| // Copyright 2012 the V8 project authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "src/crankshaft/lithium-allocator.h" |
| |
| #include "src/crankshaft/hydrogen.h" |
| #include "src/crankshaft/lithium-inl.h" |
| #include "src/crankshaft/lithium-allocator-inl.h" |
| #include "src/register-configuration.h" |
| #include "src/string-stream.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| const auto GetRegConfig = RegisterConfiguration::Crankshaft; |
| |
| static inline LifetimePosition Min(LifetimePosition a, LifetimePosition b) { |
| return a.Value() < b.Value() ? a : b; |
| } |
| |
| |
| static inline LifetimePosition Max(LifetimePosition a, LifetimePosition b) { |
| return a.Value() > b.Value() ? a : b; |
| } |
| |
| |
| UsePosition::UsePosition(LifetimePosition pos, |
| LOperand* operand, |
| LOperand* hint) |
| : operand_(operand), |
| hint_(hint), |
| pos_(pos), |
| next_(NULL), |
| requires_reg_(false), |
| register_beneficial_(true) { |
| if (operand_ != NULL && operand_->IsUnallocated()) { |
| LUnallocated* unalloc = LUnallocated::cast(operand_); |
| requires_reg_ = unalloc->HasRegisterPolicy() || |
| unalloc->HasDoubleRegisterPolicy(); |
| register_beneficial_ = !unalloc->HasAnyPolicy(); |
| } |
| DCHECK(pos_.IsValid()); |
| } |
| |
| |
| bool UsePosition::HasHint() const { |
| return hint_ != NULL && !hint_->IsUnallocated(); |
| } |
| |
| |
| bool UsePosition::RequiresRegister() const { |
| return requires_reg_; |
| } |
| |
| |
| bool UsePosition::RegisterIsBeneficial() const { |
| return register_beneficial_; |
| } |
| |
| |
| void UseInterval::SplitAt(LifetimePosition pos, Zone* zone) { |
| DCHECK(Contains(pos) && pos.Value() != start().Value()); |
| UseInterval* after = new(zone) UseInterval(pos, end_); |
| after->next_ = next_; |
| next_ = after; |
| end_ = pos; |
| } |
| |
| |
| #ifdef DEBUG |
| |
| |
| void LiveRange::Verify() const { |
| UsePosition* cur = first_pos_; |
| while (cur != NULL) { |
| DCHECK(Start().Value() <= cur->pos().Value() && |
| cur->pos().Value() <= End().Value()); |
| cur = cur->next(); |
| } |
| } |
| |
| |
| bool LiveRange::HasOverlap(UseInterval* target) const { |
| UseInterval* current_interval = first_interval_; |
| while (current_interval != NULL) { |
| // Intervals overlap if the start of one is contained in the other. |
| if (current_interval->Contains(target->start()) || |
| target->Contains(current_interval->start())) { |
| return true; |
| } |
| current_interval = current_interval->next(); |
| } |
| return false; |
| } |
| |
| |
| #endif |
| |
| |
| LiveRange::LiveRange(int id, Zone* zone) |
| : id_(id), |
| spilled_(false), |
| kind_(UNALLOCATED_REGISTERS), |
| assigned_register_(kInvalidAssignment), |
| last_interval_(NULL), |
| first_interval_(NULL), |
| first_pos_(NULL), |
| parent_(NULL), |
| next_(NULL), |
| current_interval_(NULL), |
| last_processed_use_(NULL), |
| current_hint_operand_(NULL), |
| spill_operand_(new (zone) LOperand()), |
| spill_start_index_(kMaxInt) {} |
| |
| |
| void LiveRange::set_assigned_register(int reg, Zone* zone) { |
| DCHECK(!HasRegisterAssigned() && !IsSpilled()); |
| assigned_register_ = reg; |
| ConvertOperands(zone); |
| } |
| |
| |
| void LiveRange::MakeSpilled(Zone* zone) { |
| DCHECK(!IsSpilled()); |
| DCHECK(TopLevel()->HasAllocatedSpillOperand()); |
| spilled_ = true; |
| assigned_register_ = kInvalidAssignment; |
| ConvertOperands(zone); |
| } |
| |
| |
| bool LiveRange::HasAllocatedSpillOperand() const { |
| DCHECK(spill_operand_ != NULL); |
| return !spill_operand_->IsIgnored(); |
| } |
| |
| |
| void LiveRange::SetSpillOperand(LOperand* operand) { |
| DCHECK(!operand->IsUnallocated()); |
| DCHECK(spill_operand_ != NULL); |
| DCHECK(spill_operand_->IsIgnored()); |
| spill_operand_->ConvertTo(operand->kind(), operand->index()); |
| } |
| |
| |
| UsePosition* LiveRange::NextUsePosition(LifetimePosition start) { |
| UsePosition* use_pos = last_processed_use_; |
| if (use_pos == NULL) use_pos = first_pos(); |
| while (use_pos != NULL && use_pos->pos().Value() < start.Value()) { |
| use_pos = use_pos->next(); |
| } |
| last_processed_use_ = use_pos; |
| return use_pos; |
| } |
| |
| |
| UsePosition* LiveRange::NextUsePositionRegisterIsBeneficial( |
| LifetimePosition start) { |
| UsePosition* pos = NextUsePosition(start); |
| while (pos != NULL && !pos->RegisterIsBeneficial()) { |
| pos = pos->next(); |
| } |
| return pos; |
| } |
| |
| |
| UsePosition* LiveRange::PreviousUsePositionRegisterIsBeneficial( |
| LifetimePosition start) { |
| UsePosition* pos = first_pos(); |
| UsePosition* prev = NULL; |
| while (pos != NULL && pos->pos().Value() < start.Value()) { |
| if (pos->RegisterIsBeneficial()) prev = pos; |
| pos = pos->next(); |
| } |
| return prev; |
| } |
| |
| |
| UsePosition* LiveRange::NextRegisterPosition(LifetimePosition start) { |
| UsePosition* pos = NextUsePosition(start); |
| while (pos != NULL && !pos->RequiresRegister()) { |
| pos = pos->next(); |
| } |
| return pos; |
| } |
| |
| |
| bool LiveRange::CanBeSpilled(LifetimePosition pos) { |
| // We cannot spill a live range that has a use requiring a register |
| // at the current or the immediate next position. |
| UsePosition* use_pos = NextRegisterPosition(pos); |
| if (use_pos == NULL) return true; |
| return |
| use_pos->pos().Value() > pos.NextInstruction().InstructionEnd().Value(); |
| } |
| |
| |
| LOperand* LiveRange::CreateAssignedOperand(Zone* zone) { |
| LOperand* op = NULL; |
| if (HasRegisterAssigned()) { |
| DCHECK(!IsSpilled()); |
| switch (Kind()) { |
| case GENERAL_REGISTERS: |
| op = LRegister::Create(assigned_register(), zone); |
| break; |
| case DOUBLE_REGISTERS: |
| op = LDoubleRegister::Create(assigned_register(), zone); |
| break; |
| default: |
| UNREACHABLE(); |
| } |
| } else if (IsSpilled()) { |
| DCHECK(!HasRegisterAssigned()); |
| op = TopLevel()->GetSpillOperand(); |
| DCHECK(!op->IsUnallocated()); |
| } else { |
| LUnallocated* unalloc = new(zone) LUnallocated(LUnallocated::NONE); |
| unalloc->set_virtual_register(id_); |
| op = unalloc; |
| } |
| return op; |
| } |
| |
| |
| UseInterval* LiveRange::FirstSearchIntervalForPosition( |
| LifetimePosition position) const { |
| if (current_interval_ == NULL) return first_interval_; |
| if (current_interval_->start().Value() > position.Value()) { |
| current_interval_ = NULL; |
| return first_interval_; |
| } |
| return current_interval_; |
| } |
| |
| |
| void LiveRange::AdvanceLastProcessedMarker( |
| UseInterval* to_start_of, LifetimePosition but_not_past) const { |
| if (to_start_of == NULL) return; |
| if (to_start_of->start().Value() > but_not_past.Value()) return; |
| LifetimePosition start = |
| current_interval_ == NULL ? LifetimePosition::Invalid() |
| : current_interval_->start(); |
| if (to_start_of->start().Value() > start.Value()) { |
| current_interval_ = to_start_of; |
| } |
| } |
| |
| |
| void LiveRange::SplitAt(LifetimePosition position, |
| LiveRange* result, |
| Zone* zone) { |
| DCHECK(Start().Value() < position.Value()); |
| DCHECK(result->IsEmpty()); |
| // Find the last interval that ends before the position. If the |
| // position is contained in one of the intervals in the chain, we |
| // split that interval and use the first part. |
| UseInterval* current = FirstSearchIntervalForPosition(position); |
| |
| // If the split position coincides with the beginning of a use interval |
| // we need to split use positons in a special way. |
| bool split_at_start = false; |
| |
| if (current->start().Value() == position.Value()) { |
| // When splitting at start we need to locate the previous use interval. |
| current = first_interval_; |
| } |
| |
| while (current != NULL) { |
| if (current->Contains(position)) { |
| current->SplitAt(position, zone); |
| break; |
| } |
| UseInterval* next = current->next(); |
| if (next->start().Value() >= position.Value()) { |
| split_at_start = (next->start().Value() == position.Value()); |
| break; |
| } |
| current = next; |
| } |
| |
| // Partition original use intervals to the two live ranges. |
| UseInterval* before = current; |
| UseInterval* after = before->next(); |
| result->last_interval_ = (last_interval_ == before) |
| ? after // Only interval in the range after split. |
| : last_interval_; // Last interval of the original range. |
| result->first_interval_ = after; |
| last_interval_ = before; |
| |
| // Find the last use position before the split and the first use |
| // position after it. |
| UsePosition* use_after = first_pos_; |
| UsePosition* use_before = NULL; |
| if (split_at_start) { |
| // The split position coincides with the beginning of a use interval (the |
| // end of a lifetime hole). Use at this position should be attributed to |
| // the split child because split child owns use interval covering it. |
| while (use_after != NULL && use_after->pos().Value() < position.Value()) { |
| use_before = use_after; |
| use_after = use_after->next(); |
| } |
| } else { |
| while (use_after != NULL && use_after->pos().Value() <= position.Value()) { |
| use_before = use_after; |
| use_after = use_after->next(); |
| } |
| } |
| |
| // Partition original use positions to the two live ranges. |
| if (use_before != NULL) { |
| use_before->next_ = NULL; |
| } else { |
| first_pos_ = NULL; |
| } |
| result->first_pos_ = use_after; |
| |
| // Discard cached iteration state. It might be pointing |
| // to the use that no longer belongs to this live range. |
| last_processed_use_ = NULL; |
| current_interval_ = NULL; |
| |
| // Link the new live range in the chain before any of the other |
| // ranges linked from the range before the split. |
| result->parent_ = (parent_ == NULL) ? this : parent_; |
| result->kind_ = result->parent_->kind_; |
| result->next_ = next_; |
| next_ = result; |
| |
| #ifdef DEBUG |
| Verify(); |
| result->Verify(); |
| #endif |
| } |
| |
| |
| // This implements an ordering on live ranges so that they are ordered by their |
| // start positions. This is needed for the correctness of the register |
| // allocation algorithm. If two live ranges start at the same offset then there |
| // is a tie breaker based on where the value is first used. This part of the |
| // ordering is merely a heuristic. |
| bool LiveRange::ShouldBeAllocatedBefore(const LiveRange* other) const { |
| LifetimePosition start = Start(); |
| LifetimePosition other_start = other->Start(); |
| if (start.Value() == other_start.Value()) { |
| UsePosition* pos = first_pos(); |
| if (pos == NULL) return false; |
| UsePosition* other_pos = other->first_pos(); |
| if (other_pos == NULL) return true; |
| return pos->pos().Value() < other_pos->pos().Value(); |
| } |
| return start.Value() < other_start.Value(); |
| } |
| |
| |
| void LiveRange::ShortenTo(LifetimePosition start) { |
| LAllocator::TraceAlloc("Shorten live range %d to [%d\n", id_, start.Value()); |
| DCHECK(first_interval_ != NULL); |
| DCHECK(first_interval_->start().Value() <= start.Value()); |
| DCHECK(start.Value() < first_interval_->end().Value()); |
| first_interval_->set_start(start); |
| } |
| |
| |
| void LiveRange::EnsureInterval(LifetimePosition start, |
| LifetimePosition end, |
| Zone* zone) { |
| LAllocator::TraceAlloc("Ensure live range %d in interval [%d %d[\n", |
| id_, |
| start.Value(), |
| end.Value()); |
| LifetimePosition new_end = end; |
| while (first_interval_ != NULL && |
| first_interval_->start().Value() <= end.Value()) { |
| if (first_interval_->end().Value() > end.Value()) { |
| new_end = first_interval_->end(); |
| } |
| first_interval_ = first_interval_->next(); |
| } |
| |
| UseInterval* new_interval = new(zone) UseInterval(start, new_end); |
| new_interval->next_ = first_interval_; |
| first_interval_ = new_interval; |
| if (new_interval->next() == NULL) { |
| last_interval_ = new_interval; |
| } |
| } |
| |
| |
| void LiveRange::AddUseInterval(LifetimePosition start, |
| LifetimePosition end, |
| Zone* zone) { |
| LAllocator::TraceAlloc("Add to live range %d interval [%d %d[\n", |
| id_, |
| start.Value(), |
| end.Value()); |
| if (first_interval_ == NULL) { |
| UseInterval* interval = new(zone) UseInterval(start, end); |
| first_interval_ = interval; |
| last_interval_ = interval; |
| } else { |
| if (end.Value() == first_interval_->start().Value()) { |
| first_interval_->set_start(start); |
| } else if (end.Value() < first_interval_->start().Value()) { |
| UseInterval* interval = new(zone) UseInterval(start, end); |
| interval->set_next(first_interval_); |
| first_interval_ = interval; |
| } else { |
| // Order of instruction's processing (see ProcessInstructions) guarantees |
| // that each new use interval either precedes or intersects with |
| // last added interval. |
| DCHECK(start.Value() < first_interval_->end().Value()); |
| first_interval_->start_ = Min(start, first_interval_->start_); |
| first_interval_->end_ = Max(end, first_interval_->end_); |
| } |
| } |
| } |
| |
| |
| void LiveRange::AddUsePosition(LifetimePosition pos, |
| LOperand* operand, |
| LOperand* hint, |
| Zone* zone) { |
| LAllocator::TraceAlloc("Add to live range %d use position %d\n", |
| id_, |
| pos.Value()); |
| UsePosition* use_pos = new(zone) UsePosition(pos, operand, hint); |
| UsePosition* prev_hint = NULL; |
| UsePosition* prev = NULL; |
| UsePosition* current = first_pos_; |
| while (current != NULL && current->pos().Value() < pos.Value()) { |
| prev_hint = current->HasHint() ? current : prev_hint; |
| prev = current; |
| current = current->next(); |
| } |
| |
| if (prev == NULL) { |
| use_pos->set_next(first_pos_); |
| first_pos_ = use_pos; |
| } else { |
| use_pos->next_ = prev->next_; |
| prev->next_ = use_pos; |
| } |
| |
| if (prev_hint == NULL && use_pos->HasHint()) { |
| current_hint_operand_ = hint; |
| } |
| } |
| |
| |
| void LiveRange::ConvertOperands(Zone* zone) { |
| LOperand* op = CreateAssignedOperand(zone); |
| UsePosition* use_pos = first_pos(); |
| while (use_pos != NULL) { |
| DCHECK(Start().Value() <= use_pos->pos().Value() && |
| use_pos->pos().Value() <= End().Value()); |
| |
| if (use_pos->HasOperand()) { |
| DCHECK(op->IsRegister() || op->IsDoubleRegister() || |
| !use_pos->RequiresRegister()); |
| use_pos->operand()->ConvertTo(op->kind(), op->index()); |
| } |
| use_pos = use_pos->next(); |
| } |
| } |
| |
| |
| bool LiveRange::CanCover(LifetimePosition position) const { |
| if (IsEmpty()) return false; |
| return Start().Value() <= position.Value() && |
| position.Value() < End().Value(); |
| } |
| |
| |
| bool LiveRange::Covers(LifetimePosition position) { |
| if (!CanCover(position)) return false; |
| UseInterval* start_search = FirstSearchIntervalForPosition(position); |
| for (UseInterval* interval = start_search; |
| interval != NULL; |
| interval = interval->next()) { |
| DCHECK(interval->next() == NULL || |
| interval->next()->start().Value() >= interval->start().Value()); |
| AdvanceLastProcessedMarker(interval, position); |
| if (interval->Contains(position)) return true; |
| if (interval->start().Value() > position.Value()) return false; |
| } |
| return false; |
| } |
| |
| |
| LifetimePosition LiveRange::FirstIntersection(LiveRange* other) { |
| UseInterval* b = other->first_interval(); |
| if (b == NULL) return LifetimePosition::Invalid(); |
| LifetimePosition advance_last_processed_up_to = b->start(); |
| UseInterval* a = FirstSearchIntervalForPosition(b->start()); |
| while (a != NULL && b != NULL) { |
| if (a->start().Value() > other->End().Value()) break; |
| if (b->start().Value() > End().Value()) break; |
| LifetimePosition cur_intersection = a->Intersect(b); |
| if (cur_intersection.IsValid()) { |
| return cur_intersection; |
| } |
| if (a->start().Value() < b->start().Value()) { |
| a = a->next(); |
| if (a == NULL || a->start().Value() > other->End().Value()) break; |
| AdvanceLastProcessedMarker(a, advance_last_processed_up_to); |
| } else { |
| b = b->next(); |
| } |
| } |
| return LifetimePosition::Invalid(); |
| } |
| |
| LAllocator::LAllocator(int num_values, HGraph* graph) |
| : zone_(graph->isolate()->allocator(), ZONE_NAME), |
| chunk_(NULL), |
| live_in_sets_(graph->blocks()->length(), zone()), |
| live_ranges_(num_values * 2, zone()), |
| fixed_live_ranges_(NULL), |
| fixed_double_live_ranges_(NULL), |
| unhandled_live_ranges_(num_values * 2, zone()), |
| active_live_ranges_(8, zone()), |
| inactive_live_ranges_(8, zone()), |
| reusable_slots_(8, zone()), |
| next_virtual_register_(num_values), |
| first_artificial_register_(num_values), |
| mode_(UNALLOCATED_REGISTERS), |
| num_registers_(-1), |
| graph_(graph), |
| has_osr_entry_(false), |
| allocation_ok_(true) {} |
| |
| void LAllocator::InitializeLivenessAnalysis() { |
| // Initialize the live_in sets for each block to NULL. |
| int block_count = graph_->blocks()->length(); |
| live_in_sets_.Initialize(block_count, zone()); |
| live_in_sets_.AddBlock(NULL, block_count, zone()); |
| } |
| |
| |
| BitVector* LAllocator::ComputeLiveOut(HBasicBlock* block) { |
| // Compute live out for the given block, except not including backward |
| // successor edges. |
| BitVector* live_out = new(zone()) BitVector(next_virtual_register_, zone()); |
| |
| // Process all successor blocks. |
| for (HSuccessorIterator it(block->end()); !it.Done(); it.Advance()) { |
| // Add values live on entry to the successor. Note the successor's |
| // live_in will not be computed yet for backwards edges. |
| HBasicBlock* successor = it.Current(); |
| BitVector* live_in = live_in_sets_[successor->block_id()]; |
| if (live_in != NULL) live_out->Union(*live_in); |
| |
| // All phi input operands corresponding to this successor edge are live |
| // out from this block. |
| int index = successor->PredecessorIndexOf(block); |
| const ZoneList<HPhi*>* phis = successor->phis(); |
| for (int i = 0; i < phis->length(); ++i) { |
| HPhi* phi = phis->at(i); |
| if (!phi->OperandAt(index)->IsConstant()) { |
| live_out->Add(phi->OperandAt(index)->id()); |
| } |
| } |
| } |
| |
| return live_out; |
| } |
| |
| |
| void LAllocator::AddInitialIntervals(HBasicBlock* block, |
| BitVector* live_out) { |
| // Add an interval that includes the entire block to the live range for |
| // each live_out value. |
| LifetimePosition start = LifetimePosition::FromInstructionIndex( |
| block->first_instruction_index()); |
| LifetimePosition end = LifetimePosition::FromInstructionIndex( |
| block->last_instruction_index()).NextInstruction(); |
| BitVector::Iterator iterator(live_out); |
