== make all ;
 in /home/Andi/ghc_head/nofib/shootout/pidigits
------------------------------------------------------------------------
HC = /home/Andi/ghc_head/inplace/bin/ghc-stage2
HC_OPTS = -O2 -Rghc-timing -H32m -hisuf hi -fllvm -rtsopts -O2
RUNTEST_OPTS = -ghc-timing
==nofib== pidigits: time to compile Main follows...
/home/Andi/ghc_head/inplace/bin/ghc-stage2 -O2 -Rghc-timing -H32m -hisuf hi -fllvm -rtsopts -O2 -c Main.hs -o Main.o
ghc-stage2.exe: panic! (the 'impossible' happened)
  (GHC version 8.5.20180401 for x86_64-unknown-mingw32):
        Each block should be reachable from only one ProcPoint

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

<<ghc: 506688344 bytes, 156 GCs, 7738569/16639872 avg/max bytes residency (5 samples), 37M in use, 0.000 INIT (0.000 elapsed), 0.344 MUT (0.333 elapsed), 0.062 GC (0.112 elapsed) :ghc>>
make[1]: *** [../../mk/suffix.mk:23: Main.o] Error 1
Failed making all in pidigits: 1
make: *** [../mk/ghc-recurse.mk:69: all] Error 1

$ opt --version
LLVM (http://llvm.org/):
  LLVM version 5.0.1
  Optimized build.
  Default target: x86_64-w64-windows-gnu
  Host CPU: skylake

This is on commit 8b823f27