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RE: type argument in FUNCTION_ARG macro
Ok thanks, I'll keep on with plan B (INIT_CUMULATIVE_LIBCALL_ARGS with special libcall handling)
De?: Ian Lance Taylor [mailto:email@example.com]
Envoyé?: vendredi 4 mai 2012 15:58
À?: BELBACHIR Selim
Objet?: Re: type argument in FUNCTION_ARG macro
BELBACHIR Selim <firstname.lastname@example.org> writes:
> I'm working on an architecture where the calling convention depends on the type of the parameter (i.e. pointers are passed into $C regs and non-pointers are passed into $R regs). I've implemented this difference by using the POINTER_TYPE_P() macro on the 'type' argument of the FUNCTION_ARG macro.
> I'm having a problem with this approach with calls to libgcc function
> like _Unwind_SjLj_Register(struct foo * ). As this function is invoked as a library function, the 'type' argument to the FUNCTION_ARG() macro is NULL. Thus, the pointer parameter is not passed as pointer but the function body expects a pointer.
> Any ideas on how to get around this problem?
If possible, avoid using SJLJ exceptions. DWARF exceptions are better.
I see three ways to go.
Change the middle-end to avoid using emit_library_call when calling _Unwind_SjLj_Register. There is no particular reason for making this a special library call. But this is probably a bit painful to implement.
Define INIT_CUMULATIVE_LIBCALL_ARGS for your target, and check the function. If it's _Unwind_SjLj_Register, apply special handling. This option is nice because you only have to change your backend.
Change the implementation of _Unwind_SjLj_Register to take a parameter of type uintptr_t, and cast it to struct SjLj_Function_Context *.