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From: David Edelsohn <dje.gcc@gmail.com>
Date: Thu, 15 Jul 2021 11:29:11 -0400
Message-ID: <CAGWvny=nJD9DnoDPJObJ1pQEJbww1OjZtK2JV6Bshvb=m_dziA@mail.gmail.com>
Subject: Re: [PATCH, committed] rs6000: Don't let swaps pass break multiply
 low-part (PR101129)
To: Bill Schmidt <wschmidt@linux.ibm.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>, 
 Segher Boessenkool <segher@kernel.crashing.org>
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On Thu, Jul 15, 2021 at 11:25 AM Bill Schmidt <wschmidt@linux.ibm.com> wrot=
e:
>
> Hi,
>
> Segher preapproved this patch in https://gcc.gnu.org/PR101129.  It differ=
s slightly from what was posted there, needing an additional test to ensure=
 the insn is a SET.  The patch also includes the test case provided by the =
OP.  Bootstrap and regtest succeeded on P9 little-endian.
>
> This bug has been around a long time, so the fix should be backported to =
all open releases.  Is this okay after some burn-in time?
>
> Thanks!
> Bill
>
> rs6000: Don't let swaps pass break multiply low-part (PR101129)
>
> 2021-07-15  Bill Schmidt  <wschmidt@linux.ibm.com>
>
> gcc/
> * config/rs6000/rs6000-p8swap.c (has_part_mult): New.
> (rs6000_analyze_swaps): Insns containing a subreg of a mult are
> not swappable.
>
> gcc/testsuite/
> * gcc.target/powerpc/pr101129.c: New.

Thanks for fixing this so quickly.

Okay everywhere.

Thanks, David