x64: Use a short encoding of addq and subq for 32-bit immediates.

runtime/vm/assembler_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/heap.h"
 #include "vm/memory_region.h"
@@ skipping 1653 matching lines @@
     EmitRegisterREX(reg, REX_W);
     EmitComplex(0, Operand(reg), imm);
   } else {
     movq(TMP, imm);
     addq(reg, TMP);
   }
 }
 
 
 void Assembler::addq(const Address& address, const Immediate& imm) {
-  // TODO(srdjan): Implement shorter version for imm32.
-  movq(TMP, imm);
-  addq(address, TMP);
+  if (imm.is_int32()) {
+    AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+    EmitOperandREX(0, address, REX_W);
+    EmitComplex(0, Operand(address), imm);
+  } else {
+    movq(TMP, imm);
+    addq(address, TMP);
+  }
 }
 
 
 void Assembler::addq(const Address& address, Register reg) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   EmitOperandREX(reg, address, REX_W);
   EmitUint8(0x01);
   EmitOperand(reg & 7, address);
 }
 
@@ skipping 141 matching lines @@
 
 void Assembler::subq(const Address& address, Register reg) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   EmitOperandREX(reg, address, REX_W);
   EmitUint8(0x29);
   EmitOperand(reg & 7, address);
 }
 
 
 void Assembler::subq(const Address& address, const Immediate& imm) {
-  // TODO(srdjan): Implement shorter version for imm32.
-  movq(TMP, imm);
-  subq(address, TMP);
+  if (imm.is_int32()) {
+    AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+    EmitOperandREX(0, address, REX_W);
+    EmitComplex(5, Operand(address), imm);
+  } else {
+    movq(TMP, imm);
+    subq(address, TMP);
+  }
 }
 
 
 void Assembler::shll(Register reg, const Immediate& imm) {
   EmitGenericShift(false, 4, reg, imm);
 }
 
 
 void Assembler::shll(Register operand, Register shifter) {
   EmitGenericShift(false, 4, operand, shifter);
@@ skipping 1224 matching lines @@
 
 
 const char* Assembler::FpuRegisterName(FpuRegister reg) {
   ASSERT((0 <= reg) && (reg < kNumberOfXmmRegisters));
   return xmm_reg_names[reg];
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64