Make some constants' meaning clear for X64

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 137 matching lines @@
       // Operand is lea(scratch, Operand(kRootRegister, delta));
       // Opcodes : REX.W 8D ModRM Disp8/Disp32  - 4 or 7.
       int size = 4;
       if (!is_int8(static_cast<int32_t>(delta))) {
         size += 3;  // Need full four-byte displacement in lea.
       }
       return size;
     }
   }
   // Size of movq(destination, src);
-  return 10;
+  return Assembler::kMoveAddressIntoScratchRegisterInstructionLength;
 }
 
 
 void MacroAssembler::PushAddress(ExternalReference source) {
   int64_t address = reinterpret_cast<int64_t>(source.address());
   if (is_int32(address) && !Serializer::enabled()) {
     if (emit_debug_code()) {
       movq(kScratchRegister, BitCast<int64_t>(kZapValue), RelocInfo::NONE64);
     }
     push(Immediate(static_cast<int32_t>(address)));
@@ skipping 2334 matching lines @@
 
 
 void MacroAssembler::Jump(Handle<Code> code_object, RelocInfo::Mode rmode) {
   // TODO(X64): Inline this
   jmp(code_object, rmode);
 }
 
 
 int MacroAssembler::CallSize(ExternalReference ext) {
   // Opcode for call kScratchRegister is: Rex.B FF D4 (three bytes).
-  const int kCallInstructionSize = 3;
-  return LoadAddressSize(ext) + kCallInstructionSize;
+  return LoadAddressSize(ext) +
+         Assembler::kCallScratchRegisterInstructionLength;
 }
 
 
 void MacroAssembler::Call(ExternalReference ext) {
 #ifdef DEBUG
   int end_position = pc_offset() + CallSize(ext);
 #endif
   LoadAddress(kScratchRegister, ext);
   call(kScratchRegister);
 #ifdef DEBUG
@@ skipping 2169 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