bug#58434: Native compile results in error if -march and -mtune are specified

[Loreno Heer]

>> From: Andrea Corallo <akrl@sdf.org>
>> Cc: Loreno Heer <loreno.heer@bluewin.ch>, 58434@debbugs.gnu.org
>> Date: Tue, 11 Oct 2022 19:43:22 +0000
>>
>>> OK, so the compiler told you it doesn't support -march=native, so you
>>> will have to specify the exact architecture.
>>>
>>> Btw, I think you should use native-comp-driver-options for this, not
>>> native-comp-compiler-options.  Andrea, am I right?  I think GCC is
>>> "driver" and "compiler" means cc1, no?  (If I'm right, we need to fix
>>> the doc strings.)
>>
>> Hi Eli,
>>
>> native-comp-driver-options is for assembler and linker while
>> native-comp-compiler-options is for the compiler.  AFAIK 'march' affects
>> code generation so it should got to the compiler, then I believe the use
>> of native-comp-compiler-options here is correct.
> 
> OK, so I guess the only problem is that the compiler doesn't support
> "-march=native", and needs a specific architecture instead of a
> generic one.

Yes, but there might be some disadvantages of specifying the
architecture directly. For example cache sizes are not supplied.
(https://stackoverflow.com/questions/5470257/how-to-see-which-flags-march-native-will-activate?noredirect=1&lq=1)