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 FINAL : public Reducer { 16 public: 17 virtual Reduction Reduce(Node* node) 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 DCHECK_NE(node, replacement); 35 return Replace(replacement); 36 } 37 }; 38 } 39 } 40 } // namespace v8::internal::compiler 41 42 #endif // V8_COMPILER_PHI_REDUCER_H_ 43
