[GHC] #8892: Ghc panics (variable not found)

[GHC]

#8892: Ghc panics (variable not found)
-----------------------------------+---------------------------------------
       Reporter:  jwlato           |             Owner:
           Type:  bug              |            Status:  new
       Priority:  normal           |         Milestone:
      Component:  Compiler         |           Version:  7.8.1-rc2
       Keywords:                   |  Operating System:  Unknown/Multiple
   Architecture:                   |   Type of failure:  Compile-time crash
  Unknown/Multiple                 |         Test Case:
     Difficulty:  Unknown          |          Blocking:
     Blocked By:                   |
Related Tickets:                   |
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 When attempting to compile a module with ghc-7.8-RC2, using the flags
 `--ghc-options=-j8 -O2  -Werror`, I encountered this error:

 {{{
     ghc: panic! (the 'impossible' happened)
   (GHC version 7.8.0.20140228 for x86_64-unknown-linux):
   StgCmmEnv: variable not found
     foldlM'_loop{v i1iSV} [lid]
     local binds for:
 }}}

 followed by about 1100 bindings (none of are the binding in question).
 Omitting the `-j` flag makes no difference.  Building `-O0` succeeds.

 I don't have a standalone test case, and it's not clear to me how to make
 one as I have no idea what's causing this.  I'll try to narrow it down,
 but if anyone could suggest some flags to twiddle or some other factor to
 adjust I'd appreciate it.  I'm suspecting that it's a function referenced
 from inlining something vector-related.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8892>
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