Allow HPhis to have an invalid merge index.

src/hydrogen-escape-analysis.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 92 matching lines @@
   HCapturedObject* state = NewState(previous);
   for (int index = 0; index < number_of_values_; index++) {
     HValue* operand = old_state->OperandAt(index);
     state->SetOperandAt(index, operand);
   }
   return state;
 }
 
 
 // Insert a newly created phi into the given block and fill all incoming
-// edges with the given value. The merge index is chosen so that it is
-// unique for this particular scalar replacement index.
+// edges with the given value.
 HPhi* HEscapeAnalysisPhase::NewPhiAndInsert(
     HBasicBlock* block, HValue* incoming_value, int index) {
   Zone* zone = graph()->zone();
-  HBasicBlock* pred = block->predecessors()->first();
-  int phi_index = pred->last_environment()->length() + cumulative_values_;
-  HPhi* phi = new(zone) HPhi(phi_index + index, zone);
+  HPhi* phi = new(zone) HPhi(HPhi::kInvalidMergedIndex, zone);
   for (int i = 0; i < block->predecessors()->length(); i++) {
     phi->AddInput(incoming_value);
   }
   block->AddPhi(phi);
   return phi;
 }
 
 
 // Performs a forward data-flow analysis of all loads and stores on the
 // given captured allocation. This uses a reverse post-order iteration
@@ skipping 152 matching lines @@
     AnalyzeDataFlow(allocate);
 
     cumulative_values_ += number_of_values_;
     ASSERT(allocate->HasNoUses());
     ASSERT(!allocate->IsLinked());
   }
 }
 
 
 } }  // namespace v8::internal