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Unified Diff: src/globals.h

Issue 6446: Revert 428. Breaks 64-bit compilation. (Closed) Base URL: http://v8.googlecode.com/svn/branches/bleeding_edge/
Patch Set: Created 12 years, 2 months ago
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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_
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