[GHC] #8951: genSym uses atomic_inc but doesn't link arm_atomic_spin_lock

[GHC]

#8951: genSym uses atomic_inc but doesn't link arm_atomic_spin_lock
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              Reporter:  cjwatson    |            Owner:
                  Type:  bug         |           Status:  patch
              Priority:  normal      |        Milestone:  7.8.4
             Component:  Build       |          Version:  7.8.1-rc1
  System                             |         Keywords:
            Resolution:              |     Architecture:  arm
      Operating System:  Linux       |       Difficulty:  Unknown
       Type of failure:  Building    |       Blocked By:
  GHC failed                         |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by Austin Seipp <austin@…>):

 In [changeset:"df1307f079ae69dcd735e0973de987b141d509da/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="df1307f079ae69dcd735e0973de987b141d509da"
 Link pre-ARMv6 spinlocks into all RTS variants

 Summary:
 For compatibility with ARM machines from pre v6, the RTS provides
 implementations of certain atomic operations. Previously, these
 were only included in the threaded RTS.

 But ghc (the library) contains the code in compiler/cbits/genSym.c, which
 uses these operations if there is more than one capability. But there is
 only
 one libHSghc, so the linker wants to resolve these symbols in every case.

 By providing these operations in all RTSs, the linker is happy. The only
 downside is a small amount of dead code in the non-threaded RTS on old ARM
 machines.

 Test Plan: It helped here.

 Reviewers: bgamari, austin

 Reviewed By: bgamari, austin

 Subscribers: carter, thomie

 Differential Revision: https://phabricator.haskell.org/D564

 GHC Trac Issues: #8951
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8951#comment:9>
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