[ARM] How to query gas for target properties?

[Christophe Lyon]

Hi,

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.

Any trick?

Thanks