[GHC] #3971: FFI callback segfaults on PPC

[GHC]

#3971: FFI callback segfaults on PPC
-------------------------------+--------------------------------------------
    Reporter:  wkahl           |        Owner:               
        Type:  bug             |       Status:  new          
    Priority:  normal          |    Milestone:  _|_          
   Component:  Compiler (FFI)  |      Version:  6.12.3       
    Keywords:                  |   Difficulty:               
          Os:  Linux           |     Testcase:               
Architecture:  powerpc         |      Failure:  Runtime crash
-------------------------------+--------------------------------------------
Changes (by Mikolaj):

 * cc: mikolaj.konarski@… (added)
  * failure:  None/Unknown => Runtime crash
  * version:  6.12.1 RC1 => 6.12.3


Comment:

 Reproduced on the just released 6.12.3 (so probably unrelated to #4038)
 and on Debian's ghc6_6.12.1-13. I'm getting exactly the same output as
 reported above for the modified CallBacker and I have a similar problem
 when using callbacks in gth2hs (see
 [http://hackage.haskell.org/trac/gtk2hs/ticket/1192]).

 I'm quite ignorant here, but it may not only be PPC specific, but also
 processor model specific, because the relevant GHC code is written in
 assembler and you can't compile via C (-fvia-C does not work on PPC Linux,
 as reported elsewhere) to delegate emission of legal assembler code to
 GCC. My processor type is 7447A and gdb suggests some of the instructions
 emitted for callbacks are invalid.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3971#comment:12>
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