alpha sjlj exception handling

[Richard Henderson <rth@cygnus.com>]

So I decided to track down some of the errors we get on Alpha with the
exception bits -- using sjlj still, since it is supposed to be using
the non-local goto support, it ought to work at least a little bit.

And I find that the generated code somehow expects the call-saved
registers to be preserved even though no one seems to save them.

From looking at what anyone is emitting, I would think at a non-local
goto label we would have to assume all registers except for the fp and
sp, which we restored getting back here, are dead. 

Where is this supposed to happen in the regular case of non-local goto?


r~