1 /*
2 * Copyright (c) 2026, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2018, 2025, Red Hat, Inc. All rights reserved.
4 * Copyright (c) 2012, 2026 SAP SE. All rights reserved.
5 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 *
7 * This code is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 only, as
9 * published by the Free Software Foundation.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 *
25 */
26
27 #include "asm/macroAssembler.inline.hpp"
28 #include "gc/shared/gc_globals.hpp"
29 #include "gc/shared/gcArguments.hpp"
30 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
31 #include "gc/shenandoah/mode/shenandoahMode.hpp"
32 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
33 #include "gc/shenandoah/shenandoahBarrierSetAssembler.hpp"
34 #include "gc/shenandoah/shenandoahForwarding.hpp"
35 #include "gc/shenandoah/shenandoahHeap.hpp"
36 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
37 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
38 #include "gc/shenandoah/shenandoahRuntime.hpp"
39 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "macroAssembler_ppc.hpp"
42 #include "runtime/javaThread.hpp"
43 #include "runtime/sharedRuntime.hpp"
44 #include "utilities/globalDefinitions.hpp"
45 #include "vm_version_ppc.hpp"
46 #ifdef COMPILER1
47 #include "c1/c1_LIRAssembler.hpp"
48 #include "c1/c1_MacroAssembler.hpp"
49 #include "gc/shenandoah/c1/shenandoahBarrierSetC1.hpp"
50 #endif
51 #ifdef COMPILER2
52 #include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
53 #endif
54
55 #define __ masm->
56
57 void ShenandoahBarrierSetAssembler::satb_barrier(MacroAssembler *masm,
58 Register base, RegisterOrConstant ind_or_offs,
59 Register tmp1, Register tmp2, Register tmp3,
60 MacroAssembler::PreservationLevel preservation_level) {
61 if (ShenandoahSATBBarrier) {
62 __ block_comment("satb_barrier (shenandoahgc) {");
63 satb_barrier_impl(masm, 0, base, ind_or_offs, tmp1, tmp2, tmp3, preservation_level);
64 __ block_comment("} satb_barrier (shenandoahgc)");
65 }
66 }
67
68 void ShenandoahBarrierSetAssembler::load_reference_barrier(MacroAssembler *masm, DecoratorSet decorators,
69 Register base, RegisterOrConstant ind_or_offs,
70 Register dst,
71 Register tmp1, Register tmp2,
72 MacroAssembler::PreservationLevel preservation_level) {
73 if (ShenandoahLoadRefBarrier) {
74 __ block_comment("load_reference_barrier (shenandoahgc) {");
75 load_reference_barrier_impl(masm, decorators, base, ind_or_offs, dst, tmp1, tmp2, preservation_level);
76 __ block_comment("} load_reference_barrier (shenandoahgc)");
77 }
78 }
79
80 void ShenandoahBarrierSetAssembler::arraycopy_prologue(MacroAssembler *masm, DecoratorSet decorators, BasicType type,
81 Register src, Register dst, Register count,
82 Register preserve1, Register preserve2) {
83 Register R11_tmp = R11_scratch1;
84
85 assert_different_registers(src, dst, count, R11_tmp, noreg);
86 if (preserve1 != noreg) {
87 // Technically not required, but likely to indicate an error.
88 assert_different_registers(preserve1, preserve2);
89 }
90
91 /* ==== Check whether barrier is required (optimizations) ==== */
92 // Fast path: Component type of array is not a reference type.
93 if (!is_reference_type(type)) {
94 return;
95 }
96
97 bool dest_uninitialized = (decorators & IS_DEST_UNINITIALIZED) != 0;
98
99 // Fast path: No barrier required if for every barrier type, it is either disabled or would not store
100 // any useful information.
101 if ((!ShenandoahSATBBarrier || dest_uninitialized) && !ShenandoahLoadRefBarrier) {
102 return;
103 }
104
105 __ block_comment("arraycopy_prologue (shenandoahgc) {");
106 Label skip_prologue;
107
108 // Fast path: Array is of length zero.
109 __ cmpdi(CR0, count, 0);
110 __ beq(CR0, skip_prologue);
111
112 /* ==== Check whether barrier is required (gc state) ==== */
113 __ lbz(R11_tmp, in_bytes(ShenandoahThreadLocalData::gc_state_offset()),
114 R16_thread);
115
116 // The set of garbage collection states requiring barriers depends on the available barrier types and the
117 // type of the reference in question.
118 // For instance, satb barriers may be skipped if it is certain that the overridden values are not relevant
119 // for the garbage collector.
120 const int required_states = ShenandoahSATBBarrier && dest_uninitialized
121 ? ShenandoahHeap::HAS_FORWARDED
122 : ShenandoahHeap::HAS_FORWARDED | ShenandoahHeap::MARKING;
123
124 __ andi_(R11_tmp, R11_tmp, required_states);
125 __ beq(CR0, skip_prologue);
126
127 /* ==== Invoke runtime ==== */
128 // Save to-be-preserved registers.
129 int highest_preserve_register_index = 0;
130 {
131 if (preserve1 != noreg && preserve1->is_volatile()) {
132 __ std(preserve1, -BytesPerWord * ++highest_preserve_register_index, R1_SP);
133 }
134 if (preserve2 != noreg && preserve2 != preserve1 && preserve2->is_volatile()) {
135 __ std(preserve2, -BytesPerWord * ++highest_preserve_register_index, R1_SP);
136 }
137
138 __ std(src, -BytesPerWord * ++highest_preserve_register_index, R1_SP);
139 __ std(dst, -BytesPerWord * ++highest_preserve_register_index, R1_SP);
140 __ std(count, -BytesPerWord * ++highest_preserve_register_index, R1_SP);
141
142 __ save_LR(R11_tmp);
143 __ push_frame_reg_args(-BytesPerWord * highest_preserve_register_index,
144 R11_tmp);
145 }
146
147 // Invoke runtime.
148 address jrt_address = nullptr;
149 if (UseCompressedOops) {
150 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::arraycopy_barrier_narrow_oop);
151 } else {
152 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::arraycopy_barrier_oop);
153 }
154 assert(jrt_address != nullptr, "jrt routine cannot be found");
155
156 __ call_VM_leaf(jrt_address, src, dst, count);
157
158 // Restore to-be-preserved registers.
159 {
160 __ pop_frame();
161 __ restore_LR(R11_tmp);
162
163 __ ld(count, -BytesPerWord * highest_preserve_register_index--, R1_SP);
164 __ ld(dst, -BytesPerWord * highest_preserve_register_index--, R1_SP);
165 __ ld(src, -BytesPerWord * highest_preserve_register_index--, R1_SP);
166
167 if (preserve2 != noreg && preserve2 != preserve1 && preserve2->is_volatile()) {
168 __ ld(preserve2, -BytesPerWord * highest_preserve_register_index--, R1_SP);
169 }
170 if (preserve1 != noreg && preserve1->is_volatile()) {
171 __ ld(preserve1, -BytesPerWord * highest_preserve_register_index--, R1_SP);
172 }
173 }
174
175 __ bind(skip_prologue);
176 __ block_comment("} arraycopy_prologue (shenandoahgc)");
177 }
178
179 void ShenandoahBarrierSetAssembler::arraycopy_epilogue(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
180 Register dst, Register count,
181 Register preserve) {
182 if (ShenandoahCardBarrier && is_reference_type(type)) {
183 __ block_comment("arraycopy_epilogue (shenandoahgc) {");
184 gen_write_ref_array_post_barrier(masm, decorators, dst, count, preserve);
185 __ block_comment("} arraycopy_epilogue (shenandoahgc)");
186 }
187 }
188
189 // The to-be-enqueued value can either be determined
190 // - dynamically by passing the reference's address information (load mode) or
191 // - statically by passing a register the value is stored in (preloaded mode)
192 // - for performance optimizations in cases where the previous value is known (currently not implemented) and
193 // - for incremental-update barriers.
194 //
195 // decorators: The previous value's decorator set.
196 // In "load mode", the value must equal '0'.
197 // base: Base register of the reference's address (load mode).
198 // In "preloaded mode", the register must equal 'noreg'.
199 // ind_or_offs: Index or offset of the reference's address (load mode).
200 // If 'base' equals 'noreg' (preloaded mode), the passed value is ignored.
201 // pre_val: Register holding the to-be-stored value (preloaded mode).
202 // In "load mode", this register acts as a temporary register and must
203 // thus not be 'noreg'. In "preloaded mode", its content will be sustained.
204 // tmp1/tmp2: Temporary registers, one of which must be non-volatile in "preloaded mode".
205 void ShenandoahBarrierSetAssembler::satb_barrier_impl(MacroAssembler *masm, DecoratorSet decorators,
206 Register base, RegisterOrConstant ind_or_offs,
207 Register pre_val,
208 Register tmp1, Register tmp2,
209 MacroAssembler::PreservationLevel preservation_level) {
210 assert(ShenandoahSATBBarrier, "Should be checked by caller");
211 assert_different_registers(tmp1, tmp2, pre_val, noreg);
212
213 Label skip_barrier;
214
215 /* ==== Determine necessary runtime invocation preservation measures ==== */
216 const bool needs_frame = preservation_level >= MacroAssembler::PRESERVATION_FRAME_LR;
217 const bool preserve_gp_registers = preservation_level >= MacroAssembler::PRESERVATION_FRAME_LR_GP_REGS;
218 const bool preserve_fp_registers = preservation_level >= MacroAssembler::PRESERVATION_FRAME_LR_GP_FP_REGS;
219
220 // Check whether marking is active.
221 __ lbz(tmp1, in_bytes(ShenandoahThreadLocalData::gc_state_offset()), R16_thread);
222
223 __ andi_(tmp1, tmp1, ShenandoahHeap::MARKING);
224 __ beq(CR0, skip_barrier);
225
226 /* ==== Determine the reference's previous value ==== */
227 bool preloaded_mode = base == noreg;
228 Register pre_val_save = noreg;
229
230 if (preloaded_mode) {
231 // Previous value has been passed to the method, so it must not be determined manually.
232 // In case 'pre_val' is a volatile register, it must be saved across the C-call
233 // as callers may depend on its value.
234 // Unless the general purposes registers are saved anyway, one of the temporary registers
235 // (i.e., 'tmp1' and 'tmp2') is used to the preserve 'pre_val'.
236 if (!preserve_gp_registers && pre_val->is_volatile()) {
237 pre_val_save = !tmp1->is_volatile() ? tmp1 : tmp2;
238 assert(!pre_val_save->is_volatile(), "at least one of the temporary registers must be non-volatile");
239 }
240
241 if ((decorators & IS_NOT_NULL) != 0) {
242 #ifdef ASSERT
243 __ cmpdi(CR0, pre_val, 0);
244 __ asm_assert_ne("null oop is not allowed");
245 #endif // ASSERT
246 } else {
247 __ cmpdi(CR0, pre_val, 0);
248 __ beq(CR0, skip_barrier);
249 }
250 } else {
251 // Load from the reference address to determine the reference's current value (before the store is being performed).
252 // Contrary to the given value in "preloaded mode", it is not necessary to preserve it.
253 assert(decorators == 0, "decorator set must be empty");
254 assert(base != noreg, "base must be a register");
255 assert(!ind_or_offs.is_register() || ind_or_offs.as_register() != noreg, "ind_or_offs must be a register");
256 if (UseCompressedOops) {
257 __ lwz(pre_val, ind_or_offs, base);
258 } else {
259 __ ld(pre_val, ind_or_offs, base);
260 }
261
262 __ cmpdi(CR0, pre_val, 0);
263 __ beq(CR0, skip_barrier);
264
265 if (UseCompressedOops) {
266 __ decode_heap_oop_not_null(pre_val);
267 }
268 }
269
270 /* ==== Try to enqueue the to-be-stored value directly into thread's local SATB mark queue ==== */
271 {
272 Label runtime;
273 Register Rbuffer = tmp1, Rindex = tmp2;
274
275 // Check whether the queue has enough capacity to store another oop.
276 // If not, jump to the runtime to commit the buffer and to allocate a new one.
277 // (The buffer's index corresponds to the amount of remaining free space.)
278 __ ld(Rindex, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset()), R16_thread);
279 __ cmpdi(CR0, Rindex, 0);
280 __ beq(CR0, runtime); // If index == 0 (buffer is full), goto runtime.
281
282 // Capacity suffices. Decrement the queue's size by the size of one oop.
283 // (The buffer is filled contrary to the heap's growing direction, i.e., it is filled downwards.)
284 __ addi(Rindex, Rindex, -wordSize);
285 __ std(Rindex, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset()), R16_thread);
286
287 // Enqueue the previous value and skip the invocation of the runtime.
288 __ ld(Rbuffer, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset()), R16_thread);
289 __ stdx(pre_val, Rbuffer, Rindex);
290 __ b(skip_barrier);
291
292 __ bind(runtime);
293 }
294
295 /* ==== Invoke runtime to commit SATB mark queue to gc and allocate a new buffer ==== */
296 // Save to-be-preserved registers.
297 int nbytes_save = 0;
298
299 if (needs_frame) {
300 if (preserve_gp_registers) {
301 nbytes_save = (preserve_fp_registers
302 ? MacroAssembler::num_volatile_gp_regs + MacroAssembler::num_volatile_fp_regs
303 : MacroAssembler::num_volatile_gp_regs) * BytesPerWord;
304 __ save_volatile_gprs(R1_SP, -nbytes_save, preserve_fp_registers);
305 }
306
307 __ save_LR(tmp1);
308 __ push_frame_reg_args(nbytes_save, tmp2);
309 }
310
311 if (!preserve_gp_registers && preloaded_mode && pre_val->is_volatile()) {
312 assert(pre_val_save != noreg, "nv_save must not be noreg");
313
314 // 'pre_val' register must be saved manually unless general-purpose are preserved in general.
315 __ mr(pre_val_save, pre_val);
316 }
317
318 // Invoke runtime.
319 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_barrier_pre), pre_val);
320
321 // Restore to-be-preserved registers.
322 if (!preserve_gp_registers && preloaded_mode && pre_val->is_volatile()) {
323 __ mr(pre_val, pre_val_save);
324 }
325
326 if (needs_frame) {
327 __ pop_frame();
328 __ restore_LR(tmp1);
329
330 if (preserve_gp_registers) {
331 __ restore_volatile_gprs(R1_SP, -nbytes_save, preserve_fp_registers);
332 }
333 }
334
335 __ bind(skip_barrier);
336 }
337
338 void ShenandoahBarrierSetAssembler::resolve_forward_pointer_not_null(MacroAssembler *masm, Register dst, Register tmp) {
339 __ block_comment("resolve_forward_pointer_not_null (shenandoahgc) {");
340
341 Register tmp1 = tmp,
342 R0_tmp2 = R0;
343 assert_different_registers(dst, tmp1, R0_tmp2, noreg);
344
345 // If the object has been evacuated, the mark word layout is as follows:
346 // | forwarding pointer (62-bit) | '11' (2-bit) |
347
348 // The invariant that stack/thread pointers have the lowest two bits cleared permits retrieving
349 // the forwarding pointer solely by inversing the lowest two bits.
350 // This invariant follows inevitably from hotspot's minimal alignment.
351 assert(markWord::marked_value <= (unsigned long) MinObjAlignmentInBytes,
352 "marked value must not be higher than hotspot's minimal alignment");
353
354 Label done;
355
356 // Load the object's mark word.
357 __ ld(tmp1, oopDesc::mark_offset_in_bytes(), dst);
358
359 // Load the bit mask for the lock bits.
360 __ li(R0_tmp2, markWord::lock_mask_in_place);
361
362 // Check whether all bits matching the bit mask are set.
363 // If that is the case, the object has been evacuated and the most significant bits form the forward pointer.
364 __ andc_(R0_tmp2, R0_tmp2, tmp1);
365
366 assert(markWord::lock_mask_in_place == markWord::marked_value,
367 "marked value must equal the value obtained when all lock bits are being set");
368 __ xori(tmp1, tmp1, markWord::lock_mask_in_place);
369 __ isel(dst, CR0, Assembler::equal, false, tmp1);
370
371 __ bind(done);
372 __ block_comment("} resolve_forward_pointer_not_null (shenandoahgc)");
373 }
374
375 // base: Base register of the reference's address.
376 // ind_or_offs: Index or offset of the reference's address (load mode).
377 // dst: Reference's address. In case the object has been evacuated, this is the to-space version
378 // of that object.
379 void ShenandoahBarrierSetAssembler::load_reference_barrier_impl(
380 MacroAssembler *masm, DecoratorSet decorators,
381 Register base, RegisterOrConstant ind_or_offs,
382 Register dst,
383 Register tmp1, Register tmp2,
384 MacroAssembler::PreservationLevel preservation_level) {
385 if (ind_or_offs.is_register()) {
386 assert_different_registers(tmp1, tmp2, base, ind_or_offs.as_register(), dst, noreg);
387 } else {
388 assert_different_registers(tmp1, tmp2, base, dst, noreg);
389 }
390
391 Label skip_barrier;
392
393 bool is_strong = ShenandoahBarrierSet::is_strong_access(decorators);
394 bool is_weak = ShenandoahBarrierSet::is_weak_access(decorators);
395 bool is_phantom = ShenandoahBarrierSet::is_phantom_access(decorators);
396 bool is_native = ShenandoahBarrierSet::is_native_access(decorators);
397 bool is_narrow = UseCompressedOops && !is_native;
398
399 /* ==== Check whether heap is stable ==== */
400 __ lbz(tmp2, in_bytes(ShenandoahThreadLocalData::gc_state_offset()), R16_thread);
401
402 if (is_strong) {
403 // For strong references, the heap is considered stable if "has forwarded" is not active.
404 __ andi_(tmp1, tmp2, ShenandoahHeap::HAS_FORWARDED | ShenandoahHeap::EVACUATION);
405 __ beq(CR0, skip_barrier);
406 #ifdef ASSERT
407 // "evacuation" -> (implies) "has forwarded". If we reach this code, "has forwarded" must thus be set.
408 __ andi_(tmp1, tmp1, ShenandoahHeap::HAS_FORWARDED);
409 __ asm_assert_ne("'has forwarded' is missing");
410 #endif // ASSERT
411 } else {
412 // For all non-strong references, the heap is considered stable if not any of "has forwarded",
413 // "root set processing", and "weak reference processing" is active.
414 // The additional phase conditions are in place to avoid the resurrection of weak references (see JDK-8266440).
415 Label skip_fastpath;
416 __ andi_(tmp1, tmp2, ShenandoahHeap::WEAK_ROOTS);
417 __ bne(CR0, skip_fastpath);
418
419 __ andi_(tmp1, tmp2, ShenandoahHeap::HAS_FORWARDED | ShenandoahHeap::EVACUATION);
420 __ beq(CR0, skip_barrier);
421 #ifdef ASSERT
422 // "evacuation" -> (implies) "has forwarded". If we reach this code, "has forwarded" must thus be set.
423 __ andi_(tmp1, tmp1, ShenandoahHeap::HAS_FORWARDED);
424 __ asm_assert_ne("'has forwarded' is missing");
425 #endif // ASSERT
426
427 __ bind(skip_fastpath);
428 }
429
430 /* ==== Check whether region is in collection set ==== */
431 if (is_strong) {
432 // Shenandoah stores metadata on regions in a continuous area of memory in which a single byte corresponds to
433 // an entire region of the shenandoah heap. At present, only the least significant bit is of significance
434 // and indicates whether the region is part of the collection set.
435 //
436 // All regions are of the same size and are always aligned by a power of two.
437 // Any address can thus be shifted by a fixed number of bits to retrieve the address prefix shared by
438 // all objects within that region (region identification bits).
439 //
440 // | unused bits | region identification bits | object identification bits |
441 // (Region size depends on a couple of criteria, such as page size, user-provided arguments and the max heap size.
442 // The number of object identification bits can thus not be determined at compile time.)
443 //
444 // ------------------------------------------------------- <--- cs (collection set) base address
445 // | lost space due to heap space base address -> 'ShenandoahHeap::in_cset_fast_test_addr()'
446 // | (region identification bits contain heap base offset)
447 // |------------------------------------------------------ <--- cs base address + (heap_base >> region size shift)
448 // | collection set in the proper -> shift: 'region_size_bytes_shift_jint()'
449 // |
450 // |------------------------------------------------------ <--- cs base address + (heap_base >> region size shift)
451 // + number of regions
452 __ load_const_optimized(tmp2, ShenandoahHeap::in_cset_fast_test_addr(), tmp1);
453 __ srdi(tmp1, dst, ShenandoahHeapRegion::region_size_bytes_shift_jint());
454 __ lbzx(tmp2, tmp1, tmp2);
455 __ andi_(tmp2, tmp2, 1);
456 __ beq(CR0, skip_barrier);
457 }
458
459 /* ==== Invoke runtime ==== */
460 // Save to-be-preserved registers.
461 int nbytes_save = 0;
462
463 const bool needs_frame = preservation_level >= MacroAssembler::PRESERVATION_FRAME_LR;
464 const bool preserve_gp_registers = preservation_level >= MacroAssembler::PRESERVATION_FRAME_LR_GP_REGS;
465 const bool preserve_fp_registers = preservation_level >= MacroAssembler::PRESERVATION_FRAME_LR_GP_FP_REGS;
466
467 if (needs_frame) {
468 if (preserve_gp_registers) {
469 nbytes_save = (preserve_fp_registers
470 ? MacroAssembler::num_volatile_gp_regs + MacroAssembler::num_volatile_fp_regs
471 : MacroAssembler::num_volatile_gp_regs) * BytesPerWord;
472 __ save_volatile_gprs(R1_SP, -nbytes_save, preserve_fp_registers);
473 }
474
475 __ save_LR(tmp1);
476 __ push_frame_reg_args(nbytes_save, tmp1);
477 }
478
479 // Calculate the reference's absolute address.
480 __ add(R4_ARG2, ind_or_offs, base);
481
482 // Invoke runtime.
483 address jrt_address = nullptr;
484
485 if (is_strong) {
486 if (is_narrow) {
487 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong_narrow);
488 } else {
489 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong);
490 }
491 } else if (is_weak) {
492 if (is_narrow) {
493 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_weak_narrow);
494 } else {
495 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_weak);
496 }
497 } else {
498 assert(is_phantom, "only remaining strength");
499 assert(!is_narrow, "phantom access cannot be narrow");
500 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_phantom);
501 }
502 assert(jrt_address != nullptr, "jrt routine cannot be found");
503
504 __ call_VM_leaf(jrt_address, dst /* reference */, R4_ARG2 /* reference address */);
505
506 // Restore to-be-preserved registers.
507 if (preserve_gp_registers) {
508 __ mr(R0, R3_RET);
509 } else {
510 __ mr_if_needed(dst, R3_RET);
511 }
512
513 if (needs_frame) {
514 __ pop_frame();
515 __ restore_LR(tmp1);
516
517 if (preserve_gp_registers) {
518 __ restore_volatile_gprs(R1_SP, -nbytes_save, preserve_fp_registers);
519 __ mr(dst, R0);
520 }
521 }
522
523 __ bind(skip_barrier);
524 }
525
526 // base: Base register of the reference's address.
527 // ind_or_offs: Index or offset of the reference's address.
528 // L_handle_null: An optional label that will be jumped to if the reference is null.
529 void ShenandoahBarrierSetAssembler::load_at(
530 MacroAssembler *masm, DecoratorSet decorators, BasicType type,
531 Register base, RegisterOrConstant ind_or_offs, Register dst,
532 Register tmp1, Register tmp2,
533 MacroAssembler::PreservationLevel preservation_level, Label *L_handle_null) {
534 // Register must not clash, except 'base' and 'dst'.
535 if (ind_or_offs.is_register()) {
536 if (base != noreg) {
537 assert_different_registers(tmp1, tmp2, base, ind_or_offs.register_or_noreg(), R0, noreg);
538 }
539 assert_different_registers(tmp1, tmp2, dst, ind_or_offs.register_or_noreg(), R0, noreg);
540 } else {
541 if (base == noreg) {
542 assert_different_registers(tmp1, tmp2, base, R0, noreg);
543 }
544 assert_different_registers(tmp1, tmp2, dst, R0, noreg);
545 }
546
547 /* ==== Apply load barrier, if required ==== */
548 if (ShenandoahBarrierSet::need_load_reference_barrier(decorators, type)) {
549 assert(is_reference_type(type), "need_load_reference_barrier must check whether type is a reference type");
550
551 // If 'dst' clashes with either 'base' or 'ind_or_offs', use an intermediate result register
552 // to keep the values of those alive until the load reference barrier is applied.
553 Register intermediate_dst = (dst == base || (ind_or_offs.is_register() && dst == ind_or_offs.as_register()))
554 ? tmp2
555 : dst;
556
557 BarrierSetAssembler::load_at(masm, decorators, type,
558 base, ind_or_offs,
559 intermediate_dst,
560 tmp1, noreg,
561 preservation_level, L_handle_null);
562
563 load_reference_barrier(masm, decorators,
564 base, ind_or_offs,
565 intermediate_dst,
566 tmp1, R0,
567 preservation_level);
568
569 __ mr_if_needed(dst, intermediate_dst);
570 } else {
571 BarrierSetAssembler::load_at(masm, decorators, type,
572 base, ind_or_offs,
573 dst,
574 tmp1, tmp2,
575 preservation_level, L_handle_null);
576 }
577
578 /* ==== Apply keep-alive barrier, if required (e.g., to inhibit weak reference resurrection) ==== */
579 if (ShenandoahBarrierSet::need_keep_alive_barrier(decorators, type)) {
580 if (ShenandoahSATBBarrier) {
581 __ block_comment("keep_alive_barrier (shenandoahgc) {");
582 satb_barrier_impl(masm, 0, noreg, noreg, dst, tmp1, tmp2, preservation_level);
583 __ block_comment("} keep_alive_barrier (shenandoahgc)");
584 }
585 }
586 }
587
588 void ShenandoahBarrierSetAssembler::card_barrier(MacroAssembler* masm, Register base, RegisterOrConstant ind_or_offs, Register tmp) {
589 assert(ShenandoahCardBarrier, "Should have been checked by caller");
590 assert_different_registers(base, tmp, R0);
591
592 if (ind_or_offs.is_constant()) {
593 __ add_const_optimized(base, base, ind_or_offs.as_constant(), tmp);
594 } else {
595 __ add(base, ind_or_offs.as_register(), base);
596 }
597
598 __ ld(tmp, in_bytes(ShenandoahThreadLocalData::card_table_offset()), R16_thread); /* tmp = *[R16_thread + card_table_offset] */
599 __ srdi(base, base, CardTable::card_shift());
600 __ li(R0, CardTable::dirty_card_val());
601 __ stbx(R0, tmp, base);
602 }
603
604 // base: Base register of the reference's address.
605 // ind_or_offs: Index or offset of the reference's address.
606 // val: To-be-stored value/reference's new value.
607 void ShenandoahBarrierSetAssembler::store_at(MacroAssembler *masm, DecoratorSet decorators, BasicType type,
608 Register base, RegisterOrConstant ind_or_offs, Register val,
609 Register tmp1, Register tmp2, Register tmp3,
610 MacroAssembler::PreservationLevel preservation_level) {
611 // 1: non-reference types require no barriers
612 if (!is_reference_type(type)) {
613 BarrierSetAssembler::store_at(masm, decorators, type,
614 base, ind_or_offs,
615 val,
616 tmp1, tmp2, tmp3,
617 preservation_level);
618 return;
619 }
620
621 bool storing_non_null = (val != noreg);
622
623 // 2: pre-barrier: SATB needs the previous value
624 if (ShenandoahBarrierSet::need_satb_barrier(decorators, type)) {
625 satb_barrier(masm, base, ind_or_offs, tmp1, tmp2, tmp3, preservation_level);
626 }
627
628 // Store!
629 BarrierSetAssembler::store_at(masm, decorators, type,
630 base, ind_or_offs,
631 val,
632 tmp1, tmp2, tmp3,
633 preservation_level);
634
635 // 3: post-barrier: card barrier needs store address
636 if (ShenandoahBarrierSet::need_card_barrier(decorators, type) && storing_non_null) {
637 card_barrier(masm, base, ind_or_offs, tmp1);
638 }
639 }
640
641 void ShenandoahBarrierSetAssembler::try_resolve_jobject_in_native(MacroAssembler *masm,
642 Register dst, Register jni_env, Register obj,
643 Register tmp, Label &slowpath) {
644 __ block_comment("try_resolve_jobject_in_native (shenandoahgc) {");
645
646 assert_different_registers(jni_env, obj, tmp);
647
648 Label done;
649
650 // Fast path: Reference is null (JNI tags are zero for null pointers).
651 __ cmpdi(CR0, obj, 0);
652 __ beq(CR0, done);
653
654 // Resolve jobject using standard implementation.
655 BarrierSetAssembler::try_resolve_jobject_in_native(masm, dst, jni_env, obj, tmp, slowpath);
656
657 // Check whether heap is stable.
658 __ lbz(tmp,
659 in_bytes(ShenandoahThreadLocalData::gc_state_offset() - JavaThread::jni_environment_offset()),
660 jni_env);
661
662 __ andi_(tmp, tmp, ShenandoahHeap::EVACUATION | ShenandoahHeap::HAS_FORWARDED);
663 __ bne(CR0, slowpath);
664
665 __ bind(done);
666 __ block_comment("} try_resolve_jobject_in_native (shenandoahgc)");
667 }
668
669 void ShenandoahBarrierSetAssembler::try_resolve_weak_handle(MacroAssembler *masm, Register obj,
670 Register tmp, Label &slow_path) {
671 __ block_comment("try_resolve_weak_handle (shenandoahgc) {");
672
673 assert_different_registers(obj, tmp);
674
675 Label done;
676
677 // Resolve weak handle using the standard implementation.
678 BarrierSetAssembler::try_resolve_weak_handle(masm, obj, tmp, slow_path);
679
680 // Check if the reference is null, and if it is, take the fast path.
681 __ cmpdi(CR0, obj, 0);
682 __ beq(CR0, done);
683
684 // Check if the heap is under weak-reference/roots processing, in
685 // which case we need to take the slow path.
686 __ lbz(tmp, in_bytes(ShenandoahThreadLocalData::gc_state_offset()), R16_thread);
687 __ andi_(tmp, tmp, ShenandoahHeap::WEAK_ROOTS);
688 __ bne(CR0, slow_path);
689 __ bind(done);
690
691 __ block_comment("} try_resolve_weak_handle (shenandoahgc)");
692 }
693
694 // Special shenandoah CAS implementation that handles false negatives due
695 // to concurrent evacuation. That is, the CAS operation is intended to succeed in
696 // the following scenarios (success criteria):
697 // s1) The reference pointer ('base_addr') equals the expected ('expected') pointer.
698 // s2) The reference pointer refers to the from-space version of an already-evacuated
699 // object, whereas the expected pointer refers to the to-space version of the same object.
700 // Situations in which the reference pointer refers to the to-space version of an object
701 // and the expected pointer refers to the from-space version of the same object can not occur due to
702 // shenandoah's strong to-space invariant. This also implies that the reference stored in 'new_val'
703 // can not refer to the from-space version of an already-evacuated object.
704 //
705 // To guarantee correct behavior in concurrent environments, two races must be addressed:
706 // r1) A concurrent thread may heal the reference pointer (i.e., it is no longer referring to the
707 // from-space version but to the to-space version of the object in question).
708 // In this case, the CAS operation should succeed.
709 // r2) A concurrent thread may mutate the reference (i.e., the reference pointer refers to an entirely different object).
710 // In this case, the CAS operation should fail.
711 //
712 // By default, the value held in the 'result' register is zero to indicate failure of CAS,
713 // non-zero to indicate success. If 'is_cae' is set, the result is the most recently fetched
714 // value from 'base_addr' rather than a boolean success indicator.
715 void ShenandoahBarrierSetAssembler::cmpxchg_oop(MacroAssembler *masm, Register base_addr,
716 Register expected, Register new_val, Register tmp1, Register tmp2,
717 bool is_cae, Register result) {
718 __ block_comment("cmpxchg_oop (shenandoahgc) {");
719
720 assert_different_registers(base_addr, new_val, tmp1, tmp2, result, R0);
721 assert_different_registers(base_addr, expected, tmp1, tmp2, result, R0);
722
723 // Potential clash of 'success_flag' and 'tmp' is being accounted for.
724 Register success_flag = is_cae ? noreg : result,
725 current_value = is_cae ? result : tmp1,
726 tmp = is_cae ? tmp1 : result,
727 initial_value = tmp2;
728
729 Label done, step_four;
730
731 __ bind(step_four);
732
733 /* ==== Step 1 ("Standard" CAS) ==== */
734 // Fast path: The values stored in 'expected' and 'base_addr' are equal.
735 // Given that 'expected' must refer to the to-space object of an evacuated object (strong to-space invariant),
736 // no special processing is required.
737 if (UseCompressedOops) {
738 __ cmpxchgw(CR0, current_value, expected, new_val, base_addr, MacroAssembler::MemBarNone,
739 false, success_flag, nullptr, true);
740 } else {
741 __ cmpxchgd(CR0, current_value, expected, new_val, base_addr, MacroAssembler::MemBarNone,
742 false, success_flag, nullptr, true);
743 }
744
745 // Skip the rest of the barrier if the CAS operation succeeds immediately.
746 // If it does not, the value stored at the address is either the from-space pointer of the
747 // referenced object (success criteria s2)) or simply another object.
748 __ beq(CR0, done);
749
750 /* ==== Step 2 (Null check) ==== */
751 // The success criteria s2) cannot be matched with a null pointer
752 // (null pointers cannot be subject to concurrent evacuation). The failure of the CAS operation is thus legitimate.
753 __ cmpdi(CR0, current_value, 0);
754 __ beq(CR0, done);
755
756 /* ==== Step 3 (reference pointer refers to from-space version; success criteria s2)) ==== */
757 // To check whether the reference pointer refers to the from-space version, the forward
758 // pointer of the object referred to by the reference is resolved and compared against the expected pointer.
759 // If this check succeed, another CAS operation is issued with the from-space pointer being the expected pointer.
760 //
761 // Save the potential from-space pointer.
762 __ mr(initial_value, current_value);
763
764 // Resolve forward pointer.
765 if (UseCompressedOops) { __ decode_heap_oop_not_null(current_value); }
766 resolve_forward_pointer_not_null(masm, current_value, tmp);
767 if (UseCompressedOops) { __ encode_heap_oop_not_null(current_value); }
768
769 if (!is_cae) {
770 // 'success_flag' was overwritten by call to 'resovle_forward_pointer_not_null'.
771 // Load zero into register for the potential failure case.
772 __ li(success_flag, 0);
773 }
774 __ cmpd(CR0, current_value, expected);
775 __ bne(CR0, done);
776
777 // Discard fetched value as it might be a reference to the from-space version of an object.
778 if (UseCompressedOops) {
779 __ cmpxchgw(CR0, R0, initial_value, new_val, base_addr, MacroAssembler::MemBarNone,
780 false, success_flag);
781 } else {
782 __ cmpxchgd(CR0, R0, initial_value, new_val, base_addr, MacroAssembler::MemBarNone,
783 false, success_flag);
784 }
785
786 /* ==== Step 4 (Retry CAS with to-space pointer (success criteria s2) under race r1)) ==== */
787 // The reference pointer could have been healed whilst the previous CAS operation was being performed.
788 // Another CAS operation must thus be issued with the to-space pointer being the expected pointer.
789 // If that CAS operation fails as well, race r2) must have occurred, indicating that
790 // the operation failure is legitimate.
791 //
792 // To keep the code's size small and thus improving cache (icache) performance, this highly
793 // unlikely case should be handled by the smallest possible code. Instead of emitting a third,
794 // explicit CAS operation, the code jumps back and reuses the first CAS operation (step 1)
795 // (passed arguments are identical).
796 //
797 // A failure of the CAS operation in step 1 would imply that the overall CAS operation is supposed
798 // to fail. Jumping back to step 1 requires, however, that step 2 and step 3 are re-executed as well.
799 // It is thus important to ensure that a re-execution of those steps does not put program correctness
800 // at risk:
801 // - Step 2: Either terminates in failure (desired result) or falls through to step 3.
802 // - Step 3: Terminates if the comparison between the forwarded, fetched pointer and the expected value
803 // fails. Unless the reference has been updated in the meanwhile once again, this is
804 // guaranteed to be the case.
805 // In case of a concurrent update, the CAS would be retried again. This is legitimate
806 // in terms of program correctness (even though it is not desired).
807 __ bne(CR0, step_four);
808
809 __ bind(done);
810 __ block_comment("} cmpxchg_oop (shenandoahgc)");
811 }
812
813 void ShenandoahBarrierSetAssembler::gen_write_ref_array_post_barrier(MacroAssembler* masm, DecoratorSet decorators,
814 Register addr, Register count, Register preserve) {
815 assert(ShenandoahCardBarrier, "Should have been checked by caller");
816 assert_different_registers(addr, count, R0);
817
818 Label L_skip_loop, L_store_loop;
819
820 __ sldi_(count, count, LogBytesPerHeapOop);
821
822 // Zero length? Skip.
823 __ beq(CR0, L_skip_loop);
824
825 __ addi(count, count, -BytesPerHeapOop);
826 __ add(count, addr, count);
827 // Use two shifts to clear out those low order two bits! (Cannot opt. into 1.)
