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

[Han-Kuan Chen via llvm-commits]

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@@ -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());
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HanKuanChen wrote:

Before the PR, there is no difference between VL0 and nullptr. The opcode must be the same for all VL.
After the PR, VL0 cannot be used because opcode may be different.
I don't know why VL0 is used in the beginning since pass VL0 and nullptr will get the same result for propagateIRFlags.

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