X64: Fix bugs affecting Win64.

test/cctest/test-api.cc

 // Copyright 2007-2009 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 710 matching lines @@
     CHECK_EQ(static_cast<int64_t>(value), value_obj->Value());
   }
 }
 
 
 THREADED_TEST(BigInteger) {
   v8::HandleScope scope;
   LocalContext env;
   // We cannot add one to a Smi::kMaxValue without wrapping.
   if (i::kSmiValueSize < 32) {
-    int32_t value = i::Smi::kMaxValue + 1;
+    // The casts allow this to compile, even if Smi::kMaxValue is 2^31-1.
+    // The code will not be run in that case, due to the "if" guard.
+    int32_t value =
+        static_cast<int32_t>(static_cast<uint32_t>(i::Smi::kMaxValue) + 1);
     CHECK(value > i::Smi::kMaxValue);
     CHECK(!i::Smi::IsValid(value));
     Local<v8::Integer> value_obj = v8::Integer::New(value);
     CHECK_EQ(static_cast<int64_t>(value), value_obj->Value());
   }
 }
 
 
 THREADED_TEST(TinyUnsignedInteger) {
   v8::HandleScope scope;
@@ skipping 7325 matching lines @@
     env->Global()->Set(v8_str("get_stack_limit"), fun);
     CompileRun("get_stack_limit();");
 
     CHECK(stack_limit == set_limit);
   }
   {
     v8::Locker locker;
     CHECK(stack_limit == set_limit);
   }
 }