[GHC] #9031: ghc panic: RegAlloc.Liveness.computeLivenss

[GHC]

#9031: ghc panic: RegAlloc.Liveness.computeLivenss
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       Reporter:  jwlato           |             Owner:
           Type:  bug              |            Status:  new
       Priority:  normal           |         Milestone:
      Component:  Compiler         |           Version:  7.8.2
       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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 I have some code where ghc consistently panics with

 {{{
   RegAlloc.Liveness.computeLivenss
     SCCs aren't in reverse dependent order
     bad blockId c1kek
 }}}

 The only reference I can find to that block in the dumped output is here:

 {{{
      REC
         c1kej:
               movq $block{v c1keo}_info,(%rbp)
               movsd 7(%rbx),%vSSE_s1ivM
               movsd 15(%rbx),%vSSE_s1ivN
               movq 96(%rbp),%rbx
               movsd %vSSE_s1ivN,88(%rbp)
               movsd %vSSE_s1ivM,96(%rbp)
               testq $7,%rbx
               jne _c1keo
               jmp _c1kep
         c1kpo:
               movq $block{v c1kej}_info,(%rbp)
               movq %vI_s1it5,%rbx
               movq $0,120(%rbp)
               testq $7,%rbx
               jne _c1kej
               jmp _c1kek,
 }}}

 There doesn't appear to be any reference to {{{c1kpo}}} either.

 Unfortunately I don't yet have a test case I can provide; I'll keep
 working on that.  Building with -dcore-lint and -dcmm-lint don't show any
 extra errors.

 This is with ghc-7.8.2 using NCG.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9031>
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