);
448 }
449 __ movptr(Address(rsp, (--slot) * wordSize), rcx);
450 __ movptr(Address(rsp, (--slot) * wordSize), rdx);
451 __ movptr(Address(rsp, (--slot) * wordSize), rdi);
452 __ movptr(Address(rsp, (--slot) * wordSize), rsi);
453 #ifdef _LP64
454 __ movptr(Address(rsp, (--slot) * wordSize), r8);
455 __ movptr(Address(rsp, (--slot) * wordSize), r9);
456 __ movptr(Address(rsp, (--slot) * wordSize), r10);
457 __ movptr(Address(rsp, (--slot) * wordSize), r11);
458 // r12-r15 are callee saved in all calling conventions
459 #endif
460 assert(slot == 0, "must use all slots");
461
462 // Shuffle registers such that dst is in c_rarg0 and addr in c_rarg1.
463 #ifdef _LP64
464 Register arg0 = c_rarg0, arg1 = c_rarg1;
465 #else
466 Register arg0 = rdi, arg1 = rsi;
467 #endif
468 if (dst == arg1) {
469 __ lea(arg0, src);
470 __ xchgptr(arg1, arg0);
471 } else {
472 __ lea(arg1, src);
473 __ movptr(arg0, dst);
474 }
475
476 if (is_strong) {
477 if (is_narrow) {
478 __ super_call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong_narrow), arg0, arg1);
479 } else {
480 __ super_call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong), arg0, arg1);
481 }
482 } else if (is_weak) {
483 if (is_narrow) {
484 __ super_call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_weak_narrow), arg0, arg1);
485 } else {
486 __ super_call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_weak), arg0, arg1);
487 }
488 } else {
489 assert(is_phantom, "only remaining strength");
490 assert(!is_narrow, "phantom access cannot be narrow");
491 __ super_call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_phantom), arg0, arg1);
492 }
493
494 #ifdef _LP64
495 __ movptr(r11, Address(rsp, (slot++) * wordSize));
496 __ movptr(r10, Address(rsp, (slot++) * wordSize));
497 __ movptr(r9, Address(rsp, (slot++) * wordSize));
498 __ movptr(r8, Address(rsp, (slot++) * wordSize));
499 #endif
500 __ movptr(rsi, Address(rsp, (slot++) * wordSize));
501 __ movptr(rdi, Address(rsp, (slot++) * wordSize));
502 __ movptr(rdx, Address(rsp, (slot++) * wordSize));
503 __ movptr(rcx, Address(rsp, (slot++) * wordSize));
504
505 if (dst != rax) {
506 __ movptr(dst, rax);
507 __ movptr(rax, Address(rsp, (slot++) * wordSize));
508 }
509
510 assert(slot == num_saved_regs, "must use all slots");
511 __ addptr(rsp, num_saved_regs * wordSize);
512
513 restore_machine_state(masm, /* handle_gpr = */ false, /* handle_fp = */ true);
514
515 __ bind(not_cset);
516
517 if (is_strong) {
518 __ pop(tmp2);
519 __ pop(tmp1);
520 }
521
522 __ bind(heap_stable);
523
524 __ block_comment("} load_reference_barrier");
525
526 #ifndef _LP64
527 __ pop(thread);
528 #endif
529 }
530
531 void ShenandoahBarrierSetAssembler::iu_barrier(MacroAssembler* masm, Register dst, Register tmp) {
532 if (ShenandoahIUBarrier) {
533 iu_barrier_impl(masm, dst, tmp);
534 }
535 }
536
537 void ShenandoahBarrierSetAssembler::iu_barrier_impl(MacroAssembler* masm, Register dst, Register tmp) {
538 assert(ShenandoahIUBarrier, "should be enabled");
539
540 if (dst == noreg) return;
541
542 if (ShenandoahIUBarrier) {
543 save_machine_state(masm, /* handle_gpr = */ true, /* handle_fp = */ true);
544
545 #ifdef _LP64
546 Register thread = r15_thread;
547 #else
548 Register thread = rcx;
549 if (thread == dst || thread == tmp) {
550 thread = rdi;
551 }
552 if (thread == dst || thread == tmp) {
553 thread = rbx;
554 }
555 __ get_thread(thread);
556 #endif
557 assert_different_registers(dst, tmp, thread);
558
559 satb_write_barrier_pre(masm, noreg, dst, thread, tmp, true, false);
560
561 restore_machine_state(masm, /* handle_gpr = */ true, /* handle_fp = */ true);
562 }
563 }
564
565 //
566 // Arguments:
567 //
568 // Inputs:
569 // src: oop location, might be clobbered
570 // tmp1: scratch register, might not be valid.
571 //
572 // Output:
573 // dst: oop loaded from src location
574 //
575 // Kill:
576 // tmp1 (if it is valid)
577 //
578 void ShenandoahBarrierSetAssembler::load_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
579 Register dst, Address src, Register tmp1, Register tmp_thread) {
580 // 1: non-reference load, no additional barrier is needed
581 if (!is_reference_type(type)) {
582 BarrierSetAssembler::load_at(masm, decorators, type, dst, src, tmp1, tmp_thread);
583 return;
584 }
585
586 assert((decorators & ON_UNKNOWN_OOP_REF) == 0, "Not expected");
587
588 // 2: load a reference from src location and apply LRB if needed
589 if (ShenandoahBarrierSet::need_load_reference_barrier(decorators, type)) {
590 Register result_dst = dst;
591 bool use_tmp1_for_dst = false;
592
593 // Preserve src location for LRB
594 if (dst == src.base() || dst == src.index()) {
595 // Use tmp1 for dst if possible, as it is not used in BarrierAssembler::load_at()
596 if (tmp1->is_valid() && tmp1 != src.base() && tmp1 != src.index()) {
597 dst = tmp1;
598 use_tmp1_for_dst = true;
599 } else {
600 dst = rdi;
601 __ push(dst);
602 }
603 assert_different_registers(dst, src.base(), src.index());
604 }
605
606 BarrierSetAssembler::load_at(masm, decorators, type, dst, src, tmp1, tmp_thread);
607
608 load_reference_barrier(masm, dst, src, decorators);
609
610 // Move loaded oop to final destination
611 if (dst != result_dst) {
612 __ movptr(result_dst, dst);
613
614 if (!use_tmp1_for_dst) {
615 __ pop(dst);
616 }
617
618 dst = result_dst;
619 }
620 } else {
621 BarrierSetAssembler::load_at(masm, decorators, type, dst, src, tmp1, tmp_thread);
622 }
623
624 // 3: apply keep-alive barrier if needed
625 if (ShenandoahBarrierSet::need_keep_alive_barrier(decorators, type)) {
626 save_machine_state(masm, /* handle_gpr = */ true, /* handle_fp = */ true);
627
628 Register thread = NOT_LP64(tmp_thread) LP64_ONLY(r15_thread);
629 assert_different_registers(dst, tmp1, tmp_thread);
630 if (!thread->is_valid()) {
631 thread = rdx;
632 }
633 NOT_LP64(__ get_thread(thread));
634 // Generate the SATB pre-barrier code to log the value of
635 // the referent field in an SATB buffer.
636 shenandoah_write_barrier_pre(masm /* masm */,
637 noreg /* obj */,
638 dst /* pre_val */,
639 thread /* thread */,
640 tmp1 /* tmp */,
641 true /* tosca_live */,
642 true /* expand_call */);
643
644 restore_machine_state(masm, /* handle_gpr = */ true, /* handle_fp = */ true);
645 }
646 }
647
648 void ShenandoahBarrierSetAssembler::store_check(MacroAssembler* masm, Register obj) {
649 assert(ShenandoahCardBarrier, "Should have been checked by caller");
650
651 // Does a store check for the oop in register obj. The content of
652 // register obj is destroyed afterwards.
653
654 ShenandoahBarrierSet* ctbs = ShenandoahBarrierSet::barrier_set();
655 CardTable* ct = ctbs->card_table();
656
657 __ shrptr(obj, CardTable::card_shift());
658
659 Address card_addr;
660
661 // The calculation for byte_map_base is as follows:
662 // byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
663 // So this essentially converts an address to a displacement and it will
664 // never need to be relocated. On 64-bit however the value may be too
665 // large for a 32-bit displacement.
666 intptr_t byte_map_base = (intptr_t)ct->byte_map_base();
667 if (__ is_simm32(byte_map_base)) {
668 card_addr = Address(noreg, obj, Address::times_1, byte_map_base);
669 } else {
670 // By doing it as an ExternalAddress 'byte_map_base' could be converted to a rip-relative
671 // displacement and done in a single instruction given favorable mapping and a
672 // smarter version of as_Address. However, 'ExternalAddress' generates a relocation
673 // entry and that entry is not properly handled by the relocation code.
674 AddressLiteral cardtable((address)byte_map_base, relocInfo::none);
675 Address index(noreg, obj, Address::times_1);
676 card_addr = __ as_Address(ArrayAddress(cardtable, index), rscratch1);
677 }
678
679 int dirty = CardTable::dirty_card_val();
680 if (UseCondCardMark) {
681 Label L_already_dirty;
682 __ cmpb(card_addr, dirty);
683 __ jccb(Assembler::equal, L_already_dirty);
684 __ movb(card_addr, dirty);
685 __ bind(L_already_dirty);
686 } else {
687 __ movb(card_addr, dirty);
688 }
689 }
690
691 void ShenandoahBarrierSetAssembler::store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
692 Address dst, Register val, Register tmp1, Register tmp2, Register tmp3) {
693
694 bool on_oop = is_reference_type(type);
695 bool in_heap = (decorators & IN_HEAP) != 0;
696 bool as_normal = (decorators & AS_NORMAL) != 0;
697 if (on_oop && in_heap) {
698 bool needs_pre_barrier = as_normal;
699
700 Register rthread = LP64_ONLY(r15_thread) NOT_LP64(rcx);
701 // flatten object address if needed
702 // We do it regardless of precise because we need the registers
703 if (dst.index() == noreg && dst.disp() == 0) {
704 if (dst.base() != tmp1) {
705 __ movptr(tmp1, dst.base());
706 }
707 } else {
708 __ lea(tmp1, dst);
709 }
710
711 assert_different_registers(val, tmp1, tmp2, tmp3, rthread);
712
713 #ifndef _LP64
714 __ get_thread(rthread);
715 InterpreterMacroAssembler *imasm = static_cast<InterpreterMacroAssembler*>(masm);
716 imasm->save_bcp();
717 #endif
718
719 if (needs_pre_barrier) {
720 shenandoah_write_barrier_pre(masm /*masm*/,
721 tmp1 /* obj */,
722 tmp2 /* pre_val */,
723 rthread /* thread */,
724 tmp3 /* tmp */,
725 val != noreg /* tosca_live */,
726 false /* expand_call */);
727 }
728 if (val == noreg) {
729 BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp1, 0), val, noreg, noreg, noreg);
730 } else {
731 iu_barrier(masm, val, tmp3);
732 BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp1, 0), val, noreg, noreg, noreg);
733 if (ShenandoahCardBarrier) {
734 store_check(masm, tmp1);
735 }
736 }
737 NOT_LP64(imasm->restore_bcp());
738 } else {
739 BarrierSetAssembler::store_at(masm, decorators, type, dst, val, tmp1, tmp2, tmp3);
740 }
741 }
742
743 void ShenandoahBarrierSetAssembler::try_resolve_jobject_in_native(MacroAssembler* masm, Register jni_env,
744 Register obj, Register tmp, Label& slowpath) {
745 Label done;
746 // Resolve jobject
747 BarrierSetAssembler::try_resolve_jobject_in_native(masm, jni_env, obj, tmp, slowpath);
748
749 // Check for null.
750 __ testptr(obj, obj);
751 __ jcc(Assembler::zero, done);
752
753 Address gc_state(jni_env, ShenandoahThreadLocalData::gc_state_offset() - JavaThread::jni_environment_offset());
754 __ testb(gc_state, ShenandoahHeap::EVACUATION);
755 __ jccb(Assembler::notZero, slowpath);
756 __ bind(done);
757 }
758
759 // Special Shenandoah CAS implementation that handles false negatives
760 // due to concurrent evacuation.
