Introduce "optimized_out" oddball marker for compilers.

src/crankshaft/hydrogen-environment-liveness.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 
 #include "src/crankshaft/hydrogen-environment-liveness.h"
 
 
 namespace v8 {
 namespace internal {
@@ skipping 19 matching lines @@
     first_simulate_invalid_for_index_.Add(
         new(zone()) BitVector(maximum_environment_size_, zone()), zone());
   }
 }
 
 
 void HEnvironmentLivenessAnalysisPhase::ZapEnvironmentSlot(
     int index, HSimulate* simulate) {
   int operand_index = simulate->ToOperandIndex(index);
   if (operand_index == -1) {
-    simulate->AddAssignedValue(index, graph()->GetConstantUndefined());
+    simulate->AddAssignedValue(index, graph()->GetConstantOptimizedOut());
   } else {
-    simulate->SetOperandAt(operand_index, graph()->GetConstantUndefined());
+    simulate->SetOperandAt(operand_index, graph()->GetConstantOptimizedOut());
   }
 }
 
 
 void HEnvironmentLivenessAnalysisPhase::ZapEnvironmentSlotsInSuccessors(
     HBasicBlock* block, BitVector* live) {
   // When a value is live in successor A but dead in B, we must
   // explicitly zap it in B.
   for (HSuccessorIterator it(block->end()); !it.Done(); it.Advance()) {
     HBasicBlock* successor = it.Current();
@@ skipping 170 matching lines @@
 bool HEnvironmentLivenessAnalysisPhase::VerifyClosures(
     Handle<JSFunction> a, Handle<JSFunction> b) {
   Heap::RelocationLock for_heap_access(isolate()->heap());
   AllowHandleDereference for_verification;
   return a.is_identical_to(b);
 }
 #endif
 
 }  // namespace internal
 }  // namespace v8