[llvm] [LV] Vectorize maxnum/minnum w/o fast-math flags. (PR #148239)

[Florian Hahn via llvm-commits]

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@@ -4345,10 +4345,16 @@ VectorizationFactor LoopVectorizationPlanner::selectVectorizationFactor() {
 
 bool LoopVectorizationPlanner::isCandidateForEpilogueVectorization(
     ElementCount VF) const {
-  // Cross iteration phis such as reductions need special handling and are
-  // currently unsupported.
-  if (any_of(OrigLoop->getHeader()->phis(),
-             [&](PHINode &Phi) { return Legal->isFixedOrderRecurrence(&Phi); }))
+  // Cross iteration phis such as first-order recurrences and FMaxNum/FMinNum
+  // reductions need special handling and are currently unsupported.
+  if (any_of(OrigLoop->getHeader()->phis(), [&](PHINode &Phi) {
+        if (Legal->isReductionVariable(&Phi)) {
+          RecurKind RK =
+              Legal->getRecurrenceDescriptor(&Phi).getRecurrenceKind();
+          return RK == RecurKind::FMinNum || RK == RecurKind::FMaxNum;
+        }
+        return Legal->isFixedOrderRecurrence(&Phi);
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fhahn wrote:

Updated, thanks

https://github.com/llvm/llvm-project/pull/148239