[GHC] #9740: D380 caused fft2 regressions

[GHC]

#9740: D380 caused fft2 regressions
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              Reporter:  dfeuer      |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:  7.10.1
             Component:  Core        |          Version:  7.8.3
  Libraries                          |         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:  Phab:D390   |
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Comment (by dfeuer):

 Replying to [comment:5 nomeata]:
 > It fixed the regression in T7257:
 > http://ghcspeed-
 nomeata.rhcloud.com/timeline/?exe=2&base=2%2B68&ben=tests%2Falloc%2FT7257&env=1&revs=50&equid=on
 > but not the one in fft2:
 > http://ghcspeed-
 nomeata.rhcloud.com/timeline/?exe=2&base=2%2B68&ben=nofib%2Fallocs%2Ffft2&env=1&revs=50&equid=on
 >
 > Do your measurements disagree, or were you just expecting this to fix
 it. Could you have a second look?

 That's most peculiar. I had not measured T7257, but I ''definitely'' saw
 an improvement in fft2, unless I read something all wrong. I'm running
 nofib now and will review the numbers again.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9740#comment:6>
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