[RS6000] Implement -mno-pltseq

[Alan Modra]

On Thu, Jan 10, 2019 at 05:09:06AM -0600, Segher Boessenkool wrote:
> On Mon, Jan 07, 2019 at 12:54:02PM +1030, Alan Modra wrote:
> > Since the last patch untangled inline PLT and TLS marker support there
> > now isn't a way of requesting the older long call sequences on a
> > compiler built with inline PLT support.  This patch adds support for
> > a new -mno-pltseq option.
> 
> Is this a useful option to have?

I figure the most use it will get is by gcc maintainers and others
investigating bug reports.  You get a bug report and can't reproduce
the failure even though compiler flags and gcc version are well
specified.  -mno-pltseq gives you a way of quickly trying out
something that might be different in their auto-host.h to yours.

> It needs documentation (in the manual), then.

OK, will do.

-- 
Alan Modra
Australia Development Lab, IBM