Well, I’d much rather avoid creating the duplication in the first place, than to create and try to CSE it away. Others have suggested ways of doing so, following the pattern of existing RULES.
Simon
From: David Feuer [mailto:david.feuer@gmail.com]
Sent: 15 August 2014 16:41
To: ghc-devs; Simon Peyton Jones
Subject: Re: [GHC] #9434: GHC.List.reverse does not fuse
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" mailto:ghc-devs@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
