Add a comment noting that the fdiv -> fmul conversion won't generate

multiplication by a denormal, and some tests checking that.

llvm-svn: 154431

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index b5b20284c1d..ae7c941b134 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5769,9 +5769,9 @@ SDValue DAGCombiner::visitFDIV(SDNode *N) {
     APFloat N1APF = N1CFP->getValueAPF();
     APFloat Recip(N1APF.getSemantics(), 1); // 1.0
     APFloat::opStatus st = Recip.divide(N1APF, APFloat::rmNearestTiesToEven);
-    // Only do the transform if the reciprocal is not too horrible (eg not NaN)
-    // and the reciprocal is a legal fp imm.
-    if ((st == APFloat::opOK || st == APFloat::opInexact) &&
+    // Only do the transform if the reciprocal is a legal fp immediate that
+    // isn't too nasty (eg NaN, denormal, ...).
+    if ((st == APFloat::opOK || st == APFloat::opInexact) && // Not too nasty
         (!LegalOperations ||
          // FIXME: custom lowering of ConstantFP might fail (see e.g. ARM
          // backend)... we should handle this gracefully after Legalize.