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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/114211] [13 Regression] wrong code with -O -fno-tree-coalesce-vars since r13-1907
Date: Tue, 05 Mar 2024 11:35:05 +0000	[thread overview]
Message-ID: <bug-114211-4-JW4ggRn1lT@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-114211-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114211

--- Comment #9 from Uroš Bizjak <ubizjak at gmail dot com> ---
Noticed this in passing:

-->     movq    %rcx, %rdx
        addq    v(%rip), %rax
        adcq    v+8(%rip), %rdx
        vmovq   %rax, %xmm1
        vpinsrq $1, %rdx, %xmm1, %xmm0

We could use %rcx instead of %rdx to eliminate the marked move. This is an
artefact of post-reload split of *add<dwi>3_doubleword. The _doubleword
patterns use only general regs, so they could be split before reload as well.
IIRC, there were some minor RA problems with the later approach, but as years
passed and LRA improved, perhaps the split point can be moved before reload.

Something to try (again) for gcc-15. It is just the case of using
ix86_pre_reload_split instead of reload_completed.

  parent reply	other threads:[~2024-03-05 11:35 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-02 19:03 [Bug tree-optimization/114211] New: [13/14 Regression] wrong code with -O -fno-tree-coalesce-vars zsojka at seznam dot cz
2024-03-02 20:59 ` [Bug target/114211] " pinskia at gcc dot gnu.org
2024-03-04 10:08 ` rguenth at gcc dot gnu.org
2024-03-04 15:00 ` [Bug rtl-optimization/114211] " ubizjak at gmail dot com
2024-03-04 18:32 ` [Bug rtl-optimization/114211] [13/14 Regression] wrong code with -O -fno-tree-coalesce-vars since r13-1907 jakub at gcc dot gnu.org
2024-03-04 18:59 ` jakub at gcc dot gnu.org
2024-03-04 19:41 ` jakub at gcc dot gnu.org
2024-03-05  9:33 ` cvs-commit at gcc dot gnu.org
2024-03-05  9:38 ` [Bug rtl-optimization/114211] [13 " jakub at gcc dot gnu.org
2024-03-05 11:35 ` ubizjak at gmail dot com [this message]
2024-03-15 23:29 ` cvs-commit at gcc dot gnu.org
2024-03-18 14:41 ` jakub at gcc dot gnu.org

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