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Subject: [Bug ipa/103246] [12 Regression] 416.gamess miscompare with -O2 -g
 -flto=auto since r12-5223-gecdf414bd89e6ba251f6b3f494407139b4dbae0e
Date: Wed, 17 Nov 2021 21:06:08 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103246

--- Comment #21 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jan Hubicka <hubicka@gcc.gnu.org>:

https://gcc.gnu.org/g:425369bf3068a9f840d1c2f04a4d4c38e924d4dc

commit r12-5351-g425369bf3068a9f840d1c2f04a4d4c38e924d4dc
Author: Jan Hubicka <jh@suse.cz>
Date:   Wed Nov 17 22:04:26 2021 +0100

    Fix modref summary streaming

    Fixes bug in streaming in modref access tree that now cause a failure
    of gamess benchmark.  The bug is quite old (present in GCC11 release) b=
ut
it
    needs quite interesting series of events to manifest. In particular
     1) At lto time ISRA turns some parameters passed by reference to scalar
     2) At lto time modref computes summaries for old parameters and then
updates
        them but does so quite stupidly believing that the load from parame=
ters
        are now unkonwn loads (rather than optimized out).
        This renders summary not very useful since it thinks every memory
aliasing
        int is now accssed (as opposed as parameter dereference)
     3) At stream in we notice too early that summary is useless, set
every_access
        flag and drop the list.  However while reading rest of the summary =
we
        overwrite the flag back to 0 which makes us to lose part of summary.
     4) right selection of partitions needs to be done to avoid late modref
from
        recalculating and thus fixing the summary.

    This patch fixes the stream in bug, however we also should fix updating=
 of
    summaries.

    gcc/ChangeLog:

    2021-11-17  Jan Hubicka  <hubicka@ucw.cz>

            PR ipa/103246
            * ipa-modref.c (read_modref_records): Fix streaminig in of
every_access
            flag.=