| while (!iterator.Done()) { |
| int operand_index = iterator.Current(); |
| LiveRange* range = LiveRangeFor(operand_index); |
| range->AddUseInterval(start, end, zone()); |
| iterator.Advance(); |
| } |
| } |
| |
| |
| int LAllocator::FixedDoubleLiveRangeID(int index) { |
| return -index - 1 - Register::kNumRegisters; |
| } |
| |
| |
| LOperand* LAllocator::AllocateFixed(LUnallocated* operand, |
| int pos, |
| bool is_tagged) { |
| TraceAlloc("Allocating fixed reg for op %d\n", operand->virtual_register()); |
| DCHECK(operand->HasFixedPolicy()); |
| if (operand->HasFixedSlotPolicy()) { |
| operand->ConvertTo(LOperand::STACK_SLOT, operand->fixed_slot_index()); |
| } else if (operand->HasFixedRegisterPolicy()) { |
| int reg_index = operand->fixed_register_index(); |
| operand->ConvertTo(LOperand::REGISTER, reg_index); |
| } else if (operand->HasFixedDoubleRegisterPolicy()) { |
| int reg_index = operand->fixed_register_index(); |
| operand->ConvertTo(LOperand::DOUBLE_REGISTER, reg_index); |
| } else { |
| UNREACHABLE(); |
| } |
| if (is_tagged) { |
| TraceAlloc("Fixed reg is tagged at %d\n", pos); |
| LInstruction* instr = InstructionAt(pos); |
| if (instr->HasPointerMap()) { |
| instr->pointer_map()->RecordPointer(operand, chunk()->zone()); |
| } |
| } |
| return operand; |
| } |
| |
| |
| LiveRange* LAllocator::FixedLiveRangeFor(int index) { |
| DCHECK(index < Register::kNumRegisters); |
| LiveRange* result = fixed_live_ranges_[index]; |
| if (result == NULL) { |
| result = new(zone()) LiveRange(FixedLiveRangeID(index), chunk()->zone()); |
| DCHECK(result->IsFixed()); |
| result->kind_ = GENERAL_REGISTERS; |
| SetLiveRangeAssignedRegister(result, index); |
| fixed_live_ranges_[index] = result; |
| } |
| return result; |
| } |
| |
| |
| LiveRange* LAllocator::FixedDoubleLiveRangeFor(int index) { |
| DCHECK(index < DoubleRegister::kMaxNumRegisters); |
| LiveRange* result = fixed_double_live_ranges_[index]; |
| if (result == NULL) { |
| result = new(zone()) LiveRange(FixedDoubleLiveRangeID(index), |
| chunk()->zone()); |
| DCHECK(result->IsFixed()); |
| result->kind_ = DOUBLE_REGISTERS; |
| SetLiveRangeAssignedRegister(result, index); |
| fixed_double_live_ranges_[index] = result; |
| } |
| return result; |
| } |
| |
| |
| LiveRange* LAllocator::LiveRangeFor(int index) { |
| if (index >= live_ranges_.length()) { |
| live_ranges_.AddBlock(NULL, index - live_ranges_.length() + 1, zone()); |
| } |
| LiveRange* result = live_ranges_[index]; |
| if (result == NULL) { |
| result = new(zone()) LiveRange(index, chunk()->zone()); |
| live_ranges_[index] = result; |
| } |
| return result; |
| } |
| |
| |
| LGap* LAllocator::GetLastGap(HBasicBlock* block) { |
| int last_instruction = block->last_instruction_index(); |
| int index = chunk_->NearestGapPos(last_instruction); |
| return GapAt(index); |
| } |
| |
| |
| HPhi* LAllocator::LookupPhi(LOperand* operand) const { |
| if (!operand->IsUnallocated()) return NULL; |
| int index = LUnallocated::cast(operand)->virtual_register(); |
| HValue* instr = graph_->LookupValue(index); |
| if (instr != NULL && instr->IsPhi()) { |
| return HPhi::cast(instr); |
| } |
| return NULL; |
| } |
| |
| |
| LiveRange* LAllocator::LiveRangeFor(LOperand* operand) { |
| if (operand->IsUnallocated()) { |
| return LiveRangeFor(LUnallocated::cast(operand)->virtual_register()); |
| } else if (operand->IsRegister()) { |
| return FixedLiveRangeFor(operand->index()); |
| } else if (operand->IsDoubleRegister()) { |
| return FixedDoubleLiveRangeFor(operand->index()); |
| } else { |
| return NULL; |
| } |
| } |
| |
| |
| void LAllocator::Define(LifetimePosition position, |
| LOperand* operand, |
| LOperand* hint) { |
| LiveRange* range = LiveRangeFor(operand); |
| if (range == NULL) return; |
| |
| if (range->IsEmpty() || range->Start().Value() > position.Value()) { |
| // Can happen if there is a definition without use. |
| range->AddUseInterval(position, position.NextInstruction(), zone()); |
| range->AddUsePosition(position.NextInstruction(), NULL, NULL, zone()); |
| } else { |
| range->ShortenTo(position); |
| } |
| |
| if (operand->IsUnallocated()) { |
| LUnallocated* unalloc_operand = LUnallocated::cast(operand); |
| range->AddUsePosition(position, unalloc_operand, hint, zone()); |
| } |
| } |
| |
| |
| void LAllocator::Use(LifetimePosition block_start, |
| LifetimePosition position, |
| LOperand* operand, |
| LOperand* hint) { |
| LiveRange* range = LiveRangeFor(operand); |
| if (range == NULL) return; |
| if (operand->IsUnallocated()) { |
| LUnallocated* unalloc_operand = LUnallocated::cast(operand); |
| range->AddUsePosition(position, unalloc_operand, hint, zone()); |
| } |
| range->AddUseInterval(block_start, position, zone()); |
| } |
| |
| |
| void LAllocator::AddConstraintsGapMove(int index, |
| LOperand* from, |
| LOperand* to) { |
| LGap* gap = GapAt(index); |
| LParallelMove* move = gap->GetOrCreateParallelMove(LGap::START, |
| chunk()->zone()); |
| if (from->IsUnallocated()) { |
| const ZoneList<LMoveOperands>* move_operands = move->move_operands(); |
| for (int i = 0; i < move_operands->length(); ++i) { |
| LMoveOperands cur = move_operands->at(i); |
| LOperand* cur_to = cur.destination(); |
| if (cur_to->IsUnallocated()) { |
| if (LUnallocated::cast(cur_to)->virtual_register() == |
| LUnallocated::cast(from)->virtual_register()) { |
| move->AddMove(cur.source(), to, chunk()->zone()); |
| return; |
| } |
| } |
| } |
| } |
| move->AddMove(from, to, chunk()->zone()); |
| } |
| |
| |
| void LAllocator::MeetRegisterConstraints(HBasicBlock* block) { |
| int start = block->first_instruction_index(); |
| int end = block->last_instruction_index(); |
| if (start == -1) return; |
| for (int i = start; i <= end; ++i) { |
| if (IsGapAt(i)) { |
| LInstruction* instr = NULL; |
| LInstruction* prev_instr = NULL; |
| if (i < end) instr = InstructionAt(i + 1); |
| if (i > start) prev_instr = InstructionAt(i - 1); |
| MeetConstraintsBetween(prev_instr, instr, i); |
| if (!AllocationOk()) return; |
| } |
| } |
| } |
| |
| |
| void LAllocator::MeetConstraintsBetween(LInstruction* first, |
| LInstruction* second, |
| int gap_index) { |
| // Handle fixed temporaries. |
| if (first != NULL) { |
| for (TempIterator it(first); !it.Done(); it.Advance()) { |
| LUnallocated* temp = LUnallocated::cast(it.Current()); |
| if (temp->HasFixedPolicy()) { |
| AllocateFixed(temp, gap_index - 1, false); |
| } |
| } |
| } |
| |
| // Handle fixed output operand. |
| if (first != NULL && first->Output() != NULL) { |
| LUnallocated* first_output = LUnallocated::cast(first->Output()); |
| LiveRange* range = LiveRangeFor(first_output->virtual_register()); |
| bool assigned = false; |
| if (first_output->HasFixedPolicy()) { |
| LUnallocated* output_copy = first_output->CopyUnconstrained( |
| chunk()->zone()); |
| bool is_tagged = HasTaggedValue(first_output->virtual_register()); |
| AllocateFixed(first_output, gap_index, is_tagged); |
| |
| // This value is produced on the stack, we never need to spill it. |
| if (first_output->IsStackSlot()) { |
| range->SetSpillOperand(first_output); |
| range->SetSpillStartIndex(gap_index - 1); |
| assigned = true; |
| } |
| chunk_->AddGapMove(gap_index, first_output, output_copy); |
| } |
| |
| if (!assigned) { |
| range->SetSpillStartIndex(gap_index); |
| |
| // This move to spill operand is not a real use. Liveness analysis |
| // and splitting of live ranges do not account for it. |
| // Thus it should be inserted to a lifetime position corresponding to |
| // the instruction end. |
| LGap* gap = GapAt(gap_index); |
| LParallelMove* move = gap->GetOrCreateParallelMove(LGap::BEFORE, |
| chunk()->zone()); |
| move->AddMove(first_output, range->GetSpillOperand(), |
| chunk()->zone()); |
| } |
| } |
| |
| // Handle fixed input operands of second instruction. |
| if (second != NULL) { |
| for (UseIterator it(second); !it.Done(); it.Advance()) { |
| LUnallocated* cur_input = LUnallocated::cast(it.Current()); |
| if (cur_input->HasFixedPolicy()) { |
| LUnallocated* input_copy = cur_input->CopyUnconstrained( |
| chunk()->zone()); |
| bool is_tagged = HasTaggedValue(cur_input->virtual_register()); |
| AllocateFixed(cur_input, gap_index + 1, is_tagged); |
| AddConstraintsGapMove(gap_index, input_copy, cur_input); |
| } else if (cur_input->HasWritableRegisterPolicy()) { |
| // The live range of writable input registers always goes until the end |
| // of the instruction. |
| DCHECK(!cur_input->IsUsedAtStart()); |
| |
| LUnallocated* input_copy = cur_input->CopyUnconstrained( |
| chunk()->zone()); |
| int vreg = GetVirtualRegister(); |
| if (!AllocationOk()) return; |
| cur_input->set_virtual_register(vreg); |
| |
| if (RequiredRegisterKind(input_copy->virtual_register()) == |
| DOUBLE_REGISTERS) { |
| double_artificial_registers_.Add( |
| cur_input->virtual_register() - first_artificial_register_, |
| zone()); |
| } |
| |
| AddConstraintsGapMove(gap_index, input_copy, cur_input); |
| } |
| } |
| } |
| |
| // Handle "output same as input" for second instruction. |
| if (second != NULL && second->Output() != NULL) { |
| LUnallocated* second_output = LUnallocated::cast(second->Output()); |
| if (second_output->HasSameAsInputPolicy()) { |
