https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108540
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Ah, so back_threader::find_taken_edge_cond calls
path_range_query::range_of_stmt
on the d_1 == 0.0 with the assumption that d_1 is -0.0,
fold_using_range::range_of_range_op sees
(gdb) p debug (range1)
[frange] double [-0.0 (-0x0.0p+0), -0.0 (-0x0.0p+0)]
(gdb) p debug (range2)
[frange] double [0.0 (0x0.0p+0), 0.0 (0x0.0p+0)]
(that is correct) and foperator_equal::fold_range is called on those.
There we trigger the
604 // We can be sure the values are always equal or not if both ranges
605 // consist of a single value, and then compare them.
606 else if (op1.singleton_p () && op2.singleton_p ())
607 {
608 if (op1 == op2)
609 r = range_true (type);
610 else
611 r = range_false (type);
612 }
code, which is clearly wrong if both ops are singleton zeros with different
sign.
