return SDValue();
SDValue VecIn1, VecIn2;
+ bool UsesZeroVector = false;
for (unsigned i = 0; i != NumInScalars; ++i) {
+ SDValue Op = N->getOperand(i);
// Ignore undef inputs.
- if (N->getOperand(i).getOpcode() == ISD::UNDEF) continue;
+ if (Op.getOpcode() == ISD::UNDEF) continue;
+
+ // See if we can combine this build_vector into a blend with a zero vector.
+ if (!VecIn2.getNode() && ((Op.getOpcode() == ISD::Constant &&
+ cast<ConstantSDNode>(Op.getNode())->isNullValue()) ||
+ (Op.getOpcode() == ISD::ConstantFP &&
+ cast<ConstantFPSDNode>(Op.getNode())->getValueAPF().isZero()))) {
+ UsesZeroVector = true;
+ continue;
+ }
// If this input is something other than a EXTRACT_VECTOR_ELT with a
// constant index, bail out.
- if (N->getOperand(i).getOpcode() != ISD::EXTRACT_VECTOR_ELT ||
- !isa<ConstantSDNode>(N->getOperand(i).getOperand(1))) {
+ if (Op.getOpcode() != ISD::EXTRACT_VECTOR_ELT ||
+ !isa<ConstantSDNode>(Op.getOperand(1))) {
VecIn1 = VecIn2 = SDValue(nullptr, 0);
break;
}
// We allow up to two distinct input vectors.
- SDValue ExtractedFromVec = N->getOperand(i).getOperand(0);
+ SDValue ExtractedFromVec = Op.getOperand(0);
if (ExtractedFromVec == VecIn1 || ExtractedFromVec == VecIn2)
continue;
if (!VecIn1.getNode()) {
VecIn1 = ExtractedFromVec;
- } else if (!VecIn2.getNode()) {
+ } else if (!VecIn2.getNode() && !UsesZeroVector) {
VecIn2 = ExtractedFromVec;
} else {
// Too many inputs.
if (VecIn1.getNode()) {
SmallVector<int, 8> Mask;
for (unsigned i = 0; i != NumInScalars; ++i) {
- if (N->getOperand(i).getOpcode() == ISD::UNDEF) {
+ unsigned Opcode = N->getOperand(i).getOpcode();
+ if (Opcode == ISD::UNDEF) {
Mask.push_back(-1);
continue;
}
+ // Operands can also be zero.
+ if (Opcode != ISD::EXTRACT_VECTOR_ELT) {
+ assert(UsesZeroVector &&
+ (Opcode == ISD::Constant || Opcode == ISD::ConstantFP) &&
+ "Unexpected node found!");
+ Mask.push_back(NumInScalars+i);
+ continue;
+ }
+
// If extracting from the first vector, just use the index directly.
SDValue Extract = N->getOperand(i);
SDValue ExtVal = Extract.getOperand(1);
+ unsigned ExtIndex = cast<ConstantSDNode>(ExtVal)->getZExtValue();
if (Extract.getOperand(0) == VecIn1) {
- unsigned ExtIndex = cast<ConstantSDNode>(ExtVal)->getZExtValue();
if (ExtIndex > VT.getVectorNumElements())
return SDValue();
}
// Otherwise, use InIdx + VecSize
- unsigned Idx = cast<ConstantSDNode>(ExtVal)->getZExtValue();
- Mask.push_back(Idx+NumInScalars);
+ Mask.push_back(NumInScalars+ExtIndex);
}
+ // Avoid introducing illegal shuffles with zero.
+ if (UsesZeroVector && !TLI.isVectorClearMaskLegal(Mask, VT))
+ return SDValue();
+
// We can't generate a shuffle node with mismatched input and output types.
// Attempt to transform a single input vector to the correct type.
if ((VT != VecIn1.getValueType())) {
VecIn1, DAG.getUNDEF(VecIn1.getValueType()));
}
- // If VecIn2 is unused then change it to undef.
- VecIn2 = VecIn2.getNode() ? VecIn2 : DAG.getUNDEF(VT);
+ if (UsesZeroVector)
+ VecIn2 = VT.isInteger() ? DAG.getConstant(0, VT) :
+ DAG.getConstantFP(0.0, VT);
+ else
+ // If VecIn2 is unused then change it to undef.
+ VecIn2 = VecIn2.getNode() ? VecIn2 : DAG.getUNDEF(VT);
// Check that we were able to transform all incoming values to the same
// type.