Remove the obsolete OverwriteMode optimization.

src/code-stubs-hydrogen.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/v8.h"
 
 #include "src/bailout-reason.h"
 #include "src/code-stubs.h"
 #include "src/field-index.h"
 #include "src/hydrogen.h"
@@ skipping 1212 matching lines @@
             left_type, right_type, result_type,
             state.fixed_right_arg(), allocation_mode);
   }
 
   // If we encounter a generic argument, the number conversion is
   // observable, thus we cannot afford to bail out after the fact.
   if (!state.HasSideEffects()) {
     result = EnforceNumberType(result, result_type);
   }
 
-  // Reuse the double box of one of the operands if we are allowed to (i.e.
-  // chained binops).
-  if (state.CanReuseDoubleBox()) {
-    HValue* operand = (state.mode() == OVERWRITE_LEFT) ? left : right;
-    IfBuilder if_heap_number(this);
-    if_heap_number.If<HHasInstanceTypeAndBranch>(operand, HEAP_NUMBER_TYPE);
-    if_heap_number.Then();
-    Add<HStoreNamedField>(operand, HObjectAccess::ForHeapNumberValue(), result);
-    Push(operand);
-    if_heap_number.Else();
-    Push(result);
-    if_heap_number.End();
-    result = Pop();
-  }
-
   return result;
 }
 
 
 Handle<Code> BinaryOpICStub::GenerateCode() {
   return DoGenerateCode(this);
 }
 
 
 template <>
@@ skipping 1005 matching lines @@
   // megamorphic case is handled as part of the default stub.
   DCHECK(!FLAG_vector_ics);
 
   // Probe the stub cache.
   Add<HTailCallThroughMegamorphicCache>(receiver, name);
 
   // We never continue.
   return graph()->GetConstant0();
 }
 } }  // namespace v8::internal