[GHC] #13193: Integer (gmp) performance regression?

[GHC]

#13193: Integer (gmp) performance regression?
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        Reporter:  j.waldmann        |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:  newcomer
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Runtime           |  (amd64)
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by rwbarton):

 Aha! the source code I was looking at changed since the version of the
 object code I was examining. So disregard the second point above.

 Phab:D2278 is new in HEAD; the old implementation was basically `x - y = x
 + (-y)`, which has to allocate `-y`. I think the code could still be made
 somewhat shorter/better, but that would be a relatively minor improvement.

 j.waldmann, could you test with a perf build of HEAD?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13193#comment:7>
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