From: Uros Bizjak <ubizjak@gmail.com>
To: Richard Biener <rguenther@suse.de>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH 1/2] target/113255 - avoid REG_POINTER on a pointer difference
Date: Thu, 1 Feb 2024 15:57:00 +0100 [thread overview]
Message-ID: <CAFULd4Y5GorBrR=rmzsq8VqRpYGhXEBb8BUfWjVj915y9Y5yNw@mail.gmail.com> (raw)
In-Reply-To: <65bba833.050a0220.c81b6.4347SMTPIN_ADDED_MISSING@mx.google.com>
On Thu, Feb 1, 2024 at 3:18 PM Richard Biener <rguenther@suse.de> wrote:
>
> The following avoids re-using a register holding a pointer (and
> thus might be REG_POINTER) for the result of a pointer difference
> computation. That might confuse heuristics in (broken) RTL alias
> analysis which relies on REG_POINTER indicating that we're
> dealing with one.
>
> This alone doesn't fix anything.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, OK for trunk
> and branches (as necessary)?
LGTM, also for branches.
Thanks,
Uros.
>
> Thanks,
> Richard.
>
> PR target/113255
> * config/i386/i386-expand.cc
> (expand_set_or_cpymem_prologue_epilogue_by_misaligned_moves):
> Use a new pseudo for the skipped number of bytes.
> ---
> gcc/config/i386/i386-expand.cc | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
> index 0d817fc3f3b..26c48e8b0c8 100644
> --- a/gcc/config/i386/i386-expand.cc
> +++ b/gcc/config/i386/i386-expand.cc
> @@ -8090,7 +8090,7 @@ expand_set_or_cpymem_prologue_epilogue_by_misaligned_moves (rtx destmem, rtx src
> /* See how many bytes we skipped. */
> saveddest = expand_simple_binop (GET_MODE (*destptr), MINUS, saveddest,
> *destptr,
> - saveddest, 1, OPTAB_DIRECT);
> + NULL_RTX, 1, OPTAB_DIRECT);
> /* Adjust srcptr and count. */
> if (!issetmem)
> *srcptr = expand_simple_binop (GET_MODE (*srcptr), MINUS, *srcptr,
> --
> 2.35.3
>
next parent reply other threads:[~2024-02-01 14:57 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <65bba833.050a0220.c81b6.4347SMTPIN_ADDED_MISSING@mx.google.com>
2024-02-01 14:57 ` Uros Bizjak [this message]
2024-02-01 14:18 Richard Biener
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