Use weak cells in map checks in polymorphic ICs.

src/x64/macro-assembler-x64.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"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
@@ skipping 2834 matching lines @@
   if (dst.is(rax)) {
     AllowDeferredHandleDereference embedding_raw_address;
     load_rax(cell.location(), RelocInfo::CELL);
   } else {
     Move(dst, cell, RelocInfo::CELL);
     movp(dst, Operand(dst, 0));
   }
 }
 
 
+void MacroAssembler::CmpWeakValue(Register value, Register scratch,
+                                  Handle<WeakCell> cell) {
+  Move(scratch, cell, RelocInfo::EMBEDDED_OBJECT);
+  cmpp(value, FieldOperand(scratch, WeakCell::kValueOffset));
+}
+
+
 void MacroAssembler::Drop(int stack_elements) {
   if (stack_elements > 0) {
     addp(rsp, Immediate(stack_elements * kPointerSize));
   }
 }
 
 
 void MacroAssembler::DropUnderReturnAddress(int stack_elements,
                                             Register scratch) {
   DCHECK(stack_elements > 0);
@@ skipping 2529 matching lines @@
   if (mag.shift > 0) sarl(rdx, Immediate(mag.shift));
   movl(rax, dividend);
   shrl(rax, Immediate(31));
   addl(rdx, rax);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64