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// 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.
#ifndef V8_COMPILER_PHI_REDUCER_H_
#define V8_COMPILER_PHI_REDUCER_H_
#include "src/compiler/graph-reducer.h"
namespace v8 {
namespace internal {
namespace compiler {
// Replaces redundant phis if all the inputs are the same or the phi itself.
class PhiReducer V8_FINAL : public Reducer {
public:
virtual Reduction Reduce(Node* node) V8_OVERRIDE {
if (node->opcode() != IrOpcode::kPhi &&
node->opcode() != IrOpcode::kEffectPhi)
return NoChange();
int n = node->op()->InputCount();
if (n == 1) return Replace(node->InputAt(0));
Node* replacement = NULL;
Node::Inputs inputs = node->inputs();
for (InputIter it = inputs.begin(); n > 0; --n, ++it) {
Node* input = *it;
if (input != node && input != replacement) {
if (replacement != NULL) return NoChange();
replacement = input;
}
}
DCHECK_NE(node, replacement);
return Replace(replacement);
}
};
}
}
} // namespace v8::internal::compiler
#endif // V8_COMPILER_PHI_REDUCER_H_
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