Fix an issue in SimplifySetCC() specific to vector comparisons.

When folding X == X we need to check getBooleanContents() to determine if the
result is a vector of ones or a vector of negative ones. 

I tried creating a test case, but the problem seems to only be exposed on a
much older version of clang (around r144500).
rdar://10923049

llvm-svn: 153966

1 files changed, 10 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 792de756217..460e284c001 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -2432,8 +2432,16 @@ TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
 
   if (N0 == N1) {
     // We can always fold X == X for integer setcc's.
-    if (N0.getValueType().isInteger())
-      return DAG.getConstant(ISD::isTrueWhenEqual(Cond), VT);
+    if (N0.getValueType().isInteger()) {
+      switch (getBooleanContents(N0.getValueType().isVector())) {
+      default: llvm_unreachable ("Unknown boolean content.");
+      case UndefinedBooleanContent: 
+      case ZeroOrOneBooleanContent: 
+        return DAG.getConstant(ISD::isTrueWhenEqual(Cond), VT);
+      case ZeroOrNegativeOneBooleanContent:
+        return DAG.getConstant(ISD::isTrueWhenEqual(Cond) ? -1 : 0, VT);
+      }
+    }
     unsigned UOF = ISD::getUnorderedFlavor(Cond);
     if (UOF == 2)   // FP operators that are undefined on NaNs.
       return DAG.getConstant(ISD::isTrueWhenEqual(Cond), VT);