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From: "jamborm at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug ipa/113359] [13 Regression] LTO miscompilation of ceph on
 aarch64
Date: Wed, 07 Feb 2024 17:01:48 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113359

--- Comment #14 from Martin Jambor <jamborm at gcc dot gnu.org> ---
(In reply to rguenther@suse.de from comment #13)
> Might be also an interaction with IPA ICF in case there's a pointer to
> the pair involved?

Yes, this is exactly what seems to be happening.  The problem goes
away with -fno-icf.

(Possibly because the testcase uses -fno-strict-aliasing,) IPA-ICF
merges two functions which copy a structure and that access type it
what IPA-SRA saves, but loads only the one of the merged functions.
SRA then uses the (wrong) type to split aggregate copies into copies
by individual fields.

I have talked to Honza about this.  It seems that IPA-ICF needs to be
careful about aggreage with holes in different places.  The ideal next
step would be to create a testcase not dependent on IPA-SRA.=