| LUnallocated* cur_input = LUnallocated::cast(second->FirstInput()); |
| int output_vreg = second_output->virtual_register(); |
| int input_vreg = cur_input->virtual_register(); |
| |
| LUnallocated* input_copy = cur_input->CopyUnconstrained( |
| chunk()->zone()); |
| cur_input->set_virtual_register(second_output->virtual_register()); |
| AddConstraintsGapMove(gap_index, input_copy, cur_input); |
| |
| if (HasTaggedValue(input_vreg) && !HasTaggedValue(output_vreg)) { |
| int index = gap_index + 1; |
| LInstruction* instr = InstructionAt(index); |
| if (instr->HasPointerMap()) { |
| instr->pointer_map()->RecordPointer(input_copy, chunk()->zone()); |
| } |
| } else if (!HasTaggedValue(input_vreg) && HasTaggedValue(output_vreg)) { |
| // The input is assumed to immediately have a tagged representation, |
| // before the pointer map can be used. I.e. the pointer map at the |
| // instruction will include the output operand (whose value at the |
| // beginning of the instruction is equal to the input operand). If |
| // this is not desired, then the pointer map at this instruction needs |
| // to be adjusted manually. |
| } |
| } |
| } |
| } |
| |
| |
| void LAllocator::ProcessInstructions(HBasicBlock* block, BitVector* live) { |
| int block_start = block->first_instruction_index(); |
| int index = block->last_instruction_index(); |
| |
| LifetimePosition block_start_position = |
| LifetimePosition::FromInstructionIndex(block_start); |
| |
| while (index >= block_start) { |
| LifetimePosition curr_position = |
| LifetimePosition::FromInstructionIndex(index); |
| |
| if (IsGapAt(index)) { |
| // We have a gap at this position. |
| LGap* gap = GapAt(index); |
| LParallelMove* move = gap->GetOrCreateParallelMove(LGap::START, |
| chunk()->zone()); |
| const ZoneList<LMoveOperands>* move_operands = move->move_operands(); |
| for (int i = 0; i < move_operands->length(); ++i) { |
| LMoveOperands* cur = &move_operands->at(i); |
| if (cur->IsIgnored()) continue; |
| LOperand* from = cur->source(); |
| LOperand* to = cur->destination(); |
| HPhi* phi = LookupPhi(to); |
| LOperand* hint = to; |
| if (phi != NULL) { |
| // This is a phi resolving move. |
| if (!phi->block()->IsLoopHeader()) { |
| hint = LiveRangeFor(phi->id())->current_hint_operand(); |
| } |
| } else { |
| if (to->IsUnallocated()) { |
| if (live->Contains(LUnallocated::cast(to)->virtual_register())) { |
| Define(curr_position, to, from); |
| live->Remove(LUnallocated::cast(to)->virtual_register()); |
| } else { |
| cur->Eliminate(); |
| continue; |
| } |
| } else { |
| Define(curr_position, to, from); |
| } |
| } |
| Use(block_start_position, curr_position, from, hint); |
| if (from->IsUnallocated()) { |
| live->Add(LUnallocated::cast(from)->virtual_register()); |
| } |
| } |
| } else { |
| DCHECK(!IsGapAt(index)); |
| LInstruction* instr = InstructionAt(index); |
| |
| if (instr != NULL) { |
| LOperand* output = instr->Output(); |
| if (output != NULL) { |
| if (output->IsUnallocated()) { |
| live->Remove(LUnallocated::cast(output)->virtual_register()); |
| } |
| Define(curr_position, output, NULL); |
| } |
| |
| if (instr->ClobbersRegisters()) { |
| for (int i = 0; i < Register::kNumRegisters; ++i) { |
| if (GetRegConfig()->IsAllocatableGeneralCode(i)) { |
| if (output == NULL || !output->IsRegister() || |
| output->index() != i) { |
| LiveRange* range = FixedLiveRangeFor(i); |
| range->AddUseInterval(curr_position, |
| curr_position.InstructionEnd(), zone()); |
| } |
| } |
| } |
| } |
| |
| if (instr->ClobbersDoubleRegisters(isolate())) { |
| for (int i = 0; i < DoubleRegister::kMaxNumRegisters; ++i) { |
| if (GetRegConfig()->IsAllocatableDoubleCode(i)) { |
| if (output == NULL || !output->IsDoubleRegister() || |
| output->index() != i) { |
| LiveRange* range = FixedDoubleLiveRangeFor(i); |
| range->AddUseInterval(curr_position, |
| curr_position.InstructionEnd(), zone()); |
| } |
| } |
| } |
| } |
| |
| for (UseIterator it(instr); !it.Done(); it.Advance()) { |
| LOperand* input = it.Current(); |
| |
| LifetimePosition use_pos; |
| if (input->IsUnallocated() && |
| LUnallocated::cast(input)->IsUsedAtStart()) { |
| use_pos = curr_position; |
| } else { |
| use_pos = curr_position.InstructionEnd(); |
| } |
| |
| Use(block_start_position, use_pos, input, NULL); |
| if (input->IsUnallocated()) { |
| live->Add(LUnallocated::cast(input)->virtual_register()); |
| } |
| } |
| |
| for (TempIterator it(instr); !it.Done(); it.Advance()) { |
| LOperand* temp = it.Current(); |
| if (instr->ClobbersTemps()) { |
| if (temp->IsRegister()) continue; |
| if (temp->IsUnallocated()) { |
| LUnallocated* temp_unalloc = LUnallocated::cast(temp); |
| if (temp_unalloc->HasFixedPolicy()) { |
| continue; |
| } |
| } |
| } |
| Use(block_start_position, curr_position.InstructionEnd(), temp, NULL); |
| Define(curr_position, temp, NULL); |
| |
| if (temp->IsUnallocated()) { |
| LUnallocated* temp_unalloc = LUnallocated::cast(temp); |
| if (temp_unalloc->HasDoubleRegisterPolicy()) { |
| double_artificial_registers_.Add( |
| temp_unalloc->virtual_register() - first_artificial_register_, |
| zone()); |
| } |
| } |
| } |
| } |
| } |
| |
| index = index - 1; |
| } |
| } |
| |
| |
| void LAllocator::ResolvePhis(HBasicBlock* block) { |
| const ZoneList<HPhi*>* phis = block->phis(); |
| for (int i = 0; i < phis->length(); ++i) { |
| HPhi* phi = phis->at(i); |
| LUnallocated* phi_operand = |
| new (chunk()->zone()) LUnallocated(LUnallocated::NONE); |
| phi_operand->set_virtual_register(phi->id()); |
| for (int j = 0; j < phi->OperandCount(); ++j) { |
| HValue* op = phi->OperandAt(j); |
| LOperand* operand = NULL; |
| if (op->IsConstant() && op->EmitAtUses()) { |
| HConstant* constant = HConstant::cast(op); |
| operand = chunk_->DefineConstantOperand(constant); |
| } else { |
| DCHECK(!op->EmitAtUses()); |
| LUnallocated* unalloc = |
| new(chunk()->zone()) LUnallocated(LUnallocated::ANY); |
| unalloc->set_virtual_register(op->id()); |
| operand = unalloc; |
| } |
| HBasicBlock* cur_block = block->predecessors()->at(j); |
| // The gap move must be added without any special processing as in |
| // the AddConstraintsGapMove. |
| chunk_->AddGapMove(cur_block->last_instruction_index() - 1, |
| operand, |
| phi_operand); |
| |
| // We are going to insert a move before the branch instruction. |
| // Some branch instructions (e.g. loops' back edges) |
| // can potentially cause a GC so they have a pointer map. |
| // By inserting a move we essentially create a copy of a |
| // value which is invisible to PopulatePointerMaps(), because we store |
| // it into a location different from the operand of a live range |
| // covering a branch instruction. |
| // Thus we need to manually record a pointer. |
| LInstruction* branch = |
| InstructionAt(cur_block->last_instruction_index()); |
| if (branch->HasPointerMap()) { |
| if (phi->representation().IsTagged() && !phi->type().IsSmi()) { |
| branch->pointer_map()->RecordPointer(phi_operand, chunk()->zone()); |
| } else if (!phi->representation().IsDouble()) { |
| branch->pointer_map()->RecordUntagged(phi_operand, chunk()->zone()); |
| } |
| } |
| } |
| |
| LiveRange* live_range = LiveRangeFor(phi->id()); |
| LLabel* label = chunk_->GetLabel(phi->block()->block_id()); |
| label->GetOrCreateParallelMove(LGap::START, chunk()->zone())-> |
| AddMove(phi_operand, live_range->GetSpillOperand(), chunk()->zone()); |
| live_range->SetSpillStartIndex(phi->block()->first_instruction_index()); |
| } |
| } |
| |
| |
| bool LAllocator::Allocate(LChunk* chunk) { |
| DCHECK(chunk_ == NULL); |
| chunk_ = static_cast<LPlatformChunk*>(chunk); |
| assigned_registers_ = |
| new (chunk->zone()) BitVector(Register::kNumRegisters, chunk->zone()); |
| assigned_double_registers_ = new (chunk->zone()) |
| BitVector(DoubleRegister::kMaxNumRegisters, chunk->zone()); |
| MeetRegisterConstraints(); |
| if (!AllocationOk()) return false; |
| ResolvePhis(); |
| BuildLiveRanges(); |
| AllocateGeneralRegisters(); |
| if (!AllocationOk()) return false; |
| AllocateDoubleRegisters(); |
| if (!AllocationOk()) return false; |
| PopulatePointerMaps(); |
| ConnectRanges(); |
| ResolveControlFlow(); |
| return true; |
| } |
| |
| |
| void LAllocator::MeetRegisterConstraints() { |
| LAllocatorPhase phase("L_Register constraints", this); |
| const ZoneList<HBasicBlock*>* blocks = graph_->blocks(); |
| for (int i = 0; i < blocks->length(); ++i) { |
| HBasicBlock* block = blocks->at(i); |
| MeetRegisterConstraints(block); |
| if (!AllocationOk()) return; |
| } |
| } |
| |
| |
| void LAllocator::ResolvePhis() { |
| LAllocatorPhase phase("L_Resolve phis", this); |
| |
| // Process the blocks in reverse order. |
| const ZoneList<HBasicBlock*>* blocks = graph_->blocks(); |
| for (int block_id = blocks->length() - 1; block_id >= 0; --block_id) { |
| HBasicBlock* block = blocks->at(block_id); |
| ResolvePhis(block); |
| } |
| } |
| |
| |
| void LAllocator::ResolveControlFlow(LiveRange* range, |
| HBasicBlock* block, |
| HBasicBlock* pred) { |
| LifetimePosition pred_end = |
| LifetimePosition::FromInstructionIndex(pred->last_instruction_index()); |
| LifetimePosition cur_start = |
| LifetimePosition::FromInstructionIndex(block->first_instruction_index()); |
| LiveRange* pred_cover = NULL; |
| LiveRange* cur_cover = NULL; |
| LiveRange* cur_range = range; |
| while (cur_range != NULL && (cur_cover == NULL || pred_cover == NULL)) { |
| if (cur_range->CanCover(cur_start)) { |
| DCHECK(cur_cover == NULL); |
| cur_cover = cur_range; |
| } |
| if (cur_range->CanCover(pred_end)) { |
| DCHECK(pred_cover == NULL); |
| pred_cover = cur_range; |
| } |
| cur_range = cur_range->next(); |
| } |
| |
| if (cur_cover->IsSpilled()) return; |
| DCHECK(pred_cover != NULL && cur_cover != NULL); |
| if (pred_cover != cur_cover) { |
| LOperand* pred_op = pred_cover->CreateAssignedOperand(chunk()->zone()); |
| LOperand* cur_op = cur_cover->CreateAssignedOperand(chunk()->zone()); |
| if (!pred_op->Equals(cur_op)) { |
| LGap* gap = NULL; |
| if (block->predecessors()->length() == 1) { |
| gap = GapAt(block->first_instruction_index()); |
| } else { |
| DCHECK(pred->end()->SecondSuccessor() == NULL); |
| gap = GetLastGap(pred); |
| |
| // We are going to insert a move before the branch instruction. |
| // Some branch instructions (e.g. loops' back edges) |
| // can potentially cause a GC so they have a pointer map. |
| // By inserting a move we essentially create a copy of a |
| // value which is invisible to PopulatePointerMaps(), because we store |
| // it into a location different from the operand of a live range |
| // covering a branch instruction. |
| // Thus we need to manually record a pointer. |
| LInstruction* branch = InstructionAt(pred->last_instruction_index()); |
| if (branch->HasPointerMap()) { |
| if (HasTaggedValue(range->id())) { |
| branch->pointer_map()->RecordPointer(cur_op, chunk()->zone()); |
| } else if (!cur_op->IsDoubleStackSlot() && |
| !cur_op->IsDoubleRegister()) { |
| branch->pointer_map()->RemovePointer(cur_op); |
| } |
| } |
| } |
| gap->GetOrCreateParallelMove( |
| LGap::START, chunk()->zone())->AddMove(pred_op, cur_op, |
| chunk()->zone()); |
| } |
| } |
| } |
| |
| |
| LParallelMove* LAllocator::GetConnectingParallelMove(LifetimePosition pos) { |
| int index = pos.InstructionIndex(); |
| if (IsGapAt(index)) { |
| LGap* gap = GapAt(index); |
| return gap->GetOrCreateParallelMove( |
| pos.IsInstructionStart() ? LGap::START : LGap::END, chunk()->zone()); |
| } |
| int gap_pos = pos.IsInstructionStart() ? (index - 1) : (index + 1); |
| return GapAt(gap_pos)->GetOrCreateParallelMove( |
| (gap_pos < index) ? LGap::AFTER : LGap::BEFORE, chunk()->zone()); |
| } |
| |
| |
| HBasicBlock* LAllocator::GetBlock(LifetimePosition pos) { |
| LGap* gap = GapAt(chunk_->NearestGapPos(pos.InstructionIndex())); |
| return gap->block(); |
| } |
| |
| |
| void LAllocator::ConnectRanges() { |
| LAllocatorPhase phase("L_Connect ranges", this); |
| for (int i = 0; i < live_ranges()->length(); ++i) { |
| LiveRange* first_range = live_ranges()->at(i); |
| if (first_range == NULL || first_range->parent() != NULL) continue; |
| |
| LiveRange* second_range = first_range->next(); |
| while (second_range != NULL) { |
| LifetimePosition pos = second_range->Start(); |
| |
| if (!second_range->IsSpilled()) { |
| // Add gap move if the two live ranges touch and there is no block |
| // boundary. |
| if (first_range->End().Value() == pos.Value()) { |
| bool should_insert = true; |
| if (IsBlockBoundary(pos)) { |
| should_insert = CanEagerlyResolveControlFlow(GetBlock(pos)); |
| } |
| if (should_insert) { |
| LParallelMove* move = GetConnectingParallelMove(pos); |
| LOperand* prev_operand = first_range->CreateAssignedOperand( |
| chunk()->zone()); |
| LOperand* cur_operand = second_range->CreateAssignedOperand( |
| chunk()->zone()); |
| move->AddMove(prev_operand, cur_operand, |
| chunk()->zone()); |
| } |
| } |
| } |
| |
| first_range = second_range; |
| second_range = second_range->next(); |
| } |
| } |
| } |
| |
| |
| bool LAllocator::CanEagerlyResolveControlFlow(HBasicBlock* block) const { |
| if (block->predecessors()->length() != 1) return false; |
| return block->predecessors()->first()->block_id() == block->block_id() - 1; |
| } |
| |
| |
| void LAllocator::ResolveControlFlow() { |
| LAllocatorPhase phase("L_Resolve control flow", this); |
| const ZoneList<HBasicBlock*>* blocks = graph_->blocks(); |
| for (int block_id = 1; block_id < blocks->length(); ++block_id) { |
| HBasicBlock* block = blocks->at(block_id); |
| if (CanEagerlyResolveControlFlow(block)) continue; |
| BitVector* live = live_in_sets_[block->block_id()]; |
| BitVector::Iterator iterator(live); |
| while (!iterator.Done()) { |
| int operand_index = iterator.Current(); |
| for (int i = 0; i < block->predecessors()->length(); ++i) { |
| HBasicBlock* cur = block->predecessors()->at(i); |
| LiveRange* cur_range = LiveRangeFor(operand_index); |
| ResolveControlFlow(cur_range, block, cur); |
| } |
| iterator.Advance(); |
| } |
| } |
| } |
| |
| |
| void LAllocator::BuildLiveRanges() { |
| LAllocatorPhase phase("L_Build live ranges", this); |
| InitializeLivenessAnalysis(); |
| // Process the blocks in reverse order. |
| const ZoneList<HBasicBlock*>* blocks = graph_->blocks(); |
| for (int block_id = blocks->length() - 1; block_id >= 0; --block_id) { |
| HBasicBlock* block = blocks->at(block_id); |
| BitVector* live = ComputeLiveOut(block); |
| // Initially consider all live_out values live for the entire block. We |
| // will shorten these intervals if necessary. |
| AddInitialIntervals(block, live); |
| |
| // Process the instructions in reverse order, generating and killing |
| // live values. |
| ProcessInstructions(block, live); |
| // All phi output operands are killed by this block. |
| const ZoneList<HPhi*>* phis = block->phis(); |
| for (int i = 0; i < phis->length(); ++i) { |
| // The live range interval already ends at the first instruction of the |
| // block. |
| HPhi* phi = phis->at(i); |
| live->Remove(phi->id()); |
| |
| LOperand* hint = NULL; |
| LOperand* phi_operand = NULL; |
| LGap* gap = GetLastGap(phi->block()->predecessors()->at(0)); |
| LParallelMove* move = gap->GetOrCreateParallelMove(LGap::START, |
| chunk()->zone()); |
| for (int j = 0; j < move->move_operands()->length(); ++j) { |
| LOperand* to = move->move_operands()->at(j).destination(); |
| if (to->IsUnallocated() && |
| LUnallocated::cast(to)->virtual_register() == phi->id()) { |
| hint = move->move_operands()->at(j).source(); |
| phi_operand = to; |
| break; |
| } |
| } |
| DCHECK(hint != NULL); |
| |
| LifetimePosition block_start = LifetimePosition::FromInstructionIndex( |
| block->first_instruction_index()); |
| Define(block_start, phi_operand, hint); |
| } |
| |
| // Now live is live_in for this block except not including values live |
| // out on backward successor edges. |
| live_in_sets_[block_id] = live; |
| |
| // If this block is a loop header go back and patch up the necessary |
| // predecessor blocks. |
| if (block->IsLoopHeader()) { |
| // TODO(kmillikin): Need to be able to get the last block of the loop |
| // in the loop information. Add a live range stretching from the first |
| // loop instruction to the last for each value live on entry to the |
| // header. |
| HBasicBlock* back_edge = block->loop_information()->GetLastBackEdge(); |
| BitVector::Iterator iterator(live); |
| LifetimePosition start = LifetimePosition::FromInstructionIndex( |
| block->first_instruction_index()); |
| LifetimePosition end = LifetimePosition::FromInstructionIndex( |
| back_edge->last_instruction_index()).NextInstruction(); |
| while (!iterator.Done()) { |
| int operand_index = iterator.Current(); |
| LiveRange* range = LiveRangeFor(operand_index); |
| range->EnsureInterval(start, end, zone()); |
| iterator.Advance(); |
| } |
| |
| for (int i = block->block_id() + 1; i <= back_edge->block_id(); ++i) { |
| live_in_sets_[i]->Union(*live); |
| } |
| } |
| |
| #ifdef DEBUG |
| if (block_id == 0) { |
| BitVector::Iterator iterator(live); |
| bool found = false; |
| while (!iterator.Done()) { |
| found = true; |
| int operand_index = iterator.Current(); |
| { |
| AllowHandleDereference allow_deref; |
| PrintF("Function: %s\n", chunk_->info()->GetDebugName().get()); |
| } |
| PrintF("Value %d used before first definition!\n", operand_index); |
| LiveRange* range = LiveRangeFor(operand_index); |
| PrintF("First use is at %d\n", range->first_pos()->pos().Value()); |
| iterator.Advance(); |
| } |
| DCHECK(!found); |
| } |
| #endif |
| } |
| |
| for (int i = 0; i < live_ranges_.length(); ++i) { |
| if (live_ranges_[i] != NULL) { |
| live_ranges_[i]->kind_ = RequiredRegisterKind(live_ranges_[i]->id()); |
| } |
| } |
| } |
| |
| |
| bool LAllocator::SafePointsAreInOrder() const { |
| const ZoneList<LPointerMap*>* pointer_maps = chunk_->pointer_maps(); |
| int safe_point = 0; |
| for (int i = 0; i < pointer_maps->length(); ++i) { |
| LPointerMap* map = pointer_maps->at(i); |
| if (safe_point > map->lithium_position()) return false; |
| safe_point = map->lithium_position(); |
| } |
| return true; |
| } |
| |
| |
| void LAllocator::PopulatePointerMaps() { |
| LAllocatorPhase phase("L_Populate pointer maps", this); |
| const ZoneList<LPointerMap*>* pointer_maps = chunk_->pointer_maps(); |
| |
| DCHECK(SafePointsAreInOrder()); |
| |
| // Iterate over all safe point positions and record a pointer |
