[llvm] [LSR] Fix matching vscale immediates (PR #100080)

[Benjamin Maxwell via llvm-commits]

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@@ -947,7 +947,8 @@ static Immediate ExtractImmediate(const SCEV *&S, ScalarEvolution &SE) {
                            SCEV::FlagAnyWrap);
     return Result;
   } else if (EnableVScaleImmediates)
-    if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S))
+    if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S);
+        M && M->getNumOperands() == 2)
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MacDue wrote:

Sure, makes sense :+1: 

https://github.com/llvm/llvm-project/pull/100080