Re: [RFA] findvar.c: support LOC_BASEREG[_ARG] on Harvard archs

[Jim Blandy <jimb@zwingli.cygnus.com>]

Nick Duffek <nsd@redhat.com> writes:
> At the moment, GDB doesn't apply the necessary POINTER_TO_ADDRESS
> translation to the base register value used for finding LOC_BASEREG and
> LOC_BASEREG_ARG variables.
> 
> This patch applies that translation.  Okay to apply?

(I think David Taylor is the maintainer for findvar.c.)

The idea seems fine.  The alternative would be to have that code call
value_from_register and then value_as_pointer, as is done for
LOC_REGPARM_ADDR, rather than banging the bits yourself with
get_saved_register and extract_address.  But if you are going to bang
the bits yourself, you do need to call POINTER_TO_ADDRESS.

I think it would be a little cleaner to use `lookup_pointer_type
(type)' instead of builtin_type_void_data_ptr; that gives more
information to the target's POINTER_TO_ADDRESS function.  ANSI C says
void * can be used as a generic type for all data pointers, but GDB is
supposed to support other languages, too.

You should do similar things for LOC_INDIRECT, LOC_REF_ARG,
LOC_THREAD_LOCAL_STATIC.  I think it's not needed for
LOC_REGPARM_ADDR; value_as_pointer should do the work.




> 
> ChangeLog:
> 
> 	* findvar.c (read_var_value): Filter LOC_BASEREG and
> 	LOC_BASEREG_ARG register values through POINTER_TO_ADDRESS.
> 
> Nick Duffek
> <nsd@redhat.com>
> 
> [patch follows]
> 
> Index: gdb/findvar.c
> ===================================================================
> diff -up gdb/findvar.c gdb/findvar.c
> --- gdb/findvar.c	Mon Jul 16 12:41:21 2001
> +++ gdb/findvar.c	Mon Jul 16 12:39:40 2001
> @@ -612,9 +612,10 @@ addresses have not been bound by the dyn
>      case LOC_BASEREG_ARG:
>        {
>  	char *buf = (char*) alloca (MAX_REGISTER_RAW_SIZE);
> +	memset (buf, 0, MAX_REGISTER_RAW_SIZE);
>  	get_saved_register (buf, NULL, NULL, frame, SYMBOL_BASEREG (var),
>  			    NULL);
> -	addr = extract_address (buf, REGISTER_RAW_SIZE (SYMBOL_BASEREG (var)));
> +	addr = POINTER_TO_ADDRESS (builtin_type_void_data_ptr, buf);
>  	addr += SYMBOL_VALUE (var);
>  	break;
>        }
>