Performance regressions in HEAD

[Simon Peyton-Jones]

Neil

| > Is this the same as you and Simon have been subsequently discussing
| (stack, heap checks), or is it another performance bug?
|
| This is an entirely separate performance bug. The heap check makes one
| of the two variants run 10% slower. This bug effects both variants,
| and gives a 150% slowdown.


I'd like to reproduce this performance regression.  Is it the same as this:

| I've got an inner loop that I think I can see is strict in the Int
| argument being passed around, but that GHC 6.6.1 isn't unboxing. In the
| following example both functions take a GHC.Base.Int, which I think
| should be an Int#.

Or is it something else?  If the latter, could you send the program whose performance decreases from 6.6 to HEAD?

Thanks

Simon