Reland parts of 'Use weak cells in map checks in polymorphic ICs'

src/x87/macro-assembler-x87.h

 // 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.
 
 #ifndef V8_X87_MACRO_ASSEMBLER_X87_H_
 #define V8_X87_MACRO_ASSEMBLER_X87_H_
 
 #include "src/assembler.h"
 #include "src/bailout-reason.h"
 #include "src/frames.h"
@@ skipping 259 matching lines @@
 
   void CmpObject(Register reg, Handle<Object> object) {
     AllowDeferredHandleDereference heap_object_check;
     if (object->IsHeapObject()) {
       CmpHeapObject(reg, Handle<HeapObject>::cast(object));
     } else {
       cmp(reg, Immediate(object));
     }
   }
 
+  void CmpWeakValue(Register value, Handle<WeakCell> cell, Register scratch);
+  void LoadWeakValue(Register value, Handle<WeakCell> cell, Label* miss);
+
   // ---------------------------------------------------------------------------
   // JavaScript invokes
 
   // Invoke the JavaScript function code by either calling or jumping.
   void InvokeCode(Register code,
                   const ParameterCount& expected,
                   const ParameterCount& actual,
                   InvokeFlag flag,
                   const CallWrapper& call_wrapper) {
     InvokeCode(Operand(code), expected, actual, flag, call_wrapper);
@@ skipping 786 matching lines @@
   }                                                                       \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_X87_MACRO_ASSEMBLER_X87_H_