761 void ShenandoahBarrierSetAssembler::cmpxchg_oop(MacroAssembler* masm,
762 Register res, Address addr, Register oldval, Register newval,
763 bool exchange, Register tmp1, Register tmp2) {
764 assert(ShenandoahCASBarrier, "Should only be used when CAS barrier is enabled");
765 assert(oldval == rax, "must be in rax for implicit use in cmpxchg");
766 assert_different_registers(oldval, tmp1, tmp2);
767 assert_different_registers(newval, tmp1, tmp2);
768
769 Label L_success, L_failure;
770
771 // Remember oldval for retry logic below
772 #ifdef _LP64
773 if (UseCompressedOops) {
774 __ movl(tmp1, oldval);
775 } else
776 #endif
777 {
778 __ movptr(tmp1, oldval);
779 }
780
781 // Step 1. Fast-path.
782 //
783 // Try to CAS with given arguments. If successful, then we are done.
784
785 #ifdef _LP64
786 if (UseCompressedOops) {
787 __ lock();
788 __ cmpxchgl(newval, addr);
789 } else
790 #endif
791 {
792 __ lock();
793 __ cmpxchgptr(newval, addr);
794 }
795 __ jcc(Assembler::equal, L_success);
796
797 // Step 2. CAS had failed. This may be a false negative.
798 //
799 // The trouble comes when we compare the to-space pointer with the from-space
800 // pointer to the same object. To resolve this, it will suffice to resolve
801 // the value from memory -- this will give both to-space pointers.
802 // If they mismatch, then it was a legitimate failure.
803 //
804 // Before reaching to resolve sequence, see if we can avoid the whole shebang
805 // with filters.
806
807 // Filter: when offending in-memory value is null, the failure is definitely legitimate
808 __ testptr(oldval, oldval);
809 __ jcc(Assembler::zero, L_failure);
810
811 // Filter: when heap is stable, the failure is definitely legitimate
812 #ifdef _LP64
813 const Register thread = r15_thread;
814 #else
815 const Register thread = tmp2;
816 __ get_thread(thread);
817 #endif
818 Address gc_state(thread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
819 __ testb(gc_state, ShenandoahHeap::HAS_FORWARDED);
820 __ jcc(Assembler::zero, L_failure);
821
822 #ifdef _LP64
823 if (UseCompressedOops) {
824 __ movl(tmp2, oldval);
825 __ decode_heap_oop(tmp2);
826 } else
827 #endif
828 {
829 __ movptr(tmp2, oldval);
830 }
831
832 // Decode offending in-memory value.
833 // Test if-forwarded
834 __ testb(Address(tmp2, oopDesc::mark_offset_in_bytes()), markWord::marked_value);
835 __ jcc(Assembler::noParity, L_failure); // When odd number of bits, then not forwarded
836 __ jcc(Assembler::zero, L_failure); // When it is 00, then also not forwarded
837
838 // Load and mask forwarding pointer
839 __ movptr(tmp2, Address(tmp2, oopDesc::mark_offset_in_bytes()));
840 __ shrptr(tmp2, 2);
841 __ shlptr(tmp2, 2);
842
843 #ifdef _LP64
844 if (UseCompressedOops) {
845 __ decode_heap_oop(tmp1); // decode for comparison
846 }
847 #endif
848
849 // Now we have the forwarded offender in tmp2.
850 // Compare and if they don't match, we have legitimate failure
851 __ cmpptr(tmp1, tmp2);
852 __ jcc(Assembler::notEqual, L_failure);
853
854 // Step 3. Need to fix the memory ptr before continuing.
855 //
856 // At this point, we have from-space oldval in the register, and its to-space
857 // address is in tmp2. Let's try to update it into memory. We don't care if it
858 // succeeds or not. If it does, then the retrying CAS would see it and succeed.
859 // If this fixup fails, this means somebody else beat us to it, and necessarily
860 // with to-space ptr store. We still have to do the retry, because the GC might
861 // have updated the reference for us.
862
863 #ifdef _LP64
864 if (UseCompressedOops) {
865 __ encode_heap_oop(tmp2); // previously decoded at step 2.
866 }
867 #endif
868
869 #ifdef _LP64
870 if (UseCompressedOops) {
871 __ lock();
872 __ cmpxchgl(tmp2, addr);
873 } else
874 #endif
875 {
876 __ lock();
877 __ cmpxchgptr(tmp2, addr);
878 }
879
880 // Step 4. Try to CAS again.
