[LLVMdev] LowerCALL (TargetLowering)

[Nikhil Patil]

Hi,

I am trying to write a LowerCALL() function for my (custom) target ISA.
All I need to do is map a CALL instruction directly onto an SDNode that
takes an equal number of arguments (very much alike intrinsics, except
that these are custom to my target.) I do not need to implement any call
sequences, stack frames etc.

I get the following assertion failure:

llc: LegalizeDAG.cpp:834: llvm::SDOperand <unnamed>::SelectionDAGLegalize::LegalizeOp(llvm::SDOperand): Assertion `Tmp3.Val->getNumValues() == Result.Val->getNumValues() && "Lowering call/formal_arguments produced unexpected # results!"' failed.

This is what my LowerCALL looks like:

SDOperand MCTargetLowering::LowerCALL(SDOperand Op, SelectionDAG &DAG) {
    SDOperand Chain     = Op.getOperand(0);
    bool isVarArg       = cast<ConstantSDNode>(Op.getOperand(2))->getValue() != 0;
    assert(!isVarArg);
    bool isTailCall     = cast<ConstantSDNode>(Op.getOperand(3))->getValue() != 0;
    SDOperand Callee    = Op.getOperand(4);
    MVT::ValueType RetVT= Op.Val->getValueType(0);
    unsigned NumOps     = (Op.getNumOperands() - 5) / 2;

    std::string Name;
    if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee))
	Name = G->getGlobal()->getName();
    else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(Callee))
	Name = S->getSymbol();

    unsigned opcode = funcname_to_opc[Name];
    assert(opcode != 0 && "Unknown function call.");

    std::vector<MVT::ValueType> Tys;
    std::vector<SDOperand> Ops;

    for (unsigned i = 0; i != NumOps; ++i) {
	SDOperand Arg = Op.getOperand(5+2*i);
	Tys.push_back(Arg.getValueType());
	Ops.push_back(Arg);
    }
    Tys.push_back(MVT::Other);
    Ops.push_back(Chain);

    Chain = DAG.getNode(opcode, Tys, &Ops[0], Ops.size());

    assert(RetVT == MVT::Other);
    return Chain;
}

Everything works fine for functions with no arguments, but otherwise I
get this assert. Can anyone point out my mistake?

Any help will be greatly appreciated,

Thanks,
Nikhil