1 /*
2 * Copyright (c) 2018, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "asm/macroAssembler.inline.hpp"
26 #include "gc/g1/g1BarrierSet.hpp"
27 #include "gc/g1/g1BarrierSetAssembler.hpp"
28 #include "gc/g1/g1BarrierSetRuntime.hpp"
29 #include "gc/g1/g1CardTable.hpp"
30 #include "gc/g1/g1HeapRegion.hpp"
31 #include "gc/g1/g1ThreadLocalData.hpp"
32 #include "gc/shared/collectedHeap.hpp"
33 #include "interpreter/interp_masm.hpp"
34 #include "runtime/javaThread.hpp"
35 #include "runtime/sharedRuntime.hpp"
36 #ifdef COMPILER1
37 #include "c1/c1_LIRAssembler.hpp"
38 #include "c1/c1_MacroAssembler.hpp"
39 #include "gc/g1/c1/g1BarrierSetC1.hpp"
40 #endif // COMPILER1
41 #ifdef COMPILER2
42 #include "gc/g1/c2/g1BarrierSetC2.hpp"
43 #endif // COMPILER2
44
45 #define __ masm->
46
47 void G1BarrierSetAssembler::gen_write_ref_array_pre_barrier(MacroAssembler* masm, DecoratorSet decorators,
48 Register addr, Register count, RegSet saved_regs) {
49 bool dest_uninitialized = (decorators & IS_DEST_UNINITIALIZED) != 0;
50 if (!dest_uninitialized) {
51 Label done;
52 Address in_progress(rthread, in_bytes(G1ThreadLocalData::satb_mark_queue_active_offset()));
53
54 // Is marking active?
55 if (in_bytes(SATBMarkQueue::byte_width_of_active()) == 4) {
56 __ ldrw(rscratch1, in_progress);
57 } else {
58 assert(in_bytes(SATBMarkQueue::byte_width_of_active()) == 1, "Assumption");
59 __ ldrb(rscratch1, in_progress);
60 }
61 __ cbzw(rscratch1, done);
62
63 __ push(saved_regs, sp);
64 if (count == c_rarg0) {
65 if (addr == c_rarg1) {
66 // exactly backwards!!
67 __ mov(rscratch1, c_rarg0);
68 __ mov(c_rarg0, c_rarg1);
69 __ mov(c_rarg1, rscratch1);
70 } else {
71 __ mov(c_rarg1, count);
72 __ mov(c_rarg0, addr);
73 }
74 } else {
75 __ mov(c_rarg0, addr);
76 __ mov(c_rarg1, count);
77 }
78 if (UseCompressedOops) {
79 __ call_VM_leaf(CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_array_pre_narrow_oop_entry), 2);
80 } else {
81 __ call_VM_leaf(CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_array_pre_oop_entry), 2);
82 }
83 __ pop(saved_regs, sp);
84
85 __ bind(done);
86 }
87 }
88
89 void G1BarrierSetAssembler::gen_write_ref_array_post_barrier(MacroAssembler* masm,
90 DecoratorSet decorators,
91 Register start,
92 Register count,
93 Register scratch,
94 RegSet saved_regs) {
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 // save the live input values
210 RegSet saved = RegSet::of(pre_val);
211 FloatRegSet fsaved;
212
213 // Barriers might be emitted when converting between (scalarized) calling
214 // conventions for inline types. Save all argument registers before calling
215 // into the runtime.
216
217 // TODO 8366717 This came with 8284161: Implementation of Virtual Threads (Preview) later in May 2022
218 // Check if it's sufficient
219 //__ push_call_clobbered_registers();
220 assert_different_registers(rscratch1, pre_val); // push_CPU_state trashes rscratch1
221 __ push_CPU_state(true);
222
223 // Calling the runtime using the regular call_VM_leaf mechanism generates
224 // code (generated by InterpreterMacroAssember::call_VM_leaf_base)
225 // that checks that the *(rfp+frame::interpreter_frame_last_sp) == nullptr.
226 //
227 // If we care generating the pre-barrier without a frame (e.g. in the
228 // intrinsified Reference.get() routine) then rfp might be pointing to
229 // the caller frame and so this check will most likely fail at runtime.
230 //
231 // Expanding the call directly bypasses the generation of the check.
232 // So when we do not have have a full interpreter frame on the stack
233 // expand_call should be passed true.
234
235 if (expand_call) {
236 assert(pre_val != c_rarg1, "smashed arg");
237 __ super_call_VM_leaf(CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_pre_entry), pre_val, thread);
238 } else {
239 __ call_VM_leaf(CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_pre_entry), pre_val, thread);
240 }
241
242 __ pop_CPU_state(true);
243
244 __ bind(done);
245
246 }
247
248 static void generate_post_barrier(MacroAssembler* masm,
249 const Register store_addr,
250 const Register new_val,
251 const Register thread,
252 const Register tmp1,
253 const Register tmp2,
254 Label& done,
255 bool new_val_may_be_null) {
256 assert(thread == rthread, "must be");
257 assert_different_registers(store_addr, new_val, thread, tmp1, tmp2, noreg, rscratch1);
258
259 // Does store cross heap regions?
260 __ eor(tmp1, store_addr, new_val); // tmp1 := store address ^ new value
261 __ lsr(tmp1, tmp1, G1HeapRegion::LogOfHRGrainBytes); // tmp1 := ((store address ^ new value) >> LogOfHRGrainBytes)
262 __ cbz(tmp1, done);
263 // Crosses regions, storing null?
264 if (new_val_may_be_null) {
265 __ cbz(new_val, done);
266 }
267 // Storing region crossing non-null.
268 __ lsr(tmp1, store_addr, CardTable::card_shift()); // tmp1 := card address relative to card table base
269
270 Address card_table_addr(thread, in_bytes(G1ThreadLocalData::card_table_base_offset()));
271 __ ldr(tmp2, card_table_addr); // tmp2 := card table base address
272 if (UseCondCardMark) {
273 __ ldrb(rscratch1, Address(tmp1, tmp2)); // rscratch1 := card
274 // Instead of loading clean_card_val and comparing, we exploit the fact that
275 // the LSB of non-clean cards is always 0, and the LSB of clean cards 1.
276 __ tbz(rscratch1, 0, done);
277 }
278 static_assert(G1CardTable::dirty_card_val() == 0, "must be to use zr");
279 __ strb(zr, Address(tmp1, tmp2)); // *(card address) := dirty_card_val
280 }
281
282 void G1BarrierSetAssembler::g1_write_barrier_post(MacroAssembler* masm,
283 Register store_addr,
284 Register new_val,
285 Register thread,
286 Register tmp1,
287 Register tmp2) {
288 Label done;
289 generate_post_barrier(masm, store_addr, new_val, thread, tmp1, tmp2, done, false /* new_val_may_be_null */);
290 __ bind(done);
291 }
292
293 #if defined(COMPILER2)
294
295 static void generate_c2_barrier_runtime_call(MacroAssembler* masm, G1BarrierStubC2* stub, const Register arg, const address runtime_path) {
296 SaveLiveRegisters save_registers(masm, stub);
297 if (c_rarg0 != arg) {
298 __ mov(c_rarg0, arg);
299 }
300 __ mov(c_rarg1, rthread);
301 __ mov(rscratch1, runtime_path);
302 __ blr(rscratch1);
303 }
304
305 void G1BarrierSetAssembler::g1_write_barrier_pre_c2(MacroAssembler* masm,
306 Register obj,
307 Register pre_val,
308 Register thread,
309 Register tmp1,
310 Register tmp2,
311 G1PreBarrierStubC2* stub) {
312 assert(thread == rthread, "must be");
313 assert_different_registers(obj, pre_val, tmp1, tmp2);
314 assert(pre_val != noreg && tmp1 != noreg && tmp2 != noreg, "expecting a register");
315
316 stub->initialize_registers(obj, pre_val, thread, tmp1, tmp2);
317
318 generate_pre_barrier_fast_path(masm, thread, tmp1);
319 // If marking is active (*(mark queue active address) != 0), jump to stub (slow path)
320 __ cbnzw(tmp1, *stub->entry());
321
322 __ bind(*stub->continuation());
323 }
324
325 void G1BarrierSetAssembler::generate_c2_pre_barrier_stub(MacroAssembler* masm,
326 G1PreBarrierStubC2* stub) const {
327 Assembler::InlineSkippedInstructionsCounter skip_counter(masm);
328 Label runtime;
329 Register obj = stub->obj();
330 Register pre_val = stub->pre_val();
331 Register thread = stub->thread();
332 Register tmp1 = stub->tmp1();
333 Register tmp2 = stub->tmp2();
334
335 __ bind(*stub->entry());
336 generate_pre_barrier_slow_path(masm, obj, pre_val, thread, tmp1, tmp2, *stub->continuation(), runtime);
337
338 __ bind(runtime);
339 generate_c2_barrier_runtime_call(masm, stub, pre_val, CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_pre_entry));
340 __ b(*stub->continuation());
341 }
342
343 void G1BarrierSetAssembler::g1_write_barrier_post_c2(MacroAssembler* masm,
344 Register store_addr,
345 Register new_val,
346 Register thread,
347 Register tmp1,
348 Register tmp2,
349 bool new_val_may_be_null) {
350 Label done;
351 generate_post_barrier(masm, store_addr, new_val, thread, tmp1, tmp2, done, new_val_may_be_null);
352 __ bind(done);
353 }
354
355 #endif // COMPILER2
356
357 void G1BarrierSetAssembler::load_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
358 Register dst, Address src, Register tmp1, Register tmp2) {
359 bool on_oop = is_reference_type(type);
360 bool on_weak = (decorators & ON_WEAK_OOP_REF) != 0;
361 bool on_phantom = (decorators & ON_PHANTOM_OOP_REF) != 0;
362 bool on_reference = on_weak || on_phantom;
363 ModRefBarrierSetAssembler::load_at(masm, decorators, type, dst, src, tmp1, tmp2);
364 if (on_oop && on_reference) {
365 // LR is live. It must be saved around calls.
366 __ enter(/*strip_ret_addr*/true); // barrier may call runtime
367 // Generate the G1 pre-barrier code to log the value of
368 // the referent field in an SATB buffer.
369 g1_write_barrier_pre(masm /* masm */,
370 noreg /* obj */,
371 dst /* pre_val */,
372 rthread /* thread */,
373 tmp1 /* tmp1 */,
374 tmp2 /* tmp2 */,
375 true /* tosca_live */,
376 true /* expand_call */);
377 __ leave();
378 }
379 }
380
381 void G1BarrierSetAssembler::oop_store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
382 Address dst, Register val, Register tmp1, Register tmp2, Register tmp3) {
383
384 bool in_heap = (decorators & IN_HEAP) != 0;
385 bool as_normal = (decorators & AS_NORMAL) != 0;
386 bool dest_uninitialized = (decorators & IS_DEST_UNINITIALIZED) != 0;
387
388 bool needs_pre_barrier = as_normal && !dest_uninitialized;
389 bool needs_post_barrier = (val != noreg && in_heap);
390
391 assert_different_registers(val, tmp1, tmp2, tmp3);
392
393 // flatten object address if needed
394 if (dst.index() == noreg && dst.offset() == 0) {
395 if (dst.base() != tmp3) {
396 __ mov(tmp3, dst.base());
397 }
398 } else {
399 __ lea(tmp3, dst);
400 }
401
402 if (needs_pre_barrier) {
403 g1_write_barrier_pre(masm,
404 tmp3 /* obj */,
405 tmp2 /* pre_val */,
406 rthread /* thread */,
407 tmp1 /* tmp1 */,
408 rscratch2 /* tmp2 */,
409 val != noreg /* tosca_live */,
410 false /* expand_call */);
411 }
412
413 if (val == noreg) {
414 BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp3, 0), noreg, noreg, noreg, noreg);
415 } else {
416 // G1 barrier needs uncompressed oop for region cross check.
