[llvm] [SLP] NFC. Replace TreeEntry::setOperandsInOrder with VLOperands. (PR #113880)

[Han-Kuan Chen via llvm-commits]

================
@@ -8591,46 +8572,13 @@ void BoUpSLP::buildTree_rec(ArrayRef<Value *> VL, unsigned Depth,
 
       TreeEntry *TE = newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
                                    ReuseShuffleIndices);
-      // Sort operands of the instructions so that each side is more likely to
-      // have the same opcode.
-      if (isCommutative(VL0)) {
-        ValueList Left, Right;
-        reorderInputsAccordingToOpcode(VL, Left, Right, *this);
-        TE->setOperand(0, Left);
-        TE->setOperand(1, Right);
-        SmallVector<ValueList> Operands;
-        for (unsigned I : seq<unsigned>(2, CI->arg_size())) {
-          Operands.emplace_back();
-          if (isVectorIntrinsicWithScalarOpAtArg(ID, I))
-            continue;
----------------
HanKuanChen wrote:

But for `IntrinsicInst` which is NOT commutative, all arguments will be stored into a TreeEntry (and SLP will not call `buildTree_rec` for those arguments).

If we have to "avoid calling setOperand for isVectorIntrinsicWithScalarOpAtArg args" for commutative `IntrinsicInst`, we have to do something like the following patch.
```
diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index d8c596eb875d..54210cc0b149 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -3267,8 +3267,18 @@ private:
     void setOperand(ArrayRef<Value *> VL, const BoUpSLP &R,
                     bool RequireReorder = false) {
       VLOperands Ops(VL, R);
-      if (RequireReorder)
+      if (RequireReorder) {
         Ops.reorder();
+        if (auto *CI = dyn_cast<CallInst>(VL[0])) {
+          Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, R.TLI);
+          for (unsigned I : seq<unsigned>(CI->arg_size())) {
+            if (isVectorIntrinsicWithScalarOpAtArg(ID, I))
+              continue;
+            setOperand(I, Ops.getVL(I));
+          }
+          return;
+        }
+      }
       for (unsigned I :
            seq<unsigned>(cast<Instruction>(VL[0])->getNumOperands()))
         setOperand(I, Ops.getVL(I));
```

But it does not look elegant.

https://github.com/llvm/llvm-project/pull/113880