Re: #16100: T11627a fails sometimes on CI

#16100: T11627a fails sometimes on CI
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        Reporter:  mpickering        |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.3
      Resolution:                    |             Keywords:  ci-breakage
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 `T949` also occasionally fails on CI with the same panic ([https://ghc-
 gitlab.s3.amazonaws.com/6b/86/6b86b273ff34fce19d6b804eff5a3f5747ada4eaa22f1d49c01e52ddb7875b4b/2019_02_24/34877/53941/job.log
 ?response-content-type=text/plain%3B%20charset%3Dutf-8&response-content-
 disposition=inline&X-Amz-Expires=600&X-Amz-Date=20190224T124746Z&X-Amz-
 Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAI3NPPHETCY4XXTOA/20190224
 /us-east-1/s3/aws4_request&X-Amz-SignedHeaders=host&X-Amz-
 Signature=0d3ff67589490a67b80abbc045c7de427519f6f05ce24bc2685f70fa41a258c2
 example] from a `validate-x86_64-linux-deb9-llvm` configuration):

 {{{
 Wrong exit code for T949(prof_hc_hb)(expected 0 , actual 134 )
 Stderr ( T949 ):
 T949: internal error: LDV_recordDead: Failed to find counter for closure
 0x4200105000
     (GHC version 8.9.20190224 for x86_64_unknown_linux)
     Please report this as a GHC bug:
 https://www.haskell.org/ghc/reportabug
 Aborted (core dumped)
 *** unexpected failure for T949(prof_hc_hb)

 <elided>

 Unexpected results from:
 TEST="T949"

 SUMMARY for test run started at Sun Feb 24 10:46:01 2019 UTC
  0:24:09 spent to go through
     6844 total tests, which gave rise to
    26554 test cases, of which
    19235 were skipped

       42 had missing libraries
     7137 expected passes
      139 expected failures

        0 caused framework failures
        0 caused framework warnings
        0 unexpected passes
        1 unexpected failures
        0 unexpected stat failures

 Unexpected failures:
    profiling/should_run/T949.run  T949 [bad exit code] (prof_hc_hb)
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16100#comment:5>