// Select constant vector splats whose value only has a consecutive sequence
// of right-most bits set (e.g. 0b00...0011...11).
//
// In addition to the requirements of selectVSplat(), this function returns
// true and sets Imm if:
// * The splat value is the same width as the elements of the vector
// * The splat value is a consecutive sequence of right-most bits.
//
// This function looks through ISD::BITCAST nodes.
// TODO: This might not be appropriate for big-endian MSA since BITCAST is
// sometimes a shuffle in big-endian mode.
bool MipsSEDAGToDAGISel::selectVSplatMaskR(SDValue N, SDValue &Imm) const {
APInt ImmValue;
EVT EltTy = N->getValueType(0).getVectorElementType();
if (N->getOpcode() == ISD::BITCAST)
N = N->getOperand(0);
if (selectVSplat(N.getNode(), ImmValue) &&
ImmValue.getBitWidth() == EltTy.getSizeInBits()) {
// Extract the run of set bits starting with bit zero, and test that the
// result is the same as the original value
if (ImmValue == (ImmValue & ~(ImmValue + 1))) {
Imm = CurDAG->getTargetConstant(ImmValue.countPopulation(), EltTy);
return true;
}
}
return false;
}
