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Re: kernel-2.2.1-undefined references.



[ __builtin_constant_p ]

> It works in development versions of egcs, but as far as I know of it does
> not work in _any_ released version of gcc. It certainly is not something
> you can really use anyway, as using it requires that all users have to
> upgrade: which may be acceptable in some environments, but is certainly
> not an option in most places.

If the feature gives a clear win, it is possible to use it with a
preprocessor check.  To oversimplify a bit:

#if __GNUC_MINOR__ > threshold
... code using the feature
#else
... older code
#endif

Since this conditional compilation gives one more thing to test for, the
developers might choose not to use it unless the win is large enough
to justify it.