[ARM] How to query gas for target properties?

[Christophe Lyon]

On 27.10.2010 15:45, Nick Clifton wrote:
> Hi Christophe,
> 
>> I'd like to write an assembly code fragment with some parts conditional
>> to some target properties.
>> For instance, on ARM, I'd like to know if the target has the Neon
>> extension, ie gas if gas was invoked with -mfpu=neon.
>>
>> I have been able to perform some other conditions (eg architecture
>> variant) through cpp, but I have found nothing enabling to know that
>> -mfpu=neon was used.
> 
> Probably the easiest method would be to write the code in C as extended 
> assembler statements and check for the presence of the __ARM_NEON__ 
> preprocessor variable.
> 


Thanks for you answer, that's what I had ended up doing.

My 1st attempts at using this macro failed because I didn't use
-mhardfp; I don't know why -mfpu=neon isn't sufficient to get
__ARM_NEON__ defined by GCC.

Thanks
Christophe.