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Jan 15, 2014 12:27:58 PM (
* What became of Simon’s better-ho-cardinality branch? See [./better-ho-cardinality].
* Try vtunes to get better numbers.
==== Use Converges in exprOkForSpeculation ====
The flag `Converges` has just about the same meaning as `exprOkForSpeculation`, so we can improve the latter by using the former.
Effect on nofib is minuscule: `-0.1%` allocations for `fluid`, no other change in allocations.
In `fluid` there are thunks calling `read_n_val`, which has a definition of `(.. ,...)`. CPR turns that in to (# ..., ... #). So currently, we are allocating a thunk for the worker of `read_n_val`, which when called will allocate a `(..,..)`, which later is taken apart by yet another two thunks `fst ..` and `snd ..`. After using the `Converges` flag, we immediately call `$wread_n_val`, which returns quickly after allocating two thunks. This also saves the thunks for `fst ..` and `snd ..`.
But: This already happens not in CorePrep, but in `Float out`. It seems that the call form `lvlCase` makes the difference, as the levels differ and later evaluation is moved out of a `(#..,..#)` construct.
* Get static numbers: How many things are ok for speculation before, how many afterwards