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Diffstat (limited to 'src/3rdparty/v8/src/lithium-allocator.cc')
| -rw-r--r-- | src/3rdparty/v8/src/lithium-allocator.cc | 2105 |
1 files changed, 2105 insertions, 0 deletions
diff --git a/src/3rdparty/v8/src/lithium-allocator.cc b/src/3rdparty/v8/src/lithium-allocator.cc new file mode 100644 index 0000000..f62a7db --- /dev/null +++ b/src/3rdparty/v8/src/lithium-allocator.cc @@ -0,0 +1,2105 @@ +// Copyright 2010 the V8 project authors. All rights reserved. +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following +// disclaimer in the documentation and/or other materials provided +// with the distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived +// from this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#include "v8.h" +#include "lithium-allocator-inl.h" + +#include "hydrogen.h" +#include "string-stream.h" + +#if V8_TARGET_ARCH_IA32 +#include "ia32/lithium-ia32.h" +#elif V8_TARGET_ARCH_X64 +#include "x64/lithium-x64.h" +#elif V8_TARGET_ARCH_ARM +#include "arm/lithium-arm.h" +#elif V8_TARGET_ARCH_MIPS +#include "mips/lithium-mips.h" +#else +#error "Unknown architecture." +#endif + +namespace v8 { +namespace internal { + + +#define DEFINE_OPERAND_CACHE(name, type) \ + name name::cache[name::kNumCachedOperands]; \ + void name::SetupCache() { \ + for (int i = 0; i < kNumCachedOperands; i++) { \ + cache[i].ConvertTo(type, i); \ + } \ + } \ + static bool name##_initialize() { \ + name::SetupCache(); \ + return true; \ + } \ + static bool name##_cache_initialized = name##_initialize(); + +DEFINE_OPERAND_CACHE(LConstantOperand, CONSTANT_OPERAND) +DEFINE_OPERAND_CACHE(LStackSlot, STACK_SLOT) +DEFINE_OPERAND_CACHE(LDoubleStackSlot, DOUBLE_STACK_SLOT) +DEFINE_OPERAND_CACHE(LRegister, REGISTER) +DEFINE_OPERAND_CACHE(LDoubleRegister, DOUBLE_REGISTER) + +#undef DEFINE_OPERAND_CACHE + + +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) + : operand_(operand), + hint_(NULL), + pos_(pos), + next_(NULL), + requires_reg_(false), + register_beneficial_(true) { + if (operand_ != NULL && operand_->IsUnallocated()) { + LUnallocated* unalloc = LUnallocated::cast(operand_); + requires_reg_ = unalloc->HasRegisterPolicy(); + register_beneficial_ = !unalloc->HasAnyPolicy(); + } + ASSERT(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) { + ASSERT(Contains(pos) && pos.Value() != start().Value()); + UseInterval* after = new UseInterval(pos, end_); + after->next_ = next_; + next_ = after; + end_ = pos; +} + + +#ifdef DEBUG + + +void LiveRange::Verify() const { + UsePosition* cur = first_pos_; + while (cur != NULL) { + ASSERT(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) + : id_(id), + spilled_(false), + assigned_register_(kInvalidAssignment), + assigned_register_kind_(NONE), + last_interval_(NULL), + first_interval_(NULL), + first_pos_(NULL), + parent_(NULL), + next_(NULL), + current_interval_(NULL), + last_processed_use_(NULL), + spill_start_index_(kMaxInt) { + spill_operand_ = new LUnallocated(LUnallocated::IGNORE); +} + + +void LiveRange::set_assigned_register(int reg, RegisterKind register_kind) { + ASSERT(!HasRegisterAssigned() && !IsSpilled()); + assigned_register_ = reg; + assigned_register_kind_ = register_kind; + ConvertOperands(); +} + + +void LiveRange::MakeSpilled() { + ASSERT(!IsSpilled()); + ASSERT(TopLevel()->HasAllocatedSpillOperand()); + spilled_ = true; + assigned_register_ = kInvalidAssignment; + ConvertOperands(); +} + + +bool LiveRange::HasAllocatedSpillOperand() const { + return spill_operand_ != NULL && !spill_operand_->IsUnallocated(); +} + + +void LiveRange::SetSpillOperand(LOperand* operand) { + ASSERT(!operand->IsUnallocated()); + ASSERT(spill_operand_ != NULL); + ASSERT(spill_operand_->IsUnallocated()); + 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::NextRegisterPosition(LifetimePosition start) { + UsePosition* pos = NextUsePosition(start); + while (pos != NULL && !pos->RequiresRegister()) { + pos = pos->next(); + } + return pos; +} + + +bool LiveRange::CanBeSpilled(LifetimePosition pos) { + // TODO(kmillikin): Comment. Now. + if (pos.Value() <= Start().Value() && HasRegisterAssigned()) return false; + + // 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().Value(); +} + + +UsePosition* LiveRange::FirstPosWithHint() const { + UsePosition* pos = first_pos_; + while (pos != NULL && !pos->HasHint()) pos = pos->next(); + return pos; +} + + +LOperand* LiveRange::CreateAssignedOperand() { + LOperand* op = NULL; + if (HasRegisterAssigned()) { + ASSERT(!IsSpilled()); + if (IsDouble()) { + op = LDoubleRegister::Create(assigned_register()); + } else { + op = LRegister::Create(assigned_register()); + } + } else if (IsSpilled()) { + ASSERT(!HasRegisterAssigned()); + op = TopLevel()->GetSpillOperand(); + ASSERT(!op->IsUnallocated()); + } else { + LUnallocated* unalloc = new 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) { + ASSERT(Start().Value() < position.Value()); + ASSERT(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; + + while (current != NULL) { + if (current->Contains(position)) { + current->SplitAt(position); + 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; + + // 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->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 = FirstPosWithHint(); + 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()); + ASSERT(first_interval_ != NULL); + ASSERT(first_interval_->start().Value() <= start.Value()); + ASSERT(start.Value() < first_interval_->end().Value()); + first_interval_->set_start(start); +} + + +void LiveRange::EnsureInterval(LifetimePosition start, LifetimePosition end) { + 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 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) { + LAllocator::TraceAlloc("Add to live range %d interval [%d %d[\n", + id_, + start.Value(), + end.Value()); + if (first_interval_ == NULL) { + UseInterval* interval = new 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 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. + ASSERT(start.Value() < first_interval_->end().Value()); + first_interval_->start_ = Min(start, first_interval_->start_); + first_interval_->end_ = Max(end, first_interval_->end_); + } + } +} + + +UsePosition* LiveRange::AddUsePosition(LifetimePosition pos, + LOperand* operand) { + LAllocator::TraceAlloc("Add to live range %d use position %d\n", + id_, + pos.Value()); + UsePosition* use_pos = new UsePosition(pos, operand); + UsePosition* prev = NULL; + UsePosition* current = first_pos_; + while (current != NULL && current->pos().Value() < pos.Value()) { + 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; + } + + return use_pos; +} + + +void LiveRange::ConvertOperands() { + LOperand* op = CreateAssignedOperand(); + UsePosition* use_pos = first_pos(); + while (use_pos != NULL) { + ASSERT(Start().Value() <= use_pos->pos().Value() && + use_pos->pos().Value() <= End().Value()); + + if (use_pos->HasOperand()) { + ASSERT(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()) { + ASSERT(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) + : chunk_(NULL), + live_in_sets_(graph->blocks()->length()), + live_ranges_(num_values * 2), + fixed_live_ranges_(NULL), + fixed_double_live_ranges_(NULL), + unhandled_live_ranges_(num_values * 2), + active_live_ranges_(8), + inactive_live_ranges_(8), + reusable_slots_(8), + next_virtual_register_(num_values), + first_artificial_register_(num_values), + mode_(NONE), + num_registers_(-1), + graph_(graph), + has_osr_entry_(false) {} + + +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); + live_in_sets_.AddBlock(NULL, block_count); +} + + +BitVector* LAllocator::ComputeLiveOut(HBasicBlock* block) { + // Compute live out for the given block, except not including backward + // successor edges. + BitVector* live_out = new BitVector(next_virtual_register_); + + // Process all successor blocks. + HBasicBlock* successor = block->end()->FirstSuccessor(); + while (successor != NULL) { + // Add values live on entry to the successor. Note the successor's + // live_in will not be computed yet for backwards edges. + 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()); + } + } + + // Check if we are done with second successor. + if (successor == block->end()->SecondSuccessor()) break; + + successor = block->end()->SecondSuccessor(); + } + + 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); + iterator.Advance(); + } +} + + +int LAllocator::FixedDoubleLiveRangeID(int index) { + return -index - 1 - Register::kNumAllocatableRegisters; +} + + +LOperand* LAllocator::AllocateFixed(LUnallocated* operand, + int pos, + bool is_tagged) { + TraceAlloc("Allocating fixed reg for op %d\n", operand->virtual_register()); + ASSERT(operand->HasFixedPolicy()); + if (operand->policy() == LUnallocated::FIXED_SLOT) { + operand->ConvertTo(LOperand::STACK_SLOT, operand->fixed_index()); + } else if (operand->policy() == LUnallocated::FIXED_REGISTER) { + int reg_index = operand->fixed_index(); + operand->ConvertTo(LOperand::REGISTER, reg_index); + } else if (operand->policy() == LUnallocated::FIXED_DOUBLE_REGISTER) { + int reg_index = operand->fixed_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); + } + } + return operand; +} + + +LiveRange* LAllocator::FixedLiveRangeFor(int index) { + ASSERT(index < Register::kNumAllocatableRegisters); + LiveRange* result = fixed_live_ranges_[index]; + if (result == NULL) { + result = new LiveRange(FixedLiveRangeID(index)); + ASSERT(result->IsFixed()); + result->set_assigned_register(index, GENERAL_REGISTERS); + fixed_live_ranges_[index] = result; + } + return result; +} + + +LiveRange* LAllocator::FixedDoubleLiveRangeFor(int index) { + ASSERT(index < DoubleRegister::kNumAllocatableRegisters); + LiveRange* result = fixed_double_live_ranges_[index]; + if (result == NULL) { + result = new LiveRange(FixedDoubleLiveRangeID(index)); + ASSERT(result->IsFixed()); + result->set_assigned_register(index, DOUBLE_REGISTERS); + 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); + } + LiveRange* result = live_ranges_[index]; + if (result == NULL) { + result = new LiveRange(index); + 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 = operand->VirtualRegister(); + 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()); + range->AddUsePosition(position.NextInstruction(), NULL); + } else { + range->ShortenTo(position); + } + + if (operand->IsUnallocated()) { + LUnallocated* unalloc_operand = LUnallocated::cast(operand); + range->AddUsePosition(position, unalloc_operand)->set_hint(hint); + } +} + + +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)->set_hint(hint); + } + range->AddUseInterval(block_start, position); +} + + +void LAllocator::AddConstraintsGapMove(int index, + LOperand* from, + LOperand* to) { + LGap* gap = GapAt(index); + LParallelMove* move = gap->GetOrCreateParallelMove(LGap::START); + 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 (cur_to->VirtualRegister() == from->VirtualRegister()) { + move->AddMove(cur.source(), to); + return; + } + } + } + } + move->AddMove(from, to); +} + + +void LAllocator::MeetRegisterConstraints(HBasicBlock* block) { + int start = block->first_instruction_index(); + int end = block->last_instruction_index(); + 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); + } + } +} + + +void LAllocator::MeetConstraintsBetween(LInstruction* first, + LInstruction* second, + int gap_index) { + // Handle fixed temporaries. + if (first != NULL) { + for (TempIterator it(first); it.HasNext(); it.Advance()) { + LUnallocated* temp = LUnallocated::cast(it.Next()); + 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->VirtualRegister()); + bool assigned = false; + if (first_output->HasFixedPolicy()) { + LUnallocated* output_copy = first_output->CopyUnconstrained(); + bool is_tagged = HasTaggedValue(first_output->VirtualRegister()); + 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); + move->AddMove(first_output, range->GetSpillOperand()); + } + } + + // Handle fixed input operands of second instruction. + if (second != NULL) { + for (UseIterator it(second); it.HasNext(); it.Advance()) { + LUnallocated* cur_input = LUnallocated::cast(it.Next()); + if (cur_input->HasFixedPolicy()) { + LUnallocated* input_copy = cur_input->CopyUnconstrained(); + bool is_tagged = HasTaggedValue(cur_input->VirtualRegister()); + AllocateFixed(cur_input, gap_index + 1, is_tagged); + AddConstraintsGapMove(gap_index, input_copy, cur_input); + } else if (cur_input->policy() == LUnallocated::WRITABLE_REGISTER) { + // The live range of writable input registers always goes until the end + // of the instruction. + ASSERT(!cur_input->IsUsedAtStart()); + + LUnallocated* input_copy = cur_input->CopyUnconstrained(); + cur_input->set_virtual_register(next_virtual_register_++); + + if (RequiredRegisterKind(input_copy->virtual_register()) == + DOUBLE_REGISTERS) { + double_artificial_registers_.Add( + cur_input->virtual_register() - first_artificial_register_); + } + + 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->VirtualRegister(); + int input_vreg = cur_input->VirtualRegister(); + + LUnallocated* input_copy = cur_input->CopyUnconstrained(); + 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); + } + } 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); + 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())->FirstHint(); + } + } else { + if (to->IsUnallocated()) { + if (live->Contains(to->VirtualRegister())) { + Define(curr_position, to, from); + live->Remove(to->VirtualRegister()); + } else { + cur->Eliminate(); + continue; + } + } else { + Define(curr_position, to, from); + } + } + Use(block_start_position, curr_position, from, hint); + if (from->IsUnallocated()) { + live->Add(from->VirtualRegister()); + } + } + } else { + ASSERT(!IsGapAt(index)); + LInstruction* instr = InstructionAt(index); + + if (instr != NULL) { + LOperand* output = instr->Output(); + if (output != NULL) { + if (output->IsUnallocated()) live->Remove(output->VirtualRegister()); + Define(curr_position, output, NULL); + } + + if (instr->IsMarkedAsCall()) { + for (int i = 0; i < Register::kNumAllocatableRegisters; ++i) { + if (output == NULL || !output->IsRegister() || + output->index() != i) { + LiveRange* range = FixedLiveRangeFor(i); + range->AddUseInterval(curr_position, + curr_position.InstructionEnd()); + } + } + } + + if (instr->IsMarkedAsCall() || instr->IsMarkedAsSaveDoubles()) { + for (int i = 0; i < DoubleRegister::kNumAllocatableRegisters; ++i) { + if (output == NULL || !output->IsDoubleRegister() || + output->index() != i) { + LiveRange* range = FixedDoubleLiveRangeFor(i); + range->AddUseInterval(curr_position, + curr_position.InstructionEnd()); + } + } + } + + for (UseIterator it(instr); it.HasNext(); it.Advance()) { + LOperand* input = it.Next(); + + 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(input->VirtualRegister()); + } + + for (TempIterator it(instr); it.HasNext(); it.Advance()) { + LOperand* temp = it.Next(); + if (instr->IsMarkedAsCall()) { + 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); + } + } + } + + 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 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 { + ASSERT(!op->EmitAtUses()); + LUnallocated* unalloc = new LUnallocated(LUnallocated::NONE); + 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); + } + + LiveRange* live_range = LiveRangeFor(phi->id()); + LLabel* label = chunk_->GetLabel(phi->block()->block_id()); + label->GetOrCreateParallelMove(LGap::START)-> + AddMove(phi_operand, live_range->GetSpillOperand()); + live_range->SetSpillStartIndex(phi->block()->first_instruction_index()); + } +} + + +void LAllocator::Allocate(LChunk* chunk) { + ASSERT(chunk_ == NULL); + chunk_ = chunk; + MeetRegisterConstraints(); + ResolvePhis(); + BuildLiveRanges(); + AllocateGeneralRegisters(); + AllocateDoubleRegisters(); + PopulatePointerMaps(); + if (has_osr_entry_) ProcessOsrEntry(); + ConnectRanges(); + ResolveControlFlow(); +} + + +void LAllocator::MeetRegisterConstraints() { + HPhase phase("Register constraints", chunk_); + first_artificial_register_ = next_virtual_register_; + const ZoneList<HBasicBlock*>* blocks = graph_->blocks(); + for (int i = 0; i < blocks->length(); ++i) { + HBasicBlock* block = blocks->at(i); + MeetRegisterConstraints(block); + } +} + + +void LAllocator::ResolvePhis() { + HPhase phase("Resolve phis", chunk_); + + // 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)) { + ASSERT(cur_cover == NULL); + cur_cover = cur_range; + } + if (cur_range->CanCover(pred_end)) { + ASSERT(pred_cover == NULL); + pred_cover = cur_range; + } + cur_range = cur_range->next(); + } + + if (cur_cover->IsSpilled()) return; + ASSERT(pred_cover != NULL && cur_cover != NULL); + if (pred_cover != cur_cover) { + LOperand* pred_op = pred_cover->CreateAssignedOperand(); + LOperand* cur_op = cur_cover->CreateAssignedOperand(); + if (!pred_op->Equals(cur_op)) { + LGap* gap = NULL; + if (block->predecessors()->length() == 1) { + gap = GapAt(block->first_instruction_index()); + } else { + ASSERT(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 insterting 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. + if (HasTaggedValue(range->id())) { + LInstruction* branch = InstructionAt(pred->last_instruction_index()); + if (branch->HasPointerMap()) { + branch->pointer_map()->RecordPointer(cur_op); + } + } + } + gap->GetOrCreateParallelMove(LGap::START)->AddMove(pred_op, cur_op); + } + } +} + + +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); + } + int gap_pos = pos.IsInstructionStart() ? (index - 1) : (index + 1); + return GapAt(gap_pos)->GetOrCreateParallelMove( + (gap_pos < index) ? LGap::AFTER : LGap::BEFORE); +} + + +HBasicBlock* LAllocator::GetBlock(LifetimePosition pos) { + LGap* gap = GapAt(chunk_->NearestGapPos(pos.InstructionIndex())); + return gap->block(); +} + + +void LAllocator::ConnectRanges() { + HPhase phase("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(); + LOperand* cur_operand = second_range->CreateAssignedOperand(); + move->AddMove(prev_operand, cur_operand); + } + } + } + + 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() { + HPhase phase("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() { + HPhase phase("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); + for (int j = 0; j < move->move_operands()->length(); ++j) { + LOperand* to = move->move_operands()->at(j).destination(); + if (to->IsUnallocated() && to->VirtualRegister() == phi->id()) { + hint = move->move_operands()->at(j).source(); + phi_operand = to; + break; + } + } + ASSERT(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); + 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(); + PrintF("Function: %s\n", + *chunk_->info()->function()->debug_name()->ToCString()); + 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(); + } + ASSERT(!found); + } +#endif + } +} + + +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() { + HPhase phase("Populate pointer maps", this); + const ZoneList<LPointerMap*>* pointer_maps = chunk_->pointer_maps(); + + ASSERT(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(); + ASSERT(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.PrevInstruction())) { + 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()); + } + + 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(); + ASSERT(!operand->IsStackSlot()); + map->RecordPointer(operand); + } + } + } +} + + +void LAllocator::ProcessOsrEntry() { + const ZoneList<LInstruction*>* instrs = chunk_->instructions(); + + // Linear search for the OSR entry instruction in the chunk. + int index = -1; + while (++index < instrs->length() && + !instrs->at(index)->IsOsrEntry()) { + } + ASSERT(index < instrs->length()); + LOsrEntry* instruction = LOsrEntry::cast(instrs->at(index)); + + LifetimePosition position = LifetimePosition::FromInstructionIndex(index); + for (int i = 0; i < live_ranges()->length(); ++i) { + LiveRange* range = live_ranges()->at(i); + if (range != NULL) { + if (range->Covers(position) && + range->HasRegisterAssigned() && + range->TopLevel()->HasAllocatedSpillOperand()) { + int reg_index = range->assigned_register(); + LOperand* spill_operand = range->TopLevel()->GetSpillOperand(); + if (range->IsDouble()) { + instruction->MarkSpilledDoubleRegister(reg_index, spill_operand); + } else { + instruction->MarkSpilledRegister(reg_index, spill_operand); + } + } + } + } +} + + +void LAllocator::AllocateGeneralRegisters() { + HPhase phase("Allocate general registers", this); + num_registers_ = Register::kNumAllocatableRegisters; + mode_ = GENERAL_REGISTERS; + AllocateRegisters(); +} + + +void LAllocator::AllocateDoubleRegisters() { + HPhase phase("Allocate double registers", this); + num_registers_ = DoubleRegister::kNumAllocatableRegisters; + mode_ = DOUBLE_REGISTERS; + AllocateRegisters(); +} + + +void LAllocator::AllocateRegisters() { + ASSERT(mode_ != NONE); + ASSERT(unhandled_live_ranges_.is_empty()); + + for (int i = 0; i < live_ranges_.length(); ++i) { + if (live_ranges_[i] != NULL) { + if (RequiredRegisterKind(live_ranges_[i]->id()) == mode_) { + AddToUnhandledUnsorted(live_ranges_[i]); + } + } + } + SortUnhandled(); + ASSERT(UnhandledIsSorted()); + + ASSERT(reusable_slots_.is_empty()); + ASSERT(active_live_ranges_.is_empty()); + ASSERT(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 { + 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()) { + ASSERT(UnhandledIsSorted()); + LiveRange* current = unhandled_live_ranges_.RemoveLast(); + ASSERT(UnhandledIsSorted()); + LifetimePosition position = current->Start(); + 