[llvm] [LV] Simplify the chain traversal in `getScaledReductions()` (NFCI) (PR #184830)

[Gaëtan Bossu via llvm-commits]

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@@ -6082,36 +6074,16 @@ getScaledReductions(VPReductionPHIRecipe *RedPhiR, VPValue *PrevValue,
       match(Op, m_FPExt(m_FMul(m_VPValue(), m_VPValue())))) {
     auto *CastRecipe = dyn_cast<VPWidenCastRecipe>(Op);
     if (!CastRecipe)
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gbossu wrote:

Curious: When does that happen? Is it for `UF=1` but `UC>1`?

https://github.com/llvm/llvm-project/pull/184830