The nvptx port [7/11+] Inform the port about call arguments

[Bernd Schmidt]

On 10/21/2014 11:53 PM, Jeff Law wrote:

> So, in the end I'm torn.  I don't like adding new hooks when they're not
> needed, but I have some reservations about relying on the order of stuff
> in CALL_INSN_FUNCTION_USAGE and I worry a bit that you might end up with
> stuff other than arguments on that list -- the PA port could filter on
> the hard registers used for passing arguments, so other stuff appearing
> isn't a big deal.

This is another worry. Also, at the moment we don't actually add the 
pseudos to CALL_INSN_FUNCTION_USAGE (that's patch 6/11), we use the regs 
saved by the call_args hook to make proper USEs in a PARALLEL. I'm not 
convinced the rest of the compiler would be too happy to see pseudos there.

So, in all I'd say it's probably possible to do it that way, but it 
feels a lot iffier than I'd be happy with. I for one didn't know about 
the PA requirement, so I could easily have broken it unknowingly if I'd 
made some random change modifying call expansion.


Bernd