Using old code generator

[Roman Cheplyaka]

Hi,

I'm looking for a workaround for #7574 [1] (I run into it when trying to
build the 'statistics' package with profiling enabled with GHC HEAD.)

The symptom is

  ghc-stage2: panic! (the 'impossible' happened)
    (GHC version 7.7.20130407 for i386-unknown-linux):
    allocateRegsAndSpill: Cannot read from uninitialized register
      %vI_cCdO

[1]: http://hackage.haskell.org/trac/ghc/ticket/7574

Do I understand correctly that this bug is specific to the new codegen?
If so, is it possible to ask the compiler to use the old codegen?
Is it okay to mix together packages compiled with both codegens?

Thanks,
Roman