O2: allocateRegsAndSpill: Cannot read from uninitialized register %vI_s154O (GHC version 7.8.2 for x86_64-unknown-linux)

When building all world with -O2 I've stuck on wxhaskell (all versions):

[11 of 16] Compiling Graphics.UI.WX.Controls ( src/Graphics/UI/WX/Controls.hs, dist/build/Graphics/UI/WX/Controls.o )

<no location info>:
    ghc: panic! (the 'impossible' happened)
  (GHC version 7.8.2 for x86_64-unknown-linux):
        allocateRegsAndSpill: Cannot read from uninitialized register
    %vI_s154O

I've stripped it down to minimal complete example (but it significantly changed error message)

ghc: panic! (the 'impossible' happened)
  (GHC version 7.8.2 for x86_64-unknown-linux):
        RegAlloc.Liveness.computeLivenss
    SCCs aren't in reverse dependent order
    bad blockId c1tU
    [NONREC
        c1uc:
                movq $-8,%rbx
                andq $main:M.AlignLeft{v rb}_closure+1,%rbx
                addq $8,%rbp
                jmp *(%rbx),
     NONREC
...

Trac metadata

Trac field	Value
Version	7.8.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture	Unknown/Multiple

Edited Mar 09, 2019 by Sergei Trofimovich

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information