[llvm] [NFC][LoopVectorize] Cache result of requiresScalarEpilogue (PR #108981)

[Florian Hahn via llvm-commits]

================
@@ -220,7 +216,8 @@ define void @vector_reverse_f32(ptr nocapture noundef writeonly %A, ptr nocaptur
 ; CHECK-NEXT:  LV: Found FP op with unsafe algebra.
 ; CHECK-NEXT:  LV: Did not find one integer induction var.
 ; CHECK-NEXT:  LV: We can vectorize this loop (with a runtime bound check)!
-; CHECK-NEXT:  LV: Loop does not require scalar epilogue
+; CHECK-NEXT:  LV: When vectorizing loop does not require scalar epilogue
+; CHECK-NEXT:  LV: When not vectorizing loop does not require scalar epilogue
----------------
fhahn wrote:

```suggestion
; CHECK-NEXT:  LV: Loop does not require scalar epilogue when vectorizing
; CHECK-NEXT:  LV: Loop does not require scalar epilogue when not vectorizing
```

Might be slightly easier to read?

https://github.com/llvm/llvm-project/pull/108981