Fix optimisations of SELECT_CC which assumed result is boolean

Some optimisations in DAGCombiner cause miscompilations for targets that use
TargetLowering::UndefinedBooleanContent, because they assume that the results
of a SELECT_CC node are boolean values, and can be safely ANDed, ORed and
XORed. These optimisations are only valid for targets that use
ZeroOrOneBooleanContent or ZeroOrNegativeOneBooleanContent.

This is a follow-up to D6210/r221693.

llvm-svn: 222123

1 files changed, 5 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 342a4278adf..709406a76a1 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -645,6 +645,10 @@ bool DAGCombiner::isSetCCEquivalent(SDValue N, SDValue &LHS, SDValue &RHS,
       !TLI.isConstFalseVal(N.getOperand(3).getNode()))
     return false;
 
+  if (TLI.getBooleanContents(N.getValueType()) ==
+      TargetLowering::UndefinedBooleanContent)
+    return false;
+
   LHS = N.getOperand(0);
   RHS = N.getOperand(1);
   CC  = N.getOperand(4);
@@ -3826,8 +3830,7 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
     return RXOR;
 
   // fold !(x cc y) -> (x !cc y)
-  if (N1C && N1C->getAPIntValue().isAllOnesValue() &&
-      isSetCCEquivalent(N0, LHS, RHS, CC)) {
+  if (TLI.isConstTrueVal(N1.getNode()) && isSetCCEquivalent(N0, LHS, RHS, CC)) {
     bool isInt = LHS.getValueType().isInteger();
     ISD::CondCode NotCC = ISD::getSetCCInverse(cast<CondCodeSDNode>(CC)->get(),
                                                isInt);