Add LoadTaggedClassIdMayBeSmi to assembly and improve performance of inline cache stubs.

runtime/vm/intermediate_language_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"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 850 matching lines @@
   return LocationSummary::Make(isolate,
                                kNumInputs,
                                Location::RequiresRegister(),
                                LocationSummary::kNoCall);
 }
 
 
 void LoadClassIdInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Register object = locs()->in(0).reg();
   Register result = locs()->out(0).reg();
-  Label load, done;
-  __ testq(object, Immediate(kSmiTagMask));
-  __ j(NOT_ZERO, &load, Assembler::kNearJump);
-  __ LoadImmediate(result, Immediate(Smi::RawValue(kSmiCid)), PP);
-  __ jmp(&done);
-  __ Bind(&load);
-  __ LoadClassId(result, object);
-  __ SmiTag(result);
-  __ Bind(&done);
+  __ LoadTaggedClassIdMayBeSmi(result, object);
 }
 
 
 CompileType LoadIndexedInstr::ComputeType() const {
   switch (class_id_) {
     case kArrayCid:
     case kImmutableArrayCid:
       return CompileType::Dynamic();
 
     case kTypedDataFloat32ArrayCid:
@@ skipping 4935 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(ArgumentCount());  // Discard arguments.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64