Support non-deoptimizing version of UnboxInt32 for integer definitions.

runtime/vm/intermediate_language_ia32.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_IA32.
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 3656 matching lines @@
     ASSERT(value == result);
     __ SmiUntag(value);
   } else if (value_cid == kMintCid) {
     ASSERT((value != result) || (out_of_range == NULL));
     LoadInt32FromMint(compiler,
                       result,
                       FieldAddress(value, lo_offset),
                       FieldAddress(value, hi_offset),
                       temp,
                       out_of_range);
+  } else if (!CanDeoptimize()) {
+    ASSERT(value == result);
+    Label done;
+    __ SmiUntag(value);
+    __ j(NOT_CARRY, &done);
+    __ movl(value, Address(value, TIMES_2, lo_offset));
+    __ Bind(&done);
   } else {
     ASSERT(value == result);
     Label done;
     __ SmiUntagOrCheckClass(value, kMintCid, temp, &done);
     __ j(NOT_EQUAL, deopt);
     if (out_of_range != NULL) {
       Register value_temp = locs()->temp(1).reg();
       __ movl(value_temp, value);
       value = value_temp;
     }
@@ skipping 3113 matching lines @@
 #if defined(DEBUG)
   __ movl(EDX, Immediate(kInvalidObjectPointer));
 #endif
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_IA32