Add SDNodes for umin, umax, smin and smax.

This adds new SDNodes for signed/unsigned min/max. These nodes are built from
select/icmp pairs matched at SDAGBuilder stage.

This patch adds the nodes, as well as legalization support and sets them to
be "expand" for all targets.

NFC for now; this will be tested when I switch AArch64 to using these new
nodes.

llvm-svn: 237423
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 878ff3a..7d98872 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -3299,6 +3299,26 @@
     Results.push_back(Tmp1);
     break;
   }
+  case ISD::SMIN:
+  case ISD::SMAX:
+  case ISD::UMIN:
+  case ISD::UMAX: {
+    // Expand Y = MAX(A, B) -> Y = (A > B) ? A : B
+    ISD::CondCode Pred;
+    switch (Node->getOpcode()) {
+    default: llvm_unreachable("How did we get here?");
+    case ISD::SMAX: Pred = ISD::SETGT; break;
+    case ISD::SMIN: Pred = ISD::SETLT; break;
+    case ISD::UMAX: Pred = ISD::SETUGT; break;
+    case ISD::UMIN: Pred = ISD::SETULT; break;
+    }
+    Tmp1 = Node->getOperand(0);
+    Tmp2 = Node->getOperand(1);
+    Tmp1 = DAG.getSelectCC(dl, Tmp1, Tmp2, Tmp1, Tmp2, Pred);
+    Results.push_back(Tmp1);
+    break;
+  }
+    
   case ISD::FMINNUM:
     Results.push_back(ExpandFPLibCall(Node, RTLIB::FMIN_F32, RTLIB::FMIN_F64,
                                       RTLIB::FMIN_F80, RTLIB::FMIN_F128,
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
index 9018489..7a3f7bc 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
@@ -71,6 +71,10 @@
   case ISD::VSELECT:     Res = PromoteIntRes_VSELECT(N); break;
   case ISD::SELECT_CC:   Res = PromoteIntRes_SELECT_CC(N); break;
   case ISD::SETCC:       Res = PromoteIntRes_SETCC(N); break;
+  case ISD::SMIN:
+  case ISD::SMAX:
+  case ISD::UMIN:
+  case ISD::UMAX:        Res = PromoteIntRes_SimpleIntBinOp(N); break;
   case ISD::SHL:         Res = PromoteIntRes_SHL(N); break;
   case ISD::SIGN_EXTEND_INREG:
                          Res = PromoteIntRes_SIGN_EXTEND_INREG(N); break;
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp
index 11b7d70..c06227b 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp
@@ -322,6 +322,10 @@
   case ISD::ANY_EXTEND_VECTOR_INREG:
   case ISD::SIGN_EXTEND_VECTOR_INREG:
   case ISD::ZERO_EXTEND_VECTOR_INREG:
+  case ISD::SMIN:
+  case ISD::SMAX:
+  case ISD::UMIN:
+  case ISD::UMAX:
     QueryType = Node->getValueType(0);
     break;
   case ISD::FP_ROUND_INREG:
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index 9afbc5e..445e882 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -671,6 +671,10 @@
   case ISD::UREM:
   case ISD::SREM:
   case ISD::FREM:
+  case ISD::SMIN:
+  case ISD::SMAX:
+  case ISD::UMIN:
+  case ISD::UMAX:
     SplitVecRes_BinOp(N, Lo, Hi);
     break;
   case ISD::FMA:
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 832437c..1915a43 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -2257,19 +2257,47 @@
 
   SmallVector<SDValue, 4> Values(NumValues);
   SDValue Cond     = getValue(I.getOperand(0));
-  SDValue TrueVal  = getValue(I.getOperand(1));
-  SDValue FalseVal = getValue(I.getOperand(2));
+  SDValue LHSVal   = getValue(I.getOperand(1));
+  SDValue RHSVal   = getValue(I.getOperand(2));
+  auto BaseOps = {Cond};
   ISD::NodeType OpCode = Cond.getValueType().isVector() ?
     ISD::VSELECT : ISD::SELECT;
 
-  for (unsigned i = 0; i != NumValues; ++i)
+  // Min/max matching is only viable if all output VTs are the same.
+  if (std::equal(ValueVTs.begin(), ValueVTs.end(), ValueVTs.begin())) {
+    Value *LHS, *RHS;
+    SelectPatternFlavor SPF = matchSelectPattern(const_cast<User*>(&I), LHS, RHS);
+    ISD::NodeType Opc = ISD::DELETED_NODE;
+    switch (SPF) {
+    case SPF_UMAX: Opc = ISD::UMAX; break;
+    case SPF_UMIN: Opc = ISD::UMIN; break;
+    case SPF_SMAX: Opc = ISD::SMAX; break;
+    case SPF_SMIN: Opc = ISD::SMIN; break;
+    default: break;
+    }
+
+    EVT VT = ValueVTs[0];
+    LLVMContext &Ctx = *DAG.getContext();
+    while (DAG.getTargetLoweringInfo().getTypeToTransformTo(Ctx, VT) != VT)
+      VT = DAG.getTargetLoweringInfo().getTypeToTransformTo(Ctx, VT);
+
+    if (Opc != ISD::DELETED_NODE &&
+        DAG.getTargetLoweringInfo().isOperationLegalOrCustom(Opc, VT)) {
+      OpCode = Opc;
+      LHSVal = getValue(LHS);
+      RHSVal = getValue(RHS);
+      BaseOps = {};
+    }
+  }
+
+  for (unsigned i = 0; i != NumValues; ++i) {
+    SmallVector<SDValue, 3> Ops(BaseOps.begin(), BaseOps.end());
+    Ops.push_back(SDValue(LHSVal.getNode(), LHSVal.getResNo() + i));
+    Ops.push_back(SDValue(RHSVal.getNode(), RHSVal.getResNo() + i));
     Values[i] = DAG.getNode(OpCode, getCurSDLoc(),
-                            TrueVal.getNode()->getValueType(TrueVal.getResNo()+i),
-                            Cond,
-                            SDValue(TrueVal.getNode(),
-                                    TrueVal.getResNo() + i),
-                            SDValue(FalseVal.getNode(),
-                                    FalseVal.getResNo() + i));
+                            LHSVal.getNode()->getValueType(LHSVal.getResNo()+i),
+                            Ops);
+  }
 
   setValue(&I, DAG.getNode(ISD::MERGE_VALUES, getCurSDLoc(),
                            DAG.getVTList(ValueVTs), Values));
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
index 9970540..96ee899 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -193,6 +193,10 @@
   case ISD::FCOPYSIGN:                  return "fcopysign";
   case ISD::FGETSIGN:                   return "fgetsign";
   case ISD::FPOW:                       return "fpow";
+  case ISD::SMIN:                       return "smin";
+  case ISD::SMAX:                       return "smax";
+  case ISD::UMIN:                       return "umin";
+  case ISD::UMAX:                       return "umax";
 
   case ISD::FPOWI:                      return "fpowi";
   case ISD::SETCC:                      return "setcc";