#7450: Regression in optimisation time of functions with many patterns (6.12 to 7.4)? -------------------------------------+------------------------------------- Reporter: iustin | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by bgamari): Ahh, yes, sorry, the above repository is at this point really just a couple of scripts for characterising the problem. `-dshow-passes` points at the specializer being much of the issue. Take the case of a 1000 constructor ADT. With GHC from `master`, the compilation takes roughly 75 seconds on my laptop. Of this it seems roughly 20 seconds is spent in the specialiser, and another 20 seconds are spent in the assembler. Otherwise the rest of the time is split between various simplifier iterations, with no single iteration taking more than a couple of seconds. If I disable specialisation the compilation time drops to 52 seconds, with the largest portion of this being a 7 second simplifier iteration. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/7450#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler