Replace manual untagging of smi with proper Smi methods

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/compiler.h"
@@ skipping 6052 matching lines @@
   const Register out = locs()->out(0).reg();
   ASSERT(left == out);
 
   Label* deopt = NULL;
   if (CanDeoptimize()) {
     deopt = compiler->AddDeoptStub(deopt_id(), ICData::kDeoptBinaryMintOp);
   }
   if (locs()->in(1).IsConstant()) {
     // Code for a constant shift amount.
     ASSERT(locs()->in(1).constant().IsSmi());
-    const int64_t shift =
-        reinterpret_cast<int64_t>(locs()->in(1).constant().raw()) >> 1;
+    const int64_t shift = Smi::Cast(locs()->in(1).constant()).Value();
     ASSERT(shift >= 0);
     switch (op_kind()) {
       case Token::kSHR:
         __ sarq(left,
                 Immediate(Utils::Minimum<int64_t>(shift, kBitsPerWord - 1)));
         break;
       case Token::kSHL: {
         ASSERT(shift < 64);
         if (can_overflow()) {
           // Check for overflow.
@@ skipping 563 matching lines @@
   compiler->AddCurrentDescriptor(stub_kind_, deopt_id_, token_pos());
   compiler->RecordSafepoint(locs());
 }
 
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64