New x86 backend and my regstack changes...

[Richard Henderson]

On Fri, Jul 02, 1999 at 03:58:40PM +0200, Jan Hubicka wrote:
> > "two" != 4?  I changed it to 2 -- if this is wrong, you'll have
> > to expand on the comment.
>
> I comment this in the mincycles variable. The cycles are counted together for
> both pipes. Because both pipes stalls two cycles, results is 2*2=4

Ok.  Will you please change around the wording a bit to make that
more clear?  Perhaps using "foo += 2 + 2" in the code will doubly
reinforce the idea.  Constant arithmetic is free, after all. ;-)

> I think there is problem in this patch. In case two UV instructions are
> paired and they have different lenghths, sched will attempt to fill the
> pipe, once the shorter finishes and this may mess up the pairing algoritmus
> at all.

Yes, I wondered about this.

> Do you have any idea how to fix this?
> In my old MD_SCHED macros I was avoiding this by letting variable issue to
> refuse all instructions (by returning negative numbers). The MD_SCHED_REORDER
> had clock parameter that it was using to test whether pipe can accept new
> instructions or not.  Do you have idea for better solution?

Not really.  I think the reorder clock parameter is a pretty
reasonable solution, actually.


r~