[LLVMdev] Adding function call in LLVM IR using IRBuilder causes assertion error

[Jeffrey Yasskin]

CreateAlloca(Type) returns an object of type Type*, the memory that
can hold an object of type Type. You probably don't want to be
creating allocas just before calling the function since 1) if that
call winds up in a loop they'll grow your stack frame without bound,
and 2) the memory they point to is initially uninitialized. Where did
the tutorial tell you to do that?

In general, when I hit one of those assertions, I gdb to it, use "p
f->dump()" to see the types of the function's arguments, and use "p
Params[i]->dump()" to see the parameter with the bad type.

On Wed, Nov 11, 2009 at 7:22 AM, Marc Claesen <claesenm at gmail.com> wrote:
> Hi,
>
> I'm trying to add function calls in the LLVM IR using the IRBuilder
> class. I've read both tutorials about functions but I still get
> assertion errors. I allocate memory for all function arguments and pass
> them as explained in the tutorial.
>
> My code is (this function is supposed to add a call to f in bb at pos):
> void addCallSite(Function *f, BasicBlock *bb, BasicBlock::iterator pos) {
>  std::vector<Value*> args;
>  IRBuilder<> builder(bb,pos);
>  for(Function::arg_iterator argit =
> f->arg_begin();argit!=f->arg_end();argit++){
>      AllocaInst* allocInst = builder.CreateAlloca(argit->getType());
>      args.push_back(allocInst);
>  }
>  builder.CreateCall(f,args.begin(),args.end());
> }
>
> This seems to work for functions without parameters (eg. int foo()), but
> once a function has a parameter I get the following assertion error:
> <llvmpath>/lib/VMCore/Instructions.cpp:297: void
> llvm::CallInst::init(llvm::Value*, llvm::Value* const*, unsigned int):
> Assertion `(i >= FTy->getNumParams() || FTy->getParamType(i) ==
> Params[i]->getType()) && "Calling a function with a bad signature!"' failed.
>
> I've checked everything I can think of and it all seems correct to me
> ... Any help would be greatly appreciated!
>
> Thanks in advance,
>
> Marc Claesen
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