[GHC] #4012: Compilation results are not deterministic

[GHC]

#4012: Compilation results are not deterministic
-------------------------------------+-------------------------------------
        Reporter:  kili              |                Owner:  niteria
            Type:  bug               |               Status:  patch
        Priority:  high              |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  6.12.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #10424            |  Differential Rev(s):  Phab:D910,
                                     |  Phab:D1073, Phab:D1133, Phab:D1192,
                                     |  Phab:D1268, Phab:D1360, Phab:D1373,
                                     |  Phab:D1396, Phab:D1457, Phab:D1468,
       Wiki Page:                    |  Phab:D1487, Phab:D1504, Phab:D1508
-------------------------------------+-------------------------------------

Comment (by Bartosz Nitka <bnitka@…>):

 In [changeset:"5b2b7e338c822c34f86e8bd3ff442a979711d1fe/ghc"
 5b2b7e33/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="5b2b7e338c822c34f86e8bd3ff442a979711d1fe"
 Make callToPats deterministic in SpecConstr

 This fixes a non-determinism bug where where depending on the
 order of uniques allocated, the specialized workers would have different
 order of arguments.

 Compare:

 ```
   $s$wgo_s1CN :: Int# -> Int -> Int#
   [LclId, Arity=2, Str=DmdType <L,U><L,U>]
   $s$wgo_s1CN =
     \ (sc_s1CI :: Int#) (sc_s1CJ :: Int) ->
       case tagToEnum# @ Bool (<=# sc_s1CI 0#) of _ [Occ=Dead] {
         False ->
           $wgo_s1BU (Just @ Int (I# (-# sc_s1CI 1#))) (Just @ Int
 sc_s1CJ);
         True -> 0#
       }
 ```

 vs

 ```
   $s$wgo_s18mTj :: Int -> Int# -> Int#
   [LclId, Arity=2, Str=DmdType <L,U><L,U>]
   $s$wgo_s18mTj =
     \ (sc_s18mTn :: Int) (sc_s18mTo :: Int#) ->
       case tagToEnum# @ Bool (<=# sc_s18mTo 0#) of _ [Occ=Dead] {
         False ->
           $wgo_s18mUc
             (Just @ Int (I# (-# sc_s18mTo 1#))) (Just @ Int sc_s18mTn);
         True -> 0#
       }
 ```

 Test Plan:
 I've added a new testcase
 ./validate

 Reviewers: simonmar, simonpj, austin, goldfire, bgamari

 Reviewed By: bgamari

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D1508

 GHC Trac Issues: #4012
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:138>
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