On Fri, Nov 24, 2000 at 06:20:33AM +0100, Andries.Brouwer@cwi.nl wrote:
> >> ... RedHat's GCC snapshot "2.96" handles this case just fine.
>
> > Now, if you can isolate the relevant part of the diff between
> > 2.95.2 and RH 2.96...
>
> Maybe I have to be more precise in the statement "gcc 2.95.2 is buggy".
>
> I just installed gcc 2.95.2 freshly ftp'ed from ftp.gnu.org, and
>
> % /usr/bin/gcc -v
> Reading specs from /usr/lib/gcc-lib/i486-suse-linux/2.95.2/specs
> gcc version 2.95.2 19991024 (release)
> % /usr/bin/gcc -Wall -O2 -o bug bug.c; ./bug
> 0x84800000
> % /usr/gcc/aeb/bin/gcc -v
> Reading specs from /usr/gcc/aeb/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/specs
> gcc version 2.95.2 19991024 (release)
> % /usr/gcc/aeb/bin/gcc -Wall -O2 -o nobug bug.c; ./nobug
> 0x0
>
> So, not all versions of gcc 2.95.2 are equal.
I believe all 2.95.2's are equal in this, I think the fact that it gives 0
in the nobug case is some other reason:
$ for i in gcc kgcc '/usr/src/gcc-trunk/obj/gcc/xgcc -B /usr/src/gcc-trunk/obj/gcc/' '/usr/src/gcc-2.95.2/obj/gcc/xgcc -B /usr/src/gcc-2.95.2/obj/gcc/'; do $i -v; for j in -mcpu=i386 -mcpu=i586 -mcpu=i686; do $i $j -O2 -o aeb aeb.c; echo -n "$i $j "; ./aeb; done; done
Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/2.96/specs
gcc version 2.96 20000731 (Red Hat Linux 7.0)
gcc -mcpu=i386 0x0
gcc -mcpu=i586 0x0
gcc -mcpu=i686 0x0
Reading specs from /usr/lib/gcc-lib/i386-glibc21-linux/egcs-2.91.66/specs
gcc version egcs-2.91.66 19990314/Linux (egcs-1.1.2 release)
kgcc -mcpu=i386 0x0
kgcc -mcpu=i586 0x0
kgcc -mcpu=i686 0x0
Reading specs from /usr/src/gcc-trunk/obj/gcc/specs
Configured with:
gcc version 2.97 20001120 (experimental)
/usr/src/gcc-trunk/obj/gcc/xgcc -B /usr/src/gcc-trunk/obj/gcc/ -mcpu=i386 0x0
/usr/src/gcc-trunk/obj/gcc/xgcc -B /usr/src/gcc-trunk/obj/gcc/ -mcpu=i586 0x0
/usr/src/gcc-trunk/obj/gcc/xgcc -B /usr/src/gcc-trunk/obj/gcc/ -mcpu=i686 0x0
Reading specs from /usr/src/gcc-2.95.2/obj/gcc/specs
gcc version 2.95.2 19991024 (release)
/usr/src/gcc-2.95.2/obj/gcc/xgcc -B /usr/src/gcc-2.95.2/obj/gcc/ -mcpu=i386 0x84800000
/usr/src/gcc-2.95.2/obj/gcc/xgcc -B /usr/src/gcc-2.95.2/obj/gcc/ -mcpu=i586 0x84800000
/usr/src/gcc-2.95.2/obj/gcc/xgcc -B /usr/src/gcc-2.95.2/obj/gcc/ -mcpu=i686 0x0
so the reason why it did not show up in the gcc you picked up from
ftp.gnu.org is that you have compiled it so that it defaults to -mcpu=i686
where the bug does not show up.
Jakub
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