Re: Interests in a breakpoint hook/breakpoint op patch?

[liam mail <liam.list@...>]

On 20 April 2012 15:52, Thomas Jericke <tjericke@indel.ch> wrote:
> For our project I have modified the Lua interpreter to support a new hook
> type (breakpoint hook) which is called every time the interpreter hits a
> breakpoint op.
> I could turn my modifications into a patch but I still need some work to do
> to have a general solution. My current solution is very adapted to my own
> needs. And as it is, the implementation should be improved as well.
> Basically I added another type of hooks that can be used with lua_sethook.
> Additionally I added a function to add a breakpoint at a source and
> linenumber. This function searches for the proto of the according source
> code and linenumber and then replaces the op_code at the first bytecode to
> op_breakpoint. Once the pc runs to such a op_breakpoint the hook is called
> (if it is installed) after the hook returns, the original op is executed.
> The reason for this patch is performance only. We tried the current Lua
> debuggers which use the line hook and it wasn't performing fast enough to
> use it with our system. With the breakpoint hook the impact on the runtime
> is close to zero as long as you don't hit a breakpoint. There is a quite big
> overhead when you install a breakpoint but this is not such a big problem as
> usually the user doesn't change his breakpoints all the time.
> Now as I said, I would need to do some work before I can release such a
> patch, so I would only do that if someone is actually interested in using
> it.
>
> --
> Thomas
>
>

There was such a patch last year sometime from the LightRoom team IIRC.
What I would like is for Rio Lua is to either include such an operator
or maybe simply not falling through the vm loop on an unknown
instruction and instead calling the debug hook if one is present.

Liam