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

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

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

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by David Malcolm
<dmalc...@gcc.gnu.org>:

https://gcc.gnu.org/g:98558117ba870d47398927f2066e469e47f39c16

commit r12-9365-g98558117ba870d47398927f2066e469e47f39c16
Author: David Malcolm <dmalc...@redhat.com>
Date:   Wed Mar 29 14:16:49 2023 -0400

    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.

    Cherrypicked from r13-5745-g77bb54b1b07add.

    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 <dmalc...@redhat.com>