[PATCH] Disable compact casesi patterns for arcv2

[Claudiu Zissulescu]

> I wonder if we should warn for the TARGET_V2 case?  Currently if the
> option is supplied on an ARCv2 (-mcompact-casesi) then the option is
> silently ignored.  This might confuse some users.

Good idea, I will update the docs accordingly.

> 
> In the non TARGET_V2 case I notice that the option is _always_
> enabled, with no option of disabling the option.  If we add a check of
> global_options_set then we can make this smarter, default on, but can
> still be tuned off if a user ever wants to.  The alternative would be
> to entirely remove the TARGET_COMPACT_CASESI flag altogether?

I would prefer to remove compact_casesi feature entirely as it is a trouble maker rather than a helper. 

> 
> While I was thinking about this I wrote the code below, it probably
> needs polishing, but gives an idea of what I have in mind.  What do
> you think?

It looks good, I will add the docs update. Coming back to u asap.
Claudiu