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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
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114211

--- Comment #9 from Uro=C5=A1 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 wel=
l.
IIRC, there were some minor RA problems with the later approach, but as yea=
rs
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.=