#2940: Do CSE after CorePrep -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: bug | Status: new Priority: lowest | Milestone: 8.0.1 Component: Compiler | Version: 6.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by osa1): Why do we need to do CSE in STG level to avoid allocation in `Either`s `fmap`? What does STG give us extra over Core? Do you mean not having type terms help? If so, how? {{{#!haskell -- RHS size: {terms: 14, types: 17, coercions: 0} Main.$fFunctorEither1_$cfmap :: forall a_aOH a1_avU b_avV. (a1_avU -> b_avV) -> Either1 a_aOH a1_avU -> Either1 a_aOH b_avV Main.$fFunctorEither1_$cfmap = \ (@ a_aOH) (@ a1_aOL) (@ b_aOM) (ds_dR3 :: a1_aOL -> b_aOM) (ds1_dR4 :: Either1 a_aOH a1_aOL) -> case ds1_dR4 of _ { Left1 x_avi -> Main.Left1 @ a_aOH @ b_aOM x_avi; Right1 y_avk -> Main.Right1 @ a_aOH @ b_aOM (ds_dR3 y_avk) } }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/2940#comment:20 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler