1 // Copyright 2012 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
7 #include "src/hydrogen.h"
8 #include "src/lithium-inl.h"
9 #include "src/lithium-allocator-inl.h"
10 #include "src/string-stream.h"
15 static inline LifetimePosition Min(LifetimePosition a, LifetimePosition b) {
16 return a.Value() < b.Value() ? a : b;
20 static inline LifetimePosition Max(LifetimePosition a, LifetimePosition b) {
21 return a.Value() > b.Value() ? a : b;
25 UsePosition::UsePosition(LifetimePosition pos,
33 register_beneficial_(true) {
34 if (operand_ != NULL && operand_->IsUnallocated()) {
35 LUnallocated* unalloc = LUnallocated::cast(operand_);
36 requires_reg_ = unalloc->HasRegisterPolicy() ||
37 unalloc->HasDoubleRegisterPolicy();
38 register_beneficial_ = !unalloc->HasAnyPolicy();
40 DCHECK(pos_.IsValid());
44 bool UsePosition::HasHint() const {
45 return hint_ != NULL && !hint_->IsUnallocated();
49 bool UsePosition::RequiresRegister() const {
54 bool UsePosition::RegisterIsBeneficial() const {
55 return register_beneficial_;
59 void UseInterval::SplitAt(LifetimePosition pos, Zone* zone) {
60 DCHECK(Contains(pos) && pos.Value() != start().Value());
61 UseInterval* after = new(zone) UseInterval(pos, end_);
71 void LiveRange::Verify() const {
72 UsePosition* cur = first_pos_;
74 DCHECK(Start().Value() <= cur->pos().Value() &&
75 cur->pos().Value() <= End().Value());
81 bool LiveRange::HasOverlap(UseInterval* target) const {
82 UseInterval* current_interval = first_interval_;
83 while (current_interval != NULL) {
84 // Intervals overlap if the start of one is contained in the other.
85 if (current_interval->Contains(target->start()) ||
86 target->Contains(current_interval->start())) {
89 current_interval = current_interval->next();
98 LiveRange::LiveRange(int id, Zone* zone)
101 kind_(UNALLOCATED_REGISTERS),
102 assigned_register_(kInvalidAssignment),
103 last_interval_(NULL),
104 first_interval_(NULL),
108 current_interval_(NULL),
109 last_processed_use_(NULL),
110 current_hint_operand_(NULL),
111 spill_operand_(new (zone) LOperand()),
112 spill_start_index_(kMaxInt) {}
115 void LiveRange::set_assigned_register(int reg, Zone* zone) {
116 DCHECK(!HasRegisterAssigned() && !IsSpilled());
117 assigned_register_ = reg;
118 ConvertOperands(zone);
122 void LiveRange::MakeSpilled(Zone* zone) {
123 DCHECK(!IsSpilled());
124 DCHECK(TopLevel()->HasAllocatedSpillOperand());
126 assigned_register_ = kInvalidAssignment;
127 ConvertOperands(zone);
131 bool LiveRange::HasAllocatedSpillOperand() const {
132 DCHECK(spill_operand_ != NULL);
133 return !spill_operand_->IsIgnored();
137 void LiveRange::SetSpillOperand(LOperand* operand) {
138 DCHECK(!operand->IsUnallocated());
139 DCHECK(spill_operand_ != NULL);
140 DCHECK(spill_operand_->IsIgnored());
141 spill_operand_->ConvertTo(operand->kind(), operand->index());
145 UsePosition* LiveRange::NextUsePosition(LifetimePosition start) {
146 UsePosition* use_pos = last_processed_use_;
147 if (use_pos == NULL) use_pos = first_pos();
148 while (use_pos != NULL && use_pos->pos().Value() < start.Value()) {
149 use_pos = use_pos->next();
151 last_processed_use_ = use_pos;
156 UsePosition* LiveRange::NextUsePositionRegisterIsBeneficial(
157 LifetimePosition start) {
158 UsePosition* pos = NextUsePosition(start);
159 while (pos != NULL && !pos->RegisterIsBeneficial()) {
166 UsePosition* LiveRange::PreviousUsePositionRegisterIsBeneficial(
167 LifetimePosition start) {
168 UsePosition* pos = first_pos();
169 UsePosition* prev = NULL;
170 while (pos != NULL && pos->pos().Value() < start.Value()) {
171 if (pos->RegisterIsBeneficial()) prev = pos;
178 UsePosition* LiveRange::NextRegisterPosition(LifetimePosition start) {
179 UsePosition* pos = NextUsePosition(start);
180 while (pos != NULL && !pos->RequiresRegister()) {
187 bool LiveRange::CanBeSpilled(LifetimePosition pos) {
188 // We cannot spill a live range that has a use requiring a register
189 // at the current or the immediate next position.
190 UsePosition* use_pos = NextRegisterPosition(pos);
191 if (use_pos == NULL) return true;
193 use_pos->pos().Value() > pos.NextInstruction().InstructionEnd().Value();
197 LOperand* LiveRange::CreateAssignedOperand(Zone* zone) {
199 if (HasRegisterAssigned()) {
200 DCHECK(!IsSpilled());
202 case GENERAL_REGISTERS:
203 op = LRegister::Create(assigned_register(), zone);
205 case DOUBLE_REGISTERS:
206 op = LDoubleRegister::Create(assigned_register(), zone);
211 } else if (IsSpilled()) {
212 DCHECK(!HasRegisterAssigned());
213 op = TopLevel()->GetSpillOperand();
214 DCHECK(!op->IsUnallocated());
216 LUnallocated* unalloc = new(zone) LUnallocated(LUnallocated::NONE);
217 unalloc->set_virtual_register(id_);
224 UseInterval* LiveRange::FirstSearchIntervalForPosition(
225 LifetimePosition position) const {
226 if (current_interval_ == NULL) return first_interval_;
227 if (current_interval_->start().Value() > position.Value()) {
228 current_interval_ = NULL;
229 return first_interval_;
231 return current_interval_;
235 void LiveRange::AdvanceLastProcessedMarker(
236 UseInterval* to_start_of, LifetimePosition but_not_past) const {
237 if (to_start_of == NULL) return;
238 if (to_start_of->start().Value() > but_not_past.Value()) return;
239 LifetimePosition start =
240 current_interval_ == NULL ? LifetimePosition::Invalid()
241 : current_interval_->start();
242 if (to_start_of->start().Value() > start.Value()) {
243 current_interval_ = to_start_of;
248 void LiveRange::SplitAt(LifetimePosition position,
251 DCHECK(Start().Value() < position.Value());
252 DCHECK(result->IsEmpty());
253 // Find the last interval that ends before the position. If the
254 // position is contained in one of the intervals in the chain, we
255 // split that interval and use the first part.
256 UseInterval* current = FirstSearchIntervalForPosition(position);
258 // If the split position coincides with the beginning of a use interval
259 // we need to split use positons in a special way.
260 bool split_at_start = false;
262 if (current->start().Value() == position.Value()) {
263 // When splitting at start we need to locate the previous use interval.
264 current = first_interval_;
267 while (current != NULL) {
268 if (current->Contains(position)) {
269 current->SplitAt(position, zone);
272 UseInterval* next = current->next();
273 if (next->start().Value() >= position.Value()) {
274 split_at_start = (next->start().Value() == position.Value());
280 // Partition original use intervals to the two live ranges.
281 UseInterval* before = current;
282 UseInterval* after = before->next();
283 result->last_interval_ = (last_interval_ == before)
284 ? after // Only interval in the range after split.
285 : last_interval_; // Last interval of the original range.
286 result->first_interval_ = after;
287 last_interval_ = before;
289 // Find the last use position before the split and the first use
290 // position after it.
291 UsePosition* use_after = first_pos_;
292 UsePosition* use_before = NULL;
293 if (split_at_start) {
294 // The split position coincides with the beginning of a use interval (the
295 // end of a lifetime hole). Use at this position should be attributed to
296 // the split child because split child owns use interval covering it.
297 while (use_after != NULL && use_after->pos().Value() < position.Value()) {
298 use_before = use_after;
299 use_after = use_after->next();
302 while (use_after != NULL && use_after->pos().Value() <= position.Value()) {
303 use_before = use_after;
304 use_after = use_after->next();
308 // Partition original use positions to the two live ranges.
309 if (use_before != NULL) {
310 use_before->next_ = NULL;
314 result->first_pos_ = use_after;
316 // Discard cached iteration state. It might be pointing
317 // to the use that no longer belongs to this live range.
318 last_processed_use_ = NULL;
319 current_interval_ = NULL;
321 // Link the new live range in the chain before any of the other
322 // ranges linked from the range before the split.
323 result->parent_ = (parent_ == NULL) ? this : parent_;
324 result->kind_ = result->parent_->kind_;
325 result->next_ = next_;
335 // This implements an ordering on live ranges so that they are ordered by their
336 // start positions. This is needed for the correctness of the register
337 // allocation algorithm. If two live ranges start at the same offset then there
338 // is a tie breaker based on where the value is first used. This part of the
339 // ordering is merely a heuristic.
340 bool LiveRange::ShouldBeAllocatedBefore(const LiveRange* other) const {
341 LifetimePosition start = Start();
342 LifetimePosition other_start = other->Start();
343 if (start.Value() == other_start.Value()) {
344 UsePosition* pos = first_pos();
345 if (pos == NULL) return false;
346 UsePosition* other_pos = other->first_pos();
347 if (other_pos == NULL) return true;
348 return pos->pos().Value() < other_pos->pos().Value();
350 return start.Value() < other_start.Value();
354 void LiveRange::ShortenTo(LifetimePosition start) {
355 LAllocator::TraceAlloc("Shorten live range %d to [%d\n", id_, start.Value());
356 DCHECK(first_interval_ != NULL);
357 DCHECK(first_interval_->start().Value() <= start.Value());
358 DCHECK(start.Value() < first_interval_->end().Value());
359 first_interval_->set_start(start);
363 void LiveRange::EnsureInterval(LifetimePosition start,
364 LifetimePosition end,
366 LAllocator::TraceAlloc("Ensure live range %d in interval [%d %d[\n",
370 LifetimePosition new_end = end;
371 while (first_interval_ != NULL &&
372 first_interval_->start().Value() <= end.Value()) {
373 if (first_interval_->end().Value() > end.Value()) {
374 new_end = first_interval_->end();
376 first_interval_ = first_interval_->next();
379 UseInterval* new_interval = new(zone) UseInterval(start, new_end);
380 new_interval->next_ = first_interval_;
381 first_interval_ = new_interval;
382 if (new_interval->next() == NULL) {
383 last_interval_ = new_interval;
388 void LiveRange::AddUseInterval(LifetimePosition start,
389 LifetimePosition end,
391 LAllocator::TraceAlloc("Add to live range %d interval [%d %d[\n",
395 if (first_interval_ == NULL) {
396 UseInterval* interval = new(zone) UseInterval(start, end);
397 first_interval_ = interval;
398 last_interval_ = interval;
400 if (end.Value() == first_interval_->start().Value()) {
401 first_interval_->set_start(start);
402 } else if (end.Value() < first_interval_->start().Value()) {
403 UseInterval* interval = new(zone) UseInterval(start, end);
404 interval->set_next(first_interval_);
405 first_interval_ = interval;
407 // Order of instruction's processing (see ProcessInstructions) guarantees
408 // that each new use interval either precedes or intersects with
409 // last added interval.
410 DCHECK(start.Value() < first_interval_->end().Value());
411 first_interval_->start_ = Min(start, first_interval_->start_);
412 first_interval_->end_ = Max(end, first_interval_->end_);
418 void LiveRange::AddUsePosition(LifetimePosition pos,
422 LAllocator::TraceAlloc("Add to live range %d use position %d\n",
425 UsePosition* use_pos = new(zone) UsePosition(pos, operand, hint);
426 UsePosition* prev_hint = NULL;
427 UsePosition* prev = NULL;
428 UsePosition* current = first_pos_;
429 while (current != NULL && current->pos().Value() < pos.Value()) {
430 prev_hint = current->HasHint() ? current : prev_hint;
432 current = current->next();
436 use_pos->set_next(first_pos_);
437 first_pos_ = use_pos;
439 use_pos->next_ = prev->next_;
440 prev->next_ = use_pos;
443 if (prev_hint == NULL && use_pos->HasHint()) {
444 current_hint_operand_ = hint;
449 void LiveRange::ConvertOperands(Zone* zone) {
450 LOperand* op = CreateAssignedOperand(zone);
451 UsePosition* use_pos = first_pos();
452 while (use_pos != NULL) {
453 DCHECK(Start().Value() <= use_pos->pos().Value() &&
454 use_pos->pos().Value() <= End().Value());
456 if (use_pos->HasOperand()) {
457 DCHECK(op->IsRegister() || op->IsDoubleRegister() ||
458 !use_pos->RequiresRegister());
459 use_pos->operand()->ConvertTo(op->kind(), op->index());
461 use_pos = use_pos->next();
466 bool LiveRange::CanCover(LifetimePosition position) const {
467 if (IsEmpty()) return false;
468 return Start().Value() <= position.Value() &&
469 position.Value() < End().Value();
473 bool LiveRange::Covers(LifetimePosition position) {
474 if (!CanCover(position)) return false;
475 UseInterval* start_search = FirstSearchIntervalForPosition(position);
476 for (UseInterval* interval = start_search;
478 interval = interval->next()) {
479 DCHECK(interval->next() == NULL ||
480 interval->next()->start().Value() >= interval->start().Value());
481 AdvanceLastProcessedMarker(interval, position);
482 if (interval->Contains(position)) return true;
483 if (interval->start().Value() > position.Value()) return false;
489 LifetimePosition LiveRange::FirstIntersection(LiveRange* other) {
490 UseInterval* b = other->first_interval();
491 if (b == NULL) return LifetimePosition::Invalid();
492 LifetimePosition advance_last_processed_up_to = b->start();
493 UseInterval* a = FirstSearchIntervalForPosition(b->start());
494 while (a != NULL && b != NULL) {
495 if (a->start().Value() > other->End().Value()) break;
496 if (b->start().Value() > End().Value()) break;
497 LifetimePosition cur_intersection = a->Intersect(b);
498 if (cur_intersection.IsValid()) {
499 return cur_intersection;
501 if (a->start().Value() < b->start().Value()) {
503 if (a == NULL || a->start().Value() > other->End().Value()) break;
504 AdvanceLastProcessedMarker(a, advance_last_processed_up_to);
509 return LifetimePosition::Invalid();
513 LAllocator::LAllocator(int num_values, HGraph* graph)
514 : zone_(graph->isolate()),
516 live_in_sets_(graph->blocks()->length(), zone()),
517 live_ranges_(num_values * 2, zone()),
518 fixed_live_ranges_(NULL),
519 fixed_double_live_ranges_(NULL),
520 unhandled_live_ranges_(num_values * 2, zone()),
521 active_live_ranges_(8, zone()),
522 inactive_live_ranges_(8, zone()),
523 reusable_slots_(8, zone()),
524 next_virtual_register_(num_values),
525 first_artificial_register_(num_values),
526 mode_(UNALLOCATED_REGISTERS),
529 has_osr_entry_(false),
530 allocation_ok_(true) {}
533 void LAllocator::InitializeLivenessAnalysis() {
534 // Initialize the live_in sets for each block to NULL.
535 int block_count = graph_->blocks()->length();
536 live_in_sets_.Initialize(block_count, zone());
537 live_in_sets_.AddBlock(NULL, block_count, zone());
541 BitVector* LAllocator::ComputeLiveOut(HBasicBlock* block) {
542 // Compute live out for the given block, except not including backward
544 BitVector* live_out = new(zone()) BitVector(next_virtual_register_, zone());
546 // Process all successor blocks.
547 for (HSuccessorIterator it(block->end()); !it.Done(); it.Advance()) {
548 // Add values live on entry to the successor. Note the successor's
549 // live_in will not be computed yet for backwards edges.
550 HBasicBlock* successor = it.Current();
551 BitVector* live_in = live_in_sets_[successor->block_id()];
552 if (live_in != NULL) live_out->Union(*live_in);
554 // All phi input operands corresponding to this successor edge are live
555 // out from this block.
556 int index = successor->PredecessorIndexOf(block);
557 const ZoneList<HPhi*>* phis = successor->phis();
558 for (int i = 0; i < phis->length(); ++i) {
559 HPhi* phi = phis->at(i);
560 if (!phi->OperandAt(index)->IsConstant()) {
561 live_out->Add(phi->OperandAt(index)->id());
570 void LAllocator::AddInitialIntervals(HBasicBlock* block,
571 BitVector* live_out) {
572 // Add an interval that includes the entire block to the live range for
573 // each live_out value.
574 LifetimePosition start = LifetimePosition::FromInstructionIndex(
575 block->first_instruction_index());
576 LifetimePosition end = LifetimePosition::FromInstructionIndex(
577 block->last_instruction_index()).NextInstruction();
578 BitVector::Iterator iterator(live_out);
579 while (!iterator.Done()) {
580 int operand_index = iterator.Current();
581 LiveRange* range = LiveRangeFor(operand_index);
582 range->AddUseInterval(start, end, zone());
588 int LAllocator::FixedDoubleLiveRangeID(int index) {
589 return -index - 1 - Register::kMaxNumAllocatableRegisters;
593 LOperand* LAllocator::AllocateFixed(LUnallocated* operand,
596 TraceAlloc("Allocating fixed reg for op %d\n", operand->virtual_register());
597 DCHECK(operand->HasFixedPolicy());
598 if (operand->HasFixedSlotPolicy()) {
599 operand->ConvertTo(LOperand::STACK_SLOT, operand->fixed_slot_index());
600 } else if (operand->HasFixedRegisterPolicy()) {
601 int reg_index = operand->fixed_register_index();
602 operand->ConvertTo(LOperand::REGISTER, reg_index);
603 } else if (operand->HasFixedDoubleRegisterPolicy()) {
604 int reg_index = operand->fixed_register_index();
605 operand->ConvertTo(LOperand::DOUBLE_REGISTER, reg_index);
610 TraceAlloc("Fixed reg is tagged at %d\n", pos);
611 LInstruction* instr = InstructionAt(pos);
612 if (instr->HasPointerMap()) {
613 instr->pointer_map()->RecordPointer(operand, chunk()->zone());
620 LiveRange* LAllocator::FixedLiveRangeFor(int index) {
621 DCHECK(index < Register::kMaxNumAllocatableRegisters);
622 LiveRange* result = fixed_live_ranges_[index];
623 if (result == NULL) {
624 result = new(zone()) LiveRange(FixedLiveRangeID(index), chunk()->zone());
625 DCHECK(result->IsFixed());
626 result->kind_ = GENERAL_REGISTERS;
627 SetLiveRangeAssignedRegister(result, index);
628 fixed_live_ranges_[index] = result;
634 LiveRange* LAllocator::FixedDoubleLiveRangeFor(int index) {
635 DCHECK(index < DoubleRegister::NumAllocatableRegisters());
636 LiveRange* result = fixed_double_live_ranges_[index];
637 if (result == NULL) {
638 result = new(zone()) LiveRange(FixedDoubleLiveRangeID(index),
640 DCHECK(result->IsFixed());
641 result->kind_ = DOUBLE_REGISTERS;
642 SetLiveRangeAssignedRegister(result, index);
643 fixed_double_live_ranges_[index] = result;
649 LiveRange* LAllocator::LiveRangeFor(int index) {
650 if (index >= live_ranges_.length()) {
651 live_ranges_.AddBlock(NULL, index - live_ranges_.length() + 1, zone());
653 LiveRange* result = live_ranges_[index];
654 if (result == NULL) {
655 result = new(zone()) LiveRange(index, chunk()->zone());
656 live_ranges_[index] = result;
662 LGap* LAllocator::GetLastGap(HBasicBlock* block) {
663 int last_instruction = block->last_instruction_index();
664 int index = chunk_->NearestGapPos(last_instruction);
669 HPhi* LAllocator::LookupPhi(LOperand* operand) const {
670 if (!operand->IsUnallocated()) return NULL;
671 int index = LUnallocated::cast(operand)->virtual_register();
672 HValue* instr = graph_->LookupValue(index);
673 if (instr != NULL && instr->IsPhi()) {
674 return HPhi::cast(instr);
680 LiveRange* LAllocator::LiveRangeFor(LOperand* operand) {
681 if (operand->IsUnallocated()) {
682 return LiveRangeFor(LUnallocated::cast(operand)->virtual_register());
683 } else if (operand->IsRegister()) {
684 return FixedLiveRangeFor(operand->index());
685 } else if (operand->IsDoubleRegister()) {
686 return FixedDoubleLiveRangeFor(operand->index());
693 void LAllocator::Define(LifetimePosition position,
696 LiveRange* range = LiveRangeFor(operand);
697 if (range == NULL) return;
699 if (range->IsEmpty() || range->Start().Value() > position.Value()) {
700 // Can happen if there is a definition without use.
701 range->AddUseInterval(position, position.NextInstruction(), zone());
702 range->AddUsePosition(position.NextInstruction(), NULL, NULL, zone());
704 range->ShortenTo(position);
707 if (operand->IsUnallocated()) {
708 LUnallocated* unalloc_operand = LUnallocated::cast(operand);
709 range->AddUsePosition(position, unalloc_operand, hint, zone());
714 void LAllocator::Use(LifetimePosition block_start,
715 LifetimePosition position,
718 LiveRange* range = LiveRangeFor(operand);
719 if (range == NULL) return;
720 if (operand->IsUnallocated()) {
721 LUnallocated* unalloc_operand = LUnallocated::cast(operand);
722 range->AddUsePosition(position, unalloc_operand, hint, zone());
724 range->AddUseInterval(block_start, position, zone());
728 void LAllocator::AddConstraintsGapMove(int index,
731 LGap* gap = GapAt(index);
732 LParallelMove* move = gap->GetOrCreateParallelMove(LGap::START,
734 if (from->IsUnallocated()) {
735 const ZoneList<LMoveOperands>* move_operands = move->move_operands();
736 for (int i = 0; i < move_operands->length(); ++i) {
737 LMoveOperands cur = move_operands->at(i);
738 LOperand* cur_to = cur.destination();
739 if (cur_to->IsUnallocated()) {
740 if (LUnallocated::cast(cur_to)->virtual_register() ==
741 LUnallocated::cast(from)->virtual_register()) {
742 move->AddMove(cur.source(), to, chunk()->zone());
748 move->AddMove(from, to, chunk()->zone());
752 void LAllocator::MeetRegisterConstraints(HBasicBlock* block) {
753 int start = block->first_instruction_index();
754 int end = block->last_instruction_index();
755 if (start == -1) return;
756 for (int i = start; i <= end; ++i) {
758 LInstruction* instr = NULL;
759 LInstruction* prev_instr = NULL;
760 if (i < end) instr = InstructionAt(i + 1);
761 if (i > start) prev_instr = InstructionAt(i - 1);
762 MeetConstraintsBetween(prev_instr, instr, i);
763 if (!AllocationOk()) return;
769 void LAllocator::MeetConstraintsBetween(LInstruction* first,
770 LInstruction* second,
772 // Handle fixed temporaries.
774 for (TempIterator it(first); !it.Done(); it.Advance()) {
775 LUnallocated* temp = LUnallocated::cast(it.Current());
776 if (temp->HasFixedPolicy()) {
777 AllocateFixed(temp, gap_index - 1, false);
782 // Handle fixed output operand.
783 if (first != NULL && first->Output() != NULL) {
784 LUnallocated* first_output = LUnallocated::cast(first->Output());
785 LiveRange* range = LiveRangeFor(first_output->virtual_register());
786 bool assigned = false;
787 if (first_output->HasFixedPolicy()) {
788 LUnallocated* output_copy = first_output->CopyUnconstrained(
790 bool is_tagged = HasTaggedValue(first_output->virtual_register());
791 AllocateFixed(first_output, gap_index, is_tagged);
793 // This value is produced on the stack, we never need to spill it.
794 if (first_output->IsStackSlot()) {
795 range->SetSpillOperand(first_output);
796 range->SetSpillStartIndex(gap_index - 1);
799 chunk_->AddGapMove(gap_index, first_output, output_copy);
803 range->SetSpillStartIndex(gap_index);
805 // This move to spill operand is not a real use. Liveness analysis
806 // and splitting of live ranges do not account for it.
807 // Thus it should be inserted to a lifetime position corresponding to
808 // the instruction end.
809 LGap* gap = GapAt(gap_index);
810 LParallelMove* move = gap->GetOrCreateParallelMove(LGap::BEFORE,
812 move->AddMove(first_output, range->GetSpillOperand(),
817 // Handle fixed input operands of second instruction.
818 if (second != NULL) {
819 for (UseIterator it(second); !it.Done(); it.Advance()) {
820 LUnallocated* cur_input = LUnallocated::cast(it.Current());
821 if (cur_input->HasFixedPolicy()) {
822 LUnallocated* input_copy = cur_input->CopyUnconstrained(
824 bool is_tagged = HasTaggedValue(cur_input->virtual_register());
825 AllocateFixed(cur_input, gap_index + 1, is_tagged);
826 AddConstraintsGapMove(gap_index, input_copy, cur_input);
827 } else if (cur_input->HasWritableRegisterPolicy()) {
828 // The live range of writable input registers always goes until the end
829 // of the instruction.
830 DCHECK(!cur_input->IsUsedAtStart());
832 LUnallocated* input_copy = cur_input->CopyUnconstrained(
834 int vreg = GetVirtualRegister();
835 if (!AllocationOk()) return;
836 cur_input->set_virtual_register(vreg);
838 if (RequiredRegisterKind(input_copy->virtual_register()) ==
840 double_artificial_registers_.Add(
841 cur_input->virtual_register() - first_artificial_register_,
845 AddConstraintsGapMove(gap_index, input_copy, cur_input);
850 // Handle "output same as input" for second instruction.
851 if (second != NULL && second->Output() != NULL) {
852 LUnallocated* second_output = LUnallocated::cast(second->Output());
853 if (second_output->HasSameAsInputPolicy()) {
854 LUnallocated* cur_input = LUnallocated::cast(second->FirstInput());
855 int output_vreg = second_output->virtual_register();
856 int input_vreg = cur_input->virtual_register();
858 LUnallocated* input_copy = cur_input->CopyUnconstrained(
860 cur_input->set_virtual_register(second_output->virtual_register());
861 AddConstraintsGapMove(gap_index, input_copy, cur_input);
863 if (HasTaggedValue(input_vreg) && !HasTaggedValue(output_vreg)) {
864 int index = gap_index + 1;
865 LInstruction* instr = InstructionAt(index);
866 if (instr->HasPointerMap()) {
867 instr->pointer_map()->RecordPointer(input_copy, chunk()->zone());
869 } else if (!HasTaggedValue(input_vreg) && HasTaggedValue(output_vreg)) {
870 // The input is assumed to immediately have a tagged representation,
871 // before the pointer map can be used. I.e. the pointer map at the
872 // instruction will include the output operand (whose value at the
873 // beginning of the instruction is equal to the input operand). If
874 // this is not desired, then the pointer map at this instruction needs
875 // to be adjusted manually.
882 void LAllocator::ProcessInstructions(HBasicBlock* block, BitVector* live) {
883 int block_start = block->first_instruction_index();
884 int index = block->last_instruction_index();
886 LifetimePosition block_start_position =
887 LifetimePosition::FromInstructionIndex(block_start);
889 while (index >= block_start) {
890 LifetimePosition curr_position =
891 LifetimePosition::FromInstructionIndex(index);
893 if (IsGapAt(index)) {
894 // We have a gap at this position.
895 LGap* gap = GapAt(index);
896 LParallelMove* move = gap->GetOrCreateParallelMove(LGap::START,
898 const ZoneList<LMoveOperands>* move_operands = move->move_operands();
899 for (int i = 0; i < move_operands->length(); ++i) {
900 LMoveOperands* cur = &move_operands->at(i);
901 if (cur->IsIgnored()) continue;
902 LOperand* from = cur->source();
903 LOperand* to = cur->destination();
904 HPhi* phi = LookupPhi(to);
907 // This is a phi resolving move.
908 if (!phi->block()->IsLoopHeader()) {
909 hint = LiveRangeFor(phi->id())->current_hint_operand();
912 if (to->IsUnallocated()) {
913 if (live->Contains(LUnallocated::cast(to)->virtual_register())) {
914 Define(curr_position, to, from);
915 live->Remove(LUnallocated::cast(to)->virtual_register());
921 Define(curr_position, to, from);
924 Use(block_start_position, curr_position, from, hint);
925 if (from->IsUnallocated()) {
926 live->Add(LUnallocated::cast(from)->virtual_register());
930 DCHECK(!IsGapAt(index));
931 LInstruction* instr = InstructionAt(index);
934 LOperand* output = instr->Output();
935 if (output != NULL) {
936 if (output->IsUnallocated()) {
937 live->Remove(LUnallocated::cast(output)->virtual_register());
939 Define(curr_position, output, NULL);
942 if (instr->ClobbersRegisters()) {
943 for (int i = 0; i < Register::kMaxNumAllocatableRegisters; ++i) {
944 if (output == NULL || !output->IsRegister() ||
945 output->index() != i) {
946 LiveRange* range = FixedLiveRangeFor(i);
947 range->AddUseInterval(curr_position,
948 curr_position.InstructionEnd(),
954 if (instr->ClobbersDoubleRegisters(isolate())) {
955 for (int i = 0; i < DoubleRegister::NumAllocatableRegisters(); ++i) {
956 if (output == NULL || !output->IsDoubleRegister() ||
957 output->index() != i) {
958 LiveRange* range = FixedDoubleLiveRangeFor(i);
959 range->AddUseInterval(curr_position,
960 curr_position.InstructionEnd(),
966 for (UseIterator it(instr); !it.Done(); it.Advance()) {
967 LOperand* input = it.Current();
969 LifetimePosition use_pos;
970 if (input->IsUnallocated() &&
971 LUnallocated::cast(input)->IsUsedAtStart()) {
972 use_pos = curr_position;
974 use_pos = curr_position.InstructionEnd();
977 Use(block_start_position, use_pos, input, NULL);
978 if (input->IsUnallocated()) {
979 live->Add(LUnallocated::cast(input)->virtual_register());
983 for (TempIterator it(instr); !it.Done(); it.Advance()) {
984 LOperand* temp = it.Current();
985 if (instr->ClobbersTemps()) {
986 if (temp->IsRegister()) continue;
987 if (temp->IsUnallocated()) {
988 LUnallocated* temp_unalloc = LUnallocated::cast(temp);
989 if (temp_unalloc->HasFixedPolicy()) {
994 Use(block_start_position, curr_position.InstructionEnd(), temp, NULL);
995 Define(curr_position, temp, NULL);
997 if (temp->IsUnallocated()) {
998 LUnallocated* temp_unalloc = LUnallocated::cast(temp);
999 if (temp_unalloc->HasDoubleRegisterPolicy()) {
1000 double_artificial_registers_.Add(
1001 temp_unalloc->virtual_register() - first_artificial_register_,
1014 void LAllocator::ResolvePhis(HBasicBlock* block) {
1015 const ZoneList<HPhi*>* phis = block->phis();
1016 for (int i = 0; i < phis->length(); ++i) {
1017 HPhi* phi = phis->at(i);
1018 LUnallocated* phi_operand =
1019 new (chunk()->zone()) LUnallocated(LUnallocated::NONE);
1020 phi_operand->set_virtual_register(phi->id());
1021 for (int j = 0; j < phi->OperandCount(); ++j) {
1022 HValue* op = phi->OperandAt(j);
1023 LOperand* operand = NULL;
1024 if (op->IsConstant() && op->EmitAtUses()) {
1025 HConstant* constant = HConstant::cast(op);
1026 operand = chunk_->DefineConstantOperand(constant);
1028 DCHECK(!op->EmitAtUses());
1029 LUnallocated* unalloc =
1030 new(chunk()->zone()) LUnallocated(LUnallocated::ANY);
1031 unalloc->set_virtual_register(op->id());
1034 HBasicBlock* cur_block = block->predecessors()->at(j);
1035 // The gap move must be added without any special processing as in
1036 // the AddConstraintsGapMove.
1037 chunk_->AddGapMove(cur_block->last_instruction_index() - 1,
1041 // We are going to insert a move before the branch instruction.
1042 // Some branch instructions (e.g. loops' back edges)
1043 // can potentially cause a GC so they have a pointer map.
1044 // By inserting a move we essentially create a copy of a
1045 // value which is invisible to PopulatePointerMaps(), because we store
1046 // it into a location different from the operand of a live range
1047 // covering a branch instruction.
1048 // Thus we need to manually record a pointer.
1049 LInstruction* branch =
1050 InstructionAt(cur_block->last_instruction_index());
1051 if (branch->HasPointerMap()) {
1052 if (phi->representation().IsTagged() && !phi->type().IsSmi()) {
1053 branch->pointer_map()->RecordPointer(phi_operand, chunk()->zone());
1054 } else if (!phi->representation().IsDouble()) {
1055 branch->pointer_map()->RecordUntagged(phi_operand, chunk()->zone());
1060 LiveRange* live_range = LiveRangeFor(phi->id());
1061 LLabel* label = chunk_->GetLabel(phi->block()->block_id());
1062 label->GetOrCreateParallelMove(LGap::START, chunk()->zone())->
1063 AddMove(phi_operand, live_range->GetSpillOperand(), chunk()->zone());
1064 live_range->SetSpillStartIndex(phi->block()->first_instruction_index());
1069 bool LAllocator::Allocate(LChunk* chunk) {
1070 DCHECK(chunk_ == NULL);
1071 chunk_ = static_cast<LPlatformChunk*>(chunk);
1072 assigned_registers_ =
1073 new(chunk->zone()) BitVector(Register::NumAllocatableRegisters(),
1075 assigned_double_registers_ =
1076 new(chunk->zone()) BitVector(DoubleRegister::NumAllocatableRegisters(),
1078 MeetRegisterConstraints();
1079 if (!AllocationOk()) return false;
1082 AllocateGeneralRegisters();
1083 if (!AllocationOk()) return false;
1084 AllocateDoubleRegisters();
1085 if (!AllocationOk()) return false;
1086 PopulatePointerMaps();
1088 ResolveControlFlow();
1093 void LAllocator::MeetRegisterConstraints() {
1094 LAllocatorPhase phase("L_Register constraints", this);
1095 const ZoneList<HBasicBlock*>* blocks = graph_->blocks();
1096 for (int i = 0; i < blocks->length(); ++i) {
1097 HBasicBlock* block = blocks->at(i);
1098 MeetRegisterConstraints(block);
1099 if (!AllocationOk()) return;
1104 void LAllocator::ResolvePhis() {
1105 LAllocatorPhase phase("L_Resolve phis", this);
1107 // Process the blocks in reverse order.
1108 const ZoneList<HBasicBlock*>* blocks = graph_->blocks();
1109 for (int block_id = blocks->length() - 1; block_id >= 0; --block_id) {
1110 HBasicBlock* block = blocks->at(block_id);
1116 void LAllocator::ResolveControlFlow(LiveRange* range,
1118 HBasicBlock* pred) {
1119 LifetimePosition pred_end =
1120 LifetimePosition::FromInstructionIndex(pred->last_instruction_index());
1121 LifetimePosition cur_start =
1122 LifetimePosition::FromInstructionIndex(block->first_instruction_index());
1123 LiveRange* pred_cover = NULL;
1124 LiveRange* cur_cover = NULL;
1125 LiveRange* cur_range = range;
1126 while (cur_range != NULL && (cur_cover == NULL || pred_cover == NULL)) {
1127 if (cur_range->CanCover(cur_start)) {
1128 DCHECK(cur_cover == NULL);
1129 cur_cover = cur_range;
1131 if (cur_range->CanCover(pred_end)) {
1132 DCHECK(pred_cover == NULL);
1133 pred_cover = cur_range;
1135 cur_range = cur_range->next();
1138 if (cur_cover->IsSpilled()) return;
1139 DCHECK(pred_cover != NULL && cur_cover != NULL);
1140 if (pred_cover != cur_cover) {
1141 LOperand* pred_op = pred_cover->CreateAssignedOperand(chunk()->zone());
1142 LOperand* cur_op = cur_cover->CreateAssignedOperand(chunk()->zone());
1143 if (!pred_op->Equals(cur_op)) {
1145 if (block->predecessors()->length() == 1) {
1146 gap = GapAt(block->first_instruction_index());
1148 DCHECK(pred->end()->SecondSuccessor() == NULL);
1149 gap = GetLastGap(pred);
1151 // We are going to insert a move before the branch instruction.
1152 // Some branch instructions (e.g. loops' back edges)
1153 // can potentially cause a GC so they have a pointer map.
1154 // By inserting a move we essentially create a copy of a
1155 // value which is invisible to PopulatePointerMaps(), because we store
1156 // it into a location different from the operand of a live range
1157 // covering a branch instruction.
