[GHC] #9831: the 'impossible' happened : iselExpr64(powerpc)

[GHC]

#9831: the 'impossible' happened : iselExpr64(powerpc)
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              Reporter:  erikd                |            Owner:  erikd
                  Type:  bug                  |           Status:  new
              Priority:  normal               |        Milestone:
             Component:  Compiler (NCG)       |          Version:  7.9
            Resolution:                       |         Keywords:
      Operating System:  Linux                |     Architecture:  powerpc
       Type of failure:  Building GHC failed  |       Difficulty:  Unknown
             Test Case:                       |       Blocked By:
              Blocking:                       |  Related Tickets:
Differential Revisions:  Phab:D560            |
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Comment (by Sergei Trofimovich <siarheit@…>):

 In [changeset:"fa31e8f4a0f853848d96549a429083941877bf8d/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="fa31e8f4a0f853848d96549a429083941877bf8d"
 powerpc: fix and enable shared libraries by default on linux

 Summary:
 And fix things all the way down to it. Namely:
     - remove 'r30' from free registers, it's an .LCTOC1 register
       for gcc. generated .plt stubs expect it to be initialised.
     - fix PicBase computation, which originally forgot to use 'tmp'
       reg in 'initializePicBase_ppc.fetchPC'
     - mark 'ForeighTarget's as implicitly using 'PicBase' register
       (see comment for details)
     - add 64-bit MO_Sub and test on alloclimit3/4 regtests
     - fix dynamic label offsets to match with .LCTOC1 offset

 Signed-off-by: Sergei Trofimovich <siarheit at google.com>

 Test Plan: validate passes equal amount of vanilla/dyn tests

 Reviewers: simonmar, erikd, austin

 Reviewed By: erikd, austin

 Subscribers: carter, thomie

 Differential Revision: https://phabricator.haskell.org/D560

 GHC Trac Issues: #8024, #9831
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9831#comment:5>
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