[GHC] #14244: ghc-prim: hs_atomicread* and hs_atomicwrite* missing barriers

[GHC]

#14244: ghc-prim: hs_atomicread* and hs_atomicwrite* missing barriers
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        Reporter:  trommler          |                Owner:  trommler
            Type:  bug               |               Status:  closed
        Priority:  high              |            Milestone:  8.4.1
       Component:  Prelude           |              Version:  8.2.1
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #12537            |  Differential Rev(s):  Phab:D4009
       Wiki Page:                    |
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Comment (by YitzGale):

 Hmm, by requiring GCC 4.7, this bans GHC from RHEL/CentOS 6, which uses
 GCC 4.4. That OS will be supported until the end of 2020, and will
 continue to be used fairly widely in the enterprise until close to then.

 Can this requirement be avoided at least for x86, amd64, and llvm builds,
 where it isn't actually needed?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14244#comment:7>
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