Index: src/globals.h |
=================================================================== |
--- src/globals.h (revision 429) |
+++ src/globals.h (working copy) |
@@ -463,42 +463,6 @@ |
#define INLINE(header) inline header |
#endif |
-// The type-based aliasing rule allows the compiler to assume that pointers of |
-// different types (for some definition of different) never alias each other. |
-// Thus the following code does not work: |
-// |
-// float f = foo(); |
-// int fbits = *(int*)(&f); |
-// |
-// The compiler 'knows' that the int pointer can't refer to f since the types |
-// don't match, so the compiler may cache f in a register, leaving random data |
-// in fbits. Using C++ style casts makes no difference, however a pointer to |
-// char data is assumed to alias any other pointer. This is the 'memcpy |
-// exception'. |
-// |
-// Bit_cast uses the memcpy exception to move the bits from a variable of one |
-// type o a variable of another type. Of course the end result is likely to |
-// be implementation dependent. Most compilers (gcc-4.2 and MSVC 2005) |
-// will completely optimize bit_cast away. |
-// |
-// There is an additional use for bit_cast. |
-// Recent gccs will warn when they see casts that may result in breakage due to |
-// the type-based aliasing rule. If you have checked that there is no breakage |
-// you can use bit_cast to cast one pointer type to another. This confuses gcc |
-// enough that it can no longer see that you have cast one pointer type to |
-// another thus avoiding the warning. |
-template <class Dest, class Source> |
-inline Dest bit_cast(const Source& source) { |
- // Compile time assertion: sizeof(Dest) == sizeof(Source) |
- // A compile error here means your Dest and Source have different sizes. |
- typedef char VerifySizesAreEqual[sizeof(Dest) == sizeof(Source) ? 1 : -1]; |
- |
- Dest dest; |
- memcpy(&dest, &source, sizeof(dest)); |
- return dest; |
-} |
- |
- |
} } // namespace v8::internal |
#endif // V8_GLOBALS_H_ |