Introduce "optimized_out" oddball marker for compilers.

src/objects-debug.cc

 // Copyright 2012 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/objects.h"
 
 #include "src/bootstrapper.h"
 #include "src/disasm.h"
 #include "src/disassembler.h"
 #include "src/field-type.h"
@@ skipping 601 matching lines @@
   CHECK(IsOddball());
   Heap* heap = GetHeap();
   VerifyHeapPointer(to_string());
   Object* number = to_number();
   if (number->IsHeapObject()) {
     CHECK(number == heap->nan_value());
   } else {
     CHECK(number->IsSmi());
     int value = Smi::cast(number)->value();
     // Hidden oddballs have negative smis.
-    const int kLeastHiddenOddballNumber = -5;
+    const int kLeastHiddenOddballNumber = -6;
     CHECK_LE(value, 1);
     CHECK(value >= kLeastHiddenOddballNumber);
   }
   if (map() == heap->undefined_map()) {
     CHECK(this == heap->undefined_value());
   } else if (map() == heap->the_hole_map()) {
     CHECK(this == heap->the_hole_value());
   } else if (map() == heap->null_map()) {
     CHECK(this == heap->null_value());
   } else if (map() == heap->boolean_map()) {
     CHECK(this == heap->true_value() ||
           this == heap->false_value());
   } else if (map() == heap->uninitialized_map()) {
     CHECK(this == heap->uninitialized_value());
   } else if (map() == heap->no_interceptor_result_sentinel_map()) {
     CHECK(this == heap->no_interceptor_result_sentinel());
   } else if (map() == heap->arguments_marker_map()) {
     CHECK(this == heap->arguments_marker());
   } else if (map() == heap->termination_exception_map()) {
     CHECK(this == heap->termination_exception());
   } else if (map() == heap->exception_map()) {
     CHECK(this == heap->exception());
+  } else if (map() == heap->optimized_out_map()) {
+    CHECK(this == heap->optimized_out());
   } else {
     UNREACHABLE();
   }
 }
 
 
 void Cell::CellVerify() {
   CHECK(IsCell());
   VerifyObjectField(kValueOffset);
 }
@@ skipping 666 matching lines @@
 
   // Both are done at the same time.
   CHECK_EQ(new_it.done(), old_it.done());
 }
 
 
 #endif  // DEBUG
 
 }  // namespace internal
 }  // namespace v8