#14880: GHC panic: updateRole -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.2.2 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: #15076 | Differential Rev(s): Phab:D4769 Wiki Page: | -------------------------------------+------------------------------------- Comment (by tdammers): So far, a naive attempt at rewriting `tcvs_of_type` in terms of `VarSet -> VarSet` didn't produce significant performance improvements; however, I have not eliminated `unionVarSet` completely yet - the `ForAll` cases in both `tcvs_of_type` and `tcvs_of_co` are both such that naively expressing them as compositions of applications of `tcvs_of_...` and `delVarSet` does not produce correct results - I assume this is because the order in which vars are added and deleted from the set matter. So I'm now testing a replacement for `delVarSet` that is written in terms of set insertions instead of set unions; hopefully this will show a bigger difference. I should probably also benchmark the relevant set operations on their own, to verify that they do indeed expose the performance issue we're suspecting. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14880#comment:49 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler