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

[Florian Hahn via llvm-commits]

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@@ -1847,6 +1847,10 @@ class TargetTransformInfo {
   /// otherwise scalar epilogue loop.
   LLVM_ABI bool preferEpilogueVectorization() const;
 
+  /// \returns True if the loop vectorizer should discard any VFs that may have
+  /// too high of a register pressure as determined by getNumberOfRegisters.
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fhahn wrote:

nit: perhaps slightly simpler wording
```suggestion
  /// \returns True if the loop vectorizer should discard any VFs where the maximum register pressure exceeds getNumberOfRegisters.
```

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