More work to allow dag combiner to promote 16-bit ops to 32-bit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101621 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index df923c6..11dca39 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1279,8 +1279,9 @@
// variable. The low bit of the shift cannot be an input sign bit unless
// the shift amount is >= the size of the datatype, which is undefined.
if (DemandedMask == 1)
- return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL, dl, Op.getValueType(),
- Op.getOperand(0), Op.getOperand(1)));
+ return TLO.CombineTo(Op,
+ TLO.DAG.getNode(ISD::SRL, dl, Op.getValueType(),
+ Op.getOperand(0), Op.getOperand(1)));
if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
EVT VT = Op.getValueType();
@@ -1465,23 +1466,29 @@
case ISD::SRL:
// Shrink SRL by a constant if none of the high bits shifted in are
// demanded.
- if (ConstantSDNode *ShAmt = dyn_cast<ConstantSDNode>(In.getOperand(1))){
- APInt HighBits = APInt::getHighBitsSet(OperandBitWidth,
- OperandBitWidth - BitWidth);
- HighBits = HighBits.lshr(ShAmt->getZExtValue());
- HighBits.trunc(BitWidth);
-
- if (ShAmt->getZExtValue() < BitWidth && !(HighBits & NewMask)) {
- // None of the shifted in bits are needed. Add a truncate of the
- // shift input, then shift it.
- SDValue NewTrunc = TLO.DAG.getNode(ISD::TRUNCATE, dl,
- Op.getValueType(),
- In.getOperand(0));
- return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL, dl,
- Op.getValueType(),
- NewTrunc,
- In.getOperand(1)));
- }
+ if (TLO.LegalTypes() &&
+ !isTypeDesirableForOp(ISD::SRL, Op.getValueType()))
+ // Do not turn (vt1 truncate (vt2 srl)) into (vt1 srl) if vt1 is
+ // undesirable.
+ break;
+ ConstantSDNode *ShAmt = dyn_cast<ConstantSDNode>(In.getOperand(1));
+ if (!ShAmt)
+ break;
+ APInt HighBits = APInt::getHighBitsSet(OperandBitWidth,
+ OperandBitWidth - BitWidth);
+ HighBits = HighBits.lshr(ShAmt->getZExtValue());
+ HighBits.trunc(BitWidth);
+
+ if (ShAmt->getZExtValue() < BitWidth && !(HighBits & NewMask)) {
+ // None of the shifted in bits are needed. Add a truncate of the
+ // shift input, then shift it.
+ SDValue NewTrunc = TLO.DAG.getNode(ISD::TRUNCATE, dl,
+ Op.getValueType(),
+ In.getOperand(0));
+ return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL, dl,
+ Op.getValueType(),
+ NewTrunc,
+ In.getOperand(1)));
}
break;
}