[llvm] GlobalISel: Use G_UADDE when narrowing G_UMULH (PR #97194)

[Thorsten Schütt via llvm-commits]

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@@ -5716,6 +5716,7 @@ void LegalizerHelper::multiplyRegisters(SmallVectorImpl<Register> &DstRegs,
                                         ArrayRef<Register> Src1Regs,
                                         ArrayRef<Register> Src2Regs,
                                         LLT NarrowTy) {
+  const LLT S1 = LLT::scalar(1);
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tschuett wrote:

Why `const` ?

https://github.com/llvm/llvm-project/pull/97194