[llvm] [VPlan] Always consider register pressure on RISC-V (PR #156951)

[Luke Lau via llvm-commits]

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@@ -3702,6 +3702,9 @@ LoopVectorizationCostModel::computeMaxVF(ElementCount UserVF, unsigned UserIC) {
 
 bool LoopVectorizationCostModel::shouldConsiderRegPressureForVF(
     ElementCount VF) {
+  if (TTI.shouldConsiderVectorizationRegPressure())
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lukel97 wrote:

I'm a bit hesitant to add another flag given that we already have to add a TTI hook here. I'm not sure if this is something that particular users would want to toggle off or on themselves. I presume it's easiest for downstream users to override this by using the TTI hook? Or did you have another use case in mind?

https://github.com/llvm/llvm-project/pull/156951