Re: two agent expression nits (one line each)

[Joel Brobecker <brobecker@adacore.com>]

Hi Stan,

> > The @item line and the following text do no agree with one another.  I'm
> > guessing that the text is correct, in which case this line:
> > 
> >     @item @code{setv} (0x2d) @var{n}: @result{} @var{v}
> > 
> > should be changed to this:
> > 
> >     @item @code{setv} (0x2d) @var{n}: @var{v} @result{} @var{v}
> 
> Yes, that is correct.
> 
> > Additionally, in gdb/common/ax.def we find the line:
> > 
> >     DEFOP (setv, 2, 0, 0, 1, 0x2d)
> > 
> >>From the comment earlier in the file:
> > 
> >        Each line is of the form:
> > 
> >        DEFOP (name, size, data_size, consumed, produced, opcode)
> > [...]
> >        CONSUMED is the number of stack elements consumed.
> >        PRODUCED is the number of stack elements produced.
> > 
> > which is saying that nothing is consumed and one item is produced.  Both
> > should be 0 or both should be 1.  Setting them both to 1 seems better
> > since if nothing is on the stack an error will occur.  So, it should be
> > changed to:
> > 
> >     DEFOP (setv, 2, 0, 1, 1, 0x2d)
> 
> Yes to this also.  From the look of things, I cloned the getv definition
> and forgot to adjust it.
> 
> Although technically an incompatible change to the bytecode language,
> anybody who tried to set a state variable within a larger expression was
> going to get odd behavior and/or stack overflow, while the common
> case of just setting the variable and discarding the result is
> unaffected.  So I think we can just make the change directly, and
> perhaps add a brief note to NEWS, to make sure that target agents
> get updated. (Mentor has one in-house separate from gdbserver, plus at
> least two customers with their own agents.)

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...

Thanks!
-- 
Joel