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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/107608] [13 Regression] Failure on
 fold-overflow-1.c and pr95115.c
Date: Mon, 28 Nov 2022 10:06:04 +0000
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X-Bugzilla-Keywords: missed-optimization, wrong-code
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107608

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #0)
> ... but then
> comes dom2 and happily replaces
>   _1 =3D 3.4028234663852885981170418348451692544e+38 * 2.0e+0;
>   return _1;
> with
>   _1 =3D 3.4028234663852885981170418348451692544e+38 * 2.0e+0;
>   return  Inf;
> (I think this is still correct)

Note this is also a pessimization code-generation wise since if we
preserve the multiplication the result is readily available in a
register but as optimized we have another constant pool entry and load.

So we might want to consider not propagating constants generated by operati=
ons
we cannot eliminate.  If the only consumer is a compare-and-branch we
can of course still end up with a seemingly dead stmt, so this would be only
for the missed optimization.=