llvm dev - Aug 2013 - [LLVMdev] Allowed types llvm.dbg.declare's "storage" parameter

Hi everyone,
I have a question about the llvm.dbg.declare instrinsic which I am using 
through DIBuilder::insertDeclare(): What kind of instructions are 
supported as the "storage" parameter? Is it only allocas? I've
also had
some success with a combination of llvm::Argument and 
DIBuilder::createComplexVariable(). That is, create a DIVariable with 
one additional OpDeref and then use DIBuilder::insertDeclare(argument, 
variable_info, basic_block). Is this kind of usage supported or do I 
always have to use allocas to make this work reliably?

Thanks in advance,
Michael