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Subject: [Bug ipa/103052] [9/10/11 Regression] Function is found to be pure
 looping but has a call to a noreturn function in it
Date: Thu, 25 Nov 2021 13:29:05 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103052

--- Comment #15 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jan Hubicka
<hubicka@gcc.gnu.org>:

https://gcc.gnu.org/g:3d1f5e86fb4351a109d45fe441b1b00d6e56c277

commit r9-9844-g3d1f5e86fb4351a109d45fe441b1b00d6e56c277
Author: Jan Hubicka <jh@suse.cz>
Date:   Sun Nov 21 00:35:22 2021 +0100

    Fix looping flag discovery in ipa-pure-const

    The testcase shows situation where there is non-trivial cycle in the
callgraph
    involving a noreturn call.  This cycle is important for const function
discovery
    but not important for pure.  IPA pure const uses same strongly connected
    components for both propagations which makes it to get suboptimal result
    (does not detect the pure flag). However local pure const gets the
situation
    right becaue it processes functions in right order.  This hits rarely
    executed code in propagate_pure_const that merge results with previously
    known state that has long standing bug in it that makes it to throw away
    the looping flag.

    Bootstrapped/regtested x86_64-linux.

    gcc/ChangeLog:

    2021-11-21  Jan Hubicka  <hubicka@ucw.cz>

            PR ipa/103052
            * ipa-pure-const.c (propagate_pure_const): Fix merging of loping
flag.

    gcc/testsuite/ChangeLog:

    2021-11-21  Jan Hubicka  <hubicka@ucw.cz>

            PR ipa/103052
            * gcc.c-torture/execute/pr103052.c: New test.

    (cherry picked from commit a0e99d5bb741d3db74a67d492f47b28217fbf88a)=