The ioref001 test is segfaulting, depending on how much stack space you give it:

$ '/home/ian/ghc/darcs/ghc/ghc/stage2-inplace/ghc' -fforce-recomp -dcore-lint -dcmm-lint -Dx86_64_unknown_linux  -dno-debug-output -o ioref001 ioref001.hs -O -fasm +RTS -K32m -RTS 

$ ./ioref001  
Stack space overflow: current size 8388608 bytes.
Use `+RTS -Ksize' to increase it.

$ ./ioref001 +RTS -K16m -RTS
Stack space overflow: current size 16000000 bytes.
Use `+RTS -Ksize' to increase it.
zsh: segmentation fault  ./ioref001 +RTS -K16m -RTS

$ ./ioref001 +RTS -K32m -RTS
done
zsh: segmentation fault  ./ioref001 +RTS -K32m -RTS

$ ./ioref001 +RTS -K100m -RTS
done