[llvm] [DAGCombiner][VP] Add DAGCombine for VP_MUL (PR #80105)

[Liao Chunyu via llvm-commits]

================
@@ -4404,20 +4408,21 @@ SDValue DAGCombiner::visitMUL(SDNode *N) {
   if (N1IsConst && ConstValue1.isOne())
     return N0;
 
-  if (SDValue NewSel = foldBinOpIntoSelect(N))
-    return NewSel;
+  if (!IsVP)
+    if (SDValue NewSel = foldBinOpIntoSelect(N))
----------------
ChunyuLiao wrote:

I'm not sure about the correctness, but this patch has to be rebase first. 

https://github.com/llvm/llvm-project/pull/80105