Re: i370 port

["Ulrich Weigand" <uweigand@de.ibm.com>]

Paul Edwards wrote:

> >> /* Store in OUTPUT a string (made with alloca) containing an
> >>    assembler-name for a local static variable named NAME.
> >>    LABELNO is an integer which is different for each call.  */
> >>
> >> #ifdef TARGET_PDPMAC
> >> #define ASM_FORMAT_PRIVATE_NAME(OUTPUT, NAME, LABELNO)  \
> >> { \
> >>   (OUTPUT) = (char *) alloca (strlen ((NAME)) + 10); \
> >>   sprintf ((OUTPUT), "__%d", (LABELNO)); \
> >> }
> >
> > How does this work?  ASM_FORMAT_PRIVATE_NAME is not supposed
> > to completely ignore the NAME argument, the function may well
> > be called with the same LABELNO but different NAME strings,
> > and this must not result in conflicting symbols ...
> 
> I have compiled the entire GCC and not come up with any duplicate
> static function names, so I think the number is always unique.

Hmm, I see that in the 3.2.x code base this is indeed true.
However, in later compilers ASM_FORMAT_PRIVATE_NAME is used
for other purposes by the middle-end, not just static function
or variable names.  You definitely can get number collisions
in later compilers ...

> > At this point, you may refer to "current_function_decl" to
> > retrieve information about the function currently being output.
> > In particular, you can retrieve the original source-level name
> > associated with the routine via DECL_NAME (current_function_decl).
> 
> Thanks a lot!  I couldn't use that directly, but this:

Why not?  I'd have thought something like

  printf ("%s", IDENTIFIER_POINTER (DECL_NAME (current_function_decl)));

should work fine ...


> c:\devel\gcc\gcc\config\i370>cvs diff -r 1.37 i370.c

B.t.w. if you use the -u or -c option to cvs diff, the diffs are
a lot more readable ...

> <            mvs_function_name);
> ---
> >            fname_as_string(0));

This is a bit problematic as fname_as_string is a function defined in
the C front-end.  If you were e.g. to build the Fortran compiler, your
back-end gets linked against the Fortran front-end instead of the C
front-end, and that function simply will not be there.  Generally,
the rule is that the back-end must not directly call front-end routines.

In any case, for C source code fname_as_string does pretty much
nothing else than what I suggested above ...

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com