Patch: prologue on NT

[Donn Terry]

Richard Henderson wrote:

> On Sat, Apr 17, 1999 at 10:33:16AM -0600, Donn Terry wrote:
> > On NT, the MS exception handling stuff is used everywhere.  (The
> > OS presumes it's present, and the code is in NTDLL.DLL.)  It in
> > turn relies on "reverse execution" to unwind the stack on the ALPHA.
> > (The same general stuff that gdb has to do on any Alpha, only
> > moreso.) Not all conceptually legal stack entry and exit sequences
> > are actually supported.  Specifically, subq as a stack push is NOT
> > supported.  If it is used, and an exception occurs, the application
> > will loop indefinitely in NTDLL.DLL.
>
> How extraordinarily lame.

I'm at home, but I've bootstrapped with your changes, and all seems
MOSTLY  OK.  However, I need to get to the bible to see exactly
what the rules are on large frame sizes; something seems wrong but
I need the reference to make sure I don't misspeak myself.  Clearly
the code will run, but whether it will unwind needs some research I
can't do from here.

Donn

P.S.  The regressions are still not in shape to tell us anything useful;
more patches coming as fast as I can put them together and make sure
they're right.