[llvm] [GlobalISel] Combine G_MERGE_VALUES of x and undef (PR #113616)

[Matt Arsenault via llvm-commits]

Thorsten =?utf-8?q?Sch=C3=BCtt?= <schuett at gmail.com>,
Thorsten =?utf-8?q?Sch=C3=BCtt?= <schuett at gmail.com>,
Thorsten =?utf-8?q?Sch=C3=BCtt?= <schuett at gmail.com>,
Thorsten =?utf-8?q?Sch=C3=BCtt?= <schuett at gmail.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/113616 at github.com>


================
@@ -922,6 +922,9 @@ class CombinerHelper {
   bool matchUnmergeValuesAnyExtBuildVector(const MachineInstr &MI,
                                            BuildFnTy &MatchInfo);
 
+  // merge_values(_, undef) -> zext
----------------
arsenm wrote:

This should fold to anyext if the anyext is legal

https://github.com/llvm/llvm-project/pull/113616