[GHC] #11158: Combine exprIsTrivial and cpe_ExprIsTrivial

[GHC]

#11158: Combine exprIsTrivial and cpe_ExprIsTrivial
-------------------------------------+-------------------------------------
        Reporter:  simonpj           |                Owner:
            Type:  task              |               Status:  closed
        Priority:  highest           |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  7.10.2
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2666
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Ben Gamari <ben@…>):

 In [changeset:"967dd5c9f59e532fe9d6484888a2bae7d02fba11/ghc"
 967dd5c9/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="967dd5c9f59e532fe9d6484888a2bae7d02fba11"
 Merge cpe_ExprIsTrivial and exprIsTrivial

 Strangely my previous attempts at resolving this all seemed to end in
 perplexing segmentation faults in the GHC testsuite (including some
 rather recent attempts). Somehow this attempt miraculously works.

 However, there was one wrinkle that I still need to work out fully: we
 need to consider Lits as non-trivial in cpeArg. Failure to do this means
 that we would transform something like,

     $trModule = TrModule "HelloWorld"#

 into

     $trModule = case "HelloWorld"# of x { __DEFAULT -> TrModule x }

 Which then fails the consistentStgInfo check in CoreToStg for reasons
 that I am still trying to work out.

 Mark T12757 as fixed

 Reviewers: simonmar, simonpj, austin

 Reviewed By: simonpj

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D2666

 GHC Trac Issues: #11158
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11158#comment:36>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler