[GHC] #8313: Poor performance of higher-order functions with unboxing

[GHC]

#8313: Poor performance of higher-order functions with unboxing
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              Reporter:  dolio       |            Owner:
                  Type:  task        |           Status:  new
              Priority:  low         |        Milestone:  ⊥
             Component:  Compiler    |          Version:  7.6.3
            Resolution:              |         Keywords:  slow unboxed
      Operating System:              |  higher order
  Unknown/Multiple                   |     Architecture:  Unknown/Multiple
       Type of failure:  Runtime     |       Difficulty:  Easy (less than 1
  performance bug                    |  hour)
             Test Case:              |       Blocked By:  6084
              Blocking:              |  Related Tickets:
Differential Revisions:              |
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Comment (by thomie):

 After compiling the program from comment:4 with `-O2`, `manual` is now 4x
 faster.
 {{{
 $ ghc-7.8.3 -O2 T8313.hs

 $ ./T8313 manual +RTS -t
 (33333333,33333334,33333334)
 <<ghc: 54888 bytes, 1 GCs, 44312/44312 avg/max bytes residency (1
 samples), 1M in use, 0.00 INIT (0.00 elapsed), 0.65 MUT (0.67 elapsed),
 0.00 GC (0.00 elapsed) :ghc>>

 $ ./T8313 auto +RTS -t
 (33333333,33333334,33333334)
 <<ghc: 4800054576 bytes, 9192 GCs, 36364/44312 avg/max bytes residency (2
 samples), 1M in use, 0.00 INIT (0.00 elapsed), 2.21 MUT (2.21 elapsed),
 0.01 GC (0.06 elapsed) :ghc>>
 }}}

 Same results with `ghc-7.9.20141115`. Still needs that performance test.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8313#comment:5>
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