[GHC] #8852: 7.8.1 uses a lot of memory when compiling attoparsec programs using <|>

[GHC]

#8852: 7.8.1 uses a lot of memory when compiling attoparsec programs using <|>
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              Reporter:  joelteon    |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Compiler    |          Version:  7.8.1-rc2
            Resolution:              |         Keywords:
      Operating System:              |     Architecture:  Unknown/Multiple
  Unknown/Multiple                   |       Difficulty:  Unknown
       Type of failure:  Compile-    |       Blocked By:
  time performance bug               |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"af4bc31c50c873344a2426d4be842f92edf17019/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="af4bc31c50c873344a2426d4be842f92edf17019"
 Do not duplicate call information in SpecConstr (Trac #8852)

 This long-standing and egregious bug meant that call information was
 being gratuitously copied, leading to an exponential blowup in the
 number of calls to be examined when function definitions are deeply
 nested.  That is what has been causing the blowup in SpecConstr's
 running time, not (as I had previously supposed) generating very large
 code.

 See Note [spec_usg includes rhs_usg]
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8852#comment:6>
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