Building the GNU/Hurd glibc with GCC 4.1, problem with `__builtin_frame_address'

[Thomas Schwinge <tschwinge at gnu dot org>]

Hello!

There is a problem when building glibc for GNU/Hurd with GCC 4.1, see
<http://savannah.gnu.org/bugs/?17647>.  This is due to a change in the
behavior of `__builtin_frame_address' in GCC 4.1:

#v+
$ cat test.c 
#include <stdio.h>

int main (int argc, ...)
{
  printf ("fa + 2\t= %p\n&argc\t= %p\n",
          (int *) __builtin_frame_address (0) + 2, &argc);
}
$ for v in 3.3 3.4 4.0 4.1; do echo GCC" $v" && gcc-"$v" -O0 test.c && ./a.out; done
GCC 3.3
fa + 2  = 0x101ad80
&argc   = 0x101ad80
GCC 3.4
fa + 2  = 0x101ad80
&argc   = 0x101ad80
GCC 4.0
fa + 2  = 0x101ad80
&argc   = 0x101ad80
GCC 4.1
fa + 2  = 0x101ad6c
&argc   = 0x101ad80
#v-

How can this be explained?


Regards,
 Thomas

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