[Bug tree-optimization/126947] [15/16/17 Regression] ICE Unable to coalesce ssa_names 4 and 8 which are marked as MUST COALESCE.

"pinskia at gcc dot gnu.org via Gcc-bugs" <[email protected]> Wed, 19 Aug 2026 17:07:25 +0000

Newsgroups	gmane.comp.gcc.bugs
Message-ID	<[email protected]/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126947

Drea Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2026-08-19
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Drea Pinski <pinskia at gcc dot gnu.org> ---
Confirmed. ifcombine is causing the issue.
It is "moving" this:
_17 = (unsigned int) flags_8(D)(ab);

right before the if.

There is a missing check for abnormal in ifcombine.