[GHC] #7847: Maintain per-generation lists of weak pointers

[GHC]

#7847: Maintain per-generation lists of weak pointers
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    Reporter:  akio              |       Owner:                              
        Type:  feature request   |      Status:  patch                       
    Priority:  normal            |   Milestone:                              
   Component:  Runtime System    |     Version:  7.7                         
    Keywords:                    |          Os:  Unknown/Multiple            
Architecture:  Unknown/Multiple  |     Failure:  Compile-time performance bug
  Difficulty:  Unknown           |    Testcase:                              
   Blockedby:                    |    Blocking:                              
     Related:                    |  
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Changes (by akio):

  * status:  infoneeded => patch


Comment:

 I cleaned up the code and removed `weak_ptr_list_tail` and
 `dead_weak_ptr_list_tail`. Rebased and validated. This change caused one
 of the test output to change, so I also attached a patch to the test
 suite.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7847#comment:11>
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