#13253: Exponential compilation time with RWST & ReaderT stack with `-02` -------------------------------------+------------------------------------- Reporter: phadej | Owner: dfeuer Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by mpickering): The reason why `-O2` is needed is because an extra pass of the simplifer is ran after the `-fliberate-case` pass. If you don't run this extra pass, there are lots of uninlined calls to `c<*>` left over. The core running with `-O` is here. Starting on about line 950 you can see all the nested calls to `<*>` which have been duplicated. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13253#comment:16 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler