Add new ISD nodes: ISD::FMINNAN and ISD::FMAXNAN

The intention of these is to be a corollary to ISD::FMINNUM/FMAXNUM,
differing only on how NaNs are treated. FMINNUM returns the non-NaN
input (when given one NaN and one non-NaN), FMINNAN returns the NaN
input instead.

This patch includes support for scalarizing, widening and splitting
vectors, but not expansion or softening. The reason is that these
should never be needed - FMINNAN nodes are only going to be created
in one place (SDAGBuilder::visitSelect) and there we'll check if the
node is legal or custom. I could preemptively add expand and soften
code, but I'm fairly opposed to adding code I can't test. It's bad
enough I can't create tests with this patch, but at least this code
will be exercised by the ARM and AArch64 backends fairly shortly.

llvm-svn: 244581

include/llvm/CodeGen/ISDOpcodes.h

@@ -514,7 +514,15 @@ namespace ISD {
     FNEG, FABS, FSQRT, FSIN, FCOS, FPOWI, FPOW,
     FLOG, FLOG2, FLOG10, FEXP, FEXP2,
     FCEIL, FTRUNC, FRINT, FNEARBYINT, FROUND, FFLOOR,
+    /// FMINNUM/FMAXNUM - Perform floating-point minimum or maximum on two
+    /// values.
+    /// In the case where a single input is NaN, the non-NaN input is returned.
+    ///
+    /// The return value of (FMINNUM 0.0, -0.0) could be either 0.0 or -0.0.
     FMINNUM, FMAXNUM,
+    /// FMINNAN/FMAXNAN - Behave identically to FMINNUM/FMAXNUM, except that
+    /// when a single input is NaN, NaN is returned.
+    FMINNAN, FMAXNAN,
 
     /// FSINCOS - Compute both fsin and fcos as a single operation.
     FSINCOS,

include/llvm/CodeGen/SelectionDAG.h

@@ -1088,6 +1088,8 @@ public:
     case ISD::ADDE:
     case ISD::FMINNUM:
     case ISD::FMAXNUM:
+    case ISD::FMINNAN:
+    case ISD::FMAXNAN:
       return true;
     default: return false;
     }

include/llvm/Target/TargetSelectionDAG.td

@@ -414,6 +414,8 @@ def fmad       : SDNode<"ISD::FMAD"       , SDTFPTernaryOp>;
 def fabs       : SDNode<"ISD::FABS"       , SDTFPUnaryOp>;
 def fminnum    : SDNode<"ISD::FMINNUM"    , SDTFPBinOp>;
 def fmaxnum    : SDNode<"ISD::FMAXNUM"    , SDTFPBinOp>;
+def fminnan    : SDNode<"ISD::FMINNAN"    , SDTFPBinOp>;
+def fmaxnan    : SDNode<"ISD::FMAXNAN"    , SDTFPBinOp>;
 def fgetsign   : SDNode<"ISD::FGETSIGN"   , SDTFPToIntOp>;
 def fneg       : SDNode<"ISD::FNEG"       , SDTFPUnaryOp>;
 def fsqrt      : SDNode<"ISD::FSQRT"      , SDTFPUnaryOp>;

lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp

@@ -299,6 +299,8 @@ SDValue VectorLegalizer::LegalizeOp(SDValue Op) {
   case ISD::FABS:
   case ISD::FMINNUM:
   case ISD::FMAXNUM:
+  case ISD::FMINNAN:
+  case ISD::FMAXNAN:
   case ISD::FCOPYSIGN:
   case ISD::FSQRT:
   case ISD::FSIN:

lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp

@@ -108,6 +108,8 @@ void DAGTypeLegalizer::ScalarizeVectorResult(SDNode *N, unsigned ResNo) {
   case ISD::FMUL:
   case ISD::FMINNUM:
   case ISD::FMAXNUM:
+  case ISD::FMINNAN:
+  case ISD::FMAXNAN:
 
   case ISD::FPOW:
   case ISD::FREM:
@@ -661,6 +663,8 @@ void DAGTypeLegalizer::SplitVectorResult(SDNode *N, unsigned ResNo) {
   case ISD::FMUL:
   case ISD::FMINNUM:
   case ISD::FMAXNUM:
+  case ISD::FMINNAN:
+  case ISD::FMAXNAN:
   case ISD::SDIV:
   case ISD::UDIV:
   case ISD::FDIV:
@@ -1960,6 +1964,8 @@ void DAGTypeLegalizer::WidenVectorResult(SDNode *N, unsigned ResNo) {
   case ISD::XOR:
   case ISD::FMINNUM:
   case ISD::FMAXNUM:
+  case ISD::FMINNAN:
+  case ISD::FMAXNAN:
     Res = WidenVecRes_Binary(N);
     break;
 

lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp

@@ -146,6 +146,8 @@ std::string SDNode::getOperationName(const SelectionDAG *G) const {
   case ISD::FABS:                       return "fabs";
   case ISD::FMINNUM:                    return "fminnum";
   case ISD::FMAXNUM:                    return "fmaxnum";
+  case ISD::FMINNAN:                    return "fminnan";
+  case ISD::FMAXNAN:                    return "fmaxnan";
   case ISD::FNEG:                       return "fneg";
   case ISD::FSQRT:                      return "fsqrt";
   case ISD::FSIN:                       return "fsin";

lib/CodeGen/TargetLoweringBase.cpp

@@ -814,6 +814,8 @@ void TargetLoweringBase::initActions() {
     setOperationAction(ISD::CONCAT_VECTORS, VT, Expand);
     setOperationAction(ISD::FMINNUM, VT, Expand);
     setOperationAction(ISD::FMAXNUM, VT, Expand);
+    setOperationAction(ISD::FMINNAN, VT, Expand);
+    setOperationAction(ISD::FMAXNAN, VT, Expand);
     setOperationAction(ISD::FMAD, VT, Expand);
     setOperationAction(ISD::SMIN, VT, Expand);
     setOperationAction(ISD::SMAX, VT, Expand);