[GHC] #11143: Feature request: Add index/read/write primops with byte offset for ByteArray#

[GHC]

#11143: Feature request: Add index/read/write primops with byte offset for
ByteArray#
-------------------------------------+-------------------------------------
        Reporter:  vagarenko         |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  7.10.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Mathnerd314):

 Can we instead have primops which take both an offset measured in bytes
 and an offset measured in terms of the type?
 {{{#!hs
 indexTYPEArray# :: ByteArray#          -> Int# {-byte offset-} -> Int#
 {-type offset-} -> TYPE#
 readTYPEArray#  :: MutableByteArray# s -> Int# {-byte offset-} -> Int#
 {-type offset-} -> State# s -> (#State# s, TYPE##)
 writeTYPEArray# :: MutableByteArray# s -> Int# {-byte offset-} -> Int#
 {-type offset-} -> TYPE# -> State# s -> State# s

 indexTYPEOffAddr# :: Addr# -> Int# {-byte offset-} -> Int# {-type offset-}
 -> TYPE
 readTYPEOffAddr# :: Addr# -> Int# {-byte offset-} -> Int# {-type offset-}
 -> State# s -> (#State# s, TYPE ##)
 writeTYPEOffAddr# :: Addr# -> Int# {-byte offset-} -> Int# {-type offset-}
 -> TYPE -> State# s -> State# s
 }}}

 All of these go through the `mkBasicIndexed{Read,Write}` functions, which
 take both a byte offset and a type offset, so it seems reasonable to
 expose that.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11143#comment:2>
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