[llvm-commits] Patch for review: Speeding up ScheduleDAG computations

[David Greene]

On Friday 29 February 2008 17:49, Evan Cheng wrote:
> Let's try to solve one problem at a time.
>
> 1. Roman's depth / height patch calculation is obviously goodness.
> Please commit that first.
> 2. It's probably safe to eliminate the "special tie-breaker" from top
> down sorting function.
> 3. We will need to fix up the sorting functions so strict ordering is
> preserved. We need to do so without breaking any of the existing test
> case. "return left->NodeNum < right->NodeNum;" doesn't. :-( What does
> "return false" mean? Is it favoring nodes that are inserted earlier?
> 4. It might be wise to add some debugging code so we can tell where
> things start diverge.
> 5. It would be nice to be able to rebalance the heap. Roman and David
> can fight it out when we get to that point. :-)

Sounds good.  I don't know what "fight it out" means, however.  :)
It's more than "nice" to rebalance the heap.  It's necessary if we
want to avoid traps when _GLIBCXX_DEBUG is enabled.  And we
want to do that because it finds lots of bugs.

                                                               -Dave