Line data    Source code

       1             : // Copyright 2013 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             : #include "src/crankshaft/hydrogen-redundant-phi.h"
       6             : #include "src/objects-inl.h"
       7             : 
       8             : namespace v8 {
       9             : namespace internal {
      10             : 
      11      283199 : void HRedundantPhiEliminationPhase::Run() {
      12             :   // Gather all phis from all blocks first.
      13      283199 :   const ZoneList<HBasicBlock*>* blocks(graph()->blocks());
      14     5060028 :   ZoneList<HPhi*> all_phis(blocks->length(), zone());
      15     9553658 :   for (int i = 0; i < blocks->length(); ++i) {
      16     4493630 :     HBasicBlock* block = blocks->at(i);
      17     5155945 :     for (int j = 0; j < block->phis()->length(); j++) {
      18      662315 :       all_phis.Add(block->phis()->at(j), zone());
      19             :     }
      20             :   }
      21             : 
      22             :   // Iteratively reduce all phis in the list.
      23      283199 :   ProcessPhis(&all_phis);
      24             : 
      25             : #if DEBUG
      26             :   // Make sure that we *really* removed all redundant phis.
      27             :   for (int i = 0; i < blocks->length(); ++i) {
      28             :     for (int j = 0; j < blocks->at(i)->phis()->length(); j++) {
      29             :       DCHECK(blocks->at(i)->phis()->at(j)->GetRedundantReplacement() == NULL);
      30             :     }
      31             :   }
      32             : #endif
      33      283199 : }
      34             : 
      35             : 
      36     4493572 : void HRedundantPhiEliminationPhase::ProcessBlock(HBasicBlock* block) {
      37     4493572 :   ProcessPhis(block->phis());
      38     4493574 : }
      39             : 
      40             : 
      41     4776767 : void HRedundantPhiEliminationPhase::ProcessPhis(const ZoneList<HPhi*>* phis) {
      42             :   bool updated;
      43     4789365 :   do {
      44             :     // Iterately replace all redundant phis in the given list.
      45             :     updated = false;
      46    12148926 :     for (int i = 0; i < phis->length(); i++) {
      47     7359561 :       HPhi* phi = phis->at(i);
      48     3326716 :       if (phi->CheckFlag(HValue::kIsDead)) continue;  // Already replaced.
      49             : 
      50     1116786 :       HValue* replacement = phi->GetRedundantReplacement();
      51     1116786 :       if (replacement != NULL) {
      52             :         phi->SetFlag(HValue::kIsDead);
      53     1290799 :         for (HUseIterator it(phi->uses()); !it.Done(); it.Advance()) {
      54     1645242 :           HValue* value = it.value();
      55     1290799 :           value->SetOperandAt(it.index(), replacement);
      56             :           // Iterate again if used in another non-dead phi.
      57     1645242 :           updated |= value->IsPhi() && !value->CheckFlag(HValue::kIsDead);
      58             :         }
      59      378260 :         phi->block()->RemovePhi(phi);
      60             :       }
      61             :     }
      62             :   } while (updated);
      63     4776767 : }
      64             : 
      65             : 
      66             : }  // namespace internal
      67             : }  // namespace v8