[GHC] #9163: Ptr should have a phantom role

[GHC]

#9163: Ptr should have a phantom role
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        Reporter:  simonpj           |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:  #9164
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Comment (by Joachim Breitner <mail@…>):

 In [changeset:"1946922c61df427e59f8a00572fd4dd6501abd98/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="1946922c61df427e59f8a00572fd4dd6501abd98"
 Make Ptr's parameter phantom

 and implement castPtr with coerce, which gives
     12% less allocation in reverse-complem
     7.3% less allocation in fasta.
     Binary sizes fell 0.1%.
 as reported and discussed in #9163.
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9163#comment:17>
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