cache misses in gcc 3.3

[law@redhat.com]

In message <20030210173107.GA24303@tornado.toronto.redhat.com>, Diego Novillo w
rites:
 >On Mon, 10 Feb 2003, Andi Kleen wrote:
 >
 >> GCSE doesn't seem to be that slow, just CSE is.
 >> 
 >Finger trouble.  I didn't mean to insert that extra 'G'.  Force
 >of habit.
Well, it's worth mentioning that there are aspects of GCSE which I expect
to be largely subsumed by the SSA work as well.

For example, null pointer check removal can be completely subsumed by
the tree-ssa code.  That code is a known memory and cpu hog (that's why
Mark brought in the blocking code in the past).  What will be *very*
interesting will be to see what value gcse/lcm has once we've got the
tree-ssa optimizer going.

While I expect there'll always be some constants or expressions that
only gcse will catch (specifically those created by the lowering process),
I expect that we can drop the memory tracking bits from gcse and maybe
simplify other stuff (like constant/copy propagation).


jeff