Segmentation fault 'cause of accessing function arguments

Hi all,

I am experimenting to run a pass inherited from CallGraphSCCPass. In
the pass, I iterate all functions in a SCC. In each iteration, I
access all arguments of a function in the following way:

  Function::arg_iterator PI = fun->arg_begin(), PE = fun->arg_end();
  ...

I have no trouble with building. However, I am troubled with
"segmentation fault" when I run the pass via:

  opt -load ../../build-llvm/Debug/lib/LLVMRCI.dylib -rci < a.out.bc

The error message is attached later.

So, am I wrong with accessing function arguments?
What are the possible causes?

Thanks,
Xiaolong

PS: ERROR MESSAGE

Identify an SCC. The number of function: 1
0 opt 0x0000000100426a32 PrintStackTrace(void*) + 38
1 opt 0x0000000100426e8c SignalHandler(int) + 254
2 libSystem.B.dylib 0x00007fff82a9880a _sigtramp + 26
3 LLVMRCI.dylib 0x000000010148e6ae (anonymous namespace)::RCI::ID + 16462
4 opt 0x0000000100010e89 llvm::Function::hasLazyArguments() const + 21
5 opt 0x00000001000114e3 llvm::Function::CheckLazyArguments() const + 21
6 opt 0x000000010013a421 llvm::Function::arg_begin() + 21
7 LLVMRCI.dylib 0x0000000101483e02 (anonymous namespace)::RCI::runOnSCC(llvm::CallGraphSCC&) + 184
8 opt 0x0000000100205686 (anonymous namespace)::CGPassManager::RunPassOnSCC(llvm::Pass*, llvm::CallGraphSCC&, llvm::CallGraph&, bool&, bool&) + 230
9 opt 0x0000000100205abe (anonymous namespace)::CGPassManager::RunAllPassesOnSCC(llvm::CallGraphSCC&, llvm::CallGraph&, bool&) + 488
10 opt 0x0000000100205d60 (anonymous namespace)::CGPassManager::runOnModule(llvm::Module&) + 352
11 opt 0x00000001003bc064 llvm::MPPassManager::runOnModule(llvm::Module&) + 384
12 opt 0x00000001003bd80d llvm::PassManagerImpl::run(llvm::Module&) + 111
13 opt 0x00000001003bd86f llvm::PassManager::run(llvm::Module&) + 33
14 opt 0x0000000100066d3b main + 3420
15 opt 0x000000010005c1c4 start + 52
16 opt 0x0000000000000004 start + 4294590068
Stack dump:
0. Program arguments: opt -load ../../build-llvm/Debug/lib/LLVMRCI.dylib -rci
1. Running pass 'CallGraph Pass Manager' on module '<stdin>'.
Segmentation fault

Hi all,

I am experimenting to run a pass inherited from CallGraphSCCPass. In
the pass, I iterate all functions in a SCC. In each iteration, I
access all arguments of a function in the following way:

  Function::arg_iterator PI = fun->arg_begin(), PE = fun->arg_end();
  ...

I have no trouble with building. However, I am troubled with
"segmentation fault" when I run the pass via:

  opt -load ../../build-llvm/Debug/lib/LLVMRCI.dylib -rci < a.out.bc

The error message is attached later.

So, am I wrong with accessing function arguments?
What are the possible causes?

Uh, I think the reason is the presence of a special node in the
callgraph. The special node has a null address, and is printed out as
an "Indirect CallGraph node".

Does anyone have the same issue? Again, I am very curious about the
presence of the special node in the callgraph. Any hint?

Thanks,
Xiaolong