[Bug tree-optimization/92706] SRA confuses FRE

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92706

--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Martin Jambor
<jamborm@gcc.gnu.org>:

https://gcc.gnu.org/g:985a8962712a56d1c9418cf05e1761f8bd20cf8f

commit r12-8913-g985a8962712a56d1c9418cf05e1761f8bd20cf8f
Author: Martin Jambor <mjambor@suse.cz>
Date:   Wed Nov 16 13:11:27 2022 +0100

    SRA: Limit replacement creation for accesses propagated from LHSs

    PR 107206 is fallout from the fix to PR 92706 where we started
    propagating accesses across assignments also from LHS to RHS of
    assignments so that we would not do harmful total scalarization of the
    aggregates on the RHS.

    But this can lead to new scalarization of these aggregates and in the
    testcase of PR 107206 these can appear in superfluous uses of
    un-initialized values and spurious warnings.

    Fixed by making sure the the accesses created by propagation in this
    direction are only used as a basis for replacements when the structure
    would be totally scalarized anyway.

    gcc/ChangeLog:

    2022-10-18  Martin Jambor  <mjambor@suse.cz>

            PR tree-optimization/107206
            * tree-sra.cc (struct access): New field
grp_result_of_prop_from_lhs.
            (analyze_access_subtree): Do not create replacements for accesses
with
            this flag when not toally scalarizing.
            (propagate_subaccesses_from_lhs): Set the new flag.

    gcc/testsuite/ChangeLog:

    2022-10-18  Martin Jambor  <mjambor@suse.cz>

            PR tree-optimization/107206
            * g++.dg/tree-ssa/pr107206.C: New test.

    (cherry picked from commit f6c168f8c06047bfaa3005e570126831b8855dcc)