[Bug c++/105871] ICE: in wide_int_to_tree_1, at tree.cc:1777 with __builtin_shufflevector() in C++ code

cvs-commit at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Thu Jun 9 15:58:27 GMT 2022


--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:


commit r13-1027-g4c334e0e4ff05d3a7ca9ebb832428c446cd0ae8d
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Jun 9 17:42:31 2022 +0200

    c++: Fix up ICE on __builtin_shufflevector constexpr evaluation [PR105871]

    As the following testcase shows, BIT_FIELD_REF result doesn't have to have
    just integral type, it can also have vector type.  And in that case
    cxx_eval_bit_field_ref just ICEs on it because it is unprepared for that
    case, creates the initial value with build_int_cst (sure, that one could be
    easily replaced with build_zero_cst) and then expects it can through
    ands and ors come up with the final value, but that doesn't work for

    We already call fold_ternary if whole is a VECTOR_CST, this patch does the
    same if the result doesn't have integral type.  And, there is no guarantee
    fold_ternary will succeed and the callers certainly don't expect NULL
    being returned, so it also diagnoses those as non-constant and returns
    original t in that case.

    2022-06-09  Jakub Jelinek  <jakub@redhat.com>

            PR c++/105871
            * constexpr.cc (cxx_eval_bit_field_ref): For BIT_FIELD_REF with
            non-integral result type use fold_ternary too like for
            from VECTOR_CST.  If fold_ternary returns NULL, diagnose
            expression, set *non_constant_p and return t, instead of returning

            * g++.dg/pr105871.C: New test.

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