1 files changed, 7 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index c69fe55a4f1..cdf4a2dac96 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -3124,6 +3124,13 @@ void SelectionDAGBuilder::visitBinary(const User &I, unsigned Opcode) {
   if (isVectorReductionOp(&I)) {
     Flags.setVectorReduction(true);
     LLVM_DEBUG(dbgs() << "Detected a reduction operation:" << I << "\n");
+
+    // If no flags are set we will propagate the incoming flags, if any flags
+    // are set, we will intersect them with the incoming flag and so we need to
+    // copy the FMF flags here.
+    if (auto *FPOp = dyn_cast<FPMathOperator>(&I)) {
+      Flags.copyFMF(*FPOp);
+    }
   }
 
   SDValue Op1 = getValue(I.getOperand(0));