Re: GAS: Handling option parsing for ARM co-processor extensions

[Nick Clifton <nickc at cambridge dot redhat dot com>]

Hi Richard,

> I've been thinking a bit about how we should handle the option parsing for 
> various ARM co-processor extensions.  Currently we have the highly bogus 
> situation where -marm9e is used to mean "add the Cirrus Maverick 
> instructions": it's bogus because arm9e is a real cpu variant from ARM.

I have been wondering whether it would be better to accept any
coporcessor instruction by default and disable their assembly only if 
explicitly requested on the command line.  Of course this assumes that
there are no ambiguities between different coprocessor instruction
sets.  But it is in keeping with assembler's current default of
accepting any normal ARM instruction and only restricting the assembly
of v4 or v5 instructions if a cpu is specified on the command line and
it does not support these instructions.

> One way I can think of doing this is to allow syntax along the following 
> lines
> 
> 	-marmX+ext1+...
> 
> Then the Maverick extensions could be added by writing
> 
> 	-marm9+maverick
> 

Anyway as the the command line options I believe that we should keep
the current set of options for backwards compatibility.  However your
proposal for handling different ISAs and extensions seems reasonable
to me, so I would accept it.

Cheers
        Nick