make sh-1 support in gcc obsolete?
Joern Rennecke
joern.rennecke@superh.com
Wed May 29 06:29:00 GMT 2002
>> 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).
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