[Bug ada/48835] Porting GNAT to GNU/Linux/m68k

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48835

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011.07.12 17:05:07
     Ever Confirmed|0                           |1

--- Comment #22 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-07-12 17:05:07 UTC ---
> The problem is that LIBGNAT_TARGET_PAIRS is applied too late, and stage 1, 2,
> and 3 gnat1 etc are built out of a fixed set of source files that your target
> fragment in gcc/ada/gcc-interface/Makefile.in cannot influence (AFAIK).

Yes, the full run-time is built only after the compiler is built.

> You can observe this easily with a bootstrap on e.g. i686-linux.  On that
> platform system.ads should be replaced by system-linux-x86.ads, but the build
> log clearly shows stage 1, 2, 3 compiling the default gcc/ada/system.ads from
> the gcc source dir and linking that .o file into gnat1 etc.  It's not until
> some time after stage 3 that the build directory's gcc/ada/rts/ is populated
> according to LIBGNAT_TARGET_PAIRS, allowing system-linux-x86.ads to get used.

It is populated only at the beginning of the build of the full run-time.  So,
in particular, system.ads is indeed used for the compiler proper in all stages.

> But that's too late for m68k, since the type-incorrect s-memory.ad{b,s} have
> already been compiled and linked into the intermediate gnat1 etc, which then
> crash in stage 2.

OK, this is more involved than envisioned initially.  I can propose a slight
variant of my earlier proposal: still the attribute, but gigi (interface
between front-end and middle-end) would be responsible for setting it on the
malloc-like functions used in Ada.