SelectionDAG: Try to expand all condition codes using getCCSwappedOperands()

This is useful for targets like R600, which only support GT, GE, NE, and EQ
condition codes as it removes the need to handle unsupported condition
codes in target specific code.

There are no tests with this commit, but R600 has been updated to take
advantage of this new feature, so its existing selectcc tests are now
testing the swapped operands path.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191601 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 58 insertions, 28 deletions

diff --git a/lib/Target/R600/R600ISelLowering.cpp b/lib/Target/R600/R600ISelLowering.cpp
index c5e814ff8c..1d2c5e1bda 100644
--- a/lib/Target/R600/R600ISelLowering.cpp
+++ b/lib/Target/R600/R600ISelLowering.cpp
@@ -38,6 +38,18 @@ R600TargetLowering::R600TargetLowering(TargetMachine &TM) :
 
   computeRegisterProperties();
 
+  setCondCodeAction(ISD::SETLE,  MVT::f32, Expand);
+  setCondCodeAction(ISD::SETLT,  MVT::f32, Expand);
+  setCondCodeAction(ISD::SETOLT, MVT::f32, Expand);
+  setCondCodeAction(ISD::SETOLE, MVT::f32, Expand);
+  setCondCodeAction(ISD::SETULT, MVT::f32, Expand);
+  setCondCodeAction(ISD::SETULE, MVT::f32, Expand);
+
+  setCondCodeAction(ISD::SETLE, MVT::i32, Expand);
+  setCondCodeAction(ISD::SETLT, MVT::i32, Expand);
+  setCondCodeAction(ISD::SETULE, MVT::i32, Expand);
+  setCondCodeAction(ISD::SETULT, MVT::i32, Expand);
+
   setOperationAction(ISD::FCOS, MVT::f32, Custom);
   setOperationAction(ISD::FSIN, MVT::f32, Custom);
 
@@ -841,16 +853,19 @@ SDValue R600TargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const
   //
   // SET* can match the following patterns:
   //
-  // select_cc f32, f32, -1,  0, cc_any
-  // select_cc f32, f32, 1.0f, 0.0f, cc_any
-  // select_cc i32, i32, -1,  0, cc_any
+  // select_cc f32, f32, -1,  0, cc_supported
+  // select_cc f32, f32, 1.0f, 0.0f, cc_supported
+  // select_cc i32, i32, -1,  0, cc_supported
   //
 
   // Move hardware True/False values to the correct operand.
-  if (isHWTrueValue(False) && isHWFalseValue(True)) {
-    ISD::CondCode CCOpcode = cast<CondCodeSDNode>(CC)->get();
+  ISD::CondCode CCOpcode = cast<CondCodeSDNode>(CC)->get();
+  ISD::CondCode InverseCC =
+     ISD::getSetCCInverse(CCOpcode, CompareVT == MVT::i32);
+  if (isHWTrueValue(False) && isHWFalseValue(True) &&
+      isCondCodeLegal(InverseCC, CompareVT.getSimpleVT())) {
     std::swap(False, True);
-    CC = DAG.getCondCode(ISD::getSetCCInverse(CCOpcode, CompareVT == MVT::i32));
+    CC = DAG.getCondCode(InverseCC);
   }
 
   if (isHWTrueValue(True) && isHWFalseValue(False) &&
@@ -863,14 +878,34 @@ SDValue R600TargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const
   //
   // CND* can match the following patterns:
   //
-  // select_cc f32, 0.0, f32, f32, cc_any
-  // select_cc f32, 0.0, i32, i32, cc_any
-  // select_cc i32, 0,   f32, f32, cc_any
-  // select_cc i32, 0,   i32, i32, cc_any
+  // select_cc f32, 0.0, f32, f32, cc_supported
+  // select_cc f32, 0.0, i32, i32, cc_supported
+  // select_cc i32, 0,   f32, f32, cc_supported
+  // select_cc i32, 0,   i32, i32, cc_supported
   //
-  if (isZero(LHS) || isZero(RHS)) {
-    SDValue Cond = (isZero(LHS) ? RHS : LHS);
-    SDValue Zero = (isZero(LHS) ? LHS : RHS);
+
+  // Try to move the zero value to the RHS
+  if (isZero(LHS)) {
+    ISD::CondCode CCOpcode = cast<CondCodeSDNode>(CC)->get();
+    // Try swapping the operands
+    ISD::CondCode CCSwapped = ISD::getSetCCSwappedOperands(CCOpcode);
+    if (isCondCodeLegal(CCSwapped, CompareVT.getSimpleVT())) {
+      std::swap(LHS, RHS);
+      CC = DAG.getCondCode(CCSwapped);
+    } else {
+      // Try inverting the conditon and then swapping the operands
+      ISD::CondCode CCInv = ISD::getSetCCInverse(CCOpcode, CompareVT.isInteger());
+      CCSwapped = ISD::getSetCCSwappedOperands(CCInv);
+      if (isCondCodeLegal(CCSwapped, CompareVT.getSimpleVT())) {
+        std::swap(True, False);
+        std::swap(LHS, RHS);
+        CC = DAG.getCondCode(CCSwapped);
+      }
+    }
+  }
+  if (isZero(RHS)) {
+    SDValue Cond = LHS;
+    SDValue Zero = RHS;
     ISD::CondCode CCOpcode = cast<CondCodeSDNode>(CC)->get();
     if (CompareVT != VT) {
       // Bitcast True / False to the correct types.  This will end up being
@@ -880,20 +915,11 @@ SDValue R600TargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const
       True = DAG.getNode(ISD::BITCAST, DL, CompareVT, True);
       False = DAG.getNode(ISD::BITCAST, DL, CompareVT, False);
     }
-    if (isZero(LHS)) {
-      CCOpcode = ISD::getSetCCSwappedOperands(CCOpcode);
-    }
 
     switch (CCOpcode) {
     case ISD::SETONE:
     case ISD::SETUNE:
     case ISD::SETNE:
-    case ISD::SETULE:
-    case ISD::SETULT:
-    case ISD::SETOLE:
-    case ISD::SETOLT:
-    case ISD::SETLE:
-    case ISD::SETLT:
       CCOpcode = ISD::getSetCCInverse(CCOpcode, CompareVT == MVT::i32);
       Temp = True;
       True = False;
@@ -1567,14 +1593,18 @@ SDValue R600TargetLowering::PerformDAGCombine(SDNode *N,
       ISD::CondCode LHSCC = cast<CondCodeSDNode>(LHS.getOperand(4))->get();
       LHSCC = ISD::getSetCCInverse(LHSCC,
                                   LHS.getOperand(0).getValueType().isInteger());
-      return DAG.getSelectCC(SDLoc(N),
-                             LHS.getOperand(0),
-                             LHS.getOperand(1),
-                             LHS.getOperand(2),
-                             LHS.getOperand(3),
-                             LHSCC);
+      if (DCI.isBeforeLegalizeOps() ||
+          isCondCodeLegal(LHSCC, LHS.getOperand(0).getSimpleValueType()))
+        return DAG.getSelectCC(SDLoc(N),
+                               LHS.getOperand(0),
+                               LHS.getOperand(1),
+                               LHS.getOperand(2),
+                               LHS.getOperand(3),
+                               LHSCC);
+      break;
     }
     }
+    return SDValue();
   }
 
   case AMDGPUISD::EXPORT: {