x64 code improvements and cleanups.

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/cpu.h"
 #include "vm/heap.h"
@@ skipping 2537 matching lines @@
     LoadObject(TMP, object, pp);
     pushq(TMP);
   } else {
     PushImmediate(Immediate(reinterpret_cast<int64_t>(object.raw())), pp);
   }
 }
 
 
 void Assembler::CompareObject(Register reg, const Object& object, Register pp) {
   if (CanLoadFromObjectPool(object)) {
-    ASSERT(reg != TMP);
-    LoadObject(TMP, object, pp);
-    cmpq(reg, TMP);
+    const int32_t offset =
+        Array::element_offset(FindObject(object, kNotPatchable));
+    cmpq(reg, Address::AddressBaseImm32(pp, offset - kHeapObjectTag));

[zra, 2014/03/17 19:29:58]

AddressBaseImm32 emits a fixed-size constant for the offset. If you just use
Address(pp, offset-kHeapObjectTag), you may sometimes get a shorter instruction
for the smaller constant.

[srdjan, 2014/03/17 19:54:32]

Done.

   } else {
     CompareImmediate(
         reg, Immediate(reinterpret_cast<int64_t>(object.raw())), pp);
   }
 }
 
 
 intptr_t Assembler::FindImmediate(int64_t imm) {
   ASSERT(Isolate::Current() != Dart::vm_isolate());
   ASSERT(!object_pool_.IsNull());
@@ skipping 693 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