#9798: Frustrating behaviour of the INLINE pragma -------------------------------------+------------------------------------- Reporter: mojojojo | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: MacOS X Architecture: x86_64 (amd64) | Type of failure: Runtime Difficulty: Unknown | performance bug Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- So I have a function "a", which uses another function "b" from another module. * Step 1. I benchmark its performance and get 250ns. * Step 2. I go and put the "INLINE" pragma on the function "b", run the benchmark again and get 500ns. That is twice as long. * Step 3. I go and add an explicit invocation of the [http://hackage.haskell.org/package/base-4.7.0.1/docs/GHC- Exts.html#v:inline inline] function over function "b" in function "a" and finally get the desired optimization: 208ns. You can reproduce the issue by executing {{{cabal bench decoding --benchmark-options=numeric}}} after cloning the trees of the following commits: * [https://github.com/nikita-volkov/postgresql- binary/commit/31e08b4f6887445c28118d25f9da808e7ca9fc86 Step 1] * [https://github.com/nikita-volkov/postgresql- binary/commit/8f29b8daebc3161dc0fa35fbd70d3f3305370a4e Step 2] * [https://github.com/nikita-volkov/postgresql- binary/commit/3d3e4378bcd8ea85cda868d6a4bf07a76a9cad2c Step 3] -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9798 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler