[llvm] [LV] Fix MVE regression from #132190 (PR #141736)

[Florian Hahn via llvm-commits]

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@@ -4384,7 +4393,10 @@ VectorizationFactor LoopVectorizationPlanner::selectVectorizationFactor() {
 
       /// Don't consider the VF if it exceeds the number of registers for the
       /// target.
-      if (RU.exceedsMaxNumRegs(TTI))
+      if (CM.useMaxBandwidth(VF.isScalable()
+                                 ? TargetTransformInfo::RGK_ScalableVector
+                                 : TargetTransformInfo::RGK_FixedWidthVector) &&
+          RU.exceedsMaxNumRegs(TTI))
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fhahn wrote:

I think this is the only use of RU, would be good to skip the register pressure computation when it's not needed

Same below

https://github.com/llvm/llvm-project/pull/141736