#9646: Strange performance bug -------------------------------------+------------------------------------- Reporter: erikd | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 (amd64) Type of failure: Runtime | Difficulty: Unknown performance bug | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by erikd): I added a a number of -ddump-* flags and reduced the `New3/GHC/InteterNatural.hs` file to contain nothing but the `timeNatural` function that we're interested in. What I found was: * Desugar stage output (file Natural.dump-ds) output is identical. * Simplifier stage ( (file Natural.dump-simpl) is different. I've added the fast and slow versions of the .dump-simpl outputs. The slow version of the code seems to have a lot more let bindings that the fast version. The fast version is more like to use case expressions. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9646#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler