Re: [RFC] TARGET_ADJUST_BREAKPOINT_ADDRESS - patch 1 of 4

[Andrew Cagney <ac131313@redhat.com>]

> On Oct 8,  2:26pm, Andrew Cagney wrote:
> 
> 
>> I also wonder if PPC64 GDB could use this to do the descriptor -> 
>> function address transformation that I described in:
>> http://sources.redhat.com/ml/gdb-patches/2003-09/msg00415.html
> 
> 
> I suppose it could, although that's definitely not the (well, my)
> intended purpose of ADJUST_BREAKPOINT_ADDRESS.  If we do wind up using
> it for this purpose, we'll want to disable the warning messages.  It
> makes no sense to have a breakpoint on the descriptor, so when used in
> this way, it'd definitely be the case that gdb is just doing the
> "right thing".  It'd be easy enough to add an argument to the method
> which passes indicating the kind of adjustment.  Off hand, I think a
> tri-state value makes sense:

right.

>     1) the adjustment can potentially alter expected behavior making
>        user warnings manditory.  E.g, FR-V architecture constraints.
> 
>     2) benign, the breakpoint's location has been moved slightly,
>        but there should be no change in expected behavior.  Perhaps
>        an informational message could be displayed for this state.
>        E.g.  - maybe - that old v850 problem that Gary Thomas once
>        told us about in which he had to sometimes place breakpoints
>        that were larger than the smallest instruction.
> 
>     3) the adjustment was necessary because to place a breakpoint on
>        the original address is wrong.  E.g, function descriptors -
>        it makes no sense to place a breakpoint on the function descriptor,
>        but it does make sense to place a breakpoint on the code address
>        that the descriptor points to.

or:

	if (the architecture can adjust things)
	  adjust
	  if (the architecture thinks the adjustment is weird)
	    warning

A follow-on change can refine it.

Andrew