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

[John David Anglin]

> I tried this with both old (gcc-3.[34]) and new gcc (gcc-4.[01]) and i 
> don't think this works....
> 
> tausq at 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 at riot:~$ gcc-4.1 -Wall -o alloca alloca.c; ./alloca
> ptr = 0xc04ca590
> old = 0xc04ca3d0
> &old[100] = 0xc04ca560

What doesn't work?  ptr - old = 0x1c0 = 7 * 64.  The preferred
stack boundary is 64 bytes.  6 * 64 = 384 bytes.  That's too
small for the requested allocation.  &old[100] - old = 0x190 = 400.
So, the results printed appear correct.

Dave
-- 
J. David Anglin                                  dave.anglin at nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6602)