| // 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/compiler/checkpoint-elimination.h" |
| |
| #include "src/compiler/node-properties.h" |
| |
| namespace v8 { |
| namespace internal { |
| namespace compiler { |
| |
| CheckpointElimination::CheckpointElimination(Editor* editor) |
| : AdvancedReducer(editor) {} |
| |
| namespace { |
| |
| // The given checkpoint is redundant if it is effect-wise dominated by another |
| // checkpoint and there is no observable write in between. For now we consider |
| // a linear effect chain only instead of true effect-wise dominance. |
| bool IsRedundantCheckpoint(Node* node) { |
| Node* effect = NodeProperties::GetEffectInput(node); |
| while (effect->op()->HasProperty(Operator::kNoWrite) && |
| effect->op()->EffectInputCount() == 1) { |
| if (effect->opcode() == IrOpcode::kCheckpoint) return true; |
| effect = NodeProperties::GetEffectInput(effect); |
| } |
| return false; |
| } |
| |
| } // namespace |
| |
| Reduction CheckpointElimination::ReduceCheckpoint(Node* node) { |
| DCHECK_EQ(IrOpcode::kCheckpoint, node->opcode()); |
| if (IsRedundantCheckpoint(node)) { |
| return Replace(NodeProperties::GetEffectInput(node)); |
| } |
| return NoChange(); |
| } |
| |
| Reduction CheckpointElimination::Reduce(Node* node) { |
| DisallowHeapAccess no_heap_access; |
| switch (node->opcode()) { |
| case IrOpcode::kCheckpoint: |
| return ReduceCheckpoint(node); |
| default: |
| break; |
| } |
| return NoChange(); |
| } |
| |
| } // namespace compiler |
| } // namespace internal |
| } // namespace v8 |