Turn redundant phi elimination into proper HPhase.

src/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 22 matching lines @@
 #include "codegen.h"
 #include "full-codegen.h"
 #include "hashmap.h"
 #include "hydrogen-dce.h"
 #include "hydrogen-environment-liveness.h"
 #include "hydrogen-escape-analysis.h"
 #include "hydrogen-infer-representation.h"
 #include "hydrogen-gvn.h"
 #include "hydrogen-osr.h"
 #include "hydrogen-range-analysis.h"
+#include "hydrogen-redundant-phi.h"
 #include "hydrogen-sce.h"
 #include "hydrogen-uint32-analysis.h"
 #include "lithium-allocator.h"
 #include "parser.h"
 #include "scopeinfo.h"
 #include "scopes.h"
 #include "stub-cache.h"
 #include "typing.h"
 
 #if V8_TARGET_ARCH_IA32
@@ skipping 2463 matching lines @@
       }
       if (instr->IsSoftDeoptimize()) {
         ASSERT(block->IsDeoptimizing());
         nullify = true;
       }
     }
   }
 }
 
 
-// Replace all phis consisting of a single non-loop operand plus any number of
-// loop operands by that single non-loop operand.
-void HGraph::EliminateRedundantPhis() {
-  HPhase phase("H_Redundant phi elimination", this);
-
-  // We do a simple fixed point iteration without any work list, because
-  // machine-generated JavaScript can lead to a very dense Hydrogen graph with
-  // an enormous work list and will consequently result in OOM. Experiments
-  // showed that this simple algorithm is good enough, and even e.g. tracking
-  // the set or range of blocks to consider is not a real improvement.
-  bool need_another_iteration;
-  ZoneList<HPhi*> redundant_phis(blocks_.length(), zone());
-  do {
-    need_another_iteration = false;
-    for (int i = 0; i < blocks_.length(); ++i) {
-      HBasicBlock* block = blocks_[i];
-      for (int j = 0; j < block->phis()->length(); j++) {
-        HPhi* phi = block->phis()->at(j);
-        HValue* replacement = phi->GetRedundantReplacement();
-        if (replacement != NULL) {
-          // Remember phi to avoid concurrent modification of the block's phis.
-          redundant_phis.Add(phi, zone());
-          for (HUseIterator it(phi->uses()); !it.Done(); it.Advance()) {
-            HValue* value = it.value();
-            value->SetOperandAt(it.index(), replacement);
-            need_another_iteration |= value->IsPhi();
-          }
-        }
-      }
-      for (int i = 0; i < redundant_phis.length(); i++) {
-        block->RemovePhi(redundant_phis[i]);
-      }
-      redundant_phis.Clear();
-    }
-  } while (need_another_iteration);
-
-#if DEBUG
-  // Make sure that we *really* removed all redundant phis.
-  for (int i = 0; i < blocks_.length(); ++i) {
-    for (int j = 0; j < blocks_[i]->phis()->length(); j++) {
-      ASSERT(blocks_[i]->phis()->at(j)->GetRedundantReplacement() == NULL);
-    }
-  }
-#endif
-}
-
-
 bool HGraph::CheckArgumentsPhiUses() {
   int block_count = blocks_.length();
   for (int i = 0; i < block_count; ++i) {
     for (int j = 0; j < blocks_[i]->phis()->length(); ++j) {
       HPhi* phi = blocks_[i]->phis()->at(j);
       // We don't support phi uses of arguments for now.
       if (phi->CheckFlag(HValue::kIsArguments)) return false;
     }
   }
   return true;
@@ skipping 827 matching lines @@
   if (FLAG_analyze_environment_liveness && maximum_environment_size() != 0) {
     Run<HEnvironmentLivenessAnalysisPhase>();
   }
 
   PropagateDeoptimizingMark();
   if (!CheckConstPhiUses()) {
     *bailout_reason = SmartArrayPointer<char>(StrDup(
         "Unsupported phi use of const variable"));
     return false;
   }
-  EliminateRedundantPhis();
+  Run<HRedundantPhiEliminationPhase>();
   if (!CheckArgumentsPhiUses()) {
     *bailout_reason = SmartArrayPointer<char>(StrDup(
         "Unsupported phi use of arguments"));
     return false;
   }
 
   // Remove dead code and phis
   if (FLAG_dead_code_elimination) Run<HDeadCodeEliminationPhase>();
   CollectPhis();
 
@@ skipping 7269 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal