Add support to load/store byte fields.

src/x64/macro-assembler-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 929 matching lines @@
   cvtlsi2sd(dst, src);
 }
 
 
 void MacroAssembler::Cvtlsi2sd(XMMRegister dst, const Operand& src) {
   xorps(dst, dst);
   cvtlsi2sd(dst, src);
 }
 
 
+void MacroAssembler::Load(Register dst, const Operand& src, Representation r) {
+  if (r.IsByte()) {
+    movzxbl(dst, src);
+  } else if (r.IsInteger32()) {
+    movl(dst, src);
+  } else {
+    movq(dst, src);
+  }
+}
+
+
+void MacroAssembler::Store(const Operand& dst, Register src, Representation r) {
+  if (r.IsByte()) {
+    movb(dst, src);
+  } else if (r.IsInteger32()) {
+    movl(dst, src);
+  } else {
+    movq(dst, src);
+  }
+}
+
+
 void MacroAssembler::Set(Register dst, int64_t x) {
   if (x == 0) {
     xorl(dst, dst);
   } else if (is_uint32(x)) {
     movl(dst, Immediate(static_cast<uint32_t>(x)));
   } else if (is_int32(x)) {
     movq(dst, Immediate(static_cast<int32_t>(x)));
   } else {
     movq(dst, x, RelocInfo::NONE64);
   }
@@ skipping 3941 matching lines @@
   j(greater, &no_memento_available);
   CompareRoot(MemOperand(scratch_reg, -AllocationMemento::kSize),
               Heap::kAllocationMementoMapRootIndex);
   bind(&no_memento_available);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64