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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/106902] [11/12/13/14 Regression] Program compiled with
 -O3 -mfma produces different result
Date: Wed, 17 May 2023 18:54:00 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106902

--- Comment #23 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Alexander Monakov from comment #22)
> Created attachment 55105 [details]
> patch 1/3
>=20
> (In reply to Richard Biener from comment #21)
> >=20
> > Sounds reasonable.  Though I wouldn't use GENERIC folding but instead
> > some folding-like code in c-family/ that for example would get invoked
> > by genericization or via the gimplification hook?  If we'd add GENERIC
> > folding in fold-const.cc or match.pd the chance is that it will pick up
> > FMAs "late".
>=20
> Agreed, thank you. I'm working on it. The attached patch implements this =
via
> c_gimplify_expr and passes bootstrap+regtest under 'configure
> --with-cpu=3Dznver2' (i.e. with fma available by default).

Hmm, seems like this should not be in the C family but the generic part of
gimplifier. Because IIRC Fortran has similar rules but IIRC fortran front-e=
nd
emits PAREN_EXPR a lot more which improves the situtation there ...=