[Bug tree-optimization/92768] [8 Regression] Maybe a wrong code for vector constants

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92768

--- Comment #21 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-8 branch has been updated by Richard Sandiford
<rsand...@gcc.gnu.org>:

https://gcc.gnu.org/g:e4efe90aec0a5f722341c1070680d2ab3a438a7d

commit r8-10058-ge4efe90aec0a5f722341c1070680d2ab3a438a7d
Author: Richard Sandiford <richard.sandif...@arm.com>
Date:   Thu Dec 5 14:20:38 2019 +0000

    Check for bitwise identity when encoding VECTOR_CSTs [PR92768]

    This PR shows that we weren't checking for bitwise-identical values
    when trying to encode a VECTOR_CST, so -0.0 was treated the same as
    0.0 for -fno-signed-zeros.  The patch adds a new OEP flag to select
    that behaviour.

    2020-02-25  Richard Sandiford  <richard.sandif...@arm.com>

    gcc/
        Backport from mainline
        2019-12-05  Richard Sandiford  <richard.sandif...@arm.com>

        PR middle-end/92768
        * tree-core.h (OEP_BITWISE): New flag.
        * fold-const.c (operand_compare::operand_equal_p): Handle it.
        * tree-vector-builder.h (tree_vector_builder::equal_p): Pass it.

    gcc/testsuite/
        PR middle-end/92768
        * gcc.dg/pr92768.c: New test.