[GHC] #14880: GHC panic: updateRole

[GHC]

#14880: GHC panic: updateRole
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler (Type    |              Version:  8.2.2
  checker)                           |
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #15076            |  Differential Rev(s):  Phab:D4769
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by tdammers):

 Speed test results: performance for the `NDFV` version is virtually
 identical to that of the baseline (which uses `FV`). So leaving out the
 list when it is not going to be demanded anyway makes absolutely no
 difference, as one would expect.

 Full logs to be attached. The relevant branches can be found on
 git.haskell.org:

 - `wip/T14880-baseline` (before the patch)
 - `wip/T14880` (patch applied as-is)
 - `wip/T14880-just-tvs` (just the move from `FV` to `VarSet`)
 - `wip/T14880-nondet-fv` (introducing the `NDFV` flavour of `FV`, but
 otherwise identical to the baseline)

 To reproduce logs, use something like:

 {{{#!bash
 for NAME in T14880-nondet-fv T14880 T14880-baseline T14880-just-tvs
 do
     echo "$NAME"
     git checkout "wip/$NAME" \
     && (
         make -j2 \
         && (/usr/bin/time --verbose \
             ~/path/to/ghc/inplace/bin/ghc-stage2 \
                 -c testsuite/tests/perf/compiler/T5631.hs \
                 -fforce-recomp \
                 +RTS -V0 -tlogs/$NAME.stat --machine-readable -RTS) \
         |& tee logs/$NAME.timing \
         && echo "$NAME"
        )
 done
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14880#comment:82>
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