[Bug analyzer/108733] -Wanalyzer-use-of-uninitialized-value false positives seen with __attribute__((cleanup))

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108733

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by David Malcolm <dmalcolm@gcc.gnu.org>:

https://gcc.gnu.org/g:125b57aa67400388a496c2c0c40d9c8c55e0c94a

commit r13-5762-g125b57aa67400388a496c2c0c40d9c8c55e0c94a
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Thu Feb 9 17:09:51 2023 -0500

    analyzer: fix further overzealous state purging [PR108733]

    PR analyzer/108733 reports various false positives in qemu from
    -Wanalyzer-use-of-uninitialized-value with __attribute__((cleanup))
    at -O1 and above.

    Root cause is that the state-purging code was failing to treat:
       _25 = MEM[(void * *)&val];
    as a usage of "val", leading to it erroneously purging the
    initialization of "val" along an execution path that didn't otherwise
    use "val", apart from the  __attribute__((cleanup)).

    Fixed thusly.

    Integration testing on the patch show this change in the number of
    diagnostics:
      -Wanalyzer-use-of-uninitialized-value
           coreutils-9.1: 18 -> 16 (-2)
              qemu-7.2.0: 87 -> 80 (-7)
    where all that I investigated appear to have been false positives, hence
    an improvement.

    gcc/analyzer/ChangeLog:
            PR analyzer/108733
            * state-purge.cc (get_candidate_for_purging): Add ADDR_EXPR
            and MEM_REF.

    gcc/testsuite/ChangeLog:
            PR analyzer/108733
            * gcc.dg/analyzer/torture/uninit-pr108733.c: New test.

    Signed-off-by: David Malcolm <dmalcolm@redhat.com>