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Re: make sh-1 support in gcc obsolete?


>> If we want to continue to support SH-1, we should have the compiler pass an
>> option to the assembler to limit the acceptable instruction set to the one
>> being used, so that regressions are caught.  Otherwise, SH-2 instruction are
>> just too likely to sneak back in.

Joel Sherrill wrote:
> OK. I went for ASM_CPU_SPEC in sh.h but this was the closest thing I
> could find.
> 
> #define ASM_SPEC  "%{ml:-little} %{mrelax:-relax}"
> 
> Is this the place that needs to be modified so -m1, etc get translated?

Yes - for the time being.
	
> I don't see the option on my sh- assembler that matches.
> 
> SH options:
> -little                 generate little endian code
> -big                    generate big endian code
> -relax                  alter jump instructions for long displacements
> -small                  align sections to 4 byte boundaries, not 16
> -dsp                    enable sh-dsp insns, and disable sh3e / sh4
> insns.

There isn't any.  It would have to be added.
How about cpu, e.g.: cpu=sh1 ?
	
> -dsp appears to be the closest option but it allows sh2 instructions.

Yes, but the machinery is all there.  If you set target_arch to arch_sh1
in md_begin, gas will only accept SH1 instructions.  If you set it to
arch_sh1_up,
it will accept code for any processor, including sh4 and sh3-dsp (but not a mix
of floating point and dsp instructions).
	
-- 
--------------------------
SuperH
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