[llvm] [LV] Use getFixedValue instead of getKnownMinValue when appropriate (PR #143526)

[Luke Lau via llvm-commits]

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@@ -331,7 +331,7 @@ Value *VPTransformState::get(const VPValue *Def, bool NeedsScalar) {
 
   bool IsSingleScalar = vputils::isSingleScalar(Def);
 
-  VPLane LastLane(IsSingleScalar ? 0 : VF.getKnownMinValue() - 1);
+  VPLane LastLane(IsSingleScalar ? 0 : VF.getFixedValue() - 1);
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lukel97 wrote:

This is an existing invariant, in the bit below there's an assertion that `!VF.isScalable()` if IsSingleScalar is false

https://github.com/llvm/llvm-project/pull/143526