Miscompilation of glibc with CVS mainline

["Martin v. Löwis"]

John David Anglin wrote:
>>As GCC is not told in any way that weak_func is actually weak, I think
>>it is glibc's fault.
> 
> 
> This is definitely a gcc problem.  This is the code arising from
> Andreas' testcase for hppa-linux at -O2:
[...]
> We have completely lost the `if'.  As a result, weak_func is always
> called.

It's not a gcc bug. weak_func is a function, so &weak_func is always 
unequal to null - that is guaranteed by the C programming language. 
That's why the compiler is entitled to eliminate the test, under the 
as-if rule. If you want to declare a function whose address can be zero, 
you need to declare it weak, using the relevant extension in GNU C.

Regards,
Martin