[turbofan] Allow truncating minus zero in add, sub, mul if we have word32 truncation.

src/type-cache.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_TYPE_CACHE_H_
 #define V8_TYPE_CACHE_H_
 
 #include "src/types.h"
 
 namespace v8 {
@@ skipping 39 matching lines @@
   Type* const kInteger = CreateRange(-V8_INFINITY, V8_INFINITY);
   Type* const kPositiveInteger = CreateRange(0.0, V8_INFINITY);
   Type* const kIntegerOrMinusZero =
       Type::Union(kInteger, Type::MinusZero(), zone());
   Type* const kIntegerOrMinusZeroOrNaN =
       Type::Union(kIntegerOrMinusZero, Type::NaN(), zone());
 
   Type* const kAdditiveSafeInteger =
       CreateRange(-4503599627370496.0, 4503599627370496.0);
   Type* const kSafeInteger = CreateRange(-kMaxSafeInteger, kMaxSafeInteger);
+  Type* const kAdditiveSafeIntegerOrMinusZero =
+      Type::Union(kAdditiveSafeInteger, Type::MinusZero(), zone());
+  Type* const kSafeIntegerOrMinusZero =
+      Type::Union(kSafeInteger, Type::MinusZero(), zone());
   Type* const kPositiveSafeInteger = CreateRange(0.0, kMaxSafeInteger);
 
   Type* const kUntaggedUndefined =
       Type::Intersect(Type::Undefined(), Type::Untagged(), zone());
 
   // Asm.js related types.
   Type* const kAsmSigned = kInt32;
   Type* const kAsmUnsigned = kUint32;
   Type* const kAsmInt = Type::Union(kAsmSigned, kAsmUnsigned, zone());
   Type* const kAsmFixnum = Type::Intersect(kAsmSigned, kAsmUnsigned, zone());
@@ skipping 72 matching lines @@
     return Type::Range(min, max, zone());
   }
 
   Zone* zone() { return &zone_; }
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TYPE_CACHE_H_