#7663: consider free variables as well as parameters in inline discounts -----------------------------+---------------------------------------------- Reporter: nfrisby | Owner: Type: feature request | Status: new Priority: normal | Component: Compiler Version: 7.7 | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Blockedby: Blocking: | Related: -----------------------------+---------------------------------------------- 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". -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7663 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler