[ValueTracking] Implement `computeKnownFPClass` for `llvm.vector.reduce.{fmin,fmax,fmaximum,fminimum}`

Closes #88408

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index e91dc07..ab2f43e 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -5032,6 +5032,19 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
 
       break;
     }
+    case Intrinsic::vector_reduce_fmax:
+    case Intrinsic::vector_reduce_fmin:
+    case Intrinsic::vector_reduce_fmaximum:
+    case Intrinsic::vector_reduce_fminimum: {
+      // reduce min/max will choose an element from one of the vector elements,
+      // so we can infer and class information that is common to all elements.
+      Known = computeKnownFPClass(II->getArgOperand(0), II->getFastMathFlags(),
+                                  InterestedClasses, Depth + 1, Q);
+      // Can only propagate sign if output is never NaN.
+      if (!Known.isKnownNeverNaN())
+        Known.SignBit.reset();
+      break;
+    }
     case Intrinsic::trunc:
     case Intrinsic::floor:
     case Intrinsic::ceil: