[GHC] #3693: Show stack traces

[GHC]

#3693: Show stack traces
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        Reporter:  jpet              |            Owner:
            Type:  feature request   |           Status:  new
        Priority:  normal            |        Milestone:  7.6.2
       Component:  Runtime System    |          Version:  6.10.4
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by scpmw):

 Hi Tarrasch

 (1) Thanks - the good thing with using DWARF is that it doesn't really
 matter how you use it. My primary use case was actually to feed it to
 ThreadScope for profiling. Other people have talked about using Linux
 "perf" tools - this kind of openness is a good thing. From my point of
 view, going over the RTS will probably be the most fruitful approach most
 of the time, simply because it can account for more of the generated
 code's quirkiness (see the "IP-1" trouble with GDB).

 (2) The LLVM backend was actually what we started with, and at this point
 we still support line-number information. Walking the stack is more
 problematic - we can declare values as being visible in DWARF using
 `llvm.dbg.declare` and friends, but (as far as I know) have no way to
 communicate unwind rules to LLVM.

 Dwarf 4 isn't really the issue here though, Dwarf 3 is sufficient - even
 DW_CFA_def_cfa_expression will probably only be needed for rare variable-
 sized stack frames.

 (3) Tthere should actually be little magic involved with building my
 branch, as everything's on by default. Just make sure you have the
 dependencies (libdwarf). Also get the stack-trace branch of the "base"
 library from my GitHub, as otherwise you won't have a top-level exception
 handler that prints a stack trace. In case you run into any problems, just
 drop me a mail.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3693#comment:48>
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