[LLVMdev] LowerCALL (TargetLowering)

[Evan Cheng]

Hi Nickhil,

The Legalizer expects lower'd call is the node that produce the same  
number of values as the non-lowered node. That's what the assertion  
is checking.

Take a look at the LowerCall routine for any other targets. You will  
see that in the non-void function case, it returns a MERGE_VALUES,  
i.e. all the results merged along with the chain.

Cheers,

Evan
On Nov 15, 2006, at 3:30 AM, Nikhil Patil wrote:

> 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
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev