[Bug tree-optimization/127521] [15/16/17 Regression] `ifcombine` incorrectly removes a masked sign-bit condition

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127521

--- Comment #4 from Drea Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Mikael Pettersson from comment #3)
> I can reproduce this on two other 16-bit int targets: pdp11 and an
> out-of-tree one.

With the testcase in comment #1, I can reproduce the bug even on x86_64 which
should make it easier to debug ...