[GHC] #9886: Undefined reference to `__sync_fetch_and_xor_8'

[GHC]

#9886: Undefined reference to `__sync_fetch_and_xor_8'
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        Reporter:  erikd                |                   Owner:  erikd
            Type:  bug                  |                  Status:  new
        Priority:  normal               |               Milestone:
       Component:  Compiler (CodeGen)   |                 Version:  7.11
      Resolution:                       |                Keywords:
Operating System:  Unknown/Multiple     |            Architecture:  powerpc
 Type of failure:  Building GHC failed  |               Test Case:
      Blocked By:                       |                Blocking:
 Related Tickets:                       |  Differential Revisions:
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Comment (by erikd):

 It seems the 64 bit primpos are *only* needed on 32 bit architectures and
 then only for the native code generators. For x86 via the native code
 generator we needed #9346 as mentioned by @tibbe, but the arm backend did
 need anything because that omly compilers via LLVM.

 That leaves PowerPC as the remaining 32 bit architecture with an NCG.
 However, if I hack the 64 bit primops like (for example) this:

 {{{#!c
 StgWord64
 hs_atomic_add64(volatile StgWord64 *x, StgWord64 val)
 {
 #if WORD_SIZE_IN_BITS == 32
         printf ("%s : %s not implemented.\n", __FILE__, __func__) ;
         exit (1);
 #else
   return __sync_fetch_and_add(x, val);
 #endif
 }
 }}}

 then building the compiler runs to completion and futhermore, the one test
 for these atomic primops,
 `testsuite/tests/concurrent/should_run/AtomicPrimops.hs` passes. It turns
 out this test operates on Int which on 32 bit platforms is a 32 bit value.

 This makes me wonder if its worth the trouble of implementing these if
 they aren't used anywhere.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9886#comment:9>
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