417 Register new_val = val;
418 if (needs_post_barrier) {
419 if (UseCompressedOops) {
420 new_val = rscratch2;
421 __ mov(new_val, val);
422 }
423 }
424
425 BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp3, 0), val, noreg, noreg, noreg);
426 if (needs_post_barrier) {
427 g1_write_barrier_post(masm,
428 tmp3 /* store_adr */,
429 new_val /* new_val */,
430 rthread /* thread */,
431 tmp1 /* tmp1 */,
432 tmp2 /* tmp2 */);
433 }
434 }
435
436 }
437
438 #ifdef COMPILER1
439
440 #undef __
441 #define __ ce->masm()->
442
443 void G1BarrierSetAssembler::gen_pre_barrier_stub(LIR_Assembler* ce, G1PreBarrierStub* stub) {
444 G1BarrierSetC1* bs = (G1BarrierSetC1*)BarrierSet::barrier_set()->barrier_set_c1();
445 // At this point we know that marking is in progress.
446 // If do_load() is true then we have to emit the
447 // load of the previous value; otherwise it has already
448 // been loaded into _pre_val.
449
450 __ bind(*stub->entry());
451
452 assert(stub->pre_val()->is_register(), "Precondition.");
453
454 Register pre_val_reg = stub->pre_val()->as_register();
455
456 if (stub->do_load()) {
457 ce->mem2reg(stub->addr(), stub->pre_val(), T_OBJECT, stub->patch_code(), stub->info(), false /*wide*/);
458 }
459 __ cbz(pre_val_reg, *stub->continuation());
460 ce->store_parameter(stub->pre_val()->as_register(), 0);
461 __ far_call(RuntimeAddress(bs->pre_barrier_c1_runtime_code_blob()->code_begin()));
462 __ b(*stub->continuation());
463 }
464
465 #undef __
466
467 void G1BarrierSetAssembler::g1_write_barrier_post_c1(MacroAssembler* masm,
468 Register store_addr,
469 Register new_val,
470 Register thread,
471 Register tmp1,
472 Register tmp2) {
473 Label done;
474 generate_post_barrier(masm, store_addr, new_val, thread, tmp1, tmp2, done, true /* new_val_may_be_null */);
475 masm->bind(done);
476 }
477
478 #define __ sasm->
479
480 void G1BarrierSetAssembler::generate_c1_pre_barrier_runtime_stub(StubAssembler* sasm) {
481 __ prologue("g1_pre_barrier", false);
482
483 // arg0 : previous value of memory
484
485 BarrierSet* bs = BarrierSet::barrier_set();
486
487 const Register pre_val = r0;
488 const Register thread = rthread;
489 const Register tmp = rscratch1;
490
491 Address in_progress(thread, in_bytes(G1ThreadLocalData::satb_mark_queue_active_offset()));
492 Address queue_index(thread, in_bytes(G1ThreadLocalData::satb_mark_queue_index_offset()));
493 Address buffer(thread, in_bytes(G1ThreadLocalData::satb_mark_queue_buffer_offset()));
494
495 Label done;
496 Label runtime;
497
498 // Is marking still active?
499 if (in_bytes(SATBMarkQueue::byte_width_of_active()) == 4) {
500 __ ldrw(tmp, in_progress);
501 } else {
502 assert(in_bytes(SATBMarkQueue::byte_width_of_active()) == 1, "Assumption");
503 __ ldrb(tmp, in_progress);
504 }
505 __ cbzw(tmp, done);
506
507 // Can we store original value in the thread's buffer?
508 __ ldr(tmp, queue_index);
509 __ cbz(tmp, runtime);
510
511 __ sub(tmp, tmp, wordSize);
512 __ str(tmp, queue_index);
513 __ ldr(rscratch2, buffer);
514 __ add(tmp, tmp, rscratch2);
515 __ load_parameter(0, rscratch2);
516 __ str(rscratch2, Address(tmp, 0));
517 __ b(done);
518
519 __ bind(runtime);
520 __ push_call_clobbered_registers();
521 __ load_parameter(0, pre_val);
522 __ call_VM_leaf(CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_pre_entry), pre_val, thread);
523 __ pop_call_clobbered_registers();
524 __ bind(done);
525
526 __ epilogue();
527 }
528
529 #undef __
530
531 #endif // COMPILER1