[llvm] [LV] Use original trip-count as the vector-trip-count if use predicated EVL instructions for tail-folding. (PR #132675)

[Mel Chen via llvm-commits]

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@@ -2426,9 +2426,18 @@ InnerLoopVectorizer::getOrCreateVectorTripCount(BasicBlock *InsertBlock) {
     return VectorTripCount;
 
   Value *TC = getTripCount();
+  Type *Ty = TC->getType();
   IRBuilder<> Builder(InsertBlock->getTerminator());
 
-  Type *Ty = TC->getType();
+  // Use original trip count as the vector trip count if use predicated EVL
+  // instructions for tail-folding.
+  if (VF.isVector() && Cost->foldTailWithEVL()) {
+    assert(!Cost->requiresScalarEpilogue(true) &&
+           "Use predicated EVL instructions for tail-folding does not allow "
+           "scalar epilogue");
+    return TC;
----------------
Mel-Chen wrote:

```suggestion
    return VectorTripCount = TC;
```

https://github.com/llvm/llvm-project/pull/132675