[GHC] #13442: Add a coercion/cast operator to CMM

[GHC]

#13442: Add a coercion/cast operator to CMM
-------------------------------------+-------------------------------------
        Reporter:  erikd             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by erikd):

 > I'm a little confused, is this supposed to be valid input Cmm?

 The `cast <F64>` is my proposed extension to CMM.

 > It seems like the goal of adding this cast is to slip past Cmm's type
 checking,

 The CMM type checker seems fine with this, its CMM's linter than
 complains.

 > but as there actually is a well-typed way to do what you want in Cmm,

 There is? Please elaborate!

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13442#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler