DAG: Change behavior of fminnum/fmaxnum nodes

Introduce new versions that follow the IEEE semantics
to help with legalization that may need quieted inputs.

There are some regressions from inserting unnecessary
canonicalizes when these are matched from fast math
fcmp + select which should be fixed in a future commit.

llvm-svn: 344914

1 files changed, 29 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index b9b99b386af..ceedd06da1d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -4113,6 +4113,35 @@ bool TargetLowering::expandFP_TO_SINT(SDNode *Node, SDValue &Result,
   return true;
 }
 
+SDValue TargetLowering::expandFMINNUM_FMAXNUM(SDNode *Node,
+                                              SelectionDAG &DAG) const {
+  SDLoc dl(Node);
+  unsigned NewOp = Node->getOpcode() == ISD::FMINNUM ?
+    ISD::FMINNUM_IEEE : ISD::FMAXNUM_IEEE;
+  EVT VT = Node->getValueType(0);
+  if (isOperationLegalOrCustom(NewOp, VT)) {
+    SDValue Quiet0 = Node->getOperand(0);
+    SDValue Quiet1 = Node->getOperand(1);
+
+    if (!Node->getFlags().hasNoNaNs()) {
+      // Insert canonicalizes if it's possible we need to quiet to get correct
+      // sNaN behavior.
+      if (!DAG.isKnownNeverSNaN(Quiet0)) {
+        Quiet0 = DAG.getNode(ISD::FCANONICALIZE, dl, VT, Quiet0,
+                             Node->getFlags());
+      }
+      if (!DAG.isKnownNeverSNaN(Quiet1)) {
+        Quiet1 = DAG.getNode(ISD::FCANONICALIZE, dl, VT, Quiet1,
+                             Node->getFlags());
+      }
+    }
+
+    return DAG.getNode(NewOp, dl, VT, Quiet0, Quiet1, Node->getFlags());
+  }
+
+  return SDValue();
+}
+
 SDValue TargetLowering::scalarizeVectorLoad(LoadSDNode *LD,
                                             SelectionDAG &DAG) const {
   SDLoc SL(LD);