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Re: tail call optimization vs. debugging
- To: Geert Bosch <bosch at gnat dot com>
- Subject: Re: tail call optimization vs. debugging
- From: Richard Henderson <rth at cygnus dot com>
- Date: Sat, 25 Mar 2000 11:35:29 -0800
- Cc: Bruno Haible <haible at ilog dot fr>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- References: <20000325171727.D8EFD34D80@nile.gnat.com>
On Sat, Mar 25, 2000 at 12:18:25PM -0500, Geert Bosch wrote:
> Here are a few yes/no debugging questions that popped up for me:
> - Will function breakpoints be hit by a tail call or sibcall?
Yes.
> - In recursive functions, will printing arguments show the argument values
> of the last (recursive) call?
On pure tail calls, yes. The new arguments get put exactly where
they should have been for a normal call.
With tail recursion (which we had before, but will trigger more often
now) I can only say "probably". It's implemented with a goto internally,
so the optimizer has the chance to not put the new arguments in place.
> - Do cases where unbounded recursion (due to tail call optimizations)
> only show a few frames in a trace-back always use bounded stack space?
Eh? If I understand the question correctly, of course.
How else could it be a tail call optimization?
r~