[Bug tree-optimization/103266] [12 regression] llvm-13 miscompilation: __builtin_assume_aligned causes over-aggressive dce

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103266

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jan Hubicka <hubi...@gcc.gnu.org>:

https://gcc.gnu.org/g:c331a75d49b6043399f5ccce72a02ccf3b0ddc56

commit r12-5379-gc331a75d49b6043399f5ccce72a02ccf3b0ddc56
Author: Jan Hubicka <j...@suse.cz>
Date:   Thu Nov 18 18:41:43 2021 +0100

    Fix modref wrt __builtin_assume_aligned

    __builtin_assume_aligned has bit contraictionary fnspec description "1cX "
    which means that parameter 1 is returned but also unused.  PTA code takes
    precedence to parameter being returned, while modref takes the info that
    parameter is unused.  This patch tweaks modref to follow PTA semantics (as
    suggested by Richard in the PR log)

    gcc/ChangeLog:

    2021-11-18  Jan Hubicka  <hubi...@ucw.cz>

            PR ipa/103266
            * ipa-modref.c (modref_eaf_analysis::merge_call_lhs_flags): Unused
            parameter may still be returned.
            (modref_eaf_analysis::analyze_ssa_name): Call merge_call_lhs_flags
            even for unused function args.

    gcc/testsuite/ChangeLog:

    2021-11-18  Jan Hubicka  <hubi...@ucw.cz>

            PR ipa/103266
            * g++.dg/torture/pr103266.C: New test.