[GHC] #13825: Allow multiple constructor fields occupy the same word

[GHC]

#13825: Allow multiple constructor fields occupy the same word
-------------------------------------+-------------------------------------
        Reporter:  michalt           |                Owner:  michalt
            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:  #605              |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Ben Gamari <ben@…>):

 In [changeset:"fe6618b14712b829b8675fc6024dd33e9598d09a/ghc" fe6618b/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="fe6618b14712b829b8675fc6024dd33e9598d09a"
 ByteCodeGen: use depth instead of offsets in BCEnv

 This is based on unfinished work in D38 started by Simon Marlow and is
 the first step for fixing #13825. (next step use byte-indexing for
 stack)

 The change boils down to adjusting everything in BCEnv by +1, which
 simplifies the code a bit.

 I've also looked into a weird stack adjustement that we did in
 `getIdValFromApStack` and moved it to `ByteCodeGen` to just keep
 everything in one place. I've left a comment about this.

 Signed-off-by: Michal Terepeta <michal.terepeta at gmail.com>

 Test Plan: ./validate

 Reviewers: austin, hvr, bgamari, simonmar

 Reviewed By: bgamari, simonmar

 Subscribers: simonmar, rwbarton, thomie

 GHC Trac Issues: #13825

 Differential Revision: https://phabricator.haskell.org/D3708
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13825#comment:7>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler