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Fix optimization of ISD::TRUNCATE on vector operands. Based on a patch

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by Micah Villmow for PR6335.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97461 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-03-01 17:59:21 +00:00
parent ce931c65ee
commit 042919c0c5
1 changed files with 5 additions and 4 deletions
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9
lib/CodeGen/SelectionDAG/TargetLowering.cpp
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@ -1441,8 +1441,10 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
case ISD::TRUNCATE: {
// Simplify the input, using demanded bit information, and compute the known
// zero/one bits live out.
unsigned OperandBitWidth =
Op.getOperand(0).getValueType().getScalarType().getSizeInBits();
APInt TruncMask = NewMask;
TruncMask.zext(Op.getOperand(0).getValueSizeInBits());
TruncMask.zext(OperandBitWidth);
if (SimplifyDemandedBits(Op.getOperand(0), TruncMask,
KnownZero, KnownOne, TLO, Depth+1))
return true;
@ -1453,15 +1455,14 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
// on the known demanded bits.
if (Op.getOperand(0).getNode()->hasOneUse()) {
SDValue In = Op.getOperand(0);
unsigned InBitWidth = In.getValueSizeInBits();
switch (In.getOpcode()) {
default: break;
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(InBitWidth,
InBitWidth - BitWidth);
APInt HighBits = APInt::getHighBitsSet(OperandBitWidth,
OperandBitWidth - BitWidth);
HighBits = HighBits.lshr(ShAmt->getZExtValue());
HighBits.trunc(BitWidth);