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From: "torvalds@linux-foundation.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/108552] Linux i386 kernel 5.14 memory
 corruption for pre_compound_page() when gcov is enabled
Date: Fri, 27 Jan 2023 17:05:27 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108552

--- Comment #31 from Linus Torvalds <torvalds@linux-foundation.org> ---
(In reply to Richard Biener from comment #26)
>=20
> Now, in principle we should have applied store-motion and not only PRE wh=
ich
> would have avoided the issue, not tricking the RA into reloading the value
> from where we store it in the loop, but the kernel uses -fno-tree-loop-im,
> preventing that.  If you enable that you'd get

Note that we use -fno-tree-loop-im only for the GCOV case, and because of
another problem with code generation with gcov. See

  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D69702

and the fix for the excessive stack use was to disable that compiler option.
See

=20
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?=
id=3Dc87bf431448b404a6ef5fbabd74c0e3e42157a7f

for the kernel commit message.=