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From: "segher at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/107172] [13 Regression] wrong code with "-O1 -ftree-vrp"
 on x86_64-linux-gnu since r13-1268-g8c99e307b20c502e
Date: Tue, 18 Oct 2022 20:14:55 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107172

--- Comment #42 from Segher Boessenkool <segher at gcc dot gnu.org> ---
(In reply to H.J. Lu from comment #41)
> (In reply to Segher Boessenkool from comment #40)
> > Let me repeat: A const_int cannot be assigned to a MODE_CC.  It has no
> > meaning.
> > This is invalid RTL.  If it ever works, or worked, that is an accident.
>=20
> Can we make it to work with a target hook? It will allow more backed
> optimizations.

No, you cannot.  A lot of generic code will not work with your special
re-interpretation of basic RTL rules.  Just write correct code in your
backend, it is not hard.=