[GHC] #11196: TypeInType performance regressions

[GHC]

#11196: TypeInType performance regressions
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        Reporter:  goldfire          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.0.2
       Component:  Compiler          |              Version:  7.11
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Richard Eisenberg <eir@…>):

 In [changeset:"0706a103ae8c9c61e6bbaadd16b32da76aa5a749/ghc"
 0706a103/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="0706a103ae8c9c61e6bbaadd16b32da76aa5a749"
 Add two small optimizations. (#11196)

 - Optimize zonking * to avoid allocation.
 - Try to avoid looking at the free variables of a type in the
   pure unifier. We need look at the variables only in the case
   of a forall.

 The performance results updates included in this also include
 a regression, but the regression is not due to this patch. When
 validating previous patches, the test case failed, but I was
 unable to reproduce outside of validation, so I let it go by, thinking
 the failure was spurious. Upon closer inspection, the perf number
 was right at the line, and the wibble between a valiation environment
 and a regular test run was enough to make the difference.
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11196#comment:13>
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