#13536: Program which terminates instantly in GHC 8.0.2 runs for minutes with 8.2.1 -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.2.1 Component: Compiler | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Yes. It's really {{{ case e of w { p1 -> w; ...; pn -> w } ===> e }}} (Core has a more general version involving strictness on `x`.) I don't know how much it happens in practice. It would not be hard to include this in `StgCse` though. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13536#comment:16 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler