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From: "marxin at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug sanitizer/99168] inconsistent behavior on -O0 and -O2 with ASAN
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Date: Mon, 22 Feb 2021 16:44:38 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99168

--- Comment #5 from Martin Li=C5=A1ka <marxin at gcc dot gnu.org> ---
(In reply to zhan3299 from comment #4)
> (In reply to Martin Li=C5=A1ka from comment #3)
> > Very interesting issue, the failure is caused by IPA ICF that merges 2
> > variables with different alignments. I've got a patch candidate.
>=20
> Hi, just curious because I am also studying the source code of GCC.
>=20
> Is this issue is about sanitizer or optimization?

It's bad optimization done by IPA ICF. The issue is gone with -fno-ipa-icf.=