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

[David Feuer]

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" <ghc-devs at haskell.org> 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:              |
> -------------------------------------+-------------------------------------
>
> 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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