[GHC] #8638: Optimize by demoting "denormalized" Integers (i.e. J# -> S#)

[GHC]

#8638: Optimize by demoting "denormalized" Integers (i.e. J# -> S#)
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        Reporter:  hvr                      |            Owner:  hvr
            Type:  feature request          |           Status:  patch
        Priority:  normal                   |        Milestone:  7.8.1
       Component:  libraries (other)        |          Version:  7.7
      Resolution:                           |         Keywords:  integer-
Operating System:  Unknown/Multiple         |  gmp
 Type of failure:  Runtime performance bug  |     Architecture:
       Test Case:                           |  Unknown/Multiple
        Blocking:                           |       Difficulty:  Unknown
                                            |       Blocked By:
                                            |  Related Tickets:
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Comment (by simonpj):

 Great.  Now, what's happening in `symalg` and `kahan` (+4.7 and 6.7%
 resp)?

 Working on these small deltas seems tiresome, but what is a small delta in
 one program can be a massive one in another.  It's not that we must have
 uniform improvement; just that we like to know ''why'' something gets
 worse, and deem it an acceptable compromise.

 What is puzzling to me is that I don't think `smartJ#` does ''any''
 allocation (apart from its result) so I don't see why allocation should
 ever increase.

 Thanks

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8638#comment:7>
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