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Date: Tue, 21 Mar 2023 13:21:06 -0500
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Pat Haugen <pthaugen@linux.ibm.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>, "Kewen.Lin" <linkw@linux.ibm.com>,
        David Edelsohn <dje.gcc@gmail.com>,
        Peter Bergner <bergner@linux.ibm.com>
Subject: Re: [PATCH V2, rs6000] Tweak modulo define_insns to eliminate register copy
Message-ID: <20230321182106.GI25951@gate.crashing.org>
References: <0e1a14ae-a16a-5af7-82be-c868d792d00d@linux.ibm.com>
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Hi!

On Tue, Mar 21, 2023 at 07:10:04AM -0500, Pat Haugen wrote:
> Updated patch with review comments addressed: fixed up testcase and added
> another testcase to verify peephole is functional.
> 
> Don't force target of modulo into a distinct register.
> 
> The define_insns for the modulo operation currently force the target 
> register
> to a distinct reg in preparation for a possible future peephole combining
> div/mod. But this can lead to cases of a needless copy being inserted. Fixed
> with the following patch.

> +/* { dg-final { scan-assembler-not {\mmodsd\M} } } */
> +/* { dg-final { scan-assembler-not {\mmodud\M} } } */

You can do
  /* { dg-final { scan-assembler-not {\mmod[su]d\M} } } */
if you want?

With or without that, okay for trunk.  Thanks!


Segher