On x64 use 32bit idiv when possible instead of 64bit one.

runtime/vm/disassembler_x64.cc

 // Copyright (c) 2012, 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/disassembler.h"
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_IA32.
 #if defined(TARGET_ARCH_X64)
 #include "platform/utils.h"
 #include "vm/allocation.h"
@@ skipping 52 matching lines @@
   { 0x2A, BYTE_REG_OPER_OP_ORDER, "sub" },
   { 0x2B, REG_OPER_OP_ORDER,      "sub" },
   { 0x30, BYTE_OPER_REG_OP_ORDER, "xor" },
   { 0x31, OPER_REG_OP_ORDER,      "xor" },
   { 0x32, BYTE_REG_OPER_OP_ORDER, "xor" },
   { 0x33, REG_OPER_OP_ORDER,      "xor" },
   { 0x38, BYTE_OPER_REG_OP_ORDER, "cmp" },
   { 0x39, OPER_REG_OP_ORDER,      "cmp" },
   { 0x3A, BYTE_REG_OPER_OP_ORDER, "cmp" },
   { 0x3B, REG_OPER_OP_ORDER,      "cmp" },
-  { 0x63, REG_OPER_OP_ORDER,      "movsxlq" },
+  { 0x63, REG_OPER_OP_ORDER,      "movsxd" },
   { 0x84, BYTE_REG_OPER_OP_ORDER, "test" },
   { 0x85, REG_OPER_OP_ORDER,      "test" },
   { 0x86, BYTE_REG_OPER_OP_ORDER, "xchg" },
   { 0x87, REG_OPER_OP_ORDER,      "xchg" },
   { 0x88, BYTE_OPER_REG_OP_ORDER, "mov" },
   { 0x89, OPER_REG_OP_ORDER,      "mov" },
   { 0x8A, BYTE_REG_OPER_OP_ORDER, "mov" },
   { 0x8B, REG_OPER_OP_ORDER,      "mov" },
   { 0x8D, REG_OPER_OP_ORDER,      "lea" },
   { -1, UNSET_OP_ORDER, "" }
@@ skipping 1834 matching lines @@
                                   pc);
     pc += instruction_length;
   }
 
   return;
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64