[RFC] C++ vs forced unwinding
Wed Apr 2 17:15:00 GMT 2003
Richard Henderson wrote:
>Does it help to know that ia64 and x86_64 *always* include
>unwind tables, and so it will continue to "just work" there? ;-)
Same on s390(x) ...
>Really, I think it's about time to revisit re-enabling unwind
>tables by default in C. The overhead when using current
>binutils and glibc has dropped to just about zero.
Plus you get the advantage that you don't need to maintain
a stack backchain (frame pointer links etc.) at run time
any more, while still being able to get backtraces.
There's just two things that really should be fixed:
- gcc's __builtin_return_address / __builtin_frame_address should be
using unwind tables instead of hardcoded assumptions about just how
a frame