[GHC] #13518: CMM compiles with 8.0.2, fails with git HEAD

[GHC]

#13518: CMM compiles with 8.0.2, fails with git HEAD
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        Reporter:  erikd             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  error/warning at compile-time      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 To clarify, I think this would need to look something like,
 {{{

     reserve FLOAT_STACK_WDS = ptr {
         I32[ptr] = %sx32(w);
         f = F_[ptr];
     }

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13518#comment:3>
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