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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/99927] [11 Regression] Maybe wrong code since
 r11-39-gf9e1ea10e657af9f
Date: Tue, 06 Apr 2021 13:57:09 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99927

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gn=
u.org
             Status|NEW                         |ASSIGNED

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Interestingly, it only reproduces on AMD CPUs and not Intel.
The bug is in:
        xorl    %edx, %edx
        divl    %edi
        movl    $1, %eax
        cmove   %edx, %eax
divl leaves ZF undefined as documented (and as seen in RTL), but we use tha=
t in
the cmove instruction.=