#14211: Compiler is unable to INLINE as well as the programmer can manually -------------------------------------+------------------------------------- Reporter: harendra | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 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: -------------------------------------+------------------------------------- The test case is in this repo on the `inlining-issue` branch: https://github.com/harendra-kumar/ghc-perf/tree/inlining-issue. Performance with manually inlining a function is more than 10% faster compared to factoring out code and using INLINE pragma. `stack bench` for compiler inlined code {{{ time 46.71 ms (45.53 ms .. 47.79 ms) }}} `stack bench --flag ghc-perf:manual` for manually inlined code {{{ time 39.46 ms (38.92 ms .. 39.94 ms) }}} Here is the relevant code: {{{#!hs {-# INLINE bindWith #-} bindWith :: (forall c. AsyncT m c -> AsyncT m c -> AsyncT m c) -> AsyncT m a -> (a -> AsyncT m b) -> AsyncT m b bindWith k (AsyncT m) f = AsyncT $ \_ stp yld -> let run x = (runAsyncT x) Nothing stp yld yield a _ Nothing = run $ f a yield a _ (Just r) = run $ f a `k` (bindWith k r f) in m Nothing stp yield instance Monad m => Monad (AsyncT m) where return a = AsyncT $ \ctx _ yld -> yld a ctx Nothing #ifdef MANUAL_INLINE AsyncT m >>= f = AsyncT $ \_ stp yld -> let run x = (runAsyncT x) Nothing stp yld yield a _ Nothing = run $ f a yield a _ (Just r) = run $ f a <> (r >>= f) in m Nothing stp yield #else (>>=) = bindWith (<>) #endif }}} I have seen this many times. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14211 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler