sjlj-exceptions ICE. simplified test case

[Geert Bosch]

On 26 Apr 2000 13:15:22 -0700, Jason Merrill wrote:

  We ought have a fallback unwinder, perhaps based on gdb code.  For SPARC
  this would be trivial, and remove the need for any unwind information in
  most cases.

This would be really great, and solves most of the issues wrt. the unwinding
tables. What I think would be ideal is to be able to compile with -fno-unwind-tables,
and have the resulting code be "unwindable" by the fallback unwinder.

Actually GNAT currently uses an unwind mechanism for x86 which works by
scanning the prologue. This code is well documented and should be easily 
adaptable; I would be willing to do the work if people agree that having
such an unwinder would be nice.

  -Geert