Merging r258611:

[oota-llvm.git] / lib / Target / AArch64 / AArch64ISelDAGToDAG.cpp

diff --git a/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp b/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
index 4311198403fa551d491002701d3e77a1ea4efd07..6c868880bcac4f760719ce3da759f3f62d5b7aae 100644 (file)
--- a/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
+++ b/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
@@ -1974,7 +1974,8 @@ static bool isBitfieldPositioningOp(SelectionDAG *CurDAG, SDValue Op,
 // f = Opc Opd0, Opd1, LSB, MSB ; where Opc is a BFM, LSB = imm, and MSB = imm2
 static bool isBitfieldInsertOpFromOr(SDNode *N, unsigned &Opc, SDValue &Dst,
                                      SDValue &Src, unsigned &ImmR,
-                                     unsigned &ImmS, SelectionDAG *CurDAG) {
+                                     unsigned &ImmS, const APInt &UsefulBits,
+                                     SelectionDAG *CurDAG) {
   assert(N->getOpcode() == ISD::OR && "Expect a OR operation");
 
   // Set Opc
@@ -1988,8 +1989,6 @@ static bool isBitfieldInsertOpFromOr(SDNode *N, unsigned &Opc, SDValue &Dst,
 
   // Because of simplify-demanded-bits in DAGCombine, involved masks may not
   // have the expected shape. Try to undo that.
-  APInt UsefulBits;
-  getUsefulBits(SDValue(N, 0), UsefulBits);
 
   unsigned NumberOfIgnoredLowBits = UsefulBits.countTrailingZeros();
   unsigned NumberOfIgnoredHighBits = UsefulBits.countLeadingZeros();
@@ -2083,11 +2082,18 @@ SDNode *AArch64DAGToDAGISel::SelectBitfieldInsertOp(SDNode *N) {
   unsigned Opc;
   unsigned LSB, MSB;
   SDValue Opd0, Opd1;
+  EVT VT = N->getValueType(0);
+  APInt NUsefulBits;
+  getUsefulBits(SDValue(N, 0), NUsefulBits);
+
+  // If all bits are not useful, just return UNDEF.
+  if (!NUsefulBits)
+    return CurDAG->SelectNodeTo(N, TargetOpcode::IMPLICIT_DEF, VT);
 
-  if (!isBitfieldInsertOpFromOr(N, Opc, Opd0, Opd1, LSB, MSB, CurDAG))
+  if (!isBitfieldInsertOpFromOr(N, Opc, Opd0, Opd1, LSB, MSB, NUsefulBits,
+                                CurDAG))
     return nullptr;
 
-  EVT VT = N->getValueType(0);
   SDLoc dl(N);
   SDValue Ops[] = { Opd0,
                     Opd1,