Check for negative 0 when deciding whether a constant has type Integer32.

src/number-info.h

 // 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 97 matching lines @@
   }
 
   // Return the weakest (least precise) common type.
   static NumberInfo Combine(NumberInfo a, NumberInfo b) {
     return NumberInfo(static_cast<Type>(a.type_ & b.type_));
   }
 
 
   // Integer32 is an integer that can be represented as either a signed
   // 32-bit integer or as an unsigned 32-bit integer. It has to be
-  // in the range [-2^31, 2^32 - 1].
+  // in the range [-2^31, 2^32 - 1]. We also have to check for negative 0
+  // as it is not an Integer32.
   static inline bool IsInt32Double(double value) {
+    const DoubleRepresentation minus_zero(-0.0);
+    DoubleRepresentation rep(value);
+    if (rep.bits == minus_zero.bits) return false;
     if (value >= kMinInt && value <= kMaxUInt32) {
       if (value <= kMaxInt && value == static_cast<int32_t>(value)) {
         return true;
       }
       if (value == static_cast<uint32_t>(value)) return true;
     }
     return false;
   }
 
   static inline NumberInfo TypeFromValue(Handle<Object> value);
@@ skipping 96 matching lines @@
 }
 
 
 NumberInfo NumberInfo::Uninitialized() {
   return NumberInfo(kUninitializedType);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_NUMBER_INFO_H_