Eliminate intentional conversion from Smi to Int32 in HMul

src/runtime.cc

 // Copyright 2012 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 4671 matching lines @@
   int f = FastD2IChecked(f_number);
   RUNTIME_ASSERT(f >= 1 && f <= 21);
   char* str = DoubleToPrecisionCString(value, f);
   MaybeObject* res =
       isolate->heap()->AllocateStringFromOneByte(CStrVector(str));
   DeleteArray(str);
   return res;
 }
 
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_IsValidSmi) {
+  HandleScope shs(isolate);
+  ASSERT(args.length() == 1);
+
+  CONVERT_NUMBER_CHECKED(int32_t, number, Int32, args[0]);
+  if (Smi::IsValid(number)) {
+    return isolate->heap()->true_value();
+  } else {
+    return isolate->heap()->false_value();
+  }
+}
+
+
 // Returns a single character string where first character equals
 // string->Get(index).
 static Handle<Object> GetCharAt(Handle<String> string, uint32_t index) {
   if (index < static_cast<uint32_t>(string->length())) {
     string->TryFlatten();
     return LookupSingleCharacterStringFromCode(
         string->GetIsolate(),
         string->Get(index));
   }
   return Execution::CharAt(string, index);
@@ skipping 9776 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal