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Re: GC special object sizes
Op di 29-04-2003, om 20:31 schreef Geoff Keating:
> Steven Bosscher <s.bosscher@student.tudelft.nl> writes:
>
> > Hi,
> >
> > With Zack's work to make TREE_CST_RTL go away, a bunch of objects are
> > now only 20 bytes instead of 24, so they go in special page now. But
> > there are many more trees of 24 bytes per tree. All tree_exp trees with
> > two operands, for example, and there are many of those: 65 in tree.def,
> > 3 more in c-common.def, and another 11 in cp/cp-tree.def.
> >
> > So why isn't there a special page for objects with a size of 24 bytes?
>
> That's a good question. A good thing to do next would be to try
> adding such a page (for trees with two operands) and see whether it
> helps or hurts performance.
I'll try something. But it would be even more interesting to figure out
a way to get rid of the complexity field in tree_exp. It is only used
for a few simple things in the C and C++ front end (and for something in
Ada, but that one is trivial to get rid of), so for most tree_exp nodes,
it's just four wasted bytes. Especially on the tree-ssa branch, where
everything is an expression, it could be very helpful to fit tree_exp
trees in 20 instead of 24 bytes.
Greetz
Steven