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.

llvm-svn: 191601

2 files changed, 58 insertions, 76 deletions

diff --git a/llvm/lib/Target/R600/R600ISelLowering.cpp b/llvm/lib/Target/R600/R600ISelLowering.cpp
index c5e814ff8c6..1d2c5e1bda4 100644
--- a/llvm/lib/Target/R600/R600ISelLowering.cpp
+++ b/llvm/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: {
diff --git a/llvm/lib/Target/R600/R600Instructions.td b/llvm/lib/Target/R600/R600Instructions.td
index 24bc6b0241c..65ea04bd1e4 100644
--- a/llvm/lib/Target/R600/R600Instructions.td
+++ b/llvm/lib/Target/R600/R600Instructions.td
@@ -2324,54 +2324,6 @@ def KIL : Pat <
   (MASK_WRITE (KILLGT (f32 ZERO), $src0))
 >;
 
-// SGT Reverse args
-def : Pat <
-  (selectcc f32:$src0, f32:$src1, FP_ONE, FP_ZERO, COND_LT),
-  (SGT $src1, $src0)
->;
-
-// SGE Reverse args
-def : Pat <
-  (selectcc f32:$src0, f32:$src1, FP_ONE, FP_ZERO, COND_LE),
-  (SGE $src1, $src0)
->;
-
-// SETGT_DX10 reverse args
-def : Pat <
-  (selectcc f32:$src0, f32:$src1, -1, 0, COND_LT),
-  (SETGT_DX10 $src1, $src0)
->;
-
-// SETGE_DX10 reverse args
-def : Pat <
-  (selectcc f32:$src0, f32:$src1, -1, 0, COND_LE),
-  (SETGE_DX10 $src1, $src0)
->;
-
-// SETGT_INT reverse args
-def : Pat <
-  (selectcc i32:$src0, i32:$src1, -1, 0, SETLT),
-  (SETGT_INT $src1, $src0)
->;
-
-// SETGE_INT reverse args
-def : Pat <
-  (selectcc i32:$src0, i32:$src1, -1, 0, SETLE),
-  (SETGE_INT $src1, $src0)
->;
-
-// SETGT_UINT reverse args
-def : Pat <
-  (selectcc i32:$src0, i32:$src1, -1, 0, SETULT),
-  (SETGT_UINT $src1, $src0)
->;
-
-// SETGE_UINT reverse args
-def : Pat <
-  (selectcc i32:$src0, i32:$src1, -1, 0, SETULE),
-  (SETGE_UINT $src1, $src0)
->;
-
 // The next two patterns are special cases for handling 'true if ordered' and
 // 'true if unordered' conditionals.  The assumption here is that the behavior of
 // SETE and SNE conforms to the Direct3D 10 rules for floating point values