[Bug tree-optimization/126788] __builtin_convertvector upconvert + downconvert doesn't cancel out

"hjl.tools at gmail dot com via Gcc-bugs" <[email protected]> Tue, 11 Aug 2026 10:55:33 +0000

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126788

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2026-08-11
                 CC|                            |hjl.tools at gmail dot com
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
Add

/* (type) ((wide_type) a) -> a.  */
(simplify
 (convert (convert@1 @0))
  (if (ANY_INTEGRAL_TYPE_P (type)
       && ANY_INTEGRAL_TYPE_P (TREE_TYPE (@1))
       && types_match (type, TREE_TYPE (@0))
       && element_precision (type) < element_precision (TREE_TYPE (@1)))
   @0))

to match.pd works for me.