[GHC] #12622: Unboxed static pointers lead to missing SPT entries

[GHC]

#12622: Unboxed static pointers lead to missing SPT entries
-------------------------------------+-------------------------------------
        Reporter:  mboes             |                Owner:
                                     |  facundo.dominguez
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2709
       Wiki Page:                    |  Phab:D2720
-------------------------------------+-------------------------------------

Comment (by facundo.dominguez):

 I infer that:
 * `makeStatic` should never be unfolded,
 * FloatOut needs to treat it specially when **deciding what to float**
 (unlike it does now with `StaticPtr`)
 * Besides keeping the floated bindings, the optimizations should never
 inline them, or the SPT construction pass wouldn't replace the inlined
 calls to `makeStatic`.
 * the SPT construction needs to do more work (which is replacing this call
 with a StaticPtr).

 It is probably doable, but how is it simpler than using the twin data
 constructor?

 Something that could be simpler is to stop relaying on the FloatOut pass.
 Instead:
 1. As you suggest: Make `static e` expand into the ordinary function call
 `makeStatic e`
 2. Make the SPT construction phase float all such calls and insert them in
 the SPT.

 Thus there is no need to worry about unfloated calls during linting and
 there will be no interference from optimizations.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12622#comment:11>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler