[llvm] [LV] Update forced epilogue VF options to allow different VFs than main. (PR #190393)

[via llvm-commits]

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@@ -6793,6 +6800,14 @@ void LoopVectorizationPlanner::plan(ElementCount UserVF, unsigned UserIC) {
       CM.collectInLoopReductions();
       if (CM.selectUserVectorizationFactor(UserVF)) {
         LLVM_DEBUG(dbgs() << "LV: Using user VF " << UserVF << ".\n");
+        ElementCount EpilogueUserVF =
+            ElementCount::getFixed(EpilogueVectorizationForceVF);
+        if (EpilogueUserVF.isVector() &&
+            ElementCount::isKnownLT(EpilogueUserVF, UserVF)) {
+          // Build a separate plan for the forced epilogue VF.
+          CM.collectNonVectorizedAndSetWideningDecisions(EpilogueUserVF);
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ayalz wrote:

Inconsistency - not needed when building the plan for UserVF below?

https://github.com/llvm/llvm-project/pull/190393