Re: Fix PR breakpoints/2080

[Jim Blandy <jimb at red-bean dot com>]

> > Of course in optimized code we don't expect the prologue skipper to
> > work very well, and we use dwarf2 to bypass the prologue analyzer,
> > so this may not be a big deal.  But I'm somewhat curious to see if
> > we could make this extremely sophisticated i386 prologue analyzer
> > use Jim's prologue-value.[ch] interface...
>
> Well, writing that prologue analyzer will be hell of a lot more
> difficult for CISC than it is for RISC; even with Jim's
> prologue-value.[ch].

Looking at the prologue you put in gdb.arch/i386-prologue.c, I think
it'd be okay.  The 'and' would set esp to 'unknown', but that should
be okay, since the original stack pointer has been saved in ebp.

In fact, there's already a pv_logical_and operation in
prologue-value.c.  If I remember right, s390 prologues can use logical
and from time to time.