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// 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
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