1158 // Thus we need to manually record a pointer.
1159 LInstruction* branch = InstructionAt(pred->last_instruction_index());
1160 if (branch->HasPointerMap()) {
1161 if (HasTaggedValue(range->id())) {
1162 branch->pointer_map()->RecordPointer(cur_op, chunk()->zone());
1163 } else if (!cur_op->IsDoubleStackSlot() &&
1164 !cur_op->IsDoubleRegister()) {
1165 branch->pointer_map()->RemovePointer(cur_op);
1169 gap->GetOrCreateParallelMove(
1170 LGap::START, chunk()->zone())->AddMove(pred_op, cur_op,
1177 LParallelMove* LAllocator::GetConnectingParallelMove(LifetimePosition pos) {
1178 int index = pos.InstructionIndex();
1179 if (IsGapAt(index)) {
1180 LGap* gap = GapAt(index);
1181 return gap->GetOrCreateParallelMove(
1182 pos.IsInstructionStart() ? LGap::START : LGap::END, chunk()->zone());
1184 int gap_pos = pos.IsInstructionStart() ? (index - 1) : (index + 1);
1185 return GapAt(gap_pos)->GetOrCreateParallelMove(
1186 (gap_pos < index) ? LGap::AFTER : LGap::BEFORE, chunk()->zone());
1190 HBasicBlock* LAllocator::GetBlock(LifetimePosition pos) {
1191 LGap* gap = GapAt(chunk_->NearestGapPos(pos.InstructionIndex()));
1192 return gap->block();
1196 void LAllocator::ConnectRanges() {
1197 LAllocatorPhase phase("L_Connect ranges", this);
1198 for (int i = 0; i < live_ranges()->length(); ++i) {
1199 LiveRange* first_range = live_ranges()->at(i);
1200 if (first_range == NULL || first_range->parent() != NULL) continue;
1202 LiveRange* second_range = first_range->next();
1203 while (second_range != NULL) {
1204 LifetimePosition pos = second_range->Start();
1206 if (!second_range->IsSpilled()) {
1207 // Add gap move if the two live ranges touch and there is no block
1209 if (first_range->End().Value() == pos.Value()) {
1210 bool should_insert = true;
1211 if (IsBlockBoundary(pos)) {
1212 should_insert = CanEagerlyResolveControlFlow(GetBlock(pos));
1214 if (should_insert) {
1215 LParallelMove* move = GetConnectingParallelMove(pos);
1216 LOperand* prev_operand = first_range->CreateAssignedOperand(
1218 LOperand* cur_operand = second_range->CreateAssignedOperand(
1220 move->AddMove(prev_operand, cur_operand,
1226 first_range = second_range;
1227 second_range = second_range->next();
1233 bool LAllocator::CanEagerlyResolveControlFlow(HBasicBlock* block) const {
1234 if (block->predecessors()->length() != 1) return false;
1235 return block->predecessors()->first()->block_id() == block->block_id() - 1;
1239 void LAllocator::ResolveControlFlow() {
1240 LAllocatorPhase phase("L_Resolve control flow", this);
1241 const ZoneList<HBasicBlock*>* blocks = graph_->blocks();
1242 for (int block_id = 1; block_id < blocks->length(); ++block_id) {
1243 HBasicBlock* block = blocks->at(block_id);
1244 if (CanEagerlyResolveControlFlow(block)) continue;
1245 BitVector* live = live_in_sets_[block->block_id()];
1246 BitVector::Iterator iterator(live);
1247 while (!iterator.Done()) {
1248 int operand_index = iterator.Current();
1249 for (int i = 0; i < block->predecessors()->length(); ++i) {
1250 HBasicBlock* cur = block->predecessors()->at(i);
1251 LiveRange* cur_range = LiveRangeFor(operand_index);
1252 ResolveControlFlow(cur_range, block, cur);
1260 void LAllocator::BuildLiveRanges() {
1261 LAllocatorPhase phase("L_Build live ranges", this);
1262 InitializeLivenessAnalysis();
1263 // Process the blocks in reverse order.
1264 const ZoneList<HBasicBlock*>* blocks = graph_->blocks();
1265 for (int block_id = blocks->length() - 1; block_id >= 0; --block_id) {
1266 HBasicBlock* block = blocks->at(block_id);
1267 BitVector* live = ComputeLiveOut(block);
1268 // Initially consider all live_out values live for the entire block. We
1269 // will shorten these intervals if necessary.
1270 AddInitialIntervals(block, live);
1272 // Process the instructions in reverse order, generating and killing
1274 ProcessInstructions(block, live);
1275 // All phi output operands are killed by this block.
1276 const ZoneList<HPhi*>* phis = block->phis();
1277 for (int i = 0; i < phis->length(); ++i) {
1278 // The live range interval already ends at the first instruction of the
1280 HPhi* phi = phis->at(i);
1281 live->Remove(phi->id());
1283 LOperand* hint = NULL;
1284 LOperand* phi_operand = NULL;
1285 LGap* gap = GetLastGap(phi->block()->predecessors()->at(0));
1286 LParallelMove* move = gap->GetOrCreateParallelMove(LGap::START,
1288 for (int j = 0; j < move->move_operands()->length(); ++j) {
1289 LOperand* to = move->move_operands()->at(j).destination();
1290 if (to->IsUnallocated() &&
1291 LUnallocated::cast(to)->virtual_register() == phi->id()) {
1292 hint = move->move_operands()->at(j).source();
1297 DCHECK(hint != NULL);
1299 LifetimePosition block_start = LifetimePosition::FromInstructionIndex(
1300 block->first_instruction_index());
1301 Define(block_start, phi_operand, hint);
1304 // Now live is live_in for this block except not including values live
1305 // out on backward successor edges.
1306 live_in_sets_[block_id] = live;
1308 // If this block is a loop header go back and patch up the necessary
1309 // predecessor blocks.
1310 if (block->IsLoopHeader()) {
1311 // TODO(kmillikin): Need to be able to get the last block of the loop
1312 // in the loop information. Add a live range stretching from the first
1313 // loop instruction to the last for each value live on entry to the
1315 HBasicBlock* back_edge = block->loop_information()->GetLastBackEdge();
1316 BitVector::Iterator iterator(live);
1317 LifetimePosition start = LifetimePosition::FromInstructionIndex(
1318 block->first_instruction_index());
1319 LifetimePosition end = LifetimePosition::FromInstructionIndex(
1320 back_edge->last_instruction_index()).NextInstruction();
1321 while (!iterator.Done()) {
1322 int operand_index = iterator.Current();
1323 LiveRange* range = LiveRangeFor(operand_index);
1324 range->EnsureInterval(start, end, zone());
1328 for (int i = block->block_id() + 1; i <= back_edge->block_id(); ++i) {
1329 live_in_sets_[i]->Union(*live);
1334 if (block_id == 0) {
1335 BitVector::Iterator iterator(live);
1337 while (!iterator.Done()) {
1339 int operand_index = iterator.Current();
1340 if (chunk_->info()->IsStub()) {
1341 CodeStub::Major major_key = chunk_->info()->code_stub()->MajorKey();
1342 PrintF("Function: %s\n", CodeStub::MajorName(major_key, false));
1344 DCHECK(chunk_->info()->IsOptimizing());
1345 AllowHandleDereference allow_deref;
1346 PrintF("Function: %s\n",
1347 chunk_->info()->function()->debug_name()->ToCString().get());
1349 PrintF("Value %d used before first definition!\n", operand_index);
1350 LiveRange* range = LiveRangeFor(operand_index);
1351 PrintF("First use is at %d\n", range->first_pos()->pos().Value());
1359 for (int i = 0; i < live_ranges_.length(); ++i) {
1360 if (live_ranges_[i] != NULL) {
1361 live_ranges_[i]->kind_ = RequiredRegisterKind(live_ranges_[i]->id());
1367 bool LAllocator::SafePointsAreInOrder() const {
1368 const ZoneList<LPointerMap*>* pointer_maps = chunk_->pointer_maps();
1370 for (int i = 0; i < pointer_maps->length(); ++i) {
1371 LPointerMap* map = pointer_maps->at(i);
1372 if (safe_point > map->lithium_position()) return false;
1373 safe_point = map->lithium_position();
1379 void LAllocator::PopulatePointerMaps() {
1380 LAllocatorPhase phase("L_Populate pointer maps", this);
1381 const ZoneList<LPointerMap*>* pointer_maps = chunk_->pointer_maps();
1383 DCHECK(SafePointsAreInOrder());
1385 // Iterate over all safe point positions and record a pointer
1386 // for all spilled live ranges at this point.
1387 int first_safe_point_index = 0;
1388 int last_range_start = 0;
1389 for (int range_idx = 0; range_idx < live_ranges()->length(); ++range_idx) {
1390 LiveRange* range = live_ranges()->at(range_idx);
1391 if (range == NULL) continue;
1392 // Iterate over the first parts of multi-part live ranges.
1393 if (range->parent() != NULL) continue;
1394 // Skip non-pointer values.
1395 if (!HasTaggedValue(range->id())) continue;
1396 // Skip empty live ranges.
1397 if (range->IsEmpty()) continue;
1399 // Find the extent of the range and its children.
1400 int start = range->Start().InstructionIndex();
1402 for (LiveRange* cur = range; cur != NULL; cur = cur->next()) {
1403 LifetimePosition this_end = cur->End();
1404 if (this_end.InstructionIndex() > end) end = this_end.InstructionIndex();
1405 DCHECK(cur->Start().InstructionIndex() >= start);
1408 // Most of the ranges are in order, but not all. Keep an eye on when
1409 // they step backwards and reset the first_safe_point_index so we don't
1410 // miss any safe points.
1411 if (start < last_range_start) {
1412 first_safe_point_index = 0;
1414 last_range_start = start;
1416 // Step across all the safe points that are before the start of this range,
1417 // recording how far we step in order to save doing this for the next range.
1418 while (first_safe_point_index < pointer_maps->length()) {
1419 LPointerMap* map = pointer_maps->at(first_safe_point_index);
1420 int safe_point = map->lithium_position();
1421 if (safe_point >= start) break;
1422 first_safe_point_index++;
1425 // Step through the safe points to see whether they are in the range.
1426 for (int safe_point_index = first_safe_point_index;
1427 safe_point_index < pointer_maps->length();
1428 ++safe_point_index) {
1429 LPointerMap* map = pointer_maps->at(safe_point_index);
1430 int safe_point = map->lithium_position();
1432 // The safe points are sorted so we can stop searching here.
1433 if (safe_point - 1 > end) break;
1435 // Advance to the next active range that covers the current
1436 // safe point position.
1437 LifetimePosition safe_point_pos =
1438 LifetimePosition::FromInstructionIndex(safe_point);
1439 LiveRange* cur = range;
1440 while (cur != NULL && !cur->Covers(safe_point_pos)) {
1443 if (cur == NULL) continue;
1445 // Check if the live range is spilled and the safe point is after
1446 // the spill position.
1447 if (range->HasAllocatedSpillOperand() &&
1448 safe_point >= range->spill_start_index()) {
1449 TraceAlloc("Pointer for range %d (spilled at %d) at safe point %d\n",
1450 range->id(), range->spill_start_index(), safe_point);
1451 map->RecordPointer(range->GetSpillOperand(), chunk()->zone());
1454 if (!cur->IsSpilled()) {
1455 TraceAlloc("Pointer in register for range %d (start at %d) "
1456 "at safe point %d\n",
1457 cur->id(), cur->Start().Value(), safe_point);
1458 LOperand* operand = cur->CreateAssignedOperand(chunk()->zone());
1459 DCHECK(!operand->IsStackSlot());
1460 map->RecordPointer(operand, chunk()->zone());
1467 void LAllocator::AllocateGeneralRegisters() {
1468 LAllocatorPhase phase("L_Allocate general registers", this);
1469 num_registers_ = Register::NumAllocatableRegisters();
1470 mode_ = GENERAL_REGISTERS;
1471 AllocateRegisters();
1475 void LAllocator::AllocateDoubleRegisters() {
1476 LAllocatorPhase phase("L_Allocate double registers", this);
1477 num_registers_ = DoubleRegister::NumAllocatableRegisters();
1478 mode_ = DOUBLE_REGISTERS;
1479 AllocateRegisters();
1483 void LAllocator::AllocateRegisters() {
1484 DCHECK(unhandled_live_ranges_.is_empty());
1486 for (int i = 0; i < live_ranges_.length(); ++i) {
1487 if (live_ranges_[i] != NULL) {
1488 if (live_ranges_[i]->Kind() == mode_) {
1489 AddToUnhandledUnsorted(live_ranges_[i]);
1494 DCHECK(UnhandledIsSorted());
1496 DCHECK(reusable_slots_.is_empty());
1497 DCHECK(active_live_ranges_.is_empty());
1498 DCHECK(inactive_live_ranges_.is_empty());
1500 if (mode_ == DOUBLE_REGISTERS) {
1501 for (int i = 0; i < DoubleRegister::NumAllocatableRegisters(); ++i) {
1502 LiveRange* current = fixed_double_live_ranges_.at(i);
1503 if (current != NULL) {
1504 AddToInactive(current);
1508 DCHECK(mode_ == GENERAL_REGISTERS);
1509 for (int i = 0; i < fixed_live_ranges_.length(); ++i) {
1510 LiveRange* current = fixed_live_ranges_.at(i);
1511 if (current != NULL) {
1512 AddToInactive(current);
1517 while (!unhandled_live_ranges_.is_empty()) {
1518 DCHECK(UnhandledIsSorted());
1519 LiveRange* current = unhandled_live_ranges_.RemoveLast();
1520 DCHECK(UnhandledIsSorted());
1521 LifetimePosition position = current->Start();
1523 allocation_finger_ = position;
1525 TraceAlloc("Processing interval %d start=%d\n",
1529 if (current->HasAllocatedSpillOperand()) {
1530 TraceAlloc("Live range %d already has a spill operand\n", current->id());
1531 LifetimePosition next_pos = position;
1532 if (IsGapAt(next_pos.InstructionIndex())) {
1533 next_pos = next_pos.NextInstruction();
1535 UsePosition* pos = current->NextUsePositionRegisterIsBeneficial(next_pos);
1536 // If the range already has a spill operand and it doesn't need a
1537 // register immediately, split it and spill the first part of the range.
1541 } else if (pos->pos().Value() >
1542 current->Start().NextInstruction().Value()) {
1543 // Do not spill live range eagerly if use position that can benefit from
1544 // the register is too close to the start of live range.
1545 SpillBetween(current, current->Start(), pos->pos());
1546 if (!AllocationOk()) return;
1547 DCHECK(UnhandledIsSorted());
1552 for (int i = 0; i < active_live_ranges_.length(); ++i) {
1553 LiveRange* cur_active = active_live_ranges_.at(i);
1554 if (cur_active->End().Value() <= position.Value()) {
1555 ActiveToHandled(cur_active);
1556 --i; // The live range was removed from the list of active live ranges.
1557 } else if (!cur_active->Covers(position)) {
1558 ActiveToInactive(cur_active);
1559 --i; // The live range was removed from the list of active live ranges.
1563 for (int i = 0; i < inactive_live_ranges_.length(); ++i) {
1564 LiveRange* cur_inactive = inactive_live_ranges_.at(i);
1565 if (cur_inactive->End().Value() <= position.Value()) {
1566 InactiveToHandled(cur_inactive);
1567 --i; // Live range was removed from the list of inactive live ranges.
1568 } else if (cur_inactive->Covers(position)) {
1569 InactiveToActive(cur_inactive);
1570 --i; // Live range was removed from the list of inactive live ranges.
1574 DCHECK(!current->HasRegisterAssigned() && !current->IsSpilled());
1576 bool result = TryAllocateFreeReg(current);
1577 if (!AllocationOk()) return;
1579 if (!result) AllocateBlockedReg(current);
1580 if (!AllocationOk()) return;
1582 if (current->HasRegisterAssigned()) {
1583 AddToActive(current);
1587 reusable_slots_.Rewind(0);
1588 active_live_ranges_.Rewind(0);
1589 inactive_live_ranges_.Rewind(0);
1593 const char* LAllocator::RegisterName(int allocation_index) {
1594 if (mode_ == GENERAL_REGISTERS) {
1595 return Register::AllocationIndexToString(allocation_index);
1597 return DoubleRegister::AllocationIndexToString(allocation_index);
1602 void LAllocator::TraceAlloc(const char* msg, ...) {
1603 if (FLAG_trace_alloc) {
1605 va_start(arguments, msg);
1606 base::OS::VPrint(msg, arguments);
1612 bool LAllocator::HasTaggedValue(int virtual_register) const {
1613 HValue* value = graph_->LookupValue(virtual_register);
1614 if (value == NULL) return false;
1615 return value->representation().IsTagged() && !value->type().IsSmi();
1619 RegisterKind LAllocator::RequiredRegisterKind(int virtual_register) const {
1620 if (virtual_register < first_artificial_register_) {
1621 HValue* value = graph_->LookupValue(virtual_register);
1622 if (value != NULL && value->representation().IsDouble()) {
1623 return DOUBLE_REGISTERS;
1625 } else if (double_artificial_registers_.Contains(
1626 virtual_register - first_artificial_register_)) {
1627 return DOUBLE_REGISTERS;
1630 return GENERAL_REGISTERS;
1634 void LAllocator::AddToActive(LiveRange* range) {
1635 TraceAlloc("Add live range %d to active\n", range->id());
1636 active_live_ranges_.Add(range, zone());
1640 void LAllocator::AddToInactive(LiveRange* range) {
1641 TraceAlloc("Add live range %d to inactive\n", range->id());
1642 inactive_live_ranges_.Add(range, zone());
1646 void LAllocator::AddToUnhandledSorted(LiveRange* range) {
1647 if (range == NULL || range->IsEmpty()) return;
1648 DCHECK(!range->HasRegisterAssigned() && !range->IsSpilled());
1649 DCHECK(allocation_finger_.Value() <= range->Start().Value());
1650 for (int i = unhandled_live_ranges_.length() - 1; i >= 0; --i) {
1651 LiveRange* cur_range = unhandled_live_ranges_.at(i);
1652 if (range->ShouldBeAllocatedBefore(cur_range)) {
1653 TraceAlloc("Add live range %d to unhandled at %d\n", range->id(), i + 1);
1654 unhandled_live_ranges_.InsertAt(i + 1, range, zone());
1655 DCHECK(UnhandledIsSorted());
1659 TraceAlloc("Add live range %d to unhandled at start\n", range->id());
1660 unhandled_live_ranges_.InsertAt(0, range, zone());
1661 DCHECK(UnhandledIsSorted());
1665 void LAllocator::AddToUnhandledUnsorted(LiveRange* range) {
1666 if (range == NULL || range->IsEmpty()) return;
1667 DCHECK(!range->HasRegisterAssigned() && !range->IsSpilled());
1668 TraceAlloc("Add live range %d to unhandled unsorted at end\n", range->id());
1669 unhandled_live_ranges_.Add(range, zone());
1673 static int UnhandledSortHelper(LiveRange* const* a, LiveRange* const* b) {
1674 DCHECK(!(*a)->ShouldBeAllocatedBefore(*b) ||
1675 !(*b)->ShouldBeAllocatedBefore(*a));
1676 if ((*a)->ShouldBeAllocatedBefore(*b)) return 1;
1677 if ((*b)->ShouldBeAllocatedBefore(*a)) return -1;
1678 return (*a)->id() - (*b)->id();
1682 // Sort the unhandled live ranges so that the ranges to be processed first are
1683 // at the end of the array list. This is convenient for the register allocation
1684 // algorithm because it is efficient to remove elements from the end.
1685 void LAllocator::SortUnhandled() {
1686 TraceAlloc("Sort unhandled\n");
1687 unhandled_live_ranges_.Sort(&UnhandledSortHelper);
1691 bool LAllocator::UnhandledIsSorted() {
1692 int len = unhandled_live_ranges_.length();
1693 for (int i = 1; i < len; i++) {
1694 LiveRange* a = unhandled_live_ranges_.at(i - 1);
1695 LiveRange* b = unhandled_live_ranges_.at(i);
1696 if (a->Start().Value() < b->Start().Value()) return false;
1702 void LAllocator::FreeSpillSlot(LiveRange* range) {
1703 // Check that we are the last range.
1704 if (range->next() != NULL) return;
1706 if (!range->TopLevel()->HasAllocatedSpillOperand()) return;
1708 int index = range->TopLevel()->GetSpillOperand()->index();
1710 reusable_slots_.Add(range, zone());
1715 LOperand* LAllocator::TryReuseSpillSlot(LiveRange* range) {
1716 if (reusable_slots_.is_empty()) return NULL;
1717 if (reusable_slots_.first()->End().Value() >
1718 range->TopLevel()->Start().Value()) {
1721 LOperand* result = reusable_slots_.first()->TopLevel()->GetSpillOperand();
1722 reusable_slots_.Remove(0);
1727 void LAllocator::ActiveToHandled(LiveRange* range) {
1728 DCHECK(active_live_ranges_.Contains(range));
1729 active_live_ranges_.RemoveElement(range);
1730 TraceAlloc("Moving live range %d from active to handled\n", range->id());
1731 FreeSpillSlot(range);
1735 void LAllocator::ActiveToInactive(LiveRange* range) {
1736 DCHECK(active_live_ranges_.Contains(range));
1737 active_live_ranges_.RemoveElement(range);
1738 inactive_live_ranges_.Add(range, zone());
1739 TraceAlloc("Moving live range %d from active to inactive\n", range->id());
1743 void LAllocator::InactiveToHandled(LiveRange* range) {
1744 DCHECK(inactive_live_ranges_.Contains(range));
1745 inactive_live_ranges_.RemoveElement(range);
1746 TraceAlloc("Moving live range %d from inactive to handled\n", range->id());
1747 FreeSpillSlot(range);
1751 void LAllocator::InactiveToActive(LiveRange* range) {
1752 DCHECK(inactive_live_ranges_.Contains(range));
1753 inactive_live_ranges_.RemoveElement(range);
1754 active_live_ranges_.Add(range, zone());
1755 TraceAlloc("Moving live range %d from inactive to active\n", range->id());
1759 // TryAllocateFreeReg and AllocateBlockedReg assume this
1760 // when allocating local arrays.
1761 STATIC_ASSERT(DoubleRegister::kMaxNumAllocatableRegisters >=
1762 Register::kMaxNumAllocatableRegisters);
1765 bool LAllocator::TryAllocateFreeReg(LiveRange* current) {
1766 LifetimePosition free_until_pos[DoubleRegister::kMaxNumAllocatableRegisters];
1768 for (int i = 0; i < num_registers_; i++) {
1769 free_until_pos[i] = LifetimePosition::MaxPosition();
1772 for (int i = 0; i < active_live_ranges_.length(); ++i) {
1773 LiveRange* cur_active = active_live_ranges_.at(i);
1774 free_until_pos[cur_active->assigned_register()] =
1775 LifetimePosition::FromInstructionIndex(0);
1778 for (int i = 0; i < inactive_live_ranges_.length(); ++i) {
1779 LiveRange* cur_inactive = inactive_live_ranges_.at(i);
1780 DCHECK(cur_inactive->End().Value() > current->Start().Value());
1781 LifetimePosition next_intersection =
1782 cur_inactive->FirstIntersection(current);
1783 if (!next_intersection.IsValid()) continue;
1784 int cur_reg = cur_inactive->assigned_register();
1785 free_until_pos[cur_reg] = Min(free_until_pos[cur_reg], next_intersection);
1788 LOperand* hint = current->FirstHint();
1789 if (hint != NULL && (hint->IsRegister() || hint->IsDoubleRegister())) {
1790 int register_index = hint->index();
1792 "Found reg hint %s (free until [%d) for live range %d (end %d[).\n",
1793 RegisterName(register_index),
1794 free_until_pos[register_index].Value(),
1796 current->End().Value());
1798 // The desired register is free until the end of the current live range.
1799 if (free_until_pos[register_index].Value() >= current->End().Value()) {
1800 TraceAlloc("Assigning preferred reg %s to live range %d\n",
1801 RegisterName(register_index),
1803 SetLiveRangeAssignedRegister(current, register_index);
1808 // Find the register which stays free for the longest time.
1810 for (int i = 1; i < RegisterCount(); ++i) {
1811 if (free_until_pos[i].Value() > free_until_pos[reg].Value()) {
1816 LifetimePosition pos = free_until_pos[reg];
1818 if (pos.Value() <= current->Start().Value()) {
1819 // All registers are blocked.
1823 if (pos.Value() < current->End().Value()) {
1824 // Register reg is available at the range start but becomes blocked before
1825 // the range end. Split current at position where it becomes blocked.
1826 LiveRange* tail = SplitRangeAt(current, pos);
1827 if (!AllocationOk()) return false;
1828 AddToUnhandledSorted(tail);
1832 // Register reg is available at the range start and is free until
1834 DCHECK(pos.Value() >= current->End().Value());
1835 TraceAlloc("Assigning free reg %s to live range %d\n",
1838 SetLiveRangeAssignedRegister(current, reg);
1844 void LAllocator::AllocateBlockedReg(LiveRange* current) {
1845 UsePosition* register_use = current->NextRegisterPosition(current->Start());
1846 if (register_use == NULL) {
1847 // There is no use in the current live range that requires a register.
1848 // We can just spill it.
1854 LifetimePosition use_pos[DoubleRegister::kMaxNumAllocatableRegisters];
1855 LifetimePosition block_pos[DoubleRegister::kMaxNumAllocatableRegisters];
1857 for (int i = 0; i < num_registers_; i++) {
1858 use_pos[i] = block_pos[i] = LifetimePosition::MaxPosition();
1861 for (int i = 0; i < active_live_ranges_.length(); ++i) {
1862 LiveRange* range = active_live_ranges_[i];
1863 int cur_reg = range->assigned_register();
1864 if (range->IsFixed() || !range->CanBeSpilled(current->Start())) {
1865 block_pos[cur_reg] = use_pos[cur_reg] =
1866 LifetimePosition::FromInstructionIndex(0);
1868 UsePosition* next_use = range->NextUsePositionRegisterIsBeneficial(
1870 if (next_use == NULL) {
1871 use_pos[cur_reg] = range->End();
1873 use_pos[cur_reg] = next_use->pos();
1878 for (int i = 0; i < inactive_live_ranges_.length(); ++i) {
1879 LiveRange* range = inactive_live_ranges_.at(i);
1880 DCHECK(range->End().Value() > current->Start().Value());
1881 LifetimePosition next_intersection = range->FirstIntersection(current);
1882 if (!next_intersection.IsValid()) continue;
1883 int cur_reg = range->assigned_register();
1884 if (range->IsFixed()) {
1885 block_pos[cur_reg] = Min(block_pos[cur_reg], next_intersection);
1886 use_pos[cur_reg] = Min(block_pos[cur_reg], use_pos[cur_reg]);
1888 use_pos[cur_reg] = Min(use_pos[cur_reg], next_intersection);
1893 for (int i = 1; i < RegisterCount(); ++i) {
1894 if (use_pos[i].Value() > use_pos[reg].Value()) {
1899 LifetimePosition pos = use_pos[reg];
1901 if (pos.Value() < register_use->pos().Value()) {
1902 // All registers are blocked before the first use that requires a register.
1903 // Spill starting part of live range up to that use.
1904 SpillBetween(current, current->Start(), register_use->pos());
1908 if (block_pos[reg].Value() < current->End().Value()) {
1909 // Register becomes blocked before the current range end. Split before that
1911 LiveRange* tail = SplitBetween(current,
1913 block_pos[reg].InstructionStart());
1914 if (!AllocationOk()) return;
1915 AddToUnhandledSorted(tail);
1918 // Register reg is not blocked for the whole range.
