[llvm] [SLP] Make getSameOpcode support different instructions if they have same semantics. (PR #112181)

[Han-Kuan Chen via llvm-commits]

================
@@ -14935,7 +15108,7 @@ Value *BoUpSLP::vectorizeTree(TreeEntry *E, bool PostponedPHIs) {
       Value *V = Builder.CreateBinOp(
           static_cast<Instruction::BinaryOps>(E->getOpcode()), LHS,
           RHS);
-      propagateIRFlags(V, E->Scalars, VL0, It == MinBWs.end());
+      propagateIRFlags(V, E->Scalars, nullptr, It == MinBWs.end());
----------------
HanKuanChen wrote:

Yes. But actually `shl` does not have `nsw`. We should emit `mul <4 x >`.

https://github.com/llvm/llvm-project/pull/112181