Re: [RFC/RFA] gdb extension for Harvard architectures

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

Michael Snyder <msnyder@redhat.com> writes:
> > Instead of using bits, what if we added a new `const char *' field to
> > `struct type'?  Its value would be a string indicating the name of the
> > space qualifier applied to the type, or zero indicating the default.
> 
> Just to make sure I understand you, the string you propose is
> something like "code", not the fully qualified type eg. "code int *";
> right?

Yes.

> > The set of permitted space names would be determined by the
> > architecture, following some basic conventions (like `data' and
> > `code').  There would be a gdbarch method like this:
> > 
> > - int gdbarch_valid_addr_space_name_p (struct gdbarch *A, const char *NAME);
> >   Return non-zero if NAME is a valid name of an address space
> >   for architecture A.
> > 
> > The parser would recognize `@ IDENTIFIER' as a space qualifier, call
> > gdbarch_valid_addr_space_name_p to check it, and drop the value into
> > the type it creates if so.
> > 
> > The type printer would simply printf ("@%s", type->space); when printing.
> > 
> > There would be a core function:
> > 
> > - const char *type_default_addr_space (struct type *T);
> >   Return "code" if T is a pointer to function or method; return "data"
> >   otherwise.
> > 
> > The POINTER_TO_ADDRESS and ADDRESS_TO_POINTER methods, which are the
> > ones who actually *use* this info, receive the type object already,
> > and can check the space as appropriate.
> 
> OK, the reason I didn't do it like that (and I did consider it) is
>   a) it required a new field in the type struct, and
>   b) a strcmp takes longer than an integer (flag) test.
> 
> However, I agree that this might be a reasonable extension, 
> especially once we get ready to let the target architecture
> define its own address spaces.  I wanted to get a relatively
> simple initial implementation approved before I went overboard
> on complexity (it's complex enough as it is).

Okay.