#10124: Simple case analyses generate too many branches -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #6135, | Differential Revisions: #9661,#10137 | -------------------------------------+------------------------------------- Comment (by nomeata): I think these numbers might be wrong due to mistakes on my side. Now I get {{{ 1 loops, best of 10: 27.1 sec per loop 1 loops, best of 10: 41.5 sec per loop }}} so the branchless code is actually much more expensive. (This is testing `length $ filter myIsSpace $ concatMap (const ['\001'..'z']) $ [0..50000000::Int]` which produces better code than `replicate`.) Also in light of Sven Pannes’s valuable comments (https://mail.haskell.org/pipermail/ghc-devs/2015-April/008858.html) I’m inclined to abandon this idea. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10124#comment:20 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler