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

[Sam Tebbs via llvm-commits]

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@@ -7458,7 +7470,10 @@ VectorizationFactor LoopVectorizationPlanner::computeBestVF() {
       InstructionCost Cost = cost(*P, VF);
       VectorizationFactor CurrentFactor(VF, Cost, ScalarCost);
 
-      if (RU.exceedsMaxNumRegs(TTI)) {
+      if (CM.useMaxBandwidth(VF.isScalable()
+                                 ? TargetTransformInfo::RGK_ScalableVector
+                                 : TargetTransformInfo::RGK_FixedWidthVector) &&
+          RU.exceedsMaxNumRegs(TTI)) {
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SamTebbs33 wrote:

That understanding is correct. This was the behaviour before my previous PR accidentally changed it.

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