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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153966 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 792de7562177242628c06968b0d6c5dfd5d58d2d..460e284c001ffbe50148cb8ca90074455af51171 100644 (file)
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/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);