| // for all spilled live ranges at this point. |
| int first_safe_point_index = 0; |
| int last_range_start = 0; |
| for (int range_idx = 0; range_idx < live_ranges()->length(); ++range_idx) { |
| LiveRange* range = live_ranges()->at(range_idx); |
| if (range == NULL) continue; |
| // Iterate over the first parts of multi-part live ranges. |
| if (range->parent() != NULL) continue; |
| // Skip non-pointer values. |
| if (!HasTaggedValue(range->id())) continue; |
| // Skip empty live ranges. |
| if (range->IsEmpty()) continue; |
| |
| // Find the extent of the range and its children. |
| int start = range->Start().InstructionIndex(); |
| int end = 0; |
| for (LiveRange* cur = range; cur != NULL; cur = cur->next()) { |
| LifetimePosition this_end = cur->End(); |
| if (this_end.InstructionIndex() > end) end = this_end.InstructionIndex(); |
| DCHECK(cur->Start().InstructionIndex() >= start); |
| } |
| |
| // Most of the ranges are in order, but not all. Keep an eye on when |
| // they step backwards and reset the first_safe_point_index so we don't |
| // miss any safe points. |
| if (start < last_range_start) { |
| first_safe_point_index = 0; |
| } |
| last_range_start = start; |
| |
| // Step across all the safe points that are before the start of this range, |
| // recording how far we step in order to save doing this for the next range. |
| while (first_safe_point_index < pointer_maps->length()) { |
| LPointerMap* map = pointer_maps->at(first_safe_point_index); |
| int safe_point = map->lithium_position(); |
| if (safe_point >= start) break; |
| first_safe_point_index++; |
| } |
| |
| // Step through the safe points to see whether they are in the range. |
| for (int safe_point_index = first_safe_point_index; |
| safe_point_index < pointer_maps->length(); |
| ++safe_point_index) { |
| LPointerMap* map = pointer_maps->at(safe_point_index); |
| int safe_point = map->lithium_position(); |
| |
| // The safe points are sorted so we can stop searching here. |
| if (safe_point - 1 > end) break; |
| |
| // Advance to the next active range that covers the current |
| // safe point position. |
| LifetimePosition safe_point_pos = |
| LifetimePosition::FromInstructionIndex(safe_point); |
| LiveRange* cur = range; |
| while (cur != NULL && !cur->Covers(safe_point_pos)) { |
| cur = cur->next(); |
| } |
| if (cur == NULL) continue; |
| |
| // Check if the live range is spilled and the safe point is after |
| // the spill position. |
| if (range->HasAllocatedSpillOperand() && |
| safe_point >= range->spill_start_index()) { |
| TraceAlloc("Pointer for range %d (spilled at %d) at safe point %d\n", |
| range->id(), range->spill_start_index(), safe_point); |
| map->RecordPointer(range->GetSpillOperand(), chunk()->zone()); |
| } |
| |
| if (!cur->IsSpilled()) { |
| TraceAlloc("Pointer in register for range %d (start at %d) " |
| "at safe point %d\n", |
| cur->id(), cur->Start().Value(), safe_point); |
| LOperand* operand = cur->CreateAssignedOperand(chunk()->zone()); |
| DCHECK(!operand->IsStackSlot()); |
| map->RecordPointer(operand, chunk()->zone()); |
| } |
| } |
| } |
| } |
| |
| |
| void LAllocator::AllocateGeneralRegisters() { |
| LAllocatorPhase phase("L_Allocate general registers", this); |
| num_registers_ = GetRegConfig()->num_allocatable_general_registers(); |
| allocatable_register_codes_ = GetRegConfig()->allocatable_general_codes(); |
| mode_ = GENERAL_REGISTERS; |
| AllocateRegisters(); |
| } |
| |
| |
| void LAllocator::AllocateDoubleRegisters() { |
| LAllocatorPhase phase("L_Allocate double registers", this); |
| num_registers_ = GetRegConfig()->num_allocatable_double_registers(); |
| allocatable_register_codes_ = GetRegConfig()->allocatable_double_codes(); |
| mode_ = DOUBLE_REGISTERS; |
| AllocateRegisters(); |
| } |
| |
| |
| void LAllocator::AllocateRegisters() { |
| DCHECK(unhandled_live_ranges_.is_empty()); |
| |
| for (int i = 0; i < live_ranges_.length(); ++i) { |
| if (live_ranges_[i] != NULL) { |
| if (live_ranges_[i]->Kind() == mode_) { |
| AddToUnhandledUnsorted(live_ranges_[i]); |
| } |
| } |
| } |
| SortUnhandled(); |
| DCHECK(UnhandledIsSorted()); |
| |
| DCHECK(reusable_slots_.is_empty()); |
| DCHECK(active_live_ranges_.is_empty()); |
| DCHECK(inactive_live_ranges_.is_empty()); |
| |
| if (mode_ == DOUBLE_REGISTERS) { |
| for (int i = 0; i < fixed_double_live_ranges_.length(); ++i) { |
| LiveRange* current = fixed_double_live_ranges_.at(i); |
| if (current != NULL) { |
| AddToInactive(current); |
| } |
| } |
| } else { |
| DCHECK(mode_ == GENERAL_REGISTERS); |
| for (int i = 0; i < fixed_live_ranges_.length(); ++i) { |
| LiveRange* current = fixed_live_ranges_.at(i); |
| if (current != NULL) { |
| AddToInactive(current); |
| } |
| } |
| } |
| |
| while (!unhandled_live_ranges_.is_empty()) { |
| DCHECK(UnhandledIsSorted()); |
| LiveRange* current = unhandled_live_ranges_.RemoveLast(); |
| DCHECK(UnhandledIsSorted()); |
| LifetimePosition position = current->Start(); |
| #ifdef DEBUG |
| allocation_finger_ = position; |
| #endif |
| TraceAlloc("Processing interval %d start=%d\n", |
| current->id(), |
| position.Value()); |
| |
| if (current->HasAllocatedSpillOperand()) { |
| TraceAlloc("Live range %d already has a spill operand\n", current->id()); |
| LifetimePosition next_pos = position; |
| if (IsGapAt(next_pos.InstructionIndex())) { |
| next_pos = next_pos.NextInstruction(); |
| } |
| UsePosition* pos = current->NextUsePositionRegisterIsBeneficial(next_pos); |
| // If the range already has a spill operand and it doesn't need a |
| // register immediately, split it and spill the first part of the range. |
| if (pos == NULL) { |
| Spill(current); |
| continue; |
| } else if (pos->pos().Value() > |
| current->Start().NextInstruction().Value()) { |
| // Do not spill live range eagerly if use position that can benefit from |
| // the register is too close to the start of live range. |
| SpillBetween(current, current->Start(), pos->pos()); |
| if (!AllocationOk()) return; |
| DCHECK(UnhandledIsSorted()); |
| continue; |
| } |
| } |
| |
| for (int i = 0; i < active_live_ranges_.length(); ++i) { |
| LiveRange* cur_active = active_live_ranges_.at(i); |
| if (cur_active->End().Value() <= position.Value()) { |
| ActiveToHandled(cur_active); |
| --i; // The live range was removed from the list of active live ranges. |
| } else if (!cur_active->Covers(position)) { |
| ActiveToInactive(cur_active); |
| --i; // The live range was removed from the list of active live ranges. |
| } |
| } |
| |
| for (int i = 0; i < inactive_live_ranges_.length(); ++i) { |
| LiveRange* cur_inactive = inactive_live_ranges_.at(i); |
| if (cur_inactive->End().Value() <= position.Value()) { |
| InactiveToHandled(cur_inactive); |
| --i; // Live range was removed from the list of inactive live ranges. |
| } else if (cur_inactive->Covers(position)) { |
| InactiveToActive(cur_inactive); |
| --i; // Live range was removed from the list of inactive live ranges. |
| } |
| } |
| |
| DCHECK(!current->HasRegisterAssigned() && !current->IsSpilled()); |
| |
| bool result = TryAllocateFreeReg(current); |
| if (!AllocationOk()) return; |
| |
| if (!result) AllocateBlockedReg(current); |
| if (!AllocationOk()) return; |
| |
| if (current->HasRegisterAssigned()) { |
| AddToActive(current); |
| } |
| } |
| |
| reusable_slots_.Rewind(0); |
| active_live_ranges_.Rewind(0); |
| inactive_live_ranges_.Rewind(0); |
| } |
| |
| |
| const char* LAllocator::RegisterName(int allocation_index) { |
| if (mode_ == GENERAL_REGISTERS) { |
| return GetRegConfig()->GetGeneralRegisterName(allocation_index); |
| } else { |
| return GetRegConfig()->GetDoubleRegisterName(allocation_index); |
| } |
| } |
| |
| |
| void LAllocator::TraceAlloc(const char* msg, ...) { |
| if (FLAG_trace_alloc) { |
| va_list arguments; |
| va_start(arguments, msg); |
| base::OS::VPrint(msg, arguments); |
| va_end(arguments); |
| } |
| } |
| |
| |
| bool LAllocator::HasTaggedValue(int virtual_register) const { |
| HValue* value = graph_->LookupValue(virtual_register); |
| if (value == NULL) return false; |
| return value->representation().IsTagged() && !value->type().IsSmi(); |
| } |
| |
| |
| RegisterKind LAllocator::RequiredRegisterKind(int virtual_register) const { |
| if (virtual_register < first_artificial_register_) { |
| HValue* value = graph_->LookupValue(virtual_register); |
| if (value != NULL && value->representation().IsDouble()) { |
| return DOUBLE_REGISTERS; |
| } |
| } else if (double_artificial_registers_.Contains( |
| virtual_register - first_artificial_register_)) { |
| return DOUBLE_REGISTERS; |
| } |
| |
| return GENERAL_REGISTERS; |
| } |
| |
| |
| void LAllocator::AddToActive(LiveRange* range) { |
| TraceAlloc("Add live range %d to active\n", range->id()); |
| active_live_ranges_.Add(range, zone()); |
| } |
| |
| |
| void LAllocator::AddToInactive(LiveRange* range) { |
| TraceAlloc("Add live range %d to inactive\n", range->id()); |
| inactive_live_ranges_.Add(range, zone()); |
| } |
| |
| |
| void LAllocator::AddToUnhandledSorted(LiveRange* range) { |
| if (range == NULL || range->IsEmpty()) return; |
| DCHECK(!range->HasRegisterAssigned() && !range->IsSpilled()); |
| DCHECK(allocation_finger_.Value() <= range->Start().Value()); |
| for (int i = unhandled_live_ranges_.length() - 1; i >= 0; --i) { |
| LiveRange* cur_range = unhandled_live_ranges_.at(i); |
| if (range->ShouldBeAllocatedBefore(cur_range)) { |
| TraceAlloc("Add live range %d to unhandled at %d\n", range->id(), i + 1); |
| unhandled_live_ranges_.InsertAt(i + 1, range, zone()); |
| DCHECK(UnhandledIsSorted()); |
| return; |
| } |
| } |
| TraceAlloc("Add live range %d to unhandled at start\n", range->id()); |
| unhandled_live_ranges_.InsertAt(0, range, zone()); |
| DCHECK(UnhandledIsSorted()); |
| } |
| |
| |
| void LAllocator::AddToUnhandledUnsorted(LiveRange* range) { |
| if (range == NULL || range->IsEmpty()) return; |
| DCHECK(!range->HasRegisterAssigned() && !range->IsSpilled()); |
| TraceAlloc("Add live range %d to unhandled unsorted at end\n", range->id()); |
| unhandled_live_ranges_.Add(range, zone()); |
| } |
| |
| |
| static int UnhandledSortHelper(LiveRange* const* a, LiveRange* const* b) { |
| DCHECK(!(*a)->ShouldBeAllocatedBefore(*b) || |
| !(*b)->ShouldBeAllocatedBefore(*a)); |
| if ((*a)->ShouldBeAllocatedBefore(*b)) return 1; |
| if ((*b)->ShouldBeAllocatedBefore(*a)) return -1; |
| return (*a)->id() - (*b)->id(); |
| } |
| |
| |
| // Sort the unhandled live ranges so that the ranges to be processed first are |
| // at the end of the array list. This is convenient for the register allocation |
| // algorithm because it is efficient to remove elements from the end. |
| void LAllocator::SortUnhandled() { |
| TraceAlloc("Sort unhandled\n"); |
| unhandled_live_ranges_.Sort(&UnhandledSortHelper); |
| } |
| |
| |
| bool LAllocator::UnhandledIsSorted() { |
| int len = unhandled_live_ranges_.length(); |
| for (int i = 1; i < len; i++) { |
| LiveRange* a = unhandled_live_ranges_.at(i - 1); |
| LiveRange* b = unhandled_live_ranges_.at(i); |
| if (a->Start().Value() < b->Start().Value()) return false; |
| } |
| return true; |
| } |
| |
| |
| void LAllocator::FreeSpillSlot(LiveRange* range) { |
| // Check that we are the last range. |
| if (range->next() != NULL) return; |
| |
| if (!range->TopLevel()->HasAllocatedSpillOperand()) return; |
| |
| int index = range->TopLevel()->GetSpillOperand()->index(); |
| if (index >= 0) { |
| reusable_slots_.Add(range, zone()); |
| } |
| } |
| |
| |
| LOperand* LAllocator::TryReuseSpillSlot(LiveRange* range) { |
| if (reusable_slots_.is_empty()) return NULL; |
| if (reusable_slots_.first()->End().Value() > |
| range->TopLevel()->Start().Value()) { |
| return NULL; |
| } |
| LOperand* result = reusable_slots_.first()->TopLevel()->GetSpillOperand(); |
| reusable_slots_.Remove(0); |
| return result; |
| } |
| |
| |
| void LAllocator::ActiveToHandled(LiveRange* range) { |
| DCHECK(active_live_ranges_.Contains(range)); |
| active_live_ranges_.RemoveElement(range); |
| TraceAlloc("Moving live range %d from active to handled\n", range->id()); |
| FreeSpillSlot(range); |
| } |
| |
| |
| void LAllocator::ActiveToInactive(LiveRange* range) { |
| DCHECK(active_live_ranges_.Contains(range)); |
| active_live_ranges_.RemoveElement(range); |
| inactive_live_ranges_.Add(range, zone()); |
| TraceAlloc("Moving live range %d from active to inactive\n", range->id()); |
| } |
| |
| |
| void LAllocator::InactiveToHandled(LiveRange* range) { |
| DCHECK(inactive_live_ranges_.Contains(range)); |
| inactive_live_ranges_.RemoveElement(range); |
| TraceAlloc("Moving live range %d from inactive to handled\n", range->id()); |
| FreeSpillSlot(range); |
| } |
| |
| |
| void LAllocator::InactiveToActive(LiveRange* range) { |
| DCHECK(inactive_live_ranges_.Contains(range)); |
| inactive_live_ranges_.RemoveElement(range); |
| active_live_ranges_.Add(range, zone()); |
| TraceAlloc("Moving live range %d from inactive to active\n", range->id()); |
| } |
| |
| |
| bool LAllocator::TryAllocateFreeReg(LiveRange* current) { |
| DCHECK(DoubleRegister::kMaxNumRegisters >= Register::kNumRegisters); |
| |
| LifetimePosition free_until_pos[DoubleRegister::kMaxNumRegisters]; |
| |
| for (int i = 0; i < DoubleRegister::kMaxNumRegisters; i++) { |
| free_until_pos[i] = LifetimePosition::MaxPosition(); |
| } |
| |
| for (int i = 0; i < active_live_ranges_.length(); ++i) { |
| LiveRange* cur_active = active_live_ranges_.at(i); |
| free_until_pos[cur_active->assigned_register()] = |
| LifetimePosition::FromInstructionIndex(0); |
| } |
| |
| for (int i = 0; i < inactive_live_ranges_.length(); ++i) { |
| LiveRange* cur_inactive = inactive_live_ranges_.at(i); |
| DCHECK(cur_inactive->End().Value() > current->Start().Value()); |
| LifetimePosition next_intersection = |
| cur_inactive->FirstIntersection(current); |
| if (!next_intersection.IsValid()) continue; |
| int cur_reg = cur_inactive->assigned_register(); |
| free_until_pos[cur_reg] = Min(free_until_pos[cur_reg], next_intersection); |
| } |
| |
| LOperand* hint = current->FirstHint(); |
| if (hint != NULL && (hint->IsRegister() || hint->IsDoubleRegister())) { |
| int register_index = hint->index(); |
| TraceAlloc( |
| "Found reg hint %s (free until [%d) for live range %d (end %d[).\n", |
| RegisterName(register_index), |
| free_until_pos[register_index].Value(), |
| current->id(), |
| current->End().Value()); |
| |
| // The desired register is free until the end of the current live range. |
| if (free_until_pos[register_index].Value() >= current->End().Value()) { |
| TraceAlloc("Assigning preferred reg %s to live range %d\n", |
| RegisterName(register_index), |
| current->id()); |
| SetLiveRangeAssignedRegister(current, register_index); |
| return true; |
| } |
| } |
| |
| // Find the register which stays free for the longest time. |
| int reg = allocatable_register_codes_[0]; |
| for (int i = 1; i < RegisterCount(); ++i) { |
| int code = allocatable_register_codes_[i]; |
| if (free_until_pos[code].Value() > free_until_pos[reg].Value()) { |
| reg = code; |
| } |
| } |
| |
| LifetimePosition pos = free_until_pos[reg]; |
| |
| if (pos.Value() <= current->Start().Value()) { |
| // All registers are blocked. |
| return false; |
| } |
| |
| if (pos.Value() < current->End().Value()) { |
| // Register reg is available at the range start but becomes blocked before |
| // the range end. Split current at position where it becomes blocked. |
| LiveRange* tail = SplitRangeAt(current, pos); |
| if (!AllocationOk()) return false; |
| AddToUnhandledSorted(tail); |
| } |
| |
| |
| // Register reg is available at the range start and is free until |
| // the range end. |
| DCHECK(pos.Value() >= current->End().Value()); |
| TraceAlloc("Assigning free reg %s to live range %d\n", |
| RegisterName(reg), |
| current->id()); |
| SetLiveRangeAssignedRegister(current, reg); |
| |
| return true; |
| } |
| |
| |
| void LAllocator::AllocateBlockedReg(LiveRange* current) { |
| UsePosition* register_use = current->NextRegisterPosition(current->Start()); |
| if (register_use == NULL) { |
| // There is no use in the current live range that requires a register. |
| // We can just spill it. |
| Spill(current); |
| return; |
| } |
| |
| |
| LifetimePosition use_pos[DoubleRegister::kMaxNumRegisters]; |
| LifetimePosition block_pos[DoubleRegister::kMaxNumRegisters]; |
| |
| for (int i = 0; i < DoubleRegister::kMaxNumRegisters; i++) { |
| use_pos[i] = block_pos[i] = LifetimePosition::MaxPosition(); |
| } |
| |
| for (int i = 0; i < active_live_ranges_.length(); ++i) { |
| LiveRange* range = active_live_ranges_[i]; |
| int cur_reg = range->assigned_register(); |
| if (range->IsFixed() || !range->CanBeSpilled(current->Start())) { |
| block_pos[cur_reg] = use_pos[cur_reg] = |
| LifetimePosition::FromInstructionIndex(0); |
| } else { |
| UsePosition* next_use = range->NextUsePositionRegisterIsBeneficial( |
| current->Start()); |
| if (next_use == NULL) { |
| use_pos[cur_reg] = range->End(); |
| } else { |
| use_pos[cur_reg] = next_use->pos(); |
| } |
| } |
| } |
| |
| for (int i = 0; i < inactive_live_ranges_.length(); ++i) { |
| LiveRange* range = inactive_live_ranges_.at(i); |
| DCHECK(range->End().Value() > current->Start().Value()); |
| LifetimePosition next_intersection = range->FirstIntersection(current); |
| if (!next_intersection.IsValid()) continue; |
| int cur_reg = range->assigned_register(); |
| if (range->IsFixed()) { |
| block_pos[cur_reg] = Min(block_pos[cur_reg], next_intersection); |
| use_pos[cur_reg] = Min(block_pos[cur_reg], use_pos[cur_reg]); |
| } else { |
| use_pos[cur_reg] = Min(use_pos[cur_reg], next_intersection); |
| } |
| } |
| |
| int reg = allocatable_register_codes_[0]; |
| for (int i = 1; i < RegisterCount(); ++i) { |
| int code = allocatable_register_codes_[i]; |
| if (use_pos[code].Value() > use_pos[reg].Value()) { |
| reg = code; |
| } |
| } |
| |
| LifetimePosition pos = use_pos[reg]; |
| |
| if (pos.Value() < register_use->pos().Value()) { |
| // All registers are blocked before the first use that requires a register. |
| // Spill starting part of live range up to that use. |
| SpillBetween(current, current->Start(), register_use->pos()); |
| return; |
| } |
| |
| if (block_pos[reg].Value() < current->End().Value()) { |
| // Register becomes blocked before the current range end. Split before that |
| // position. |
| LiveRange* tail = SplitBetween(current, |
| current->Start(), |
