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From: "lopresti at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/32667] block copy with exact overlap is expanded as
 memcpy
Date: Thu, 23 Nov 2023 00:00:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D32667

--- Comment #29 from Patrick J. LoPresti <lopresti at gmail dot com> ---
(In reply to Jakub Jelinek from comment #27)
>=20
> No, that is not a reasonable fix, because it severely pessimizes common c=
ode
> for a theoretical only problem.

The very existence of (and interest in) this bug report means it is obvious=
ly
not "a theoretical only problem".

And of course Rich Felker is correct that the cost of the obvious fix is
trivial and not remotely "severe".

But the bottom line is that GCC is emitting library calls that invoke undef=
ined
behavior. At a minimum, GCC should document this non-standard requirement on
its runtime environment. Has anyone bothered to do that? Why not?=