#12506: Compile time regression in GHC 8. -------------------------------------+------------------------------------- Reporter: deech | Owner: bgamari Type: bug | Status: new Priority: high | Milestone: 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 bgamari): I clarify that I suspect the large term counts here are really the result of the library itself making heavy use of type classes, essentially making this yet another manfestation of #8095. The high desugaring times observed in compiling tree are due to the fact that we run `simpleOptPgm` during desugaring. I didn't have a chance to look at compilation time regressed from 7.8 to 7.10 to 8.0. When I get a chance the best next step will likely to focus on the 7.10 to 8.0 regression (since it is both newer (and therefore easier to debug) as well as larger). First verify that the desugared Core is equivalent, then look at compiler profiles to see if the compiler implementation has regressed. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12506#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler