[GHC] #14705: ghc-iserv sometimes segfaults in profiled way

[GHC]

#14705: ghc-iserv sometimes segfaults in profiled way
-------------------------------------+-------------------------------------
        Reporter:  bgamari           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Profiling         |              Version:  8.5
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Runtime crash     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 Looking at `scc001`, it looks like we get into trouble in the interpreter,
 {{{
 Program received signal SIGSEGV, Segmentation fault.
 [Switching to Thread 0x7ffff647f700 (LWP 108910)]
 interpretBCO (cap=0x216c5c0 <MainCapability>) at rts/Interpreter.c:395
 395         switch ( get_itbl(obj)->type ) {
 (gdb) print obj
 $1 = <optimized out>
 (gdb) print get_itbl(obj)
 value has been optimized out
 (gdb) print get_itbl(obj)->type
 value has been optimized out
 (gdb) info locals
 Sp = 0x420029fcc0
 SpLim = 0x42002980d0
 tagged_obj = 0x1c7b9b8 <stg_ctoi_R1p_info>
 obj = <optimized out>
 n = <optimized out>
 m = <optimized out>
 }}}

 For future reference, getting here involved,
 {{{
 $ cd testsuite/tests/profiling/should_run/
 $ make test TEST=scc001 VERBOSE=4 CLEANUP=NO
 $ gdb --args $HOME/project/inplace/lib/bin/ghc-stage2
 -B$HOME/project/inplace/lib scc001.hs -dcore-lint -ddump-bcos -v
 -fexternal-interpreter -prof -fno-state-hack -fno-full-laziness
 --interactive
 ...
 (gdb) set follow-fork-mode child
 (gdb) run
 ...
 *Main> :main
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14705#comment:1>
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