[SelectionDAG] DAG combiner for fminnan and fmaxnan

[tlively]

Summary

Depends on D52765.

[aheejin]

Is there any tests?

[tlively]

In D52768#1254736, @aheejin wrote:

Is there any tests?

No, I haven't been able to find any existing tests or an obvious place to add new ones for DAG combining. I guess the fact that all the backends still work is something.

[aheejin]

So this change is not necessarily related to minimum/maximum new intrinsics, because they are pre-existing. So this means FMINNAN/FMAXNAN nodes have not been optimized in DAG combiner so far. Strange. Anyway apparently what this does is constant folding on DAG nodes, so I think we can come up with a test?

lib/CodeGen/SelectionDAG/DAGCombiner.cpp

12110

Is this line clang-formatted?

[tlively]

• Formatting and tests

[tlively]

test/CodeGen/WebAssembly/simd-arith.ll

827 ↗

(On Diff #170502)

These transpositions show the canonicalization working.

lib/CodeGen/SelectionDAG/DAGCombiner.cpp

private:
     SDValue visitFP_EXTEND(SDNode *N);
     SDValue visitFNEG(SDNode *N);
     SDValue visitFABS(SDNode *N);
     SDValue visitFCEIL(SDNode *N);
     SDValue visitFTRUNC(SDNode *N);
     SDValue visitFFLOOR(SDNode *N);
     SDValue visitFMINNUM(SDNode *N);
     SDValue visitFMAXNUM(SDNode *N);
+    SDValue visitFMINNAN(SDNode *N);
+    SDValue visitFMAXNAN(SDNode *N);
     SDValue visitBRCOND(SDNode *N);
     SDValue visitBR_CC(SDNode *N);
     SDValue visitLOAD(SDNode *N);
 
     SDValue replaceStoreChain(StoreSDNode *ST, SDValue BetterChain);
     SDValue replaceStoreOfFPConstant(StoreSDNode *ST);
 
     SDValue visitSTORE(SDNode *N);
SDValue DAGCombiner::visit(SDNode *N) {
   case ISD::FP_ROUND:           return visitFP_ROUND(N);
   case ISD::FP_ROUND_INREG:     return visitFP_ROUND_INREG(N);
   case ISD::FP_EXTEND:          return visitFP_EXTEND(N);
   case ISD::FNEG:               return visitFNEG(N);
   case ISD::FABS:               return visitFABS(N);
   case ISD::FFLOOR:             return visitFFLOOR(N);
   case ISD::FMINNUM:            return visitFMINNUM(N);
   case ISD::FMAXNUM:            return visitFMAXNUM(N);
+  case ISD::FMINNAN:            return visitFMINNAN(N);
+  case ISD::FMAXNAN:            return visitFMAXNAN(N);
   case ISD::FCEIL:              return visitFCEIL(N);
   case ISD::FTRUNC:             return visitFTRUNC(N);
   case ISD::BRCOND:             return visitBRCOND(N);
   case ISD::BR_CC:              return visitBR_CC(N);
   case ISD::LOAD:               return visitLOAD(N);
   case ISD::STORE:              return visitSTORE(N);
   case ISD::INSERT_VECTOR_ELT:  return visitINSERT_VECTOR_ELT(N);
   case ISD::EXTRACT_VECTOR_ELT: return visitEXTRACT_VECTOR_ELT(N);
if (CFP1) {
             DAG.getNode(ISD::FNEG, SDLoc(N), VT, N0.getOperand(1)),
             N0->getFlags());
     }
   }
 
   return SDValue();
 }
 
-SDValue DAGCombiner::visitFMINNUM(SDNode *N) {
+static SDValue visitFMinMax(SelectionDAG &DAG, SDNode *N,
+                            APFloat (*Op)(const APFloat&, const APFloat&)) {
   SDValue N0 = N->getOperand(0);
   SDValue N1 = N->getOperand(1);
   EVT VT = N->getValueType(0);
   const ConstantFPSDNode *N0CFP = isConstOrConstSplatFP(N0);
   const ConstantFPSDNode *N1CFP = isConstOrConstSplatFP(N1);
 
   if (N0CFP && N1CFP) {
     const APFloat &C0 = N0CFP->getValueAPF();
     const APFloat &C1 = N1CFP->getValueAPF();
-    return DAG.getConstantFP(minnum(C0, C1), SDLoc(N), VT);
+    return DAG.getConstantFP(Op(C0, C1), SDLoc(N), VT);
   }
 
   // Canonicalize to constant on RHS.
   if (isConstantFPBuildVectorOrConstantFP(N0) &&
      !isConstantFPBuildVectorOrConstantFP(N1))
-    return DAG.getNode(ISD::FMINNUM, SDLoc(N), VT, N1, N0);
+    return DAG.getNode(N->getOpcode(), SDLoc(N), VT, N1, N0);
 
   return SDValue();
 }
 
-SDValue DAGCombiner::visitFMAXNUM(SDNode *N) {
-  SDValue N0 = N->getOperand(0);
-  SDValue N1 = N->getOperand(1);
-  EVT VT = N->getValueType(0);
-  const ConstantFPSDNode *N0CFP = isConstOrConstSplatFP(N0);
-  const ConstantFPSDNode *N1CFP = isConstOrConstSplatFP(N1);
+SDValue DAGCombiner::visitFMINNUM(SDNode *N) {
+  return visitFMinMax(DAG, N, minnum);
+}
 
-  if (N0CFP && N1CFP) {
-    const APFloat &C0 = N0CFP->getValueAPF();
-    const APFloat &C1 = N1CFP->getValueAPF();
-    return DAG.getConstantFP(maxnum(C0, C1), SDLoc(N), VT);
-  }
+SDValue DAGCombiner::visitFMAXNUM(SDNode *N) {
+  return visitFMinMax(DAG, N, maxnum);
 
-  // Canonicalize to constant on RHS.
-  if (isConstantFPBuildVectorOrConstantFP(N0) &&
-     !isConstantFPBuildVectorOrConstantFP(N1))
-    return DAG.getNode(ISD::FMAXNUM, SDLoc(N), VT, N1, N0);
+SDValue DAGCombiner::visitFMINNAN(SDNode *N) {
+  return visitFMinMax(DAG, N, minimum);
+}
 
-  return SDValue();
+SDValue DAGCombiner::visitFMAXNAN(SDNode *N) {
+  return visitFMinMax(DAG, N, maximum);
 }
 
 SDValue DAGCombiner::visitFABS(SDNode *N) {
   SDValue N0 = N->getOperand(0);
   EVT VT = N->getValueType(0);
 
   // fold (fabs c1) -> fabs(c1)
   if (isConstantFPBuildVectorOrConstantFP(N0))