From: Richard Henderson <rth@redhat.com>
To: Ulrich Weigand <uweigand@de.ibm.com>
Cc: gcc@gcc.gnu.org, ebotcazou@libertysurf.fr, jh@suse.cz
Subject: Re: [cft] subreg validation patch
Date: Mon, 15 Nov 2004 20:12:00 -0000 [thread overview]
Message-ID: <20041115200319.GA6075@redhat.com> (raw)
In-Reply-To: <200411141503.iAEF3dsY032310@53v30g15.boeblingen.de.ibm.com>
On Sun, Nov 14, 2004 at 04:03:39PM +0100, Ulrich Weigand wrote:
> Richard Henderson wrote:
>
> >Could everyone please try the following on their favorite platform
> >and report back with new failures?
>
> I've tried your patch on s390-ibm-linux and s390x-ibm-linux. On both
> platforms, bootstrap fails when building stage2, because of a bug in
> regmove_optimize. The code there tries to convert a paradoxical
> subreg move into a move with the opposite subreg on the other side,
> but completely messes up the subreg offset. The following patch
> appears to fix that problem:
Indeed. This should be ok to check in by itself.
> ... calls gen_rtx_SUBREG to form a DFmode subreg of one of the subwords of
> a TImode register.
>
> I'm not sure how to fix that, not least because I still don't understand
> why this subreg is now supposed to be invalid in the first place ...
According to the docs, it always was invalid. I guess I'll put an
exception in there for this, as with the SI->DF exception that I
have already added.
> This check is not quite the same as the check done in simplify_subreg.
> In particular, you neither check for REG_CANNOT_CHANGE_MODE_P, nor is
> there the special checks for frame-related registers. While I'm not
> quite sure I fully understand those checks, shouldn't the rules be
> the same here as in simplify_subreg?
Yes.
r~
next prev parent reply other threads:[~2004-11-15 20:04 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-11-14 18:03 Ulrich Weigand
2004-11-15 20:12 ` Richard Henderson [this message]
2004-11-15 22:02 ` Ulrich Weigand
2004-11-15 22:08 ` Richard Henderson
2004-11-15 23:22 ` Ulrich Weigand
-- strict thread matches above, loose matches on Subject: below --
2004-11-16 14:03 Ulrich Weigand
2004-11-16 21:02 ` Richard Henderson
2004-11-17 1:01 ` Richard Henderson
2004-11-13 13:17 Non-representable subregs of subword pseudoregs Eric Botcazou
2004-11-13 23:06 ` [cft] subreg validation patch Richard Henderson
2004-11-13 23:50 ` Eric Botcazou
2004-11-14 0:02 ` Richard Henderson
2004-11-14 0:21 ` Eric Botcazou
2004-11-14 4:41 ` Richard Henderson
2004-11-14 5:12 ` Richard Henderson
2004-11-14 6:14 ` Geert Bosch
2004-11-14 7:46 ` Richard Henderson
2004-11-14 10:50 ` Eric Botcazou
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