[GHC] #8763: forM_ [1..N] does not get fused (allocates 50% more)

GHC ghc-devs at haskell.org
Wed Sep 5 08:24:59 UTC 2018


#8763: forM_ [1..N] does not get fused (allocates 50% more)
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        Reporter:  nh2               |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  7.6.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #7206             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by sgraf):

 Yes, that works and seems a lot simpler! I didn't know that `INLINE` works
 'both ways', e.g. that we can prevent inlining the body into `c` this way.
 The only minor downside is that there might be more unidentified cases
 where such an `INLINE` annotation on a lambda could be beneficial.

 I'll prepare a patch and benchmark.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8763#comment:77>
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