828 __ srdi(addr, addr, CardTable::card_shift());
829 __ srdi(count, count, CardTable::card_shift());
830 __ subf(count, addr, count);
831 __ ld(R0, in_bytes(ShenandoahThreadLocalData::card_table_offset()), R16_thread);
832 __ add(addr, addr, R0);
833 __ addi(count, count, 1);
834 __ li(R0, 0);
835 __ mtctr(count);
836
837 // Byte store loop
838 __ bind(L_store_loop);
839 __ stb(R0, 0, addr);
840 __ addi(addr, addr, 1);
841 __ bdnz(L_store_loop);
842 __ bind(L_skip_loop);
843 }
844
845 #undef __
846
847 #ifdef COMPILER1
848
849 #define __ ce->masm()->
850
851 void ShenandoahBarrierSetAssembler::gen_pre_barrier_stub(LIR_Assembler *ce, ShenandoahPreBarrierStub *stub) {
852 __ block_comment("gen_pre_barrier_stub (shenandoahgc) {");
853
854 ShenandoahBarrierSetC1 *bs = (ShenandoahBarrierSetC1*) BarrierSet::barrier_set()->barrier_set_c1();
855 __ bind(*stub->entry());
856
857 // GC status has already been verified by 'ShenandoahBarrierSetC1::pre_barrier'.
858 // This stub is the slowpath of that function.
859
860 assert(stub->pre_val()->is_register(), "pre_val must be a register");
861 Register pre_val = stub->pre_val()->as_register();
862
863 // If 'do_load()' returns false, the to-be-stored value is already available in 'stub->pre_val()'
864 // ("preloaded mode" of the store barrier).
865 if (stub->do_load()) {
866 ce->mem2reg(stub->addr(), stub->pre_val(), T_OBJECT, stub->patch_code(), stub->info(), false);
867 }
868
869 // Fast path: Reference is null.
870 __ cmpdi(CR0, pre_val, 0);
871 __ bc_far_optimized(Assembler::bcondCRbiIs1_bhintNoHint, __ bi0(CR0, Assembler::equal), *stub->continuation());
872
873 // Argument passing via the stack.
874 __ std(pre_val, -8, R1_SP);
875
876 __ load_const_optimized(R0, bs->pre_barrier_c1_runtime_code_blob()->code_begin());
877 __ call_stub(R0);
878
879 __ b(*stub->continuation());
880 __ block_comment("} gen_pre_barrier_stub (shenandoahgc)");
881 }
882
883 void ShenandoahBarrierSetAssembler::gen_load_reference_barrier_stub(LIR_Assembler *ce,
884 ShenandoahLoadReferenceBarrierStub *stub) {
885 __ block_comment("gen_load_reference_barrier_stub (shenandoahgc) {");
886
887 ShenandoahBarrierSetC1 *bs = (ShenandoahBarrierSetC1*) BarrierSet::barrier_set()->barrier_set_c1();
888 __ bind(*stub->entry());
889
890 Register obj = stub->obj()->as_register();
891 Register res = stub->result()->as_register();
892 Register addr = stub->addr()->as_pointer_register();
893 Register tmp1 = stub->tmp1()->as_register();
894 Register tmp2 = stub->tmp2()->as_register();
895 assert_different_registers(addr, res, tmp1, tmp2);
896
897 #ifdef ASSERT
898 // Ensure that 'res' is 'R3_ARG1' and contains the same value as 'obj' to reduce the number of required
899 // copy instructions.
900 assert(R3_RET == res, "res must be r3");
901 __ cmpd(CR0, res, obj);
902 __ asm_assert_eq("result register must contain the reference stored in obj");
903 #endif
904
905 DecoratorSet decorators = stub->decorators();
906
907 /* ==== Check whether region is in collection set ==== */
908 // GC status (unstable) has already been verified by 'ShenandoahBarrierSetC1::load_reference_barrier_impl'.
909 // This stub is the slowpath of that function.
910
911 bool is_strong = ShenandoahBarrierSet::is_strong_access(decorators);
912 bool is_weak = ShenandoahBarrierSet::is_weak_access(decorators);
913 bool is_phantom = ShenandoahBarrierSet::is_phantom_access(decorators);
914 bool is_native = ShenandoahBarrierSet::is_native_access(decorators);
915
916 if (is_strong) {
917 // Check whether object is in collection set.
918 __ load_const_optimized(tmp2, ShenandoahHeap::in_cset_fast_test_addr(), tmp1);
919 __ srdi(tmp1, obj, ShenandoahHeapRegion::region_size_bytes_shift_jint());
920 __ lbzx(tmp2, tmp1, tmp2);
921
922 __ andi_(tmp2, tmp2, 1);
923 __ bc_far_optimized(Assembler::bcondCRbiIs1_bhintNoHint, __ bi0(CR0, Assembler::equal), *stub->continuation());
924 }
925
926 address blob_addr = nullptr;
927
928 if (is_strong) {
929 if (is_native) {
930 blob_addr = bs->load_reference_barrier_strong_native_rt_code_blob()->code_begin();
931 } else {
932 blob_addr = bs->load_reference_barrier_strong_rt_code_blob()->code_begin();
933 }
934 } else if (is_weak) {
935 blob_addr = bs->load_reference_barrier_weak_rt_code_blob()->code_begin();
936 } else {
937 assert(is_phantom, "only remaining strength");
938 blob_addr = bs->load_reference_barrier_phantom_rt_code_blob()->code_begin();
939 }
940
941 assert(blob_addr != nullptr, "code blob cannot be found");
942
943 // Argument passing via the stack. 'obj' is passed implicitly (as asserted above).
944 __ std(addr, -8, R1_SP);
945
946 __ load_const_optimized(tmp1, blob_addr, tmp2);
947 __ call_stub(tmp1);
948
949 // 'res' is 'R3_RET'. The result is thus already in the correct register.
950
951 __ b(*stub->continuation());
952 __ block_comment("} gen_load_reference_barrier_stub (shenandoahgc)");
953 }
954
955 #undef __
956
957 #define __ sasm->
958
959 void ShenandoahBarrierSetAssembler::generate_c1_pre_barrier_runtime_stub(StubAssembler *sasm) {
960 __ block_comment("generate_c1_pre_barrier_runtime_stub (shenandoahgc) {");
961
962 Label runtime, skip_barrier;
963 BarrierSet *bs = BarrierSet::barrier_set();
964
965 // Argument passing via the stack.
