Re: PATCH: extra machine-dependent passes

[DJ Delorie <dj at redhat dot com>]

> 	Alternately, isn't this just "prologue" code emitted as RTL?
> I've never done a port that used that feature, but wouldn't that
> allow the moves to be subject to the full force of the optimization
> and register allocation passes?

Effectively, except that inlined functions don't have their own
prologues.  If we did pre-alloc prologues and epilogues, the whole
"call saved" concept would dissappear, because you could just emit the
appropriate moves to/from pseudos and let gcc sort it out in the
optimizer.  That is, if the optimizer was tuned for that purpose.

If there were a way to add prologue/epilogue code before register
allocation (granted, you couldn't do the save/restores with it) that
would be useful also.  I'd much rather "return" by jumping indirect
through a pseudo register that happens to have the return address in
it, than to waste a stack slot when it's not needed.