Turn merge removable simulates into a 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 26 matching lines @@
 #include "hydrogen-dce.h"
 #include "hydrogen-environment-liveness.h"
 #include "hydrogen-escape-analysis.h"
 #include "hydrogen-infer-representation.h"
 #include "hydrogen-infer-types.h"
 #include "hydrogen-gvn.h"
 #include "hydrogen-minus-zero.h"
 #include "hydrogen-osr.h"
 #include "hydrogen-range-analysis.h"
 #include "hydrogen-redundant-phi.h"
+#include "hydrogen-removable-simulates.h"
 #include "hydrogen-representation-changes.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"
 
@@ skipping 2508 matching lines @@
   phi_list_ = new(zone()) ZoneList<HPhi*>(block_count, zone());
   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);
       phi_list_->Add(phi, zone());
     }
   }
 }
 
 
-void HGraph::MergeRemovableSimulates() {
-  HPhase phase("H_Merge removable simulates", this);
-  ZoneList<HSimulate*> mergelist(2, zone());
-  for (int i = 0; i < blocks()->length(); ++i) {
-    HBasicBlock* block = blocks()->at(i);
-    // Make sure the merge list is empty at the start of a block.
-    ASSERT(mergelist.is_empty());
-    // Nasty heuristic: Never remove the first simulate in a block. This
-    // just so happens to have a beneficial effect on register allocation.
-    bool first = true;
-    for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
-      HInstruction* current = it.Current();
-      if (current->IsLeaveInlined()) {
-        // Never fold simulates from inlined environments into simulates
-        // in the outer environment.
-        // (Before each HEnterInlined, there is a non-foldable HSimulate
-        // anyway, so we get the barrier in the other direction for free.)
-        // Simply remove all accumulated simulates without merging.  This
-        // is safe because simulates after instructions with side effects
-        // are never added to the merge list.
-        while (!mergelist.is_empty()) {
-          mergelist.RemoveLast()->DeleteAndReplaceWith(NULL);
-        }
-        continue;
-      }
-      if (current->IsReturn()) {
-        // Drop mergeable simulates in the list. This is safe because
-        // simulates after instructions with side effects are never added
-        // to the merge list.
-        while (!mergelist.is_empty()) {
-          mergelist.RemoveLast()->DeleteAndReplaceWith(NULL);
-        }
-        continue;
-      }
-      // Skip the non-simulates and the first simulate.
-      if (!current->IsSimulate()) continue;
-      if (first) {
-        first = false;
-        continue;
-      }
-      HSimulate* current_simulate = HSimulate::cast(current);
-      if ((current_simulate->previous()->HasObservableSideEffects() &&
-           !current_simulate->next()->IsSimulate()) ||
-          !current_simulate->is_candidate_for_removal()) {
-        // This simulate is not suitable for folding.
-        // Fold the ones accumulated so far.
-        current_simulate->MergeWith(&mergelist);
-        continue;
-      } else {
-        // Accumulate this simulate for folding later on.
-        mergelist.Add(current_simulate, zone());
-      }
-    }
-
-    if (!mergelist.is_empty()) {
-      // Merge the accumulated simulates at the end of the block.
-      HSimulate* last = mergelist.RemoveLast();
-      last->MergeWith(&mergelist);
-    }
-  }
-}
-
-
 void HGraph::RecursivelyMarkPhiDeoptimizeOnUndefined(HPhi* phi) {
   if (!phi->CheckFlag(HValue::kAllowUndefinedAsNaN)) return;
   phi->ClearFlag(HValue::kAllowUndefinedAsNaN);
   for (int i = 0; i < phi->OperandCount(); ++i) {
     HValue* input = phi->OperandAt(i);
     if (input->IsPhi()) {
       RecursivelyMarkPhiDeoptimizeOnUndefined(HPhi::cast(input));
     }
   }
 }
@@ skipping 482 matching lines @@
   if (FLAG_dead_code_elimination) Run<HDeadCodeEliminationPhase>();
   CollectPhis();
 
   if (has_osr()) osr()->FinishOsrValues();
 
   Run<HInferRepresentationPhase>();
 
   // Remove HSimulate instructions that have turned out not to be needed
   // after all by folding them into the following HSimulate.
   // This must happen after inferring representations.
-  MergeRemovableSimulates();
+  Run<HMergeRemovableSimulatesPhase>();
 
   MarkDeoptimizeOnUndefined();
   Run<HRepresentationChangesPhase>();
 
   Run<HInferTypesPhase>();
 
   // Must be performed before canonicalization to ensure that Canonicalize
   // will not remove semantically meaningful ToInt32 operations e.g. BIT_OR with
   // zero.
   if (FLAG_opt_safe_uint32_operations) Run<HUint32AnalysisPhase>();
@@ skipping 7025 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal