[GHC] #9276: audit ghc floating point support for IEEE (non)compliance

[GHC]

#9276: audit ghc floating point support for IEEE (non)compliance
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        Reporter:  carter            |            Owner:  carter
            Type:  task              |           Status:  new
        Priority:  high              |        Milestone:  7.10.1
       Component:  Compiler          |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:  9304              |  Related Tickets:
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Comment (by carter):

 Yeah, improving optimization requires a pretty precise soft float model of
 the target hardware's floating point semantics, with roughly three modes

  1. IEEE / machine model -- same result as if run as a normal program
  2. fast math model -- assume associativity, assume NaNs never happen
  3. excess precision --  use extra precision in the intermediate
 computation to provide as many bits of precision as possible

 adding that sort of machinery to ghc is a bit out of scope for just an
 audit (and any induced patched to provide added missing operations), but
 becomes possible once such an audit is done.  (Also a LOT of work)

 I want to get this done for 7.10, adding optimization on top can be on the
 table later though! :)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9276#comment:6>
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