diff options
Diffstat (limited to 'deps/v8/src/compiler/liveness-analyzer.cc')
-rw-r--r-- | deps/v8/src/compiler/liveness-analyzer.cc | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/deps/v8/src/compiler/liveness-analyzer.cc b/deps/v8/src/compiler/liveness-analyzer.cc new file mode 100644 index 0000000000..301106d1c3 --- /dev/null +++ b/deps/v8/src/compiler/liveness-analyzer.cc @@ -0,0 +1,200 @@ +// Copyright 2014 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/compiler/liveness-analyzer.h" +#include "src/compiler/js-graph.h" +#include "src/compiler/node.h" +#include "src/compiler/node-matchers.h" +#include "src/compiler/state-values-utils.h" + +namespace v8 { +namespace internal { +namespace compiler { + + +LivenessAnalyzer::LivenessAnalyzer(size_t local_count, Zone* zone) + : zone_(zone), blocks_(zone), local_count_(local_count), queue_(zone) {} + + +void LivenessAnalyzer::Print(std::ostream& os) { + for (auto block : blocks_) { + block->Print(os); + os << std::endl; + } +} + + +LivenessAnalyzerBlock* LivenessAnalyzer::NewBlock() { + LivenessAnalyzerBlock* result = + new (zone()->New(sizeof(LivenessAnalyzerBlock))) + LivenessAnalyzerBlock(blocks_.size(), local_count_, zone()); + blocks_.push_back(result); + return result; +} + + +LivenessAnalyzerBlock* LivenessAnalyzer::NewBlock( + LivenessAnalyzerBlock* predecessor) { + LivenessAnalyzerBlock* result = NewBlock(); + result->AddPredecessor(predecessor); + return result; +} + + +void LivenessAnalyzer::Queue(LivenessAnalyzerBlock* block) { + if (!block->IsQueued()) { + block->SetQueued(); + queue_.push(block); + } +} + + +void LivenessAnalyzer::Run(NonLiveFrameStateSlotReplacer* replacer) { + if (local_count_ == 0) { + // No local variables => nothing to do. + return; + } + + // Put all blocks into the queue. + DCHECK(queue_.empty()); + for (auto block : blocks_) { + Queue(block); + } + + // Compute the fix-point. + BitVector working_area(static_cast<int>(local_count_), zone_); + while (!queue_.empty()) { + LivenessAnalyzerBlock* block = queue_.front(); + queue_.pop(); + block->Process(&working_area, nullptr); + + for (auto i = block->pred_begin(); i != block->pred_end(); i++) { + if ((*i)->UpdateLive(&working_area)) { + Queue(*i); + } + } + } + + // Update the frame states according to the liveness. + for (auto block : blocks_) { + block->Process(&working_area, replacer); + } +} + +LivenessAnalyzerBlock::LivenessAnalyzerBlock(size_t id, size_t local_count, + Zone* zone) + : entries_(zone), + predecessors_(zone), + live_(local_count == 0 ? 1 : static_cast<int>(local_count), zone), + queued_(false), + id_(id) {} + +void LivenessAnalyzerBlock::Process(BitVector* result, + NonLiveFrameStateSlotReplacer* replacer) { + queued_ = false; + + // Copy the bitvector to the target bit vector. + result->CopyFrom(live_); + + for (auto i = entries_.rbegin(); i != entries_.rend(); i++) { + auto entry = *i; + switch (entry.kind()) { + case Entry::kLookup: + result->Add(entry.var()); + break; + case Entry::kBind: + result->Remove(entry.var()); + break; + case Entry::kCheckpoint: + if (replacer != nullptr) { + replacer->ClearNonLiveFrameStateSlots(entry.node(), result); + } + break; + } + } +} + + +bool LivenessAnalyzerBlock::UpdateLive(BitVector* working_area) { + return live_.UnionIsChanged(*working_area); +} + + +void NonLiveFrameStateSlotReplacer::ClearNonLiveFrameStateSlots( + Node* frame_state, BitVector* liveness) { + DCHECK_EQ(frame_state->opcode(), IrOpcode::kFrameState); + Node* locals_state = frame_state->InputAt(1); + DCHECK_EQ(locals_state->opcode(), IrOpcode::kStateValues); + int count = static_cast<int>(StateValuesAccess(locals_state).size()); + DCHECK_EQ(count == 0 ? 1 : count, liveness->length()); + for (int i = 0; i < count; i++) { + bool live = liveness->Contains(i) || permanently_live_.Contains(i); + if (!live || locals_state->InputAt(i) != replacement_node_) { + Node* new_values = ClearNonLiveStateValues(locals_state, liveness); + frame_state->ReplaceInput(1, new_values); + break; + } + } +} + + +Node* NonLiveFrameStateSlotReplacer::ClearNonLiveStateValues( + Node* values, BitVector* liveness) { + DCHECK(inputs_buffer_.empty()); + for (StateValuesAccess::TypedNode node : StateValuesAccess(values)) { + // Index of the next variable is its furure index in the inputs buffer, + // i.e., the buffer's size. + int var = static_cast<int>(inputs_buffer_.size()); + bool live = liveness->Contains(var) || permanently_live_.Contains(var); + inputs_buffer_.push_back(live ? node.node : replacement_node_); + } + Node* result = state_values_cache()->GetNodeForValues( + inputs_buffer_.empty() ? nullptr : &(inputs_buffer_.front()), + inputs_buffer_.size()); + inputs_buffer_.clear(); + return result; +} + + +void LivenessAnalyzerBlock::Print(std::ostream& os) { + os << "Block " << id(); + bool first = true; + for (LivenessAnalyzerBlock* pred : predecessors_) { + if (!first) { + os << ", "; + } else { + os << "; predecessors: "; + first = false; + } + os << pred->id(); + } + os << std::endl; + + for (auto entry : entries_) { + os << " "; + switch (entry.kind()) { + case Entry::kLookup: + os << "- Lookup " << entry.var() << std::endl; + break; + case Entry::kBind: + os << "- Bind " << entry.var() << std::endl; + break; + case Entry::kCheckpoint: + os << "- Checkpoint " << entry.node()->id() << std::endl; + break; + } + } + + if (live_.length() > 0) { + os << " Live set: "; + for (int i = 0; i < live_.length(); i++) { + os << (live_.Contains(i) ? "L" : "."); + } + os << std::endl; + } +} + +} // namespace compiler +} // namespace internal +} // namespace v8 |