1// Copyright 2013 the V8 project authors. All rights reserved. 2// Redistribution and use in source and binary forms, with or without 3// modification, are permitted provided that the following conditions are 4// met: 5// 6// * Redistributions of source code must retain the above copyright 7// notice, this list of conditions and the following disclaimer. 8// * Redistributions in binary form must reproduce the above 9// copyright notice, this list of conditions and the following 10// disclaimer in the documentation and/or other materials provided 11// with the distribution. 12// * Neither the name of Google Inc. nor the names of its 13// contributors may be used to endorse or promote products derived 14// from this software without specific prior written permission. 15// 16// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28#include "hydrogen-redundant-phi.h" 29 30namespace v8 { 31namespace internal { 32 33void HRedundantPhiEliminationPhase::Run() { 34 // Gather all phis from all blocks first. 35 const ZoneList<HBasicBlock*>* blocks(graph()->blocks()); 36 ZoneList<HPhi*> all_phis(blocks->length(), zone()); 37 for (int i = 0; i < blocks->length(); ++i) { 38 HBasicBlock* block = blocks->at(i); 39 for (int j = 0; j < block->phis()->length(); j++) { 40 all_phis.Add(block->phis()->at(j), zone()); 41 } 42 } 43 44 // Iteratively reduce all phis in the list. 45 ProcessPhis(&all_phis); 46 47#if DEBUG 48 // Make sure that we *really* removed all redundant phis. 49 for (int i = 0; i < blocks->length(); ++i) { 50 for (int j = 0; j < blocks->at(i)->phis()->length(); j++) { 51 ASSERT(blocks->at(i)->phis()->at(j)->GetRedundantReplacement() == NULL); 52 } 53 } 54#endif 55} 56 57 58void HRedundantPhiEliminationPhase::ProcessBlock(HBasicBlock* block) { 59 ProcessPhis(block->phis()); 60} 61 62 63void HRedundantPhiEliminationPhase::ProcessPhis(const ZoneList<HPhi*>* phis) { 64 bool updated; 65 do { 66 // Iterately replace all redundant phis in the given list. 67 updated = false; 68 for (int i = 0; i < phis->length(); i++) { 69 HPhi* phi = phis->at(i); 70 if (phi->CheckFlag(HValue::kIsDead)) continue; // Already replaced. 71 72 HValue* replacement = phi->GetRedundantReplacement(); 73 if (replacement != NULL) { 74 phi->SetFlag(HValue::kIsDead); 75 for (HUseIterator it(phi->uses()); !it.Done(); it.Advance()) { 76 HValue* value = it.value(); 77 value->SetOperandAt(it.index(), replacement); 78 // Iterate again if used in another non-dead phi. 79 updated |= value->IsPhi() && !value->CheckFlag(HValue::kIsDead); 80 } 81 phi->block()->RemovePhi(phi); 82 } 83 } 84 } while (updated); 85} 86 87 88} } // namespace v8::internal 89