[GHC] #16164: Provide bitreverse primop

[GHC]

#16164: Provide bitreverse primop
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           Reporter:  Fuuzetsu       |             Owner:  (none)
               Type:  feature        |            Status:  new
  request                            |
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.6.3
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 We already have nice primops like {{{byteSwap#}}}, it'd be nice to also
 have {{{bitreverse}}}.

 Clang provides {{{__builtin_bitreverse}}}
 (http://clang.llvm.org/docs/LanguageExtensions.html#builtin-bitreverse)
 functions which could be the default. GCC currently doesn't have a built-
 in (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50481).

 One prominent place where this primop could be used is
 Data.IntSet.Internal where it's implemented as a {{{revNat}}}. Many other
 libraries also define own versions.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16164>
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