Re: [Ada] multilib patch take two => multilib build working

[Paolo Bonzini <paolo dot bonzini at gmail dot com>]

> I had to solve one rts source issue though:
> gcc/ada/system-linux-x86_64.ads and x86.ads do hardcode the number of
> bits for a word (64 and 32 respectively), I changed them both to be
> completely the same and use GNAT defined Standard'Word_Size attribute.
>
> -   Word_Size    : constant := 64;
> -   Memory_Size  : constant := 2 ** 64;
> +   Word_Size    : constant := Standard'Word_Size;
> +   Memory_Size  : constant := 2 ** Word_Size;
>
> The same change will have to be done on other 32/64 bits Ada targets. I
> don't know if this change has adverse effect on GNAT build in some
> situations.

I think this is worthwhile on its own, before the build patch goes in.

> The patch is not complete yet of course but I'd appreciate feedback on
> wether or not I'm on the right track for 4.4 inclusion.

It looks good to me, though I'll defer to Arnaud and other adacore people.

One nit:

+GNATLIBMULTI := $(subst /,,$(MULTISUBDIR))

Please substitute / with _ instead, to avoid unlikely but possible clashes.

> guerby@gcc17:~/tmp$ gnatmake -f -g -aO/home/guerby/build-mlib7/gcc/ada/rts32 -m32 p

I guess this fixing this requires duplicating in gnatmake and gnatbind 
the logic in gcc.c that uses the info produced by genmultilib.  Search 
gcc.c for

	multilib_raw
	multilib_matches_raw
	multilib_extra
	multilib_exclusions_raw
	multilib_options
	set_multilib_dir

Maybe it makes sense to make a separate .c module for this, so that both 
the driver and gnat{make,bind} can use it.

I'm not sure how much churn is there in gcc/ada/Makefile.in.  If there 
is little, it probably makes more sense to work on a branch.  If there 
is much, it probably makes more sense to commit the partially working 
patch.  Again, I'll defer to AdaCore people on this.

Paolo