966 const int caller_stack_slots = 3;
967
968 Register R0_pre_val = R0;
969 __ ld(R0, -8, R1_SP);
970 Register R11_tmp1 = R11_scratch1;
971 __ std(R11_tmp1, -16, R1_SP);
972 Register R12_tmp2 = R12_scratch2;
973 __ std(R12_tmp2, -24, R1_SP);
974
975 /* ==== Check whether marking is active ==== */
976 // Even though gc status was checked in 'ShenandoahBarrierSetAssembler::gen_pre_barrier_stub',
977 // another check is required as a safepoint might have been reached in the meantime (JDK-8140588).
978 __ lbz(R12_tmp2, in_bytes(ShenandoahThreadLocalData::gc_state_offset()), R16_thread);
979
980 __ andi_(R12_tmp2, R12_tmp2, ShenandoahHeap::MARKING);
981 __ beq(CR0, skip_barrier);
982
983 /* ==== Add previous value directly to thread-local SATB mark queue ==== */
984 // Check queue's capacity. Jump to runtime if no free slot is available.
985 __ ld(R12_tmp2, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset()), R16_thread);
986 __ cmpdi(CR0, R12_tmp2, 0);
987 __ beq(CR0, runtime);
988
989 // Capacity suffices. Decrement the queue's size by one slot (size of one oop).
990 __ addi(R12_tmp2, R12_tmp2, -wordSize);
991 __ std(R12_tmp2, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset()), R16_thread);
992
993 // Enqueue the previous value and skip the runtime invocation.
994 __ ld(R11_tmp1, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset()), R16_thread);
995 __ stdx(R0_pre_val, R11_tmp1, R12_tmp2);
996 __ b(skip_barrier);
997
998 __ bind(runtime);
999
1000 /* ==== Invoke runtime to commit SATB mark queue to gc and allocate a new buffer ==== */
1001 // Save to-be-preserved registers.
1002 const int nbytes_save = (MacroAssembler::num_volatile_regs + caller_stack_slots) * BytesPerWord;
1003 __ save_volatile_gprs(R1_SP, -nbytes_save);
1004 __ save_LR(R11_tmp1);
1005 __ push_frame_reg_args(nbytes_save, R11_tmp1);
1006
1007 // Invoke runtime.
1008 __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_barrier_pre), R0_pre_val);
1009
1010 // Restore to-be-preserved registers.
1011 __ pop_frame();
1012 __ restore_LR(R11_tmp1);
1013 __ restore_volatile_gprs(R1_SP, -nbytes_save);
1014
1015 __ bind(skip_barrier);
1016
1017 // Restore spilled registers.
1018 __ ld(R11_tmp1, -16, R1_SP);
1019 __ ld(R12_tmp2, -24, R1_SP);
1020
1021 __ blr();
1022 __ block_comment("} generate_c1_pre_barrier_runtime_stub (shenandoahgc)");
1023 }
1024
1025 void ShenandoahBarrierSetAssembler::generate_c1_load_reference_barrier_runtime_stub(StubAssembler *sasm,
1026 DecoratorSet decorators) {
1027 __ block_comment("generate_c1_load_reference_barrier_runtime_stub (shenandoahgc) {");
1028
1029 // Argument passing via the stack.
1030 const int caller_stack_slots = 1;
1031
1032 // Save to-be-preserved registers.
1033 const int nbytes_save = (MacroAssembler::num_volatile_regs - 1 // 'R3_ARG1' is skipped
1034 + caller_stack_slots) * BytesPerWord;
1035 __ save_volatile_gprs(R1_SP, -nbytes_save, true, false);
1036
1037 // Load arguments from stack.
1038 // No load required, as assured by assertions in 'ShenandoahBarrierSetAssembler::gen_load_reference_barrier_stub'.
1039 Register R3_obj = R3_ARG1;
1040 Register R4_load_addr = R4_ARG2;
1041 __ ld(R4_load_addr, -8, R1_SP);
1042
1043 Register R11_tmp = R11_scratch1;
1044
1045 /* ==== Invoke runtime ==== */
1046 bool is_strong = ShenandoahBarrierSet::is_strong_access(decorators);
1047 bool is_weak = ShenandoahBarrierSet::is_weak_access(decorators);
1048 bool is_phantom = ShenandoahBarrierSet::is_phantom_access(decorators);
1049 bool is_native = ShenandoahBarrierSet::is_native_access(decorators);
1050
1051 address jrt_address = nullptr;
1052
1053 if (is_strong) {
1054 if (is_native) {
1055 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong);
1056 } else {
1057 if (UseCompressedOops) {
1058 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong_narrow);
1059 } else {
1060 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong);
1061 }
1062 }
1063 } else if (is_weak) {
1064 assert(!is_native, "weak load reference barrier must not be called off-heap");
1065 if (UseCompressedOops) {
1066 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_weak_narrow);
1067 } else {
1068 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_weak);
1069 }
1070 } else {
1071 assert(is_phantom, "reference type must be phantom");
1072 assert(is_native, "phantom load reference barrier must be called off-heap");
1073 jrt_address = CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_phantom);
1074 }
1075 assert(jrt_address != nullptr, "load reference barrier runtime routine cannot be found");
1076
1077 __ save_LR(R11_tmp);
1078 __ push_frame_reg_args(nbytes_save, R11_tmp);
1079
1080 // Invoke runtime. Arguments are already stored in the corresponding registers.
1081 __ call_VM_leaf(jrt_address, R3_obj, R4_load_addr);
1082
1083 // Restore to-be-preserved registers.
1084 __ pop_frame();
1085 __ restore_LR(R11_tmp);
1086 __ restore_volatile_gprs(R1_SP, -nbytes_save, true, false); // Skip 'R3_RET' register.
1087
1088 __ blr();
1089 __ block_comment("} generate_c1_load_reference_barrier_runtime_stub (shenandoahgc)");
1090 }
1091
1092 #undef __
1093
1094 #endif // COMPILER1
1095
1096 #ifdef COMPILER2
1097
1098 #undef __
1099 #define __ masm.
1100
1101 bool ShenandoahBarrierStubC2::has_live_vector_registers() {
1102 // TODO: Implement; currently assumes vector registers.
1103 return true;
1104 }
1105
1106 void ShenandoahBarrierStubC2::emit_code(MacroAssembler& masm) {
1107 assert(_needs_keep_alive_barrier || _needs_load_ref_barrier, "Why are you here?");
1108 Unimplemented();
1109 }
1110
1111 void ShenandoahBarrierStubC2::post_init(int offset) {
1112 // Do nothing.
1113 }
1114
1115 #endif // COMPILER2