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Re: [cft] subreg validation patch
- From: Ulrich Weigand <uweigand at de dot ibm dot com>
- To: rth at redhat dot com
- Cc: gcc at gcc dot gnu dot org, gcc-patches at gcc dot gnu dot org, ebotcazou at libertysurf dot fr, jh at suse dot cz
- Date: Tue, 16 Nov 2004 14:45:47 +0100 (CET)
- Subject: Re: [cft] subreg validation patch
I wrote:
>Richard Henderson <rth@redhat.com> wrote on 11/15/2004 11:02:32 PM:
>
>> Hmm. How about lowpart_subreg? At least then we won't wind up
>> with nested subregs.
>
>src is guaranteed to satisfy REG_P at this point, so this shouldn't
>be an issue. (Also, regmove.c already uses gen_lowpart_SUBREG at
>another similar location.)
On second thought, you're probably right: gen_lowpart_SUBREG may
abort (with your change), and we certainly don't want that here.
So I've changed the patch to use lowpart_subreg, and just ignore
that move if the subreg cannot be generated.
Bootstraped/regtested on s390-ibm-linux and s390x-ibm-linux
(with your patch applied as well).
OK for mainline?
Bye,
Ulrich
ChangeLog:
* regmove.c (regmove_optimize): Use lowpart_subreg instead of
gen_rtx_SUBREG with incorrect offset to compute SRC_SUBREG.
Index: gcc/regmove.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/regmove.c,v
retrieving revision 1.164
diff -c -p -r1.164 regmove.c
*** gcc/regmove.c 9 Oct 2004 19:19:24 -0000 1.164
--- gcc/regmove.c 16 Nov 2004 11:44:46 -0000
*************** regmove_optimize (rtx f, int nregs, FILE
*** 1150,1159 ****
&& GET_MODE_SIZE (GET_MODE (dst))
>= GET_MODE_SIZE (GET_MODE (SUBREG_REG (dst))))
{
- src_subreg
- = gen_rtx_SUBREG (GET_MODE (SUBREG_REG (dst)),
- src, SUBREG_BYTE (dst));
dst = SUBREG_REG (dst);
}
if (!REG_P (dst)
|| REGNO (dst) < FIRST_PSEUDO_REGISTER)
--- 1150,1160 ----
&& GET_MODE_SIZE (GET_MODE (dst))
>= GET_MODE_SIZE (GET_MODE (SUBREG_REG (dst))))
{
dst = SUBREG_REG (dst);
+ src_subreg = lowpart_subreg (GET_MODE (dst),
+ src, GET_MODE (src));
+ if (!src_subreg)
+ continue;
}
if (!REG_P (dst)
|| REGNO (dst) < FIRST_PSEUDO_REGISTER)
--
Dr. Ulrich Weigand
Linux on zSeries Development
Ulrich.Weigand@de.ibm.com