881 //
882 // This is guaranteed not to have false negatives, because oldval is definitely
883 // to-space, and memory pointer is to-space as well. Nothing is able to store
884 // from-space ptr into memory anymore. Make sure oldval is restored, after being
885 // garbled during retries.
886 //
887 #ifdef _LP64
888 if (UseCompressedOops) {
889 __ movl(oldval, tmp2);
890 } else
891 #endif
892 {
893 __ movptr(oldval, tmp2);
894 }
895
896 #ifdef _LP64
897 if (UseCompressedOops) {
898 __ lock();
899 __ cmpxchgl(newval, addr);
900 } else
901 #endif
902 {
903 __ lock();
904 __ cmpxchgptr(newval, addr);
905 }
906 if (!exchange) {
907 __ jccb(Assembler::equal, L_success); // fastpath, peeking into Step 5, no need to jump
908 }
909
910 // Step 5. If we need a boolean result out of CAS, set the flag appropriately.
911 // and promote the result. Note that we handle the flag from both the 1st and 2nd CAS.
912 // Otherwise, failure witness for CAE is in oldval on all paths, and we can return.
913
914 if (exchange) {
915 __ bind(L_failure);
916 __ bind(L_success);
917 } else {
918 assert(res != noreg, "need result register");
919
920 Label exit;
921 __ bind(L_failure);
922 __ xorptr(res, res);
923 __ jmpb(exit);
924
925 __ bind(L_success);
926 __ movptr(res, 1);
927 __ bind(exit);
928 }
929 }
930
931 #ifdef PRODUCT
932 #define BLOCK_COMMENT(str) /* nothing */
933 #else
934 #define BLOCK_COMMENT(str) __ block_comment(str)
935 #endif
936
937 #define BIND(label) bind(label); BLOCK_COMMENT(#label ":")
938
939 #define TIMES_OOP (UseCompressedOops ? Address::times_4 : Address::times_8)
940
941 void ShenandoahBarrierSetAssembler::gen_write_ref_array_post_barrier(MacroAssembler* masm, DecoratorSet decorators,
942 Register addr, Register count,
943 Register tmp) {
944 assert(ShenandoahCardBarrier, "Should have been checked by caller");
945
946 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
947 CardTable* ct = bs->card_table();
948 intptr_t disp = (intptr_t) ct->byte_map_base();
949
950 Label L_loop, L_done;
951 const Register end = count;
952 assert_different_registers(addr, end);
953
954 // Zero count? Nothing to do.
955 __ testl(count, count);
956 __ jccb(Assembler::zero, L_done);
957
958 #ifdef _LP64
959 __ leaq(end, Address(addr, count, TIMES_OOP, 0)); // end == addr+count*oop_size
960 __ subptr(end, BytesPerHeapOop); // end - 1 to make inclusive
961 __ shrptr(addr, CardTable::card_shift());
962 __ shrptr(end, CardTable::card_shift());
963 __ subptr(end, addr); // end --> cards count
964
965 __ mov64(tmp, disp);
966 __ addptr(addr, tmp);
967
968 __ BIND(L_loop);
969 __ movb(Address(addr, count, Address::times_1), 0);
970 __ decrement(count);
971 __ jccb(Assembler::greaterEqual, L_loop);
972 #else
973 __ lea(end, Address(addr, count, Address::times_ptr, -wordSize));
974 __ shrptr(addr, CardTable::card_shift());
975 __ shrptr(end, CardTable::card_shift());
976 __ subptr(end, addr); // end --> count
977
978 __ BIND(L_loop);
979 Address cardtable(addr, count, Address::times_1, disp);
980 __ movb(cardtable, 0);
981 __ decrement(count);
982 __ jccb(Assembler::greaterEqual, L_loop);
983 #endif
984
985 __ BIND(L_done);
986 }
987
988 #undef __
989
990 #ifdef COMPILER1
991
992 #define __ ce->masm()->
993
994 void ShenandoahBarrierSetAssembler::gen_pre_barrier_stub(LIR_Assembler* ce, ShenandoahPreBarrierStub* stub) {
995 ShenandoahBarrierSetC1* bs = (ShenandoahBarrierSetC1*)BarrierSet::barrier_set()->barrier_set_c1();
996 // At this point we know that marking is in progress.
997 // If do_load() is true then we have to emit the
998 // load of the previous value; otherwise it has already
999 // been loaded into _pre_val.
1000
1001 __ bind(*stub->entry());
1002 assert(stub->pre_val()->is_register(), "Precondition.");
1003
1004 Register pre_val_reg = stub->pre_val()->as_register();
1005
1006 if (stub->do_load()) {
1007 ce->mem2reg(stub->addr(), stub->pre_val(), T_OBJECT, stub->patch_code(), stub->info(), false /*wide*/);
1008 }
1009
1010 __ cmpptr(pre_val_reg, NULL_WORD);
1011 __ jcc(Assembler::equal, *stub->continuation());
1012 ce->store_parameter(stub->pre_val()->as_register(), 0);
1013 __ call(RuntimeAddress(bs->pre_barrier_c1_runtime_code_blob()->code_begin()));
1014 __ jmp(*stub->continuation());
1015
1016 }
1017
1018 void ShenandoahBarrierSetAssembler::gen_load_reference_barrier_stub(LIR_Assembler* ce, ShenandoahLoadReferenceBarrierStub* stub) {
1019 ShenandoahBarrierSetC1* bs = (ShenandoahBarrierSetC1*)BarrierSet::barrier_set()->barrier_set_c1();
1020 __ bind(*stub->entry());
1021
1022 DecoratorSet decorators = stub->decorators();
1023 bool is_strong = ShenandoahBarrierSet::is_strong_access(decorators);
1024 bool is_weak = ShenandoahBarrierSet::is_weak_access(decorators);
1025 bool is_phantom = ShenandoahBarrierSet::is_phantom_access(decorators);
1026 bool is_native = ShenandoahBarrierSet::is_native_access(decorators);
1027
1028 Register obj = stub->obj()->as_register();
1029 Register res = stub->result()->as_register();
1030 Register addr = stub->addr()->as_pointer_register();
1031 Register tmp1 = stub->tmp1()->as_register();
1032 Register tmp2 = stub->tmp2()->as_register();
1033 assert_different_registers(obj, res, addr, tmp1, tmp2);
1034
1035 Label slow_path;
1036
1037 assert(res == rax, "result must arrive in rax");
1038
1039 if (res != obj) {
1040 __ mov(res, obj);
1041 }
1042
1043 if (is_strong) {
1044 // Check for object being in the collection set.
1045 __ mov(tmp1, res);
1046 __ shrptr(tmp1, ShenandoahHeapRegion::region_size_bytes_shift_jint());
1047 __ movptr(tmp2, (intptr_t) ShenandoahHeap::in_cset_fast_test_addr());
1048 #ifdef _LP64
1049 __ movbool(tmp2, Address(tmp2, tmp1, Address::times_1));
1050 __ testbool(tmp2);
1051 #else
1052 // On x86_32, C1 register allocator can give us the register without 8-bit support.
1053 // Do the full-register access and test to avoid compilation failures.
1054 __ movptr(tmp2, Address(tmp2, tmp1, Address::times_1));
1055 __ testptr(tmp2, 0xFF);
1056 #endif
1057 __ jcc(Assembler::zero, *stub->continuation());
1058 }
1059
1060 __ bind(slow_path);
1061 ce->store_parameter(res, 0);
1062 ce->store_parameter(addr, 1);
1063 if (is_strong) {
1064 if (is_native) {
1065 __ call(RuntimeAddress(bs->load_reference_barrier_strong_native_rt_code_blob()->code_begin()));
1066 } else {
1067 __ call(RuntimeAddress(bs->load_reference_barrier_strong_rt_code_blob()->code_begin()));
1068 }
1069 } else if (is_weak) {
1070 __ call(RuntimeAddress(bs->load_reference_barrier_weak_rt_code_blob()->code_begin()));
1071 } else {
1072 assert(is_phantom, "only remaining strength");
1073 __ call(RuntimeAddress(bs->load_reference_barrier_phantom_rt_code_blob()->code_begin()));
1074 }
1075 __ jmp(*stub->continuation());
1076 }
1077
1078 #undef __
1079
1080 #define __ sasm->
1081
1082 void ShenandoahBarrierSetAssembler::generate_c1_pre_barrier_runtime_stub(StubAssembler* sasm) {
1083 __ prologue("shenandoah_pre_barrier", false);
1084 // arg0 : previous value of memory
1085
1086 __ push(rax);
1087 __ push(rdx);
1088
1089 const Register pre_val = rax;
1090 const Register thread = NOT_LP64(rax) LP64_ONLY(r15_thread);
1091 const Register tmp = rdx;
1092
1093 NOT_LP64(__ get_thread(thread);)
1094
1095 Address queue_index(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset()));
1096 Address buffer(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset()));
1097
1098 Label done;
1099 Label runtime;
1100
1101 // Is SATB still active?
