[llvm] [SLP] NFC. Make InstructionsState more constant. (PR #118609)

[Alexey Bataev via llvm-commits]

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@@ -8198,20 +8212,20 @@ void BoUpSLP::buildTree_rec(ArrayRef<Value *> VL, unsigned Depth,
     SmallVector<SmallVector<std::pair<Value *, Value *>>> Candidates;
     auto *I1 = cast<Instruction>(VL.front());
     auto *I2 = cast<Instruction>(VL.back());
-    for (int Op = 0, E = S.MainOp->getNumOperands(); Op < E; ++Op)
+    for (int Op = 0, E = S.getMainOp()->getNumOperands(); Op < E; ++Op)
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alexey-bataev wrote:

`for (int Op : seq<int>(S.getMainOp()->getNumOperands())))`

https://github.com/llvm/llvm-project/pull/118609