consider free variables as well as parameters in inline discounts
|Reported by:||nfrisby||Owned by:|
|Type of failure:||None/Unknown||Test Case:|
|Related Tickets:||Differential Revisions:|
The inliner assigns discount values for scrutinized parameters but not for scrutinized free variables.
Experimenting with an aggressive lambda float at the end of the core2core pipeline identified a situation where (effectively) assigning discounts to free variables gives a performance boost. (The free variables become parameters during the float and hence are then assigned discounts.)
For spectral/boyer2, doing the late lambda float and then simplifying results in a -7% improvement in allocation. Without the simplifications, the late lambda float alone does not change allocation: thus the lion's share of the -7% could be attained simply by assigning discounts to scrutinized free variables.
For reference: the function in boyer2 that gets inlined is a join point that arises near the top of the worker for "Rewritefns.onewayunify".