Merge V8 5.3.332.45. DO NOT MERGE
Test: Manual
FPIIM-449
Change-Id: Id3254828b068abdea3cb10442e0172a8c9a98e03
(cherry picked from commit 13e2dadd00298019ed862f2b2fc5068bba730bcf)
diff --git a/src/compiler/checkpoint-elimination.cc b/src/compiler/checkpoint-elimination.cc
new file mode 100644
index 0000000..d81e109
--- /dev/null
+++ b/src/compiler/checkpoint-elimination.cc
@@ -0,0 +1,43 @@
+// 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::Reduce(Node* node) {
+ if (node->opcode() != IrOpcode::kCheckpoint) return NoChange();
+ if (IsRedundantCheckpoint(node)) {
+ return Replace(NodeProperties::GetEffectInput(node));
+ }
+ return NoChange();
+}
+
+} // namespace compiler
+} // namespace internal
+} // namespace v8