[Bug middle-end/106495] [13 Regression] Build fails gcc/tree-ssa-threadbackward.cc:22: gcc/vec.h:890:19: error: array subscript 4294967294 is above array bounds of 'basic_block_def* [1]' [-Werror=array-bounds]

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106495

--- Comment #12 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Aldy Hernandez <aldyh@gcc.gnu.org>:

https://gcc.gnu.org/g:0025ab8747c66ce47dd6705460d5e1b0b5d37d39

commit r17-3859-g0025ab8747c66ce47dd6705460d5e1b0b5d37d39
Author: Aldy Hernandez <aldy@quesejoda.com>
Date:   Tue Sep 1 20:17:36 2026 +0000

    Add testcases for backward threading to never-executed edges [PR106495]

    r13-1924-gb9da686470d1c2 avoided threading to probably never executed
    edges but landed without a testcase.  Add two, retroactively.

    [This is all AI generated.  I used it to to go back in time, create
    testcases from the original preprocessed source code, further reduce
    it with cvise, and then distill it further to create a minimal
    reproducer for the concept, not the warning.  This allows us to keep
    a reduction of the original testcase, plus a conceptual tiny testcase
    to make sure we don't regress going forward.]

    Both FAIL before r13-1924 and PASS with it.

    Assisted-by: Claude Fable 5 (Anthropic)

    gcc/testsuite/ChangeLog:

            PR tree-optimization/106495
            PR tree-optimization/126906
            * gcc.dg/tree-ssa/pr106495-1.c: New test.
            * gcc.dg/tree-ssa/pr106495-2.c: New test.