| block_pos[reg].InstructionStart()); |
| if (!AllocationOk()) return; |
| AddToUnhandledSorted(tail); |
| } |
| |
| // Register reg is not blocked for the whole range. |
| DCHECK(block_pos[reg].Value() >= current->End().Value()); |
| TraceAlloc("Assigning blocked reg %s to live range %d\n", |
| RegisterName(reg), |
| current->id()); |
| SetLiveRangeAssignedRegister(current, reg); |
| |
| // This register was not free. Thus we need to find and spill |
| // parts of active and inactive live regions that use the same register |
| // at the same lifetime positions as current. |
| SplitAndSpillIntersecting(current); |
| } |
| |
| |
| LifetimePosition LAllocator::FindOptimalSpillingPos(LiveRange* range, |
| LifetimePosition pos) { |
| HBasicBlock* block = GetBlock(pos.InstructionStart()); |
| HBasicBlock* loop_header = |
| block->IsLoopHeader() ? block : block->parent_loop_header(); |
| |
| if (loop_header == NULL) return pos; |
| |
| UsePosition* prev_use = |
| range->PreviousUsePositionRegisterIsBeneficial(pos); |
| |
| while (loop_header != NULL) { |
| // We are going to spill live range inside the loop. |
| // If possible try to move spilling position backwards to loop header. |
| // This will reduce number of memory moves on the back edge. |
| LifetimePosition loop_start = LifetimePosition::FromInstructionIndex( |
| loop_header->first_instruction_index()); |
| |
| if (range->Covers(loop_start)) { |
| if (prev_use == NULL || prev_use->pos().Value() < loop_start.Value()) { |
| // No register beneficial use inside the loop before the pos. |
| pos = loop_start; |
| } |
| } |
| |
| // Try hoisting out to an outer loop. |
| loop_header = loop_header->parent_loop_header(); |
| } |
| |
| return pos; |
| } |
| |
| |
| void LAllocator::SplitAndSpillIntersecting(LiveRange* current) { |
| DCHECK(current->HasRegisterAssigned()); |
| int reg = current->assigned_register(); |
| LifetimePosition split_pos = current->Start(); |
| for (int i = 0; i < active_live_ranges_.length(); ++i) { |
| LiveRange* range = active_live_ranges_[i]; |
| if (range->assigned_register() == reg) { |
| UsePosition* next_pos = range->NextRegisterPosition(current->Start()); |
| LifetimePosition spill_pos = FindOptimalSpillingPos(range, split_pos); |
| if (next_pos == NULL) { |
| SpillAfter(range, spill_pos); |
| } else { |
| // When spilling between spill_pos and next_pos ensure that the range |
| // remains spilled at least until the start of the current live range. |
| // This guarantees that we will not introduce new unhandled ranges that |
| // start before the current range as this violates allocation invariant |
| // and will lead to an inconsistent state of active and inactive |
| // live-ranges: ranges are allocated in order of their start positions, |
| // ranges are retired from active/inactive when the start of the |
| // current live-range is larger than their end. |
| SpillBetweenUntil(range, spill_pos, current->Start(), next_pos->pos()); |
| } |
| if (!AllocationOk()) return; |
| ActiveToHandled(range); |
| --i; |
| } |
| } |
| |
| for (int i = 0; i < inactive_live_ranges_.length(); ++i) { |
| LiveRange* range = inactive_live_ranges_[i]; |
| DCHECK(range->End().Value() > current->Start().Value()); |
| if (range->assigned_register() == reg && !range->IsFixed()) { |
| LifetimePosition next_intersection = range->FirstIntersection(current); |
| if (next_intersection.IsValid()) { |
| UsePosition* next_pos = range->NextRegisterPosition(current->Start()); |
| if (next_pos == NULL) { |
| SpillAfter(range, split_pos); |
| } else { |
| next_intersection = Min(next_intersection, next_pos->pos()); |
| SpillBetween(range, split_pos, next_intersection); |
| } |
| if (!AllocationOk()) return; |
| InactiveToHandled(range); |
| --i; |
| } |
| } |
| } |
| } |
| |
| |
| bool LAllocator::IsBlockBoundary(LifetimePosition pos) { |
| return pos.IsInstructionStart() && |
| InstructionAt(pos.InstructionIndex())->IsLabel(); |
| } |
| |
| |
| LiveRange* LAllocator::SplitRangeAt(LiveRange* range, LifetimePosition pos) { |
| DCHECK(!range->IsFixed()); |
| TraceAlloc("Splitting live range %d at %d\n", range->id(), pos.Value()); |
| |
| if (pos.Value() <= range->Start().Value()) return range; |
| |
| // We can't properly connect liveranges if split occured at the end |
| // of control instruction. |
| DCHECK(pos.IsInstructionStart() || |
| !chunk_->instructions()->at(pos.InstructionIndex())->IsControl()); |
| |
| int vreg = GetVirtualRegister(); |
| if (!AllocationOk()) return NULL; |
| LiveRange* result = LiveRangeFor(vreg); |
| range->SplitAt(pos, result, zone()); |
| return result; |
| } |
| |
| |
| LiveRange* LAllocator::SplitBetween(LiveRange* range, |
| LifetimePosition start, |
| LifetimePosition end) { |
| DCHECK(!range->IsFixed()); |
| TraceAlloc("Splitting live range %d in position between [%d, %d]\n", |
| range->id(), |
| start.Value(), |
| end.Value()); |
| |
| LifetimePosition split_pos = FindOptimalSplitPos(start, end); |
| DCHECK(split_pos.Value() >= start.Value()); |
| return SplitRangeAt(range, split_pos); |
| } |
| |
| |
| LifetimePosition LAllocator::FindOptimalSplitPos(LifetimePosition start, |
| LifetimePosition end) { |
| int start_instr = start.InstructionIndex(); |
| int end_instr = end.InstructionIndex(); |
| DCHECK(start_instr <= end_instr); |
| |
| // We have no choice |
| if (start_instr == end_instr) return end; |
| |
| HBasicBlock* start_block = GetBlock(start); |
| HBasicBlock* end_block = GetBlock(end); |
| |
| if (end_block == start_block) { |
| // The interval is split in the same basic block. Split at the latest |
| // possible position. |
| return end; |
| } |
| |
| HBasicBlock* block = end_block; |
| // Find header of outermost loop. |
| while (block->parent_loop_header() != NULL && |
| block->parent_loop_header()->block_id() > start_block->block_id()) { |
| block = block->parent_loop_header(); |
| } |
| |
| // We did not find any suitable outer loop. Split at the latest possible |
| // position unless end_block is a loop header itself. |
| if (block == end_block && !end_block->IsLoopHeader()) return end; |
| |
| return LifetimePosition::FromInstructionIndex( |
| block->first_instruction_index()); |
| } |
| |
| |
| void LAllocator::SpillAfter(LiveRange* range, LifetimePosition pos) { |
| LiveRange* second_part = SplitRangeAt(range, pos); |
| if (!AllocationOk()) return; |
| Spill(second_part); |
| } |
| |
| |
| void LAllocator::SpillBetween(LiveRange* range, |
| LifetimePosition start, |
| LifetimePosition end) { |
| SpillBetweenUntil(range, start, start, end); |
| } |
| |
| |
| void LAllocator::SpillBetweenUntil(LiveRange* range, |
| LifetimePosition start, |
| LifetimePosition until, |
| LifetimePosition end) { |
| CHECK(start.Value() < end.Value()); |
| LiveRange* second_part = SplitRangeAt(range, start); |
| if (!AllocationOk()) return; |
| |
| if (second_part->Start().Value() < end.Value()) { |
| // The split result intersects with [start, end[. |
| // Split it at position between ]start+1, end[, spill the middle part |
| // and put the rest to unhandled. |
| LiveRange* third_part = SplitBetween( |
| second_part, |
| Max(second_part->Start().InstructionEnd(), until), |
| end.PrevInstruction().InstructionEnd()); |
| if (!AllocationOk()) return; |
| |
| DCHECK(third_part != second_part); |
| |
| Spill(second_part); |
| AddToUnhandledSorted(third_part); |
| } else { |
| // The split result does not intersect with [start, end[. |
| // Nothing to spill. Just put it to unhandled as whole. |
| AddToUnhandledSorted(second_part); |
| } |
| } |
| |
| |
| void LAllocator::Spill(LiveRange* range) { |
| DCHECK(!range->IsSpilled()); |
| TraceAlloc("Spilling live range %d\n", range->id()); |
| LiveRange* first = range->TopLevel(); |
| |
| if (!first->HasAllocatedSpillOperand()) { |
| LOperand* op = TryReuseSpillSlot(range); |
| if (op == NULL) op = chunk_->GetNextSpillSlot(range->Kind()); |
| first->SetSpillOperand(op); |
| } |
| range->MakeSpilled(chunk()->zone()); |
| } |
| |
| |
| int LAllocator::RegisterCount() const { |
| return num_registers_; |
| } |
| |
| |
| #ifdef DEBUG |
| |
| |
| void LAllocator::Verify() const { |
| for (int i = 0; i < live_ranges()->length(); ++i) { |
| LiveRange* current = live_ranges()->at(i); |
| if (current != NULL) current->Verify(); |
| } |
| } |
| |
| |
| #endif |
| |
| |
| LAllocatorPhase::LAllocatorPhase(const char* name, LAllocator* allocator) |
| : CompilationPhase(name, allocator->graph()->info()), |
| allocator_(allocator) { |
| if (FLAG_hydrogen_stats) { |
| allocator_zone_start_allocation_size_ = |
| allocator->zone()->allocation_size(); |
| } |
| } |
| |
| |
| LAllocatorPhase::~LAllocatorPhase() { |
| if (FLAG_hydrogen_stats) { |
| size_t size = allocator_->zone()->allocation_size() - |
| allocator_zone_start_allocation_size_; |
| isolate()->GetHStatistics()->SaveTiming(name(), base::TimeDelta(), size); |
| } |
| |
| if (ShouldProduceTraceOutput()) { |
| isolate()->GetHTracer()->TraceLithium(name(), allocator_->chunk()); |
| isolate()->GetHTracer()->TraceLiveRanges(name(), allocator_); |
| } |
| |
| #ifdef DEBUG |
| if (allocator_ != NULL) allocator_->Verify(); |
| #endif |
| } |
| |
| |
| } // namespace internal |
| } // namespace v8 |