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| 1 // Copyright 2014 the V8 project authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #ifndef V8_COMPILER_PHI_REDUCER_H_ |
| 6 #define V8_COMPILER_PHI_REDUCER_H_ |
| 7 |
| 8 #include "src/compiler/graph-reducer.h" |
| 9 |
| 10 namespace v8 { |
| 11 namespace internal { |
| 12 namespace compiler { |
| 13 |
| 14 // Replaces redundant phis if all the inputs are the same or the phi itself. |
| 15 class PhiReducer V8_FINAL : public Reducer { |
| 16 public: |
| 17 virtual Reduction Reduce(Node* node) V8_OVERRIDE { |
| 18 if (node->opcode() != IrOpcode::kPhi && |
| 19 node->opcode() != IrOpcode::kEffectPhi) |
| 20 return NoChange(); |
| 21 |
| 22 int n = node->op()->InputCount(); |
| 23 if (n == 1) return Replace(node->InputAt(0)); |
| 24 |
| 25 Node* replacement = NULL; |
| 26 Node::Inputs inputs = node->inputs(); |
| 27 for (InputIter it = inputs.begin(); n > 0; --n, ++it) { |
| 28 Node* input = *it; |
| 29 if (input != node && input != replacement) { |
| 30 if (replacement != NULL) return NoChange(); |
| 31 replacement = input; |
| 32 } |
| 33 } |
| 34 ASSERT_NE(node, replacement); |
| 35 return Replace(replacement); |
| 36 } |
| 37 }; |
| 38 } |
| 39 } |
| 40 } // namespace v8::internal::compiler |
| 41 |
| 42 #endif // V8_COMPILER_PHI_REDUCER_H_ |
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