1919 DCHECK(block_pos[reg].Value() >= current->End().Value());
1920 TraceAlloc("Assigning blocked reg %s to live range %d\n",
1923 SetLiveRangeAssignedRegister(current, reg);
1925 // This register was not free. Thus we need to find and spill
1926 // parts of active and inactive live regions that use the same register
1927 // at the same lifetime positions as current.
1928 SplitAndSpillIntersecting(current);
1932 LifetimePosition LAllocator::FindOptimalSpillingPos(LiveRange* range,
1933 LifetimePosition pos) {
1934 HBasicBlock* block = GetBlock(pos.InstructionStart());
1935 HBasicBlock* loop_header =
1936 block->IsLoopHeader() ? block : block->parent_loop_header();
1938 if (loop_header == NULL) return pos;
1940 UsePosition* prev_use =
1941 range->PreviousUsePositionRegisterIsBeneficial(pos);
1943 while (loop_header != NULL) {
1944 // We are going to spill live range inside the loop.
1945 // If possible try to move spilling position backwards to loop header.
1946 // This will reduce number of memory moves on the back edge.
1947 LifetimePosition loop_start = LifetimePosition::FromInstructionIndex(
1948 loop_header->first_instruction_index());
1950 if (range->Covers(loop_start)) {
1951 if (prev_use == NULL || prev_use->pos().Value() < loop_start.Value()) {
1952 // No register beneficial use inside the loop before the pos.
1957 // Try hoisting out to an outer loop.
1958 loop_header = loop_header->parent_loop_header();
1965 void LAllocator::SplitAndSpillIntersecting(LiveRange* current) {
1966 DCHECK(current->HasRegisterAssigned());
1967 int reg = current->assigned_register();
1968 LifetimePosition split_pos = current->Start();
1969 for (int i = 0; i < active_live_ranges_.length(); ++i) {
1970 LiveRange* range = active_live_ranges_[i];
1971 if (range->assigned_register() == reg) {
1972 UsePosition* next_pos = range->NextRegisterPosition(current->Start());
1973 LifetimePosition spill_pos = FindOptimalSpillingPos(range, split_pos);
1974 if (next_pos == NULL) {
1975 SpillAfter(range, spill_pos);
1977 // When spilling between spill_pos and next_pos ensure that the range
1978 // remains spilled at least until the start of the current live range.
1979 // This guarantees that we will not introduce new unhandled ranges that
1980 // start before the current range as this violates allocation invariant
1981 // and will lead to an inconsistent state of active and inactive
1982 // live-ranges: ranges are allocated in order of their start positions,
1983 // ranges are retired from active/inactive when the start of the
1984 // current live-range is larger than their end.
1985 SpillBetweenUntil(range, spill_pos, current->Start(), next_pos->pos());
1987 if (!AllocationOk()) return;
1988 ActiveToHandled(range);
1993 for (int i = 0; i < inactive_live_ranges_.length(); ++i) {
1994 LiveRange* range = inactive_live_ranges_[i];
1995 DCHECK(range->End().Value() > current->Start().Value());
1996 if (range->assigned_register() == reg && !range->IsFixed()) {
1997 LifetimePosition next_intersection = range->FirstIntersection(current);
1998 if (next_intersection.IsValid()) {
1999 UsePosition* next_pos = range->NextRegisterPosition(current->Start());
2000 if (next_pos == NULL) {
2001 SpillAfter(range, split_pos);
2003 next_intersection = Min(next_intersection, next_pos->pos());
2004 SpillBetween(range, split_pos, next_intersection);
2006 if (!AllocationOk()) return;
2007 InactiveToHandled(range);
2015 bool LAllocator::IsBlockBoundary(LifetimePosition pos) {
2016 return pos.IsInstructionStart() &&
2017 InstructionAt(pos.InstructionIndex())->IsLabel();
2021 LiveRange* LAllocator::SplitRangeAt(LiveRange* range, LifetimePosition pos) {
2022 DCHECK(!range->IsFixed());
2023 TraceAlloc("Splitting live range %d at %d\n", range->id(), pos.Value());
2025 if (pos.Value() <= range->Start().Value()) return range;
2027 // We can't properly connect liveranges if split occured at the end
2028 // of control instruction.
2029 DCHECK(pos.IsInstructionStart() ||
2030 !chunk_->instructions()->at(pos.InstructionIndex())->IsControl());
2032 int vreg = GetVirtualRegister();
2033 if (!AllocationOk()) return NULL;
2034 LiveRange* result = LiveRangeFor(vreg);
2035 range->SplitAt(pos, result, zone());
2040 LiveRange* LAllocator::SplitBetween(LiveRange* range,
2041 LifetimePosition start,
2042 LifetimePosition end) {
2043 DCHECK(!range->IsFixed());
2044 TraceAlloc("Splitting live range %d in position between [%d, %d]\n",
2049 LifetimePosition split_pos = FindOptimalSplitPos(start, end);
2050 DCHECK(split_pos.Value() >= start.Value());
2051 return SplitRangeAt(range, split_pos);
2055 LifetimePosition LAllocator::FindOptimalSplitPos(LifetimePosition start,
2056 LifetimePosition end) {
2057 int start_instr = start.InstructionIndex();
2058 int end_instr = end.InstructionIndex();
2059 DCHECK(start_instr <= end_instr);
2061 // We have no choice
2062 if (start_instr == end_instr) return end;
2064 HBasicBlock* start_block = GetBlock(start);
2065 HBasicBlock* end_block = GetBlock(end);
2067 if (end_block == start_block) {
2068 // The interval is split in the same basic block. Split at the latest
2069 // possible position.
2073 HBasicBlock* block = end_block;
2074 // Find header of outermost loop.
2075 while (block->parent_loop_header() != NULL &&
2076 block->parent_loop_header()->block_id() > start_block->block_id()) {
2077 block = block->parent_loop_header();
2080 // We did not find any suitable outer loop. Split at the latest possible
2081 // position unless end_block is a loop header itself.
2082 if (block == end_block && !end_block->IsLoopHeader()) return end;
2084 return LifetimePosition::FromInstructionIndex(
2085 block->first_instruction_index());
2089 void LAllocator::SpillAfter(LiveRange* range, LifetimePosition pos) {
2090 LiveRange* second_part = SplitRangeAt(range, pos);
2091 if (!AllocationOk()) return;
2096 void LAllocator::SpillBetween(LiveRange* range,
2097 LifetimePosition start,
2098 LifetimePosition end) {
2099 SpillBetweenUntil(range, start, start, end);
2103 void LAllocator::SpillBetweenUntil(LiveRange* range,
2104 LifetimePosition start,
2105 LifetimePosition until,
2106 LifetimePosition end) {
2107 CHECK(start.Value() < end.Value());
2108 LiveRange* second_part = SplitRangeAt(range, start);
2109 if (!AllocationOk()) return;
2111 if (second_part->Start().Value() < end.Value()) {
2112 // The split result intersects with [start, end[.
2113 // Split it at position between ]start+1, end[, spill the middle part
2114 // and put the rest to unhandled.
2115 LiveRange* third_part = SplitBetween(
2117 Max(second_part->Start().InstructionEnd(), until),
2118 end.PrevInstruction().InstructionEnd());
2119 if (!AllocationOk()) return;
2121 DCHECK(third_part != second_part);
2124 AddToUnhandledSorted(third_part);
2126 // The split result does not intersect with [start, end[.
2127 // Nothing to spill. Just put it to unhandled as whole.
2128 AddToUnhandledSorted(second_part);
2133 void LAllocator::Spill(LiveRange* range) {
2134 DCHECK(!range->IsSpilled());
2135 TraceAlloc("Spilling live range %d\n", range->id());
2136 LiveRange* first = range->TopLevel();
2138 if (!first->HasAllocatedSpillOperand()) {
2139 LOperand* op = TryReuseSpillSlot(range);
2140 if (op == NULL) op = chunk_->GetNextSpillSlot(range->Kind());
2141 first->SetSpillOperand(op);
2143 range->MakeSpilled(chunk()->zone());
2147 int LAllocator::RegisterCount() const {
2148 return num_registers_;
2155 void LAllocator::Verify() const {
2156 for (int i = 0; i < live_ranges()->length(); ++i) {
2157 LiveRange* current = live_ranges()->at(i);
2158 if (current != NULL) current->Verify();
2166 LAllocatorPhase::LAllocatorPhase(const char* name, LAllocator* allocator)
2167 : CompilationPhase(name, allocator->graph()->info()),
2168 allocator_(allocator) {
2169 if (FLAG_hydrogen_stats) {
2170 allocator_zone_start_allocation_size_ =
2171 allocator->zone()->allocation_size();
2176 LAllocatorPhase::~LAllocatorPhase() {
2177 if (FLAG_hydrogen_stats) {
2178 unsigned size = allocator_->zone()->allocation_size() -
2179 allocator_zone_start_allocation_size_;
2180 isolate()->GetHStatistics()->SaveTiming(name(), base::TimeDelta(), size);
2183 if (ShouldProduceTraceOutput()) {
2184 isolate()->GetHTracer()->TraceLithium(name(), allocator_->chunk());
2185 isolate()->GetHTracer()->TraceLiveRanges(name(), allocator_);
2189 if (allocator_ != NULL) allocator_->Verify();
2194 } } // namespace v8::internal