[GHC] #15399: Build failure on PowerPC 64-bit big endian

[GHC]

#15399: Build failure on PowerPC 64-bit big endian
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        Reporter:  trommler             |                Owner:  (none)
            Type:  bug                  |               Status:  new
        Priority:  normal               |            Milestone:
       Component:  Compiler             |              Version:  8.5
      Resolution:                       |             Keywords:
Operating System:  Linux                |         Architecture:  powerpc64
 Type of failure:  Building GHC failed  |            Test Case:
      Blocked By:                       |             Blocking:
 Related Tickets:                       |  Differential Rev(s):
       Wiki Page:                       |
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Comment (by trommler):

 My patch was not quite good enough.

 Here is another endianness issue:
 {{{
         BCO -> do
 // removed checks
             let splitWord = rawWds !! 3
             pure $ BCOClosure itbl (pts !! 0) (pts !! 1) (pts !! 2)
 // on big endian this is the wrong way around
                 (fromIntegral splitWord)
                 (fromIntegral $ shiftR splitWord (wORD_SIZE_IN_BITS `div`
 2))
                 (drop 4 rawWds)
 }}}

 I need a way to tell whether I am running on a big endian system. Is there
 any way to know
 inside without access to `DynFlags`? Is there even a portable way to read
 the first half-word from
 a word in memory?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15399#comment:3>
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