On 25/10/11 13:48, Andrew Stubbs wrote:
> On 25/10/11 13:19, Richard Earnshaw wrote:
>>> 2011-10-25 Andrew Stubbs<a...@codesourcery.com>
>>>
>>> gcc/
>>> * config/arm/bpabi.h (BE8_LINK_SPEC): Recognize generic-armv7 tuning.
>>>
>>> --- a/gcc/config/arm/bpabi.h
>>> +++ b/gcc/config/arm/bpabi.h
>>> @@ -58,6 +58,7 @@
>>> #define BE8_LINK_SPEC \
>>> " %{mbig-endian:%{march=armv7-a|mcpu=cortex-a5 \
>>> |mcpu=cortex-a8|mcpu=cortex-a9|mcpu=cortex-a15 \
>>> + |mcpu=generic-armv7* \
>>> |march=armv7-m|mcpu=cortex-m3 \
>>> |march=armv7e-m|mcpu=cortex-m4 \
>>> |march=armv6-m|mcpu=cortex-m0 \
>>
>>
>> Hmm, just thought. Shouldn't this be generic-armv7-a and not generic-armv7?
>>
>> A generic armv7 implies (to me) code that will run on all variants of
>> armv7, which includes both R and M profiles.
>
> The actual option is indeed -mcpu=generic-armv7-a, but I thought I might
> as well wildcard it since this option appears to apply to all the
> profiles, and I couldn't really see why all the existing contents should
> all be listed individually (I mean, this patch proves that doing so is a
> maintenance burden, even if in this case it wouldn't have helped).
>
> Having said that, I now see it doesn't list any R-profile options. Is
> that because it doesn't apply, or because there are just missing?
>
> I can certainly make this patch A-profile specific if this is wrong.
>
> Andrew
>
The difficulty on R profile is that although BE-32 mode is obsolete,
there is a config bit that can be set to make the CPU byte-swap the
instruction stream to make it behave largely like it is running in BE-32
mode.
I think really we should be pushing the R-profile code towards having
BE-8 as the default; but to do that we really need a compiler option
that can override this behaviour (probably -mbe-[8|32]). Once we have
that option, we can fix the compiler to prefer BE-8 as there is then a
way to get back the legacy behaviour.
R.
