[llvm] [LoopVectorizer] Only check register pressure for VFs that have been enabled via maxBandwidth (PR #149056)

[Florian Hahn via llvm-commits]

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@@ -4375,9 +4389,10 @@ VectorizationFactor LoopVectorizationPlanner::selectVectorizationFactor() {
       if (VF.isScalar())
         continue;
 
-      /// Don't consider the VF if it exceeds the number of registers for the
-      /// target.
-      if (CM.useMaxBandwidth(VF) && RUs[I].exceedsMaxNumRegs(TTI))
+      /// If the VF was proposed due to MaxBandwidth, don't consider the VF if
+      /// it exceeds the number of registers for the target.
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fhahn wrote:

This comment now mentions MaxBandwith, but calls the more generally named `shouldCalculateRegPressureForVF`, which doesn't mentioned `MaxBandwidth` in its doc-comment.  Would be good to either clarify `shouldCalculateRegPressureForVF`' doc-comment or the function name

https://github.com/llvm/llvm-project/pull/149056