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From: "amonakov at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/106902] [11/12/13 Regression] Program compiled with -O3
 -mfma produces different result
Date: Thu, 29 Sep 2022 11:28:27 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106902

--- Comment #17 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #16)
> I do think that since the only way to
> preserve expression boundaries is by PAREN_EXPR

Yes, but...

>  that the middle-end
> shouldn't care about FAST vs. ON (well, it cannot), but the language
> frontends need to ensure to emit PAREN_EXPRs for =3DON and omit them for
> =3DFAST.

this will also prevent reassociation across statements too. Doing FMA
contraction in the frontends via a match.pd rule doesn't have this drawback=
.=