[GHC] #15897: Negative MUT time in +RTS -s -RTS when heap profiling is enabled

[GHC]

#15897: Negative MUT time in +RTS -s -RTS when heap profiling is enabled
-------------------------------------+-------------------------------------
        Reporter:  maoe              |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.3
       Component:  Profiling         |              Version:  8.6.2
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Debugging         |  (amd64)
  information is incorrect           |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by osa1):

 * cc: bgamari (added)


Comment:

 If I run this program with debug runtime I get this assertion failure:

 {{{
 Main: internal error: ASSERTION FAILED: file rts/Stats.c, line 1123

     (GHC version 8.7.20181115 for x86_64_unknown_linux)
     Please report this as a GHC bug:
 http://www.haskell.org/ghc/reportabug
 zsh: abort (core dumped)  ./Main 5000000 +RTS -s -h
 }}}

 Code that fails:

 {{{
 // The subdivision of runtime into INIT/EXIT/GC/MUT is just adding
 // and subtracting, so the parts should add up to the total exactly.
 // Note that stats->total_ns is captured a tiny bit later than
 // end_exit_elapsed, so we don't use it here.
 ASSERT(stats.init_elapsed_ns \
        + stats.mutator_elapsed_ns \
        + stats.gc_elapsed_ns \
        + sum.exit_elapsed_ns \
        == end_exit_elapsed - start_init_elapsed);
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15897#comment:6>
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