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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/95798] [10/11 Regression] Initialization code ---
 suboptimal
Date: Wed, 24 Feb 2021 15:33:53 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95798

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

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

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 50249
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D50249&action=3Dedit
gcc11-pr95798.patch

Untested fix.
The #c4 qux case above is not fixed by it, but it isn't a regression, so I
think we should defer that one for GCC 12 (file a separate PR for that).
And, it would work (if done e.g. at expansion time) only when there is sign=
ed
integer overflow, so not for -fwrapv nor when e.g. the narrower type is
unsigned, so I think we need the single_use match.pd case because after tho=
se
changes, there is no way to undo that.=