[x86] Several small performance improvements.

src/compiler/x64/code-generator-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/code-generator.h"
 
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties-inl.h"
@@ skipping 852 matching lines @@
     }
   } else if (source->IsConstant()) {
     ConstantOperand* constant_source = ConstantOperand::cast(source);
     Constant src = g.ToConstant(constant_source);
     if (destination->IsRegister() || destination->IsStackSlot()) {
       Register dst = destination->IsRegister() ? g.ToRegister(destination)
                                                : kScratchRegister;
       switch (src.type()) {
         case Constant::kInt32:
           // TODO(dcarney): don't need scratch in this case.
-          __ movq(dst, Immediate(src.ToInt32()));
+          __ Set(dst, src.ToInt32());
           break;
         case Constant::kInt64:
           __ Set(dst, src.ToInt64());
           break;
         case Constant::kFloat32:
           __ Move(dst,
                   isolate()->factory()->NewNumber(src.ToFloat32(), TENURED));
           break;
         case Constant::kFloat64:
           __ Move(dst,
@@ skipping 118 matching lines @@
     }
   }
   MarkLazyDeoptSite();
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace compiler
 }  // namespace v8