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()); + ASSERT(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. + } + } + + ASSERT(!current->HasRegisterAssigned() && !current->IsSpilled()); + + bool result = TryAllocateFreeReg(current); + if (!result) { + AllocateBlockedReg(current); + } + + 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) { + ASSERT(mode_ != NONE); + if (mode_ == GENERAL_REGISTERS) { + return Register::AllocationIndexToString(allocation_index); + } else { + return DoubleRegister::AllocationIndexToString(allocation_index); + } +} + + +void LAllocator::TraceAlloc(const char* msg, ...) { + if (FLAG_trace_alloc) { + va_list arguments; + va_start(arguments, msg); + 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(); +} + + +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::RecordDefinition(HInstruction* instr, LUnallocated* operand) { + operand->set_virtual_register(instr->id()); +} + + +void LAllocator::RecordTemporary(LUnallocated* operand) { + ASSERT(next_virtual_register_ < LUnallocated::kMaxVirtualRegisters); + if (!operand->HasFixedPolicy()) { + operand->set_virtual_register(next_virtual_register_++); + } +} + + +void LAllocator::RecordUse(HValue* value, LUnallocated* operand) { + operand->set_virtual_register(value->id()); +} + + +int LAllocator::max_initial_value_ids() { + return LUnallocated::kMaxVirtualRegisters / 32; +} + + +void LAllocator::AddToActive(LiveRange* range) { + TraceAlloc("Add live range %d to active\n", range->id()); + active_live_ranges_.Add(range); +} + + +void LAllocator::AddToInactive(LiveRange* range) { + TraceAlloc("Add live range %d to inactive\n", range->id()); + inactive_live_ranges_.Add(range); +} + + +void LAllocator::AddToUnhandledSorted(LiveRange* range) { + if (range == NULL || range->IsEmpty()) return; + ASSERT(!range->HasRegisterAssigned() && !range->IsSpilled()); + 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); + ASSERT(UnhandledIsSorted()); + return; + } + } + TraceAlloc("Add live range %d to unhandled at start\n", range->id()); + unhandled_live_ranges_.InsertAt(0, range); + ASSERT(UnhandledIsSorted()); +} + + +void LAllocator::AddToUnhandledUnsorted(LiveRange* range) { + if (range == NULL || range->IsEmpty()) return; + ASSERT(!range->HasRegisterAssigned() && !range->IsSpilled()); + TraceAlloc("Add live range %d to unhandled unsorted at end\n", range->id()); + unhandled_live_ranges_.Add(range); +} + + +static int UnhandledSortHelper(LiveRange* const* a, LiveRange* const* b) { + ASSERT(!(*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); + } +} + + +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) { + ASSERT(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) { + ASSERT(active_live_ranges_.Contains(range)); + active_live_ranges_.RemoveElement(range); + inactive_live_ranges_.Add(range); + TraceAlloc("Moving live range %d from active to inactive\n", range->id()); +} + + +void LAllocator::InactiveToHandled(LiveRange* range) { + ASSERT(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) { + ASSERT(inactive_live_ranges_.Contains(range)); + inactive_live_ranges_.RemoveElement(range); + active_live_ranges_.Add(range); + TraceAlloc("Moving live range %d from inactive to active\n", range->id()); +} + + +// TryAllocateFreeReg and AllocateBlockedReg assume this +// when allocating local arrays. +STATIC_ASSERT(DoubleRegister::kNumAllocatableRegisters >= + Register::kNumAllocatableRegisters); + + +bool LAllocator::TryAllocateFreeReg(LiveRange* current) { + LifetimePosition free_until_pos[DoubleRegister::kNumAllocatableRegisters]; + + for (int i = 0; i < DoubleRegister::kNumAllocatableRegisters; 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); + ASSERT(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); + } + + UsePosition* hinted_use = current->FirstPosWithHint(); + if (hinted_use != NULL) { + LOperand* hint = hinted_use->hint(); + if (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()); + current->set_assigned_register(register_index, mode_); + return true; + } + } + } + + // Find the register which stays free for the longest time. + int reg = 0; + for (int i = 1; i < RegisterCount(); ++i) { + if (free_until_pos[i].Value() > free_until_pos[reg].Value()) { + reg = i; + } + } + + 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 = SplitAt(current, pos); + AddToUnhandledSorted(tail); + } + + + // Register reg is available at the range start and is free until + // the range end. + ASSERT(pos.Value() >= current->End().Value()); + TraceAlloc("Assigning free reg %s to live range %d\n", + RegisterName(reg), + current->id()); + current->set_assigned_register(reg, mode_); + + 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::kNumAllocatableRegisters]; + LifetimePosition block_pos[DoubleRegister::kNumAllocatableRegisters]; + + for (int i = 0; i < DoubleRegister::kNumAllocatableRegisters; 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); + ASSERT(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 = 0; + for (int i = 1; i < RegisterCount(); ++i) { + if (use_pos[i].Value() > use_pos[reg].Value()) { + reg = i; + } + } + + 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. + // + // Corner case: the first use position is equal to the start of the range. + // In this case we have nothing to spill and SpillBetween will just return + // this range to the list of unhandled ones. This will lead to the infinite + // loop. + ASSERT(current->Start().Value() < register_use->pos().Value()); + 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()); + AddToUnhandledSorted(tail); + } + + // Register reg is not blocked for the whole range. + ASSERT(block_pos[reg].Value() >= current->End().Value()); + TraceAlloc("Assigning blocked reg %s to live range %d\n", + RegisterName(reg), + current->id()); + current->set_assigned_register(reg, mode_); + + // 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); +} + + +void LAllocator::SplitAndSpillIntersecting(LiveRange* current) { + ASSERT(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()); + if (next_pos == NULL) { + SpillAfter(range, split_pos); + } else { + SpillBetween(range, split_pos, next_pos->pos()); + } + ActiveToHandled(range); + --i; + } + } + + for (int i = 0; i < inactive_live_ranges_.length(); ++i) { + LiveRange* range = inactive_live_ranges_[i]; + ASSERT(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); + } + InactiveToHandled(range); + --i; + } + } + } +} + + +bool LAllocator::IsBlockBoundary(LifetimePosition pos) { + return pos.IsInstructionStart() && + InstructionAt(pos.InstructionIndex())->IsLabel(); +} + + +LiveRange* LAllocator::SplitAt(LiveRange* range, LifetimePosition pos) { + ASSERT(!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. + ASSERT(pos.IsInstructionStart() || + !chunk_->instructions()->at(pos.InstructionIndex())->IsControl()); + + LiveRange* result = LiveRangeFor(next_virtual_register_++); + range->SplitAt(pos, result); + return result; +} + + +LiveRange* LAllocator::SplitBetween(LiveRange* range, + LifetimePosition start, + LifetimePosition end) { + ASSERT(!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); + ASSERT(split_pos.Value() >= start.Value()); + return SplitAt(range, split_pos); +} + + +LifetimePosition LAllocator::FindOptimalSplitPos(LifetimePosition start, + LifetimePosition end) { + int start_instr = start.InstructionIndex(); + int end_instr = end.InstructionIndex(); + ASSERT(start_instr <= end_instr); + + // We have no choice + if (start_instr == end_instr) return end; + + HBasicBlock* end_block = GetBlock(start); + HBasicBlock* start_block = GetBlock(end); + + if (end_block == start_block) { + // The interval is split in the same basic block. Split at 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(); + } + + if (block == end_block) return end; + + return LifetimePosition::FromInstructionIndex( + block->first_instruction_index()); +} + + +void LAllocator::SpillAfter(LiveRange* range, LifetimePosition pos) { + LiveRange* second_part = SplitAt(range, pos); + Spill(second_part); +} + + +void LAllocator::SpillBetween(LiveRange* range, + LifetimePosition start, + LifetimePosition end) { + ASSERT(start.Value() < end.Value()); + LiveRange* second_part = SplitAt(range, start); + + 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, + second_part->Start().InstructionEnd(), + end.PrevInstruction().InstructionEnd()); + + ASSERT(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) { + ASSERT(!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(mode_ == DOUBLE_REGISTERS); + first->SetSpillOperand(op); + } + range->MakeSpilled(); +} + + +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 + + +} } // namespace v8::internal |