When emitting a cmp with 0 for a lowered select, mask out the high

bits of the value carying the boolean condition, as their contents
are undefined. This fixes rdar://10887484.

llvm-svn: 151310

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 8a02162665f..94ddf861067 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -2841,6 +2841,11 @@ SDValue ARMTargetLowering::LowerSELECT(SDValue Op, SelectionDAG &DAG) const {
     }
   }
 
+  // ARM's BooleanContents value is UndefinedBooleanContent. Mask out the
+  // undefined bits before doing a full-word comparison with zero.
+  Cond = DAG.getNode(ISD::AND, dl, Cond.getValueType(), Cond,
+                     DAG.getConstant(1, Cond.getValueType()));
+
   return DAG.getSelectCC(dl, Cond,
                          DAG.getConstant(0, Cond.getValueType()),
                          SelectTrue, SelectFalse, ISD::SETNE);