#13745: Investigate compile-time regressions in regex-tdfa-1.2.2 -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: high | Milestone: 8.2.1 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 RyanGlScott): I've attached a minimized version of `regex-tdfa-1.2.2` with no external dependencies. Moreover, the slowdown in GHC 8.2 seems primarily concentrated at the `*Engine` files, so I only included what was necessary to support one of them. Here are the times that I got: {{{ $ time /opt/ghc/8.0.2/bin/ghc -O2 -fforce-recomp TextRegexTDFANewDFAEngine_FA.hs real 0m10.139s user 0m9.996s sys 0m0.116s $ time /opt/ghc/8.2.1/bin/ghc -O2 -fforce-recomp TextRegexTDFANewDFAEngine_FA.hs real 0m18.072s user 0m17.912s sys 0m0.156s }}} The `TextRegexTDFANewDFAEngine_FA.hs` file in particular is what is contributing to the difference in time, as all other modules take about the same time to compile on 8.0.2 and 8.2.1-rc2. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13745#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler