Re: two agent expression nits (one line each)

[Joel Brobecker <brobecker at adacore dot com>]

Hi David,

> > Would you mind taking care of that for us? I kept that message around
> > in the hope that I'd have a clearer picture with a little extra time,
> > but I am still not sure whether you're just suggesting a documentation
> > fix, or if you're saying we should fix the implementation...
> 
> The first part is pure documentation -- the description is correct but
> the summary line is wrong.  The second part is implementation -- the
> consumed and produced fields are used to check for stack underflow and
> overflow.
> 
> The fields are used by gdb and gdbserver for sanity checking the
> bytecode expression -- checking for underflow and overflow.
> 
> The underflow check catches bad bytecode sequences generated by GDB.
> 
> Since DEFOP has consumed as 0 when it is really 1, that means that GDB
> will think that there is more on the stack than there really is.
> 
> So, if GDB generates a bytecode sequence that underflows it might not
> catch it.  It does not currently generate bad sequences, so fixing it
> will merely help catch future lossage.
> 
> As I recall, the overflow check is used by gdbserver to verify that it
> has sufficent stack space for the expression.  The bad DEFOP line makes
> it think that the expression is using one more stack slot than reality.
> But, gdbserver has fairly generous bytecode stack space -- so unless the
> expression is really complicated, that won't happen.

Since you understand what should be done, would you mind sending
a patch in for Stan to review?

-- 
Joel