Add another check to be sure non-negative smi fits into Uint32 range.

src/x64/ic-x64.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 876 matching lines @@
   //  -- rax    : key
   //  -- rdx    : receiver
   //  -- rsp[0] : return address
   // -----------------------------------
   Label slow;
 
   // Check that the receiver isn't a smi.
   __ JumpIfSmi(rdx, &slow);
 
   // Check that the key is an array index, that is Uint32.
+  STATIC_ASSERT(kSmiValueSize <= 32);
   __ JumpIfNotPositiveSmi(rax, &slow);
 
   // Get the map of the receiver.
   __ movq(rcx, FieldOperand(rdx, HeapObject::kMapOffset));
 
   // Check that it has indexed interceptor and access checks
   // are not enabled for this object.
   __ movb(rcx, FieldOperand(rcx, Map::kBitFieldOffset));
   __ andb(rcx, Immediate(kSlowCaseBitFieldMask));
   __ cmpb(rcx, Immediate(1 << Map::kHasIndexedInterceptor));
@@ skipping 990 matching lines @@
   GenerateMiss(masm);
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64