[GHC] #11568: Regression in nofib/shootout/k-nucleotide

[GHC]

#11568: Regression in nofib/shootout/k-nucleotide
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        Reporter:  simonmar          |                Owner:  dfeuer
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by dfeuer):

 I'm seeing a lot of allocation of `j2_sbYy`. It seems this is not let-no-
 escape because it's used in non-tail position. But every use site looks
 identical (modulo distinctions that at least ''shouldn't'' matter).
 Specifically, an application of `j2_sbYy` is case-matched, and the
 non-`void#` portion of the result is passed to `$j3_sbZZ`. Something must
 be preventing GHC from seeing that `j2_sbYy` should itself call
 `$j3_sbZZ`.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11568#comment:5>
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