Better estimations of costs in outof-ssa

[Andrew MacLeod]

On Fri, 2005-07-29 at 17:21, Jan Hubicka wrote:
> > On Thu, Jul 28, 2005 at 09:22:27AM +0200, Jan Hubicka wrote:
> > > ! 		{
> > > ! 		  /* Base costs on BB frequencies bounded by 1.  */
> > > ! 		  int cost = EDGE_FREQUENCY (PHI_ARG_EDGE (phi, x));
> > > ! 
> > > ! 		  if (!cost)
> > > ! 		    cost = 1;
> > > ! 		  if (optimize_size || !maybe_hot_bb_p (bb))
> > > ! 		    cost = 1;
> > > ! 		  /* Inserting copy on critical edge is more costy
> > > ! 		     than inserting it elsewhere.  */
> > > ! 		  if (EDGE_CRITICAL_P (PHI_ARG_EDGE (phi, x)))
> > > ! 		    cost *= 2;
> > > ! 		  add_coalesce (cl, p, p2, cost);
> > 
> > Please factor out this thrice duplicated code.
> 
> OK, this moves the cost computation into add_coalesce itself.
> It seems dificult to merge this somewhat further with other places we
> compute simlar costs (such as reg-alloc) because of stubble differences
> in between these..

Ick.  Why should add_coalesce have to know or care about hot blocks and
critical edges?  It is intended to just take a simple cost.   

I would prefer to see the costs calculated by another small function or
macro.   If I want to use add_coalesce for another purpose now (and
coalesce lists are generic), I will have to write another add_coalesce,
or create dummy values for those parameters I don't care about, and have
to figure out what the correct dummy values are.

Andrew