1 /*
2 * Copyright (c) 2018, 2026, 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 "asm/macroAssembler.inline.hpp"
26 #include "code/aotCodeCache.hpp"
27 #include "gc/g1/g1BarrierSet.hpp"
28 #include "gc/g1/g1BarrierSetAssembler.hpp"
29 #include "gc/g1/g1BarrierSetRuntime.hpp"
30 #include "gc/g1/g1CardTable.hpp"
31 #include "gc/g1/g1HeapRegion.hpp"
32 #include "gc/g1/g1ThreadLocalData.hpp"
33 #include "gc/shared/collectedHeap.hpp"
34 #include "interpreter/interp_masm.hpp"
35 #include "runtime/javaThread.hpp"
36 #include "runtime/sharedRuntime.hpp"
37 #ifdef COMPILER1
38 #include "c1/c1_LIRAssembler.hpp"
39 #include "c1/c1_MacroAssembler.hpp"
40 #include "gc/g1/c1/g1BarrierSetC1.hpp"
41 #endif // COMPILER1
42 #ifdef COMPILER2
43 #include "gc/g1/c2/g1BarrierSetC2.hpp"
44 #endif // COMPILER2
45
46 #define __ masm->
47
48 void G1BarrierSetAssembler::gen_write_ref_array_pre_barrier(MacroAssembler* masm, DecoratorSet decorators,
49 Register addr, Register count, RegSet saved_regs) {
50 bool dest_uninitialized = (decorators & IS_DEST_UNINITIALIZED) != 0;
51 if (!dest_uninitialized) {
52 Label done;
53 Address in_progress(rthread, in_bytes(G1ThreadLocalData::satb_mark_queue_active_offset()));
54
55 // Is marking active?
56 if (in_bytes(SATBMarkQueue::byte_width_of_active()) == 4) {
57 __ ldrw(rscratch1, in_progress);
58 } else {
59 assert(in_bytes(SATBMarkQueue::byte_width_of_active()) == 1, "Assumption");
60 __ ldrb(rscratch1, in_progress);
61 }
62 __ cbzw(rscratch1, done);
63
64 __ push(saved_regs, sp);
65 if (count == c_rarg0) {
66 if (addr == c_rarg1) {
67 // exactly backwards!!
68 __ mov(rscratch1, c_rarg0);
69 __ mov(c_rarg0, c_rarg1);
70 __ mov(c_rarg1, rscratch1);
71 } else {
72 __ mov(c_rarg1, count);
73 __ mov(c_rarg0, addr);
74 }
75 } else {
76 __ mov(c_rarg0, addr);
77 __ mov(c_rarg1, count);
78 }
79 if (UseCompressedOops) {
80 __ call_VM_leaf(CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_array_pre_narrow_oop_entry), 2);
81 } else {
82 __ call_VM_leaf(CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_array_pre_oop_entry), 2);
83 }
84 __ pop(saved_regs, sp);
85
86 __ bind(done);
87 }
88 }
89
90 void G1BarrierSetAssembler::gen_write_ref_array_post_barrier(MacroAssembler* masm,
91 DecoratorSet decorators,
92 Register start,
93 Register count,
94 Register scratch) {
95
96 Label done;
97 Label loop;
98 Label next;
99
100 __ cbz(count, done);
101
102 // Calculate the number of card marks to set. Since the object might start and
103 // end within a card, we need to calculate this via the card table indexes of
104 // the actual start and last addresses covered by the object.
105 // Temporarily use the count register for the last element address.
106 __ lea(count, Address(start, count, Address::lsl(LogBytesPerHeapOop))); // end = start + count << LogBytesPerHeapOop
107 __ sub(count, count, BytesPerHeapOop); // Use last element address for end.
108
109 __ lsr(start, start, CardTable::card_shift());
110 __ lsr(count, count, CardTable::card_shift());
111 __ sub(count, count, start); // Number of bytes to mark - 1.
112
113 // Add card table base offset to start.
114 __ ldr(scratch, Address(rthread, in_bytes(G1ThreadLocalData::card_table_base_offset())));
115 __ add(start, start, scratch);
116
117 __ bind(loop);
118 if (UseCondCardMark) {
119 __ ldrb(scratch, Address(start, count));
120 // Instead of loading clean_card_val and comparing, we exploit the fact that
121 // the LSB of non-clean cards is always 0, and the LSB of clean cards 1.
122 __ tbz(scratch, 0, next);
123 }
124 static_assert(G1CardTable::dirty_card_val() == 0, "must be to use zr");
125 __ strb(zr, Address(start, count));
126 __ bind(next);
127 __ subs(count, count, 1);
128 __ br(Assembler::GE, loop);
129
130 __ bind(done);
131 }
132
133 static void generate_queue_test_and_insertion(MacroAssembler* masm, ByteSize index_offset, ByteSize buffer_offset, Label& runtime,
134 const Register thread, const Register value, const Register temp1, const Register temp2) {
135 assert_different_registers(value, temp1, temp2);
136 // Can we store a value in the given thread's buffer?
137 // (The index field is typed as size_t.)
138 __ ldr(temp1, Address(thread, in_bytes(index_offset))); // temp1 := *(index address)
139 __ cbz(temp1, runtime); // jump to runtime if index == 0 (full buffer)
140 // The buffer is not full, store value into it.
141 __ sub(temp1, temp1, wordSize); // temp1 := next index
142 __ str(temp1, Address(thread, in_bytes(index_offset))); // *(index address) := next index
143 __ ldr(temp2, Address(thread, in_bytes(buffer_offset))); // temp2 := buffer address
144 __ str(value, Address(temp2, temp1)); // *(buffer address + next index) := value
145 }
146
147 static void generate_pre_barrier_fast_path(MacroAssembler* masm,
148 const Register thread,
149 const Register tmp1) {
150 Address in_progress(thread, in_bytes(G1ThreadLocalData::satb_mark_queue_active_offset()));
151 // Is marking active?
152 if (in_bytes(SATBMarkQueue::byte_width_of_active()) == 4) {
153 __ ldrw(tmp1, in_progress);
154 } else {
155 assert(in_bytes(SATBMarkQueue::byte_width_of_active()) == 1, "Assumption");
156 __ ldrb(tmp1, in_progress);
157 }
158 }
159
160 static void generate_pre_barrier_slow_path(MacroAssembler* masm,
161 const Register obj,
162 const Register pre_val,
163 const Register thread,
164 const Register tmp1,
165 const Register tmp2,
166 Label& done,
167 Label& runtime) {
168 // Do we need to load the previous value?
169 if (obj != noreg) {
170 __ load_heap_oop(pre_val, Address(obj, 0), noreg, noreg, AS_RAW);
171 }
172 // Is the previous value null?
173 __ cbz(pre_val, done);
174 generate_queue_test_and_insertion(masm,
175 G1ThreadLocalData::satb_mark_queue_index_offset(),
176 G1ThreadLocalData::satb_mark_queue_buffer_offset(),
177 runtime,
178 thread, pre_val, tmp1, tmp2);
179 __ b(done);
180 }
181
182 void G1BarrierSetAssembler::g1_write_barrier_pre(MacroAssembler* masm,
183 Register obj,
184 Register pre_val,
185 Register thread,
186 Register tmp1,
187 Register tmp2,
188 bool tosca_live,
189 bool expand_call) {
190 // If expand_call is true then we expand the call_VM_leaf macro
191 // directly to skip generating the check by
192 // InterpreterMacroAssembler::call_VM_leaf_base that checks _last_sp.
193
194 assert(thread == rthread, "must be");
195
196 Label done;
197 Label runtime;
198
199 assert_different_registers(obj, pre_val, tmp1, tmp2);
200 assert(pre_val != noreg && tmp1 != noreg && tmp2 != noreg, "expecting a register");
201
202 generate_pre_barrier_fast_path(masm, thread, tmp1);
203 // If marking is not active (*(mark queue active address) == 0), jump to done
204 __ cbzw(tmp1, done);
205 generate_pre_barrier_slow_path(masm, obj, pre_val, thread, tmp1, tmp2, done, runtime);
206
207 __ bind(runtime);
208
209 assert_different_registers(rscratch1, pre_val); // push_call_clobbered_registers trashes rscratch1
210 __ push_call_clobbered_registers();
211
212 // Calling the runtime using the regular call_VM_leaf mechanism generates
213 // code (generated by InterpreterMacroAssember::call_VM_leaf_base)
214 // that checks that the *(rfp+frame::interpreter_frame_last_sp) == nullptr.
215 //
216 // If we care generating the pre-barrier without a frame (e.g. in the
217 // intrinsified Reference.get() routine) then rfp might be pointing to
218 // the caller frame and so this check will most likely fail at runtime.
219 //
220 // Expanding the call directly bypasses the generation of the check.
221 // So when we do not have have a full interpreter frame on the stack
222 // expand_call should be passed true.
223
224 if (expand_call) {
225 assert(pre_val != c_rarg1, "smashed arg");
226 __ super_call_VM_leaf(CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_pre_entry), pre_val, thread);
227 } else {
228 __ call_VM_leaf(CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_pre_entry), pre_val, thread);
229 }
230
231 __ pop_call_clobbered_registers();
232
233 __ bind(done);
234
235 }
236
237 static void generate_post_barrier(MacroAssembler* masm,
238 const Register store_addr,
239 const Register new_val,
240 const Register thread,
241 const Register tmp1,
242 const Register tmp2,
243 Label& done,
244 bool new_val_may_be_null) {
245 assert(thread == rthread, "must be");
246 assert_different_registers(store_addr, new_val, thread, tmp1, tmp2, noreg, rscratch1);
247
248 // Does store cross heap regions?
249 #if INCLUDE_CDS
250 // AOT code needs to load the barrier grain shift from the aot
251 // runtime constants area in the code cache otherwise we can compile
252 // it as an immediate operand
253 if (AOTCodeCache::is_on_for_dump()) {
254 address grain_shift_address = (address)AOTRuntimeConstants::grain_shift_address();
255 __ eor(tmp1, store_addr, new_val);
256 __ lea(tmp2, ExternalAddress(grain_shift_address));
257 __ ldrb(tmp2, tmp2);
258 __ lsrv(tmp1, tmp1, tmp2);
259 __ cbz(tmp1, done);
260 } else
261 #endif
262 {
263 __ eor(tmp1, store_addr, new_val); // tmp1 := store address ^ new value
264 __ lsr(tmp1, tmp1, G1HeapRegion::LogOfHRGrainBytes); // tmp1 := ((store address ^ new value) >> LogOfHRGrainBytes)
265 __ cbz(tmp1, done);
266 }
267
268 // Crosses regions, storing null?
269 if (new_val_may_be_null) {
270 __ cbz(new_val, done);
271 }
272 // Storing region crossing non-null.
273 __ lsr(tmp1, store_addr, CardTable::card_shift()); // tmp1 := card address relative to card table base
274
275 Address card_table_addr(thread, in_bytes(G1ThreadLocalData::card_table_base_offset()));
276 __ ldr(tmp2, card_table_addr); // tmp2 := card table base address
277 if (UseCondCardMark) {
278 __ ldrb(rscratch1, Address(tmp1, tmp2)); // rscratch1 := card
279 // Instead of loading clean_card_val and comparing, we exploit the fact that
280 // the LSB of non-clean cards is always 0, and the LSB of clean cards 1.
281 __ tbz(rscratch1, 0, done);
282 }
283 static_assert(G1CardTable::dirty_card_val() == 0, "must be to use zr");
284 __ strb(zr, Address(tmp1, tmp2)); // *(card address) := dirty_card_val
285 }
286
287 void G1BarrierSetAssembler::g1_write_barrier_post(MacroAssembler* masm,
288 Register store_addr,
289 Register new_val,
290 Register thread,
291 Register tmp1,
292 Register tmp2) {
293 Label done;
294 generate_post_barrier(masm, store_addr, new_val, thread, tmp1, tmp2, done, false /* new_val_may_be_null */);
295 __ bind(done);
296 }
297
298 #if defined(COMPILER2)
299
300 static void generate_c2_barrier_runtime_call(MacroAssembler* masm, G1BarrierStubC2* stub, const Register arg, const address runtime_path) {
301 SaveLiveRegisters save_registers(masm, stub);
302 if (c_rarg0 != arg) {
303 __ mov(c_rarg0, arg);
304 }
305 __ mov(c_rarg1, rthread);
306 __ mov(rscratch1, runtime_path);
307 __ blr(rscratch1);
308 }
309
310 void G1BarrierSetAssembler::g1_write_barrier_pre_c2(MacroAssembler* masm,
311 Register obj,
312 Register pre_val,
313 Register thread,
314 Register tmp1,
315 Register tmp2,
316 G1PreBarrierStubC2* stub) {
317 assert(thread == rthread, "must be");
318 assert_different_registers(obj, pre_val, tmp1, tmp2);
319 assert(pre_val != noreg && tmp1 != noreg && tmp2 != noreg, "expecting a register");
320
321 stub->initialize_registers(obj, pre_val, thread, tmp1, tmp2);
322
323 generate_pre_barrier_fast_path(masm, thread, tmp1);
324 // If marking is active (*(mark queue active address) != 0), jump to stub (slow path)
325 __ cbnzw(tmp1, *stub->entry());
326
327 __ bind(*stub->continuation());
328 }
329
330 void G1BarrierSetAssembler::generate_c2_pre_barrier_stub(MacroAssembler* masm,
331 G1PreBarrierStubC2* stub) const {
332 Assembler::InlineSkippedInstructionsCounter skip_counter(masm);
333 Label runtime;
334 Register obj = stub->obj();
335 Register pre_val = stub->pre_val();
336 Register thread = stub->thread();
337 Register tmp1 = stub->tmp1();
338 Register tmp2 = stub->tmp2();
339
340 __ bind(*stub->entry());
341 generate_pre_barrier_slow_path(masm, obj, pre_val, thread, tmp1, tmp2, *stub->continuation(), runtime);
342
343 __ bind(runtime);
344 generate_c2_barrier_runtime_call(masm, stub, pre_val, CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_pre_entry));
345 __ b(*stub->continuation());
346 }
347
348 void G1BarrierSetAssembler::g1_write_barrier_post_c2(MacroAssembler* masm,
349 Register store_addr,
350 Register new_val,
351 Register thread,
352 Register tmp1,
353 Register tmp2,
354 bool new_val_may_be_null) {
355 Label done;
356 generate_post_barrier(masm, store_addr, new_val, thread, tmp1, tmp2, done, new_val_may_be_null);
357 __ bind(done);
358 }
359
360 #endif // COMPILER2
361
362 void G1BarrierSetAssembler::load_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
363 Register dst, Address src, Register tmp1, Register tmp2) {
364 bool on_oop = is_reference_type(type);
365 bool on_weak = (decorators & ON_WEAK_OOP_REF) != 0;
366 bool on_phantom = (decorators & ON_PHANTOM_OOP_REF) != 0;
367 bool on_reference = on_weak || on_phantom;
368 CardTableBarrierSetAssembler::load_at(masm, decorators, type, dst, src, tmp1, tmp2);
369 if (on_oop && on_reference) {
370 // LR is live. It must be saved around calls.
371 __ enter(/*strip_ret_addr*/true); // barrier may call runtime
372 // Generate the G1 pre-barrier code to log the value of
373 // the referent field in an SATB buffer.
374 g1_write_barrier_pre(masm /* masm */,
375 noreg /* obj */,
376 dst /* pre_val */,
377 rthread /* thread */,
378 tmp1 /* tmp1 */,
379 tmp2 /* tmp2 */,
380 true /* tosca_live */,
381 true /* expand_call */);
382 __ leave();
383 }
384 }
385
386 void G1BarrierSetAssembler::oop_store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
387 Address dst, Register val, Register tmp1, Register tmp2, Register tmp3) {
388
389 bool in_heap = (decorators & IN_HEAP) != 0;
390 bool as_normal = (decorators & AS_NORMAL) != 0;
391 bool dest_uninitialized = (decorators & IS_DEST_UNINITIALIZED) != 0;
392
393 bool needs_pre_barrier = as_normal && !dest_uninitialized;
394 bool needs_post_barrier = (val != noreg && in_heap);
395
396 assert_different_registers(val, tmp1, tmp2, tmp3);
397
398 // flatten object address if needed
399 if (dst.index() == noreg && dst.offset() == 0) {
400 if (dst.base() != tmp3) {
401 __ mov(tmp3, dst.base());
402 }
403 } else {
404 __ lea(tmp3, dst);
405 }
406
407 if (needs_pre_barrier) {
408 g1_write_barrier_pre(masm,
409 tmp3 /* obj */,
410 tmp2 /* pre_val */,
411 rthread /* thread */,
412 tmp1 /* tmp1 */,
413 rscratch2 /* tmp2 */,
414 val != noreg /* tosca_live */,
415 false /* expand_call */);
416 }
417
418 if (val == noreg) {
419 BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp3, 0), noreg, noreg, noreg, noreg);
420 } else {
421 // G1 barrier needs uncompressed oop for region cross check.
422 Register new_val = val;
423 if (needs_post_barrier) {
424 if (UseCompressedOops) {
425 new_val = rscratch2;
426 __ mov(new_val, val);
427 }
428 }
429
430 BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp3, 0), val, noreg, noreg, noreg);
431 if (needs_post_barrier) {
432 g1_write_barrier_post(masm,
433 tmp3 /* store_adr */,
434 new_val /* new_val */,
435 rthread /* thread */,
436 tmp1 /* tmp1 */,
437 tmp2 /* tmp2 */);
438 }
439 }
440
441 }
442
443 #ifdef COMPILER1
444
445 #undef __
446 #define __ ce->masm()->
447
448 void G1BarrierSetAssembler::gen_pre_barrier_stub(LIR_Assembler* ce, G1PreBarrierStub* stub) {
449 G1BarrierSetC1* bs = (G1BarrierSetC1*)BarrierSet::barrier_set()->barrier_set_c1();
450 // At this point we know that marking is in progress.
451 // If do_load() is true then we have to emit the
452 // load of the previous value; otherwise it has already
453 // been loaded into _pre_val.
454
455 __ bind(*stub->entry());
456
457 assert(stub->pre_val()->is_register(), "Precondition.");
458
459 Register pre_val_reg = stub->pre_val()->as_register();
460
461 if (stub->do_load()) {
462 ce->mem2reg(stub->addr(), stub->pre_val(), T_OBJECT, stub->patch_code(), stub->info(), false /*wide*/);
463 }
464 __ cbz(pre_val_reg, *stub->continuation());
465 ce->store_parameter(stub->pre_val()->as_register(), 0);
466 __ far_call(RuntimeAddress(bs->pre_barrier_c1_runtime_code_blob()->code_begin()));
467 __ b(*stub->continuation());
468 }
469
470 #undef __
471
472 void G1BarrierSetAssembler::g1_write_barrier_post_c1(MacroAssembler* masm,
473 Register store_addr,
474 Register new_val,
475 Register thread,
476 Register tmp1,
477 Register tmp2) {
478 Label done;
479 generate_post_barrier(masm, store_addr, new_val, thread, tmp1, tmp2, done, true /* new_val_may_be_null */);
480 masm->bind(done);
481 }
482
483 #define __ sasm->
484
485 void G1BarrierSetAssembler::generate_c1_pre_barrier_runtime_stub(StubAssembler* sasm) {
486 __ prologue("g1_pre_barrier", false);
487
488 // arg0 : previous value of memory
489
490 BarrierSet* bs = BarrierSet::barrier_set();
491
492 const Register pre_val = r0;
493 const Register thread = rthread;
494 const Register tmp = rscratch1;
495
496 Address in_progress(thread, in_bytes(G1ThreadLocalData::satb_mark_queue_active_offset()));
497 Address queue_index(thread, in_bytes(G1ThreadLocalData::satb_mark_queue_index_offset()));
498 Address buffer(thread, in_bytes(G1ThreadLocalData::satb_mark_queue_buffer_offset()));
499
500 Label done;
501 Label runtime;
502
503 // Is marking still active?
504 if (in_bytes(SATBMarkQueue::byte_width_of_active()) == 4) {
505 __ ldrw(tmp, in_progress);
506 } else {
507 assert(in_bytes(SATBMarkQueue::byte_width_of_active()) == 1, "Assumption");
508 __ ldrb(tmp, in_progress);
509 }
510 __ cbzw(tmp, done);
511
512 // Can we store original value in the thread's buffer?
513 __ ldr(tmp, queue_index);
514 __ cbz(tmp, runtime);
515
516 __ sub(tmp, tmp, wordSize);
517 __ str(tmp, queue_index);
518 __ ldr(rscratch2, buffer);
519 __ add(tmp, tmp, rscratch2);
520 __ load_parameter(0, rscratch2);
521 __ str(rscratch2, Address(tmp, 0));
522 __ b(done);
523
524 __ bind(runtime);
525 __ push_call_clobbered_registers();
526 __ load_parameter(0, pre_val);
527 __ call_VM_leaf(CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_pre_entry), pre_val, thread);
528 __ pop_call_clobbered_registers();
529 __ bind(done);
530
531 __ epilogue();
532 }
533
534 #undef __
535
536 #endif // COMPILER1