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From: "aldyh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/104475] [12 Regression] Wstringop-overflow +
 atomics incorrect warning on dynamic object
Date: Sat, 12 Mar 2022 09:39:21 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104475

Aldy Hernandez <aldyh at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |law at gcc dot gnu.org

--- Comment #8 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #7)
> I think we shouldn't do anything on the optimization side - sure, the path
> isolation in the end turns out not profitable, but it's likely hard to de=
cide
> that.
>=20
> Maybe we can somehow avoid threading for a ptr =3D=3D 0 condition?  Why d=
o we
> make
> the threading profitable?

The threaders are mostly blind wrt threading a path.  If they see it, they =
will
thread it.  There are some minor things we disallow (see calls to cancel_th=
read
throughout) and the big hammer we introduced in this release with
cancel_invalid_paths() where we disallow problematic loop transformations. =
 But
mostly we thread everything that's possible.

Disallowing ptr =3D=3D 0 as well as highly unlikely paths should be trivial=
.  We
could add a simple check in cancel_invalid_paths(). Though, I assume that w=
ould
affect warning code all over, since we're reducing the amount of threadable
paths on which they depend?=