[GHC] #15754: Move free variable computation to after STG passes

[GHC]

#15754: Move free variable computation to after STG passes
-------------------------------------+-------------------------------------
        Reporter:  bgamari           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  8.6.1
      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:                    |
-------------------------------------+-------------------------------------
Description changed by bgamari:

Old description:



New description:

 Currently (we believe) `CoreToStg` is responsible for computing free
 variables. However, later STG transformations may invalidate this
 information.

 It would make more sense to defer FV computation until the end of the STG
 pipeline.

--

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15754#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler