[Bug analyzer/99771] Analyzer diagnostics should not say "<unknown>"

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99771

--- Comment #2 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:e4bb1bd60a9fd1bed36092a990aa5fed5d45bfa6

commit r11-7941-ge4bb1bd60a9fd1bed36092a990aa5fed5d45bfa6
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Mon Mar 29 16:13:32 2021 -0400

    analyzer: avoid printing '<unknown>' for SSA names [PR99771]

    We don't want to print '<unknown>' in our diagnostics, but
    PR analyzer/99771 lists various cases where -fanalyzer does, due to
    using the SSA_NAME for a temporary when determining the best tree to
    use.

    This can happen in two ways:

    (a) ...when a better expression than the SSA_NAME could be built, but
    finding it requires traversing the relationships in the region_model
    in a graph-like way, rather than by considering individual svalues and
    regions.

    (b) ...when the only remaining user of the underlying svalue is the
    SSA_NAME, typically due to the diagnostic referring to a temporary.

    I've been experimenting with fixing (a), but don't have a good fix yet.
    In the meantime, this patch addresses (b) by detecting if we have
    the SSA_NAME for a temporary, and, for the cases where it's possible,
    reconstructing a tree by walking the def-stmts.  This fixes various
    cases of (b) and ameliorates some cases of (a).

    gcc/analyzer/ChangeLog:
            PR analyzer/99771
            * analyzer.cc (maybe_reconstruct_from_def_stmt): New.
            (fixup_tree_for_diagnostic_1): New.
            (fixup_tree_for_diagnostic): New.
            * analyzer.h (fixup_tree_for_diagnostic): New decl.
            * checker-path.cc (call_event::get_desc): Call
            fixup_tree_for_diagnostic and use it for the call_with_state call.
            (warning_event::get_desc): Likewise for the final_event and
            make_label_text calls.
            * engine.cc (impl_region_model_context::on_state_leak): Likewise
            for the on_leak and add_diagnostic calls.
            * region-model.cc (region_model::get_representative_tree):
            Likewise for the result.

    gcc/testsuite/ChangeLog:
            PR analyzer/99771
            * gcc.dg/analyzer/data-model-10.c: Update expected output.
            * gcc.dg/analyzer/malloc-ipa-13.c: Likewise.
            * gcc.dg/analyzer/malloc-ipa-13a.c: New test.
            * gcc.dg/analyzer/pr99771-1.c: New test.