[GHC] #16182: Retainer Profiling is broken

[GHC]

#16182: Retainer Profiling is broken
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           Reporter:  crockeea       |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.6.3
           Keywords:  profiling      |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Runtime crash
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 I had a large program which I was trying to profile, and I noticed that
 the program always ran into a segfault when running with `+RTS -hr`. I was
 able to able to reliably get segfaults in both the `warp-tls` and `http-
 client-tls` packages, as well as a third large and independent package
 with essentially no overlapping dependencies. This led me to believe that
 the bug is in the retainer profiler itself, and is not (much) dependent on
 the code being profiled. To that point, I was able to reproduce the bug
 with the `bytestring` test suites.

 I've modified bytestring (attached) enough to make it compile with GHC
 8.6.3*. To reproduce the segfault, run

 {{{
 $ stack build --profile
 $ stack exec prop-compiled -- +RTS -hr
 }}}

 * Renamed the package to bytestring2 to avoid circular packages.
 * Removed a duplicate instance in tests/QuickCheckUtils.hs
 * Changed all test-suites to executables in the cabal file so that they
 could be compiled with profiling.

 I have confirmed the problem on Linux (Ubuntu 18.04), where prop-compiled
 quickly segfaults, and on Windows 10, where the program just hangs. [I
 observed the same behavior in all the other programs I tested: Linux
 sefaulted, and Windows just hung.]

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16182>
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