"Yao qi" <[EMAIL PROTECTED]> writes: > I am working on variable arguments on rs6000 backend and I have > browsed gcc/confi g/rs6000/rs6000.c for several times, I found > there are some functions relavtive to this issue, they are > setup_incoming_varargs, rs6000_build_builtin_va_list ,rs6000_va_start > ,rs6000_gimplify_va_arg . > > I could not know what they do just by source code. Could anybody > tell me the relationship among these routines? I think it is > important for me to understand the mechnism of GCC backend. Any > comments or advice are highly appreciate.
These are partially documented in gcc/doc/tm.texi. Unfortunately the documentation is not particularly good. These functions are all oriented around C stdarg.h functions. In brief, setup_incoming_varargs is called for a function which takes a variable number of arguments, and does any required preparation statements. build_builtin_va_list builds the va_list data type. va_start is called to implement the va_start macro. gimplify_va_arg is called to implement the va_arg macro. > I do not know what is the precondation if I want to do it? May I need > to know the architecture of PowerPC and ABI for it? You do indeed need to know the PowerPC ABIs to understand what these routines are doing and why. Ian
