1 /*
2 * Copyright (c) 2018, 2019, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25 #include "gc/shenandoah/shenandoahBarrierSetAssembler.hpp"
26 #include "gc/shenandoah/shenandoahForwarding.hpp"
27 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
28 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
29 #include "gc/shenandoah/shenandoahHeuristics.hpp"
30 #include "gc/shenandoah/shenandoahRuntime.hpp"
31 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
32 #include "interpreter/interpreter.hpp"
33 #include "interpreter/interp_masm.hpp"
34 #include "runtime/sharedRuntime.hpp"
35 #include "runtime/thread.hpp"
36 #include "utilities/macros.hpp"
37 #ifdef COMPILER1
38 #include "c1/c1_LIRAssembler.hpp"
39 #include "c1/c1_MacroAssembler.hpp"
40 #include "gc/shenandoah/c1/shenandoahBarrierSetC1.hpp"
41 #endif
42
43 #define __ masm->
44
45 address ShenandoahBarrierSetAssembler::_shenandoah_lrb = NULL;
46
47 void ShenandoahBarrierSetAssembler::arraycopy_prologue(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
48 Register src, Register dst, Register count) {
49
50 bool checkcast = (decorators & ARRAYCOPY_CHECKCAST) != 0;
51 bool disjoint = (decorators & ARRAYCOPY_DISJOINT) != 0;
52 bool obj_int = type == T_OBJECT LP64_ONLY(&& UseCompressedOops);
53 bool dest_uninitialized = (decorators & IS_DEST_UNINITIALIZED) != 0;
54
55 if (type == T_OBJECT || type == T_ARRAY) {
56 #ifdef _LP64
57 if (!checkcast) {
58 if (!obj_int) {
59 // Save count for barrier
60 __ movptr(r11, count);
61 } else if (disjoint) {
62 // Save dst in r11 in the disjoint case
63 __ movq(r11, dst);
64 }
65 }
66 #else
67 if (disjoint) {
68 __ mov(rdx, dst); // save 'to'
69 }
70 #endif
71
72 if (ShenandoahSATBBarrier && !dest_uninitialized) {
73 Register thread = NOT_LP64(rax) LP64_ONLY(r15_thread);
74 assert_different_registers(dst, count, thread); // we don't care about src here?
75 #ifndef _LP64
76 __ push(thread);
77 __ get_thread(thread);
78 #endif
79
80 Label done;
81 // Short-circuit if count == 0.
82 __ testptr(count, count);
83 __ jcc(Assembler::zero, done);
84
85 // Avoid runtime call when not marking.
86 Address gc_state(thread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
87 __ testb(gc_state, ShenandoahHeap::MARKING);
88 __ jcc(Assembler::zero, done);
89
90 __ pusha(); // push registers
91 #ifdef _LP64
92 if (count == c_rarg0) {
93 if (dst == c_rarg1) {
94 // exactly backwards!!
95 __ xchgptr(c_rarg1, c_rarg0);
96 } else {
97 __ movptr(c_rarg1, count);
98 __ movptr(c_rarg0, dst);
99 }
100 } else {
101 __ movptr(c_rarg0, dst);
102 __ movptr(c_rarg1, count);
103 }
104 if (UseCompressedOops) {
105 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_array_pre_narrow_oop_entry), 2);
106 } else {
107 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_array_pre_oop_entry), 2);
108 }
109 #else
110 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_array_pre_oop_entry),
111 dst, count);
112 #endif
113 __ popa();
114 __ bind(done);
115 NOT_LP64(__ pop(thread);)
116 }
117 }
118
119 }
120
121 void ShenandoahBarrierSetAssembler::arraycopy_epilogue(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
122 Register src, Register dst, Register count) {
123 bool checkcast = (decorators & ARRAYCOPY_CHECKCAST) != 0;
124 bool disjoint = (decorators & ARRAYCOPY_DISJOINT) != 0;
125 bool obj_int = type == T_OBJECT LP64_ONLY(&& UseCompressedOops);
126 Register tmp = rax;
127
128 if (type == T_OBJECT || type == T_ARRAY) {
129 #ifdef _LP64
130 if (!checkcast) {
131 if (!obj_int) {
132 // Save count for barrier
133 count = r11;
134 } else if (disjoint && obj_int) {
135 // Use the saved dst in the disjoint case
136 dst = r11;
137 }
138 } else {
139 tmp = rscratch1;
140 }
141 #else
142 if (disjoint) {
143 __ mov(dst, rdx); // restore 'to'
144 }
145 #endif
146
147 Register thread = NOT_LP64(rax) LP64_ONLY(r15_thread);
148 assert_different_registers(dst, thread); // do we care about src at all here?
149
150 #ifndef _LP64
151 __ push(thread);
152 __ get_thread(thread);
153 #endif
154
155 // Short-circuit if count == 0.
156 Label done;
157 __ testptr(count, count);
158 __ jcc(Assembler::zero, done);
159
160 // Skip runtime call if no forwarded objects.
161 Address gc_state(thread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
162 __ testb(gc_state, ShenandoahHeap::UPDATEREFS);
163 __ jcc(Assembler::zero, done);
164
165 __ pusha(); // push registers (overkill)
166 #ifdef _LP64
167 if (c_rarg0 == count) { // On win64 c_rarg0 == rcx
168 assert_different_registers(c_rarg1, dst);
169 __ mov(c_rarg1, count);
170 __ mov(c_rarg0, dst);
171 } else {
172 assert_different_registers(c_rarg0, count);
173 __ mov(c_rarg0, dst);
174 __ mov(c_rarg1, count);
175 }
176 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_array_post_entry), 2);
177 #else
178 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_array_post_entry),
179 dst, count);
180 #endif
181 __ popa();
182
183 __ bind(done);
184 NOT_LP64(__ pop(thread);)
185 }
186 }
187
188 void ShenandoahBarrierSetAssembler::shenandoah_write_barrier_pre(MacroAssembler* masm,
189 Register obj,
190 Register pre_val,
191 Register thread,
192 Register tmp,
193 bool tosca_live,
194 bool expand_call) {
195
196 if (ShenandoahSATBBarrier) {
197 satb_write_barrier_pre(masm, obj, pre_val, thread, tmp, tosca_live, expand_call);
198 }
199 }
200
201 void ShenandoahBarrierSetAssembler::satb_write_barrier_pre(MacroAssembler* masm,
202 Register obj,
203 Register pre_val,
204 Register thread,
205 Register tmp,
206 bool tosca_live,
207 bool expand_call) {
208 // If expand_call is true then we expand the call_VM_leaf macro
209 // directly to skip generating the check by
210 // InterpreterMacroAssembler::call_VM_leaf_base that checks _last_sp.
211
212 #ifdef _LP64
213 assert(thread == r15_thread, "must be");
214 #endif // _LP64
215
216 Label done;
217 Label runtime;
218
219 assert(pre_val != noreg, "check this code");
220
221 if (obj != noreg) {
222 assert_different_registers(obj, pre_val, tmp);
223 assert(pre_val != rax, "check this code");
224 }
225
226 Address in_progress(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_active_offset()));
227 Address index(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset()));
228 Address buffer(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset()));
229
230 Address gc_state(thread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
231 __ testb(gc_state, ShenandoahHeap::MARKING | ShenandoahHeap::TRAVERSAL);
232 __ jcc(Assembler::zero, done);
233
234 // Do we need to load the previous value?
235 if (obj != noreg) {
236 __ load_heap_oop(pre_val, Address(obj, 0), noreg, noreg, AS_RAW);
237 }
238
239 // Is the previous value null?
240 __ cmpptr(pre_val, (int32_t) NULL_WORD);
241 __ jcc(Assembler::equal, done);
242
243 // Can we store original value in the thread's buffer?
244 // Is index == 0?
245 // (The index field is typed as size_t.)
246
247 __ movptr(tmp, index); // tmp := *index_adr
248 __ cmpptr(tmp, 0); // tmp == 0?
249 __ jcc(Assembler::equal, runtime); // If yes, goto runtime
250
251 __ subptr(tmp, wordSize); // tmp := tmp - wordSize
252 __ movptr(index, tmp); // *index_adr := tmp
253 __ addptr(tmp, buffer); // tmp := tmp + *buffer_adr
254
255 // Record the previous value
256 __ movptr(Address(tmp, 0), pre_val);
257 __ jmp(done);
258
259 __ bind(runtime);
260 // save the live input values
261 if(tosca_live) __ push(rax);
262
263 if (obj != noreg && obj != rax)
264 __ push(obj);
265
266 if (pre_val != rax)
267 __ push(pre_val);
268
269 // Calling the runtime using the regular call_VM_leaf mechanism generates
270 // code (generated by InterpreterMacroAssember::call_VM_leaf_base)
271 // that checks that the *(ebp+frame::interpreter_frame_last_sp) == NULL.
272 //
273 // If we care generating the pre-barrier without a frame (e.g. in the
274 // intrinsified Reference.get() routine) then ebp might be pointing to
275 // the caller frame and so this check will most likely fail at runtime.
276 //
277 // Expanding the call directly bypasses the generation of the check.
278 // So when we do not have have a full interpreter frame on the stack
279 // expand_call should be passed true.
280
281 NOT_LP64( __ push(thread); )
282
283 #ifdef _LP64
284 // We move pre_val into c_rarg0 early, in order to avoid smashing it, should
285 // pre_val be c_rarg1 (where the call prologue would copy thread argument).
286 // Note: this should not accidentally smash thread, because thread is always r15.
287 assert(thread != c_rarg0, "smashed arg");
288 if (c_rarg0 != pre_val) {
289 __ mov(c_rarg0, pre_val);
290 }
291 #endif
292
293 if (expand_call) {
294 LP64_ONLY( assert(pre_val != c_rarg1, "smashed arg"); )
295 #ifdef _LP64
296 if (c_rarg1 != thread) {
297 __ mov(c_rarg1, thread);
298 }
299 // Already moved pre_val into c_rarg0 above
300 #else
301 __ push(thread);
302 __ push(pre_val);
303 #endif
304 __ MacroAssembler::call_VM_leaf_base(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry), 2);
305 } else {
306 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry), LP64_ONLY(c_rarg0) NOT_LP64(pre_val), thread);
307 }
308
309 NOT_LP64( __ pop(thread); )
310
311 // save the live input values
312 if (pre_val != rax)
313 __ pop(pre_val);
314
315 if (obj != noreg && obj != rax)
316 __ pop(obj);
317
318 if(tosca_live) __ pop(rax);
319
320 __ bind(done);
321 }
322
323 void ShenandoahBarrierSetAssembler::resolve_forward_pointer(MacroAssembler* masm, Register dst, Register tmp) {
324 assert(ShenandoahCASBarrier, "should be enabled");
325 Label is_null;
326 __ testptr(dst, dst);
327 __ jcc(Assembler::zero, is_null);
328 resolve_forward_pointer_not_null(masm, dst, tmp);
329 __ bind(is_null);
330 }
331
332 void ShenandoahBarrierSetAssembler::resolve_forward_pointer_not_null(MacroAssembler* masm, Register dst, Register tmp) {
333 assert(ShenandoahCASBarrier || ShenandoahLoadRefBarrier, "should be enabled");
334 // The below loads the mark word, checks if the lowest two bits are
335 // set, and if so, clear the lowest two bits and copy the result
336 // to dst. Otherwise it leaves dst alone.
337 // Implementing this is surprisingly awkward. I do it here by:
338 // - Inverting the mark word
339 // - Test lowest two bits == 0
340 // - If so, set the lowest two bits
341 // - Invert the result back, and copy to dst
342
343 bool borrow_reg = (tmp == noreg);
344 if (borrow_reg) {
345 // No free registers available. Make one useful.
346 tmp = LP64_ONLY(rscratch1) NOT_LP64(rdx);
347 __ push(tmp);
348 }
349
350 Label done;
351 __ movptr(tmp, Address(dst, oopDesc::mark_offset_in_bytes()));
352 __ notptr(tmp);
353 __ testb(tmp, markOopDesc::marked_value);
354 __ jccb(Assembler::notZero, done);
355 __ orptr(tmp, markOopDesc::marked_value);
356 __ notptr(tmp);
357 __ mov(dst, tmp);
358 __ bind(done);
359
360 if (borrow_reg) {
361 __ pop(tmp);
362 }
363 }
364
365
366 void ShenandoahBarrierSetAssembler::load_reference_barrier_not_null(MacroAssembler* masm, Register dst) {
367 assert(ShenandoahLoadRefBarrier, "Should be enabled");
368
369 Label done;
370
371 #ifdef _LP64
372 Register thread = r15_thread;
373 #else
374 Register thread = rcx;
375 if (thread == dst) {
376 thread = rbx;
377 }
378 __ push(thread);
379 __ get_thread(thread);
380 #endif
381 assert_different_registers(dst, thread);
382
383 Address gc_state(thread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
384 __ testb(gc_state, ShenandoahHeap::HAS_FORWARDED);
385 __ jccb(Assembler::zero, done);
386
387 if (dst != rax) {
388 __ xchgptr(dst, rax); // Move obj into rax and save rax into obj.
389 }
390
391 __ call(RuntimeAddress(CAST_FROM_FN_PTR(address, ShenandoahBarrierSetAssembler::shenandoah_lrb())));
392
393 if (dst != rax) {
394 __ xchgptr(rax, dst); // Swap back obj with rax.
395 }
396
397 __ bind(done);
398
399 #ifndef _LP64
400 __ pop(thread);
401 #endif
402 }
403
404 void ShenandoahBarrierSetAssembler::load_reference_barrier_native(MacroAssembler* masm, Register dst) {
405 if (!ShenandoahLoadRefBarrier) {
406 return;
407 }
408
409 Label done;
410 Label not_null;
411 Label slow_path;
412
413 // null check
414 __ testptr(dst, dst);
415 __ jcc(Assembler::notZero, not_null);
416 __ jmp(done);
417 __ bind(not_null);
418
419
420 #ifdef _LP64
421 Register thread = r15_thread;
422 #else
423 Register thread = rcx;
424 if (thread == dst) {
425 thread = rbx;
426 }
427 __ push(thread);
428 __ get_thread(thread);
429 #endif
430 assert_different_registers(dst, thread);
431
432 Address gc_state(thread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
433 __ testb(gc_state, ShenandoahHeap::EVACUATION);
434 #ifndef _LP64
435 __ pop(thread);
436 #endif
437 __ jccb(Assembler::notZero, slow_path);
438 __ jmp(done);
439 __ bind(slow_path);
440
441 if (dst != rax) {
442 __ xchgptr(dst, rax); // Move obj into rax and save rax into obj.
443 }
444 __ push(rcx);
445 __ push(rdx);
446 __ push(rdi);
447 __ push(rsi);
448 #ifdef _LP64
449 __ push(r8);
450 __ push(r9);
451 __ push(r10);
452 __ push(r11);
453 __ push(r12);
454 __ push(r13);
455 __ push(r14);
456 __ push(r15);
457 #endif
458
459 __ movptr(rdi, rax);
460 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_native), rdi);
461
462 #ifdef _LP64
463 __ pop(r15);
464 __ pop(r14);
465 __ pop(r13);
466 __ pop(r12);
467 __ pop(r11);
468 __ pop(r10);
469 __ pop(r9);
470 __ pop(r8);
471 #endif
472 __ pop(rsi);
473 __ pop(rdi);
474 __ pop(rdx);
475 __ pop(rcx);
476
477 if (dst != rax) {
478 __ xchgptr(rax, dst); // Swap back obj with rax.
479 }
480
481 __ bind(done);
482 }
483
484 void ShenandoahBarrierSetAssembler::storeval_barrier(MacroAssembler* masm, Register dst, Register tmp) {
485 if (ShenandoahStoreValEnqueueBarrier) {
486 storeval_barrier_impl(masm, dst, tmp);
487 }
488 }
489
490 void ShenandoahBarrierSetAssembler::storeval_barrier_impl(MacroAssembler* masm, Register dst, Register tmp) {
491 assert(ShenandoahStoreValEnqueueBarrier, "should be enabled");
492
493 if (dst == noreg) return;
494
495 if (ShenandoahStoreValEnqueueBarrier) {
496 // The set of registers to be saved+restored is the same as in the write-barrier above.
497 // Those are the commonly used registers in the interpreter.
498 __ pusha();
499 // __ push_callee_saved_registers();
500 __ subptr(rsp, 2 * Interpreter::stackElementSize);
501 __ movdbl(Address(rsp, 0), xmm0);
502
503 #ifdef _LP64
504 Register thread = r15_thread;
505 #else
506 Register thread = rcx;
507 if (thread == dst || thread == tmp) {
508 thread = rdi;
509 }
510 if (thread == dst || thread == tmp) {
511 thread = rbx;
512 }
513 __ get_thread(thread);
514 #endif
515 assert_different_registers(dst, tmp, thread);
516
517 satb_write_barrier_pre(masm, noreg, dst, thread, tmp, true, false);
518 __ movdbl(xmm0, Address(rsp, 0));
519 __ addptr(rsp, 2 * Interpreter::stackElementSize);
520 //__ pop_callee_saved_registers();
521 __ popa();
522 }
523 }
524
525 void ShenandoahBarrierSetAssembler::load_reference_barrier(MacroAssembler* masm, Register dst) {
526 if (ShenandoahLoadRefBarrier) {
527 Label done;
528 __ testptr(dst, dst);
529 __ jcc(Assembler::zero, done);
530 load_reference_barrier_not_null(masm, dst);
531 __ bind(done);
532 }
533 }
534
535 void ShenandoahBarrierSetAssembler::load_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
536 Register dst, Address src, Register tmp1, Register tmp_thread) {
537 bool on_oop = type == T_OBJECT || type == T_ARRAY;
538 bool on_weak = (decorators & ON_WEAK_OOP_REF) != 0;
539 bool on_phantom = (decorators & ON_PHANTOM_OOP_REF) != 0;
540 bool not_in_heap = (decorators & IN_NATIVE) != 0;
541 bool on_reference = on_weak || on_phantom;
542 bool keep_alive = (decorators & AS_NO_KEEPALIVE) == 0;
543
544 BarrierSetAssembler::load_at(masm, decorators, type, dst, src, tmp1, tmp_thread);
545 if (on_oop) {
546 if (not_in_heap) {
547 if (ShenandoahHeap::heap()->is_traversal_mode()) {
548 load_reference_barrier(masm, dst);
549 keep_alive = true;
550 } else {
551 load_reference_barrier_native(masm, dst);
552 }
553 } else {
554 load_reference_barrier(masm, dst);
555 }
556
557 if (ShenandoahKeepAliveBarrier && on_reference && keep_alive) {
558 const Register thread = NOT_LP64(tmp_thread) LP64_ONLY(r15_thread);
559 assert_different_registers(dst, tmp1, tmp_thread);
560 NOT_LP64(__ get_thread(thread));
561 // Generate the SATB pre-barrier code to log the value of
562 // the referent field in an SATB buffer.
563 shenandoah_write_barrier_pre(masm /* masm */,
564 noreg /* obj */,
565 dst /* pre_val */,
566 thread /* thread */,
567 tmp1 /* tmp */,
568 true /* tosca_live */,
569 true /* expand_call */);
570 }
571 }
572 }
573
574 void ShenandoahBarrierSetAssembler::store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
575 Address dst, Register val, Register tmp1, Register tmp2) {
576
577 bool on_oop = type == T_OBJECT || type == T_ARRAY;
578 bool in_heap = (decorators & IN_HEAP) != 0;
579 bool as_normal = (decorators & AS_NORMAL) != 0;
580 if (on_oop && in_heap) {
581 bool needs_pre_barrier = as_normal;
582
583 Register tmp3 = LP64_ONLY(r8) NOT_LP64(rsi);
584 Register rthread = LP64_ONLY(r15_thread) NOT_LP64(rcx);
585 // flatten object address if needed
586 // We do it regardless of precise because we need the registers
587 if (dst.index() == noreg && dst.disp() == 0) {
588 if (dst.base() != tmp1) {
589 __ movptr(tmp1, dst.base());
590 }
591 } else {
592 __ lea(tmp1, dst);
593 }
594
595 assert_different_registers(val, tmp1, tmp2, tmp3, rthread);
596
597 #ifndef _LP64
598 __ get_thread(rthread);
599 InterpreterMacroAssembler *imasm = static_cast<InterpreterMacroAssembler*>(masm);
600 imasm->save_bcp();
601 #endif
602
603 if (needs_pre_barrier) {
604 shenandoah_write_barrier_pre(masm /*masm*/,
605 tmp1 /* obj */,
606 tmp2 /* pre_val */,
607 rthread /* thread */,
608 tmp3 /* tmp */,
609 val != noreg /* tosca_live */,
610 false /* expand_call */);
611 }
612 if (val == noreg) {
613 BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp1, 0), val, noreg, noreg);
614 } else {
615 storeval_barrier(masm, val, tmp3);
616 BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp1, 0), val, noreg, noreg);
617 }
618 NOT_LP64(imasm->restore_bcp());
619 } else {
620 BarrierSetAssembler::store_at(masm, decorators, type, dst, val, tmp1, tmp2);
621 }
622 }
623
624 // Special Shenandoah CAS implementation that handles false negatives
625 // due to concurrent evacuation.
626 void ShenandoahBarrierSetAssembler::cmpxchg_oop(MacroAssembler* masm,
627 Register res, Address addr, Register oldval, Register newval,
628 bool exchange, Register tmp1, Register tmp2) {
629 assert(ShenandoahCASBarrier, "Should only be used when CAS barrier is enabled");
630 assert(oldval == rax, "must be in rax for implicit use in cmpxchg");
631
632 Label retry, done;
633
634 // Remember oldval for retry logic below
635 #ifdef _LP64
636 if (UseCompressedOops) {
637 __ movl(tmp1, oldval);
638 } else
639 #endif
640 {
641 __ movptr(tmp1, oldval);
642 }
643
644 // Step 1. Try to CAS with given arguments. If successful, then we are done,
645 // and can safely return.
646 if (os::is_MP()) __ lock();
647 #ifdef _LP64
648 if (UseCompressedOops) {
649 __ cmpxchgl(newval, addr);
650 } else
651 #endif
652 {
653 __ cmpxchgptr(newval, addr);
654 }
655 __ jcc(Assembler::equal, done, true);
656
657 // Step 2. CAS had failed. This may be a false negative.
658 //
659 // The trouble comes when we compare the to-space pointer with the from-space
660 // pointer to the same object. To resolve this, it will suffice to resolve both
661 // oldval and the value from memory -- this will give both to-space pointers.
662 // If they mismatch, then it was a legitimate failure.
663 //
664 #ifdef _LP64
665 if (UseCompressedOops) {
666 __ decode_heap_oop(tmp1);
667 }
668 #endif
669 resolve_forward_pointer(masm, tmp1);
670
671 #ifdef _LP64
672 if (UseCompressedOops) {
673 __ movl(tmp2, oldval);
674 __ decode_heap_oop(tmp2);
675 } else
676 #endif
677 {
678 __ movptr(tmp2, oldval);
679 }
680 resolve_forward_pointer(masm, tmp2);
681
682 __ cmpptr(tmp1, tmp2);
683 __ jcc(Assembler::notEqual, done, true);
684
685 // Step 3. Try to CAS again with resolved to-space pointers.
686 //
687 // Corner case: it may happen that somebody stored the from-space pointer
688 // to memory while we were preparing for retry. Therefore, we can fail again
689 // on retry, and so need to do this in loop, always resolving the failure
690 // witness.
691 __ bind(retry);
692 if (os::is_MP()) __ lock();
693 #ifdef _LP64
694 if (UseCompressedOops) {
695 __ cmpxchgl(newval, addr);
696 } else
697 #endif
698 {
699 __ cmpxchgptr(newval, addr);
700 }
701 __ jcc(Assembler::equal, done, true);
702
703 #ifdef _LP64
704 if (UseCompressedOops) {
705 __ movl(tmp2, oldval);
706 __ decode_heap_oop(tmp2);
707 } else
708 #endif
709 {
710 __ movptr(tmp2, oldval);
711 }
712 resolve_forward_pointer(masm, tmp2);
713
714 __ cmpptr(tmp1, tmp2);
715 __ jcc(Assembler::equal, retry, true);
716
717 // Step 4. If we need a boolean result out of CAS, check the flag again,
718 // and promote the result. Note that we handle the flag from both the CAS
719 // itself and from the retry loop.
720 __ bind(done);
721 if (!exchange) {
722 assert(res != NULL, "need result register");
723 #ifdef _LP64
724 __ setb(Assembler::equal, res);
725 __ movzbl(res, res);
726 #else
727 // Need something else to clean the result, because some registers
728 // do not have byte encoding that movzbl wants. Cannot do the xor first,
729 // because it modifies the flags.
730 Label res_non_zero;
731 __ movptr(res, 1);
732 __ jcc(Assembler::equal, res_non_zero, true);
733 __ xorptr(res, res);
734 __ bind(res_non_zero);
735 #endif
736 }
737 }
738
739 // Generate cset check. If obj is in cset, branch to in_cset label, otherwise fall through
740 // obj: Register holding the oop, preserved
741 // tmp1, tmp2: temp registers, trashed
742 void ShenandoahBarrierSetAssembler::gen_cset_check(MacroAssembler* masm, Register obj, Register tmp1, Register tmp2, Label& in_cset) {
743 // Check for object being in the collection set.
744 // TODO: Can we use only 1 register here?
745 // The source object arrives here in rax.
746 // live: rax
747 // live: tmp1
748 __ mov(tmp1, obj);
749 __ shrptr(tmp1, ShenandoahHeapRegion::region_size_bytes_shift_jint());
750 // live: tmp2
751 __ movptr(tmp2, (intptr_t) ShenandoahHeap::in_cset_fast_test_addr());
752 __ movbool(tmp2, Address(tmp2, tmp1, Address::times_1));
753 // unlive: tmp1
754 __ testbool(tmp2);
755 // unlive: tmp2
756 __ jccb(Assembler::notZero, in_cset);
757 }
758
759 // Generate check if object is resolved. Branch to resolved label, if not. Otherwise return resolved
760 // object in obj register.
761 // obj: object, resolved object on normal return
762 // tmp: temp register, trashed
763 void ShenandoahBarrierSetAssembler::gen_resolved_check(MacroAssembler* masm, Register obj, Register tmp, Label& not_resolved) {
764 __ movptr(tmp, Address(obj, oopDesc::mark_offset_in_bytes()));
765 // Test if both lowest bits are set. We trick it by negating the bits
766 // then test for both bits clear.
767 __ notptr(tmp);
768 __ testb(tmp, markOopDesc::marked_value);
769 __ jccb(Assembler::notZero, not_resolved);
770 // Clear both lower bits. It's still inverted, so set them, and then invert back.
771 __ orptr(tmp, markOopDesc::marked_value);
772 __ notptr(tmp);
773 // At this point, tmp2 contains the decoded forwarding pointer.
774 __ mov(obj, tmp);
775 }
776
777 #undef __
778
779 #ifdef COMPILER1
780
781 #define __ ce->masm()->
782
783 void ShenandoahBarrierSetAssembler::gen_pre_barrier_stub(LIR_Assembler* ce, ShenandoahPreBarrierStub* stub) {
784 ShenandoahBarrierSetC1* bs = (ShenandoahBarrierSetC1*)BarrierSet::barrier_set()->barrier_set_c1();
785 // At this point we know that marking is in progress.
786 // If do_load() is true then we have to emit the
787 // load of the previous value; otherwise it has already
788 // been loaded into _pre_val.
789
790 __ bind(*stub->entry());
791 assert(stub->pre_val()->is_register(), "Precondition.");
792
793 Register pre_val_reg = stub->pre_val()->as_register();
794
795 if (stub->do_load()) {
796 ce->mem2reg(stub->addr(), stub->pre_val(), T_OBJECT, stub->patch_code(), stub->info(), false /*wide*/, false /*unaligned*/);
797 }
798
799 __ cmpptr(pre_val_reg, (int32_t)NULL_WORD);
800 __ jcc(Assembler::equal, *stub->continuation());
801 ce->store_parameter(stub->pre_val()->as_register(), 0);
802 __ call(RuntimeAddress(bs->pre_barrier_c1_runtime_code_blob()->code_begin()));
803 __ jmp(*stub->continuation());
804
805 }
806
807 void ShenandoahBarrierSetAssembler::gen_load_reference_barrier_stub(LIR_Assembler* ce, ShenandoahLoadReferenceBarrierStub* stub) {
808 ShenandoahBarrierSetC1* bs = (ShenandoahBarrierSetC1*)BarrierSet::barrier_set()->barrier_set_c1();
809 __ bind(*stub->entry());
810
811 Register obj = stub->obj()->as_register();
812 Register res = stub->result()->as_register();
813 assert(res == rax, "result must arrive in rax");
814
815 if (res != obj) {
816 __ mov(res, obj);
817 }
818
819 // Check for null.
820 __ testptr(res, res);
821 __ jcc(Assembler::zero, *stub->continuation());
822
823 ce->store_parameter(res, 0);
824 __ call(RuntimeAddress(bs->load_reference_barrier_rt_code_blob()->code_begin()));
825
826 __ jmp(*stub->continuation());
827 }
828
829 #undef __
830
831 #define __ sasm->
832
833 void ShenandoahBarrierSetAssembler::generate_c1_pre_barrier_runtime_stub(StubAssembler* sasm) {
834 __ prologue("shenandoah_pre_barrier", false);
835 // arg0 : previous value of memory
836
837 __ push(rax);
838 __ push(rdx);
839
840 const Register pre_val = rax;
841 const Register thread = NOT_LP64(rax) LP64_ONLY(r15_thread);
842 const Register tmp = rdx;
843
844 NOT_LP64(__ get_thread(thread);)
845
846 Address queue_index(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset()));
847 Address buffer(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset()));
848
849 Label done;
850 Label runtime;
851
852 // Is SATB still active?
853 Address gc_state(thread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
854 __ testb(gc_state, ShenandoahHeap::MARKING | ShenandoahHeap::TRAVERSAL);
855 __ jcc(Assembler::zero, done);
856
857 // Can we store original value in the thread's buffer?
858
859 __ movptr(tmp, queue_index);
860 __ testptr(tmp, tmp);
861 __ jcc(Assembler::zero, runtime);
862 __ subptr(tmp, wordSize);
863 __ movptr(queue_index, tmp);
864 __ addptr(tmp, buffer);
865
866 // prev_val (rax)
867 __ load_parameter(0, pre_val);
868 __ movptr(Address(tmp, 0), pre_val);
869 __ jmp(done);
870
871 __ bind(runtime);
872
873 __ save_live_registers_no_oop_map(true);
874
875 // load the pre-value
876 __ load_parameter(0, rcx);
877 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry), rcx, thread);
878
879 __ restore_live_registers(true);
880
881 __ bind(done);
882
883 __ pop(rdx);
884 __ pop(rax);
885
886 __ epilogue();
887 }
888
889 void ShenandoahBarrierSetAssembler::generate_c1_load_reference_barrier_runtime_stub(StubAssembler* sasm) {
890 __ prologue("shenandoah_load_reference_barrier", false);
891 // arg0 : object to be resolved
892
893 Label resolve_oop, slow_path;
894
895 // We use RDI, which also serves as argument register for slow call.
