#2132: Optimise nested comparisons ---------------------------------+------------------------------------------ Reporter: simonpj | Owner: simonpj Type: bug | Status: patch Priority: low | Milestone: 7.4.1 Component: Compiler | Version: 6.8.2 Keywords: | Testcase: Blockedby: | Difficulty: Unknown Os: Unknown/Multiple | Blocking: Architecture: Unknown/Multiple | Failure: Runtime performance bug ---------------------------------+------------------------------------------
Comment(by michalt): Replying to [comment:17 basvandijk]: > Would it be hard to extend the language of RULES so that a user can perform > this optimization instead of the compiler? .. Note that this optimization goes a bit further than your example. For instance, once it knows `x ># y` and `y >=# z` it can optimize away `x <# z`. Similarly knowing `x ># 100` and `y <# 10` it can get rid of `x ==# y`. That would be probably quite difficult to do with rules (even extended). -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2132#comment:18> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler _______________________________________________ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs