[parisc-linux] Re: Looking at vfprintf.c and alloca.

[Randolph Chung <randolph@tausq.org>]

Carlos O'Donell wrote:
> I was looking at our tst-printfsz failures in glibc, and I noticed
> some very cute code in vfprintf.c. The code uses alloca to create a
> specs structure, and then using certain know addresses decides if the
> stack grows down or up.
> 
> Does this look right? Anyone care to review if this actually works
> with a newer GCC on hppa?

I tried this with both old (gcc-3.[34]) and new gcc (gcc-4.[01]) and i 
don't think this works....

tausq@riot:~$ cat alloca.c
#include <alloca.h>
#include <stdio.h>

int main(int argc, char **argv)
{
         int *old;
         int *ptr = alloca(100 * sizeof(int));

         old = ptr;

         ptr = alloca(100 * sizeof(int));

         printf("ptr = %p\nold = %p\n&old[100] = %p\n", ptr, old, 
&old[100]);
         return 0;
}
tausq@riot:~$ gcc-4.1 -Wall -o alloca alloca.c; ./alloca
ptr = 0xc04ca590
old = 0xc04ca3d0
&old[100] = 0xc04ca560

randolph
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