896 // RAX always holds the src object ptr, except after the slow call,
897 // then it holds the result. R8/RBX is used as temporary register.
898
899 Register tmp1 = rdi;
900 Register tmp2 = LP64_ONLY(r8) NOT_LP64(rbx);
901
902 __ push(tmp1);
903 __ push(tmp2);
904
905 __ load_parameter(0, rax);
906
907 gen_cset_check(sasm, rax, tmp1, tmp2, resolve_oop);
908
909 __ pop(tmp2);
910 __ pop(tmp1);
911 __ epilogue();
912
913 __ bind(resolve_oop);
914
915 gen_resolved_check(sasm, rax, tmp1, slow_path);
916
917 __ pop(tmp2);
918 __ pop(tmp1);
919 __ epilogue();
920
921 __ bind(slow_path);
922
923 __ save_live_registers_no_oop_map(true);
924 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier), rax);
925 __ restore_live_registers_except_rax(true);
926
927 __ pop(tmp2);
928 __ pop(tmp1);
929 __ epilogue();
930 }
931
932 #undef __
933
934 #endif // COMPILER1
935
936 address ShenandoahBarrierSetAssembler::shenandoah_lrb() {
937 assert(_shenandoah_lrb != NULL, "need load reference barrier stub");
938 return _shenandoah_lrb;
939 }
940
941 #define __ cgen->assembler()->
942
943 address ShenandoahBarrierSetAssembler::generate_shenandoah_lrb(StubCodeGenerator* cgen) {
944 __ align(CodeEntryAlignment);
945 StubCodeMark mark(cgen, "StubRoutines", "shenandoah_lrb");
946 address start = __ pc();
947
948 Label resolve_oop, slow_path;
949
950 // We use RDI, which also serves as argument register for slow call.
951 // RAX always holds the src object ptr, except after the slow call,
952 // then it holds the result. R8/RBX is used as temporary register.
953
954 Register tmp1 = rdi;
955 Register tmp2 = LP64_ONLY(r8) NOT_LP64(rbx);
956
957 __ push(tmp1);
958 __ push(tmp2);
959
960 gen_cset_check(cgen->assembler(), rax, tmp1, tmp2, resolve_oop);
961
962 __ pop(tmp2);
963 __ pop(tmp1);
964 __ ret(0);
965
966 __ bind(resolve_oop);
967
968 gen_resolved_check(cgen->assembler(), rax, tmp2, slow_path);
969
970 __ pop(tmp2);
971 __ pop(tmp1);
972 __ ret(0);
973
974 __ bind(slow_path);
975
976 __ push(rcx);
977 __ push(rdx);
978 __ push(rdi);
979 __ push(rsi);
980 #ifdef _LP64
981 __ push(r8);
982 __ push(r9);
983 __ push(r10);
984 __ push(r11);
985 __ push(r12);
986 __ push(r13);
987 __ push(r14);
988 __ push(r15);
989 #endif
990
991 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier), rax);
992
993 #ifdef _LP64
994 __ pop(r15);
995 __ pop(r14);
996 __ pop(r13);
997 __ pop(r12);
998 __ pop(r11);
999 __ pop(r10);
1000 __ pop(r9);
1001 __ pop(r8);
1002 #endif
1003 __ pop(rsi);
1004 __ pop(rdi);
1005 __ pop(rdx);
1006 __ pop(rcx);
1007
1008 __ pop(tmp2);
1009 __ pop(tmp1);
1010 __ ret(0);
1011
1012 return start;
1013 }
1014
1015 #undef __
1016
1017 void ShenandoahBarrierSetAssembler::barrier_stubs_init() {
1018 if (ShenandoahLoadRefBarrier) {
1019 int stub_code_size = 4096;
1020 ResourceMark rm;
1021 BufferBlob* bb = BufferBlob::create("shenandoah_barrier_stubs", stub_code_size);
1022 CodeBuffer buf(bb);
1023 StubCodeGenerator cgen(&buf);
1024 _shenandoah_lrb = generate_shenandoah_lrb(&cgen);
1025 }
1026 }