Re: [MiNT] "local return" in gnu as

[Vincent Rivière <vincent.riviere@freesbee.fr>]

Miro Kropacek wrote:
>     But that 'mc68000' definition should be definitely same in all
>     versions I think...
>
> To save someone (Vincent ;-) work, I tested various #ifdefs. Results are:
>
> gcc 2.95 uses 'mc68000' for 68000 target and 'mc68020' for 68020+.
> gcc 4.x uses 'mc68000' everytime (!) plus 'mc680x0' for 680x0 targets 
> (x>=1).

Thanks for your contribution to keep my holidays quiet :-)

One day I had a look to that GCC defines, and I went to the conclusion 
it was quite a mess. I chose to keep the standard GCC 4.x behaviour, 
plus some other defines for compatibility with old compilers.

The standard behaviour of GCC 4.x is defined here:
http://gcc.gnu.org/viewcvs/trunk/gcc/config/m68k/m68k.h?view=markup
Search for TARGET_CPU_CPP_BUILTINS
We can see the definition of the mad behaviour you have found: mc68000 
is defined everytime, including ColdFire !
Of course, that stuff could be overridden for any target, but it seems 
insane to have different defines relative to the CPU for different targets.

For compatibility with GCC 2.95, I have added the following stuff in the 
MiNT patch:

+/* The following defines are nonstandard
+   and are kept only for compatibility
+   with older versions of GCC for MiNT.  */
+
+#undef CPP_SPEC
+#define CPP_SPEC			\
+  "%{m68000:-D__M68000__} "		\
+  "%{mc68020:-D__M68020__} "		\
+  "%{m68020:-D__M68020__} "		\
+  "%{m68030:-D__M68020__} "		\
+  "%{m68040:-D__M68020__} "		\
+  "%{m68060:-D__M68020__} "		\
+  "%{m68020-40:-D__M68020__} "		\
+  "%{m68020-60:-D__M68020__} "		\
+  "%{!m680*:%{!mc680*:-D__M68000__}} "	\
+  "%{m68881:-D__M68881__} "		\
+  "%{mshort:-D__MSHORT__}"

The first field is the GCC command line option, the second one is the 
define automatically added.

We can see you can test __M68000__ to see if we are compiling for a raw 
68000. I think it is also supported by GCC 2.95 for MiNT. However this 
define does not seem to be standard for others GCC m68k targets (but who 
cares ?).

> - removing 'local' and replacing the label with some unique identifier 
> (\@) (as gas 2.13 don't know ".altmacro" keyword but uses this mode by 
> default, it seems better to me to replace this alternate notation 
> instead of checking for 2.95 gcc in asm source...)

I have no knowledge about that, I have not hacked that in the new 
binutils patch. I don't know these macro features, but your solution 
seem sensible.

Good luck.

--
Vincent Rivière