Re: [GHC] #9434: GHC.List.reverse does not fuse

Isn't this kind of thing fixed for other functions by rewriting back into the direct recursive definition if no fusion happens? On Fri, Aug 15, 2014 at 11:41 AM, David Feuer wrote:

I'm having trouble when it doesn't fuse—it ends up with duplicate bindings at the top level, because build gets inlined n times, and the result lifted out. Nothing's *wrong* with the code, except that there are multiple copies of it. On Aug 15, 2014 10:58 AM, "GHC" wrote:

...

#9434: GHC.List.reverse does not fuse

-------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.9 libraries/base | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Easy (less than 1 Unknown/Multiple | hour) Type of failure: Runtime | Blocked By: performance bug | Related Tickets: Test Case: | Blocking: | Differential Revisions: |

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Comment (by simonpj):

Great. Just check that when fusion ''doesn't'' take place, the result is good. And do a `nofib` comparison for good luck. Then submit a patch.

Thanks for doing all this work on fusion, David.

Simon

-- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9434#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

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