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Re: [GCC 3.0] Bad regression, binary size
- To: Marc dot Espie at liafa dot jussieu dot fr
- Subject: Re: [GCC 3.0] Bad regression, binary size
- From: Geoff Keating <geoffk at geoffk dot org>
- Date: 05 Jul 2001 15:30:21 -0700
- CC: gcc at gcc dot gnu dot org
- References: <20010705163930.A29149@schutzenberger.liafa.jussieu.fr>
Marc Espie <espie@schutzenberger.liafa.jussieu.fr> writes:
> After fixing a few warnings, I've managed to compile OpenBSD kernels.
> The results are BAD:
>
> 2.95.3 + peephole to handle stack adjustment, backported from current:
> -rwxr-xr-x 1 espie wheel 3994332 Jul 5 16:08 bsd
>
> 3.0:
> -rwxr-xr-x 1 espie wheel 4068067 Jul 5 16:35 bsd
>
>
> Exact same source. Both are using -O2 -Os to compile.
>
> This is on an i386.
>
> This is pretty bad. Basically, it means we can't switch to 3.0 at all.
>
> I'm going to look at the corresponding generated files, see if I can spot
> some pattern.
You might consider looking at the ix86_*_alignment functions in
i386.c. From what I can see, they don't honour -Os at all.
--
- Geoffrey Keating <geoffk@geoffk.org>