[PATCH] Fix creating illegal setcc cond codes.

[Matt Arsenault]

If GT/UGT or LT/ULT were set to expand, a comparison
with a constant would replace it with the illegal
cond code.
    
There are several more places later in this function that
will have the same basic problem.
    
Theoretically R600 should hit this problem for a test,
but for some reason it doesn't.


http://llvm-reviews.chandlerc.com/D2903

Files:
  lib/CodeGen/SelectionDAG/TargetLowering.cpp

Index: lib/CodeGen/SelectionDAG/TargetLowering.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1470,24 +1470,32 @@
     // Canonicalize GE/LE comparisons to use GT/LT comparisons.
     if (Cond == ISD::SETGE || Cond == ISD::SETUGE) {
       if (C1 == MinVal) return DAG.getConstant(1, VT);   // X >= MIN --> true
-      // X >= C0 --> X > (C0-1)
-      APInt C = C1-1;
-      if (!N1C->isOpaque() || (N1C->isOpaque() && C.getBitWidth() <= 64 &&
-                               isLegalICmpImmediate(C.getSExtValue())))
+      // X >= C0 --> X > (C0 - 1)
+      APInt C = C1 - 1;
+      ISD::CondCode NewCC = (Cond == ISD::SETGE) ? ISD::SETGT : ISD::SETUGT;
+      if ((DCI.isBeforeLegalizeOps() ||
+           isCondCodeLegal(NewCC, VT.getSimpleVT())) &&
+          (!N1C->isOpaque() || (N1C->isOpaque() && C.getBitWidth() <= 64 &&
+                                isLegalICmpImmediate(C.getSExtValue())))) {
         return DAG.getSetCC(dl, VT, N0,
                             DAG.getConstant(C, N1.getValueType()),
-                            (Cond == ISD::SETGE) ? ISD::SETGT : ISD::SETUGT);
+                            NewCC);
+      }
     }
 
     if (Cond == ISD::SETLE || Cond == ISD::SETULE) {
       if (C1 == MaxVal) return DAG.getConstant(1, VT);   // X <= MAX --> true
-      // X <= C0 --> X < (C0+1)
-      APInt C = C1+1;
-      if (!N1C->isOpaque() || (N1C->isOpaque() && C.getBitWidth() <= 64 &&
-                               isLegalICmpImmediate(C.getSExtValue())))
+      // X <= C0 --> X < (C0 + 1)
+      APInt C = C1 + 1;
+      ISD::CondCode NewCC = (Cond == ISD::SETLE) ? ISD::SETLT : ISD::SETULT;
+      if ((DCI.isBeforeLegalizeOps() ||
+           isCondCodeLegal(NewCC, VT.getSimpleVT())) &&
+          (!N1C->isOpaque() || (N1C->isOpaque() && C.getBitWidth() <= 64 &&
+                                isLegalICmpImmediate(C.getSExtValue())))) {
         return DAG.getSetCC(dl, VT, N0,
                             DAG.getConstant(C, N1.getValueType()),
-                            (Cond == ISD::SETLE) ? ISD::SETLT : ISD::SETULT);
+                            NewCC);
+      }
     }
 
     if ((Cond == ISD::SETLT || Cond == ISD::SETULT) && C1 == MinVal)
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