[Bug tree-optimization/108540] [13 Regression] Frange miscompilation of ruby since r13-3261

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108540

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:09176201ec6a21c25b1edb07f19f83be22a123f9

commit r13-5397-g09176201ec6a21c25b1edb07f19f83be22a123f9
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Jan 26 17:21:22 2023 +0100

    frange: Fix up foperator_{,not_}equal::fold_range for signed zeros
[PR108540]

    The following testcases are miscompiled, because threader sees some
    SSA_NAME would have -0.0 value and when computing range of SSA_NAME == 0.0
    foperator_equal::fold_range sees one operand has [-0.0, -0.0] singleton
    range, the other [0.0, 0.0], they aren't equal (frange operator== uses
    real_identical etc. rather than real comparisons) and so it thinks they
    compare unequal.  With signed zeros -0.0 == 0.0 is true though, so we
    need to special case the both ranges singleton code.
    Similarly, if we see op1 range being say [-42.0, -0.0] and op2 range
    [0.0, 42.0], we'd check that the intersection of the two ranges is empty
    (that is correct) and fold the result of == between such operands to
    [0, 0] which is wrong, because -0.0 == 0.0, it needs to be [0, 1].
    Similarly for foperator_not_equal::fold_range.

    2023-01-26  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/108540
            * range-op-float.cc (foperator_equal::fold_range): If both op1 and
op2
            are singletons, use range_true even if op1 != op2
            when one range is [-0.0, -0.0] and another [0.0, 0.0].  Similarly,
            even if intersection of the ranges is empty and one has
            zero low bound and another zero high bound, use
range_true_and_false
            rather than range_false.
            (foperator_not_equal::fold_range): If both op1 and op2
            are singletons, use range_false even if op1 != op2
            when one range is [-0.0, -0.0] and another [0.0, 0.0].  Similarly,
            even if intersection of the ranges is empty and one has
            zero low bound and another zero high bound, use
range_true_and_false
            rather than range_true.

            * gcc.c-torture/execute/ieee/pr108540-1.c: New test.
            * gcc.c-torture/execute/ieee/pr108540-2.c: New test.