1102 Address gc_state(thread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
1103 __ testb(gc_state, ShenandoahHeap::MARKING);
1104 __ jcc(Assembler::zero, done);
1105
1106 // Can we store original value in the thread's buffer?
1107
1108 __ movptr(tmp, queue_index);
1109 __ testptr(tmp, tmp);
1110 __ jcc(Assembler::zero, runtime);
1111 __ subptr(tmp, wordSize);
1112 __ movptr(queue_index, tmp);
1113 __ addptr(tmp, buffer);
1114
1115 // prev_val (rax)
1116 __ load_parameter(0, pre_val);
1117 __ movptr(Address(tmp, 0), pre_val);
1118 __ jmp(done);
1119
1120 __ bind(runtime);
1121
1122 __ save_live_registers_no_oop_map(true);
1123
1124 // load the pre-value
1125 __ load_parameter(0, rcx);
1126 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry), rcx, thread);
1127
1128 __ restore_live_registers(true);
1129
1130 __ bind(done);
1131
1132 __ pop(rdx);
1133 __ pop(rax);
1134
1135 __ epilogue();
1136 }
1137
1138 void ShenandoahBarrierSetAssembler::generate_c1_load_reference_barrier_runtime_stub(StubAssembler* sasm, DecoratorSet decorators) {
1139 __ prologue("shenandoah_load_reference_barrier", false);
1140 // arg0 : object to be resolved
1141
1142 __ save_live_registers_no_oop_map(true);
1143
1144 bool is_strong = ShenandoahBarrierSet::is_strong_access(decorators);
1145 bool is_weak = ShenandoahBarrierSet::is_weak_access(decorators);
1146 bool is_phantom = ShenandoahBarrierSet::is_phantom_access(decorators);
1147 bool is_native = ShenandoahBarrierSet::is_native_access(decorators);
1148
1149 #ifdef _LP64
1150 __ load_parameter(0, c_rarg0);
1151 __ load_parameter(1, c_rarg1);
1152 if (is_strong) {
1153 if (is_native) {
1154 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong), c_rarg0, c_rarg1);
1155 } else {
1156 if (UseCompressedOops) {
1157 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong_narrow), c_rarg0, c_rarg1);
1158 } else {
1159 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong), c_rarg0, c_rarg1);
1160 }
1161 }
1162 } else if (is_weak) {
1163 assert(!is_native, "weak must not be called off-heap");
1164 if (UseCompressedOops) {
1165 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_weak_narrow), c_rarg0, c_rarg1);
1166 } else {
1167 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_weak), c_rarg0, c_rarg1);
1168 }
1169 } else {
1170 assert(is_phantom, "only remaining strength");
1171 assert(is_native, "phantom must only be called off-heap");
1172 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_phantom), c_rarg0, c_rarg1);
1173 }
1174 #else
1175 __ load_parameter(0, rax);
1176 __ load_parameter(1, rbx);
1177 if (is_strong) {
1178 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong), rax, rbx);
1179 } else if (is_weak) {
1180 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_weak), rax, rbx);
1181 } else {
1182 assert(is_phantom, "only remaining strength");
1183 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_phantom), rax, rbx);
1184 }
1185 #endif
1186
1187 __ restore_live_registers_except_rax(true);
1188
1189 __ epilogue();
1190 }
1191
1192 #undef __
1193
1194 #endif // COMPILER1