| // Copyright 2016 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/interpreter/bytecode-dead-code-optimizer.h" |
| |
| namespace v8 { |
| namespace internal { |
| namespace interpreter { |
| |
| BytecodeDeadCodeOptimizer::BytecodeDeadCodeOptimizer( |
| BytecodePipelineStage* next_stage) |
| : next_stage_(next_stage), exit_seen_in_block_(false) {} |
| |
| // override |
| Handle<BytecodeArray> BytecodeDeadCodeOptimizer::ToBytecodeArray( |
| Isolate* isolate, int register_count, int parameter_count, |
| Handle<FixedArray> handler_table) { |
| return next_stage_->ToBytecodeArray(isolate, register_count, parameter_count, |
| handler_table); |
| } |
| |
| // override |
| void BytecodeDeadCodeOptimizer::Write(BytecodeNode* node) { |
| // Don't emit dead code. |
| if (exit_seen_in_block_) return; |
| |
| switch (node->bytecode()) { |
| case Bytecode::kReturn: |
| case Bytecode::kThrow: |
| case Bytecode::kReThrow: |
| exit_seen_in_block_ = true; |
| break; |
| default: |
| break; |
| } |
| |
| next_stage_->Write(node); |
| } |
| |
| // override |
| void BytecodeDeadCodeOptimizer::WriteJump(BytecodeNode* node, |
| BytecodeLabel* label) { |
| // Don't emit dead code. |
| // TODO(rmcilroy): For forward jumps we could mark the label as dead, thereby |
| // avoiding emitting dead code when we bind the label. |
| if (exit_seen_in_block_) return; |
| |
| switch (node->bytecode()) { |
| case Bytecode::kJump: |
| case Bytecode::kJumpConstant: |
| exit_seen_in_block_ = true; |
| break; |
| default: |
| break; |
| } |
| |
| next_stage_->WriteJump(node, label); |
| } |
| |
| // override |
| void BytecodeDeadCodeOptimizer::BindLabel(BytecodeLabel* label) { |
| next_stage_->BindLabel(label); |
| exit_seen_in_block_ = false; |
| } |
| |
| // override |
| void BytecodeDeadCodeOptimizer::BindLabel(const BytecodeLabel& target, |
| BytecodeLabel* label) { |
| next_stage_->BindLabel(target, label); |
| // exit_seen_in_block_ was reset when target was bound, so shouldn't be |
| // changed here. |
| } |
| |
| } // namespace interpreter |
| } // namespace internal |
| } // namespace v8 |