Re: [GHC] #16005: Don't use a generic apply thunk for known calls

#16005: Don't use a generic apply thunk for known calls -------------------------------------+------------------------------------- Reporter: sgraf | Owner: (none) Type: task | Status: patch Priority: normal | Milestone: 8.6.3 Component: Compiler | Version: 8.6.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D5414 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Sebastian Graf ): In [changeset:"dc54c07cf18356a64cbe04aa9772c7f4c9fbc11d/ghc" dc54c07/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="dc54c07cf18356a64cbe04aa9772c7f4c9fbc11d" Don't use a generic apply thunk for known calls Summary: Currently, an AP thunk like `sat = f a b c` will not have its own entry point and info pointer and will instead reuse a generic apply thunk like `stg_ap_4_upd`. That's great from a code size perspective, but if `f` is a known function, a specialised entry point with a plain call can be much faster than figuring out the arity and doing dynamic dispatch. This looks at `f`s arity to figure out if it is a known function and if so, it will not lower it to a generic apply function. Benchmark results are encouraging: No changes to allocation, but 0.2% less counted instructions. Test Plan: Validates locally Reviewers: simonmar, osa1, simonpj, bgamari Reviewed By: simonpj Subscribers: rwbarton, carter GHC Trac Issues: #16005 Differential Revision: https://phabricator.haskell.org/D5414 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16005#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler