more m68k breakage on m68k-linux

[Bernardo Innocenti]

Roman Zippel wrote:

>> hm.. the problem I see is that the register allocator is initialised
>> with random garbage. Eg FIXED_REGISTERS is 24 elts big, thus 
>> initial_fixed_regs[] is also only 24 elts and in init_reg_sets() we
>> copy a random 25th elt into fixed_regs[] and risk segfault.
>> I am pretty sure more it results in more damage later on.
> 
> 
> I can confirm that it causes problems, after fixing FIXED_REGISTERS and 
> CALL_USED_REGISTERS I can finally bootstrap gcc again, but my tree has 
> another fix for a subtle miscompilation, which I still have to test 
> separately. reg_class and all related macros still have to be fixed though.

Well done!

I'm convinced that argptr missing from FIXED_REGISTERS was an anomaly,
but I still don't quite understand how it would affect init_reg_sets().
Could you elaborate?

-- 
  // Bernardo Innocenti - Develer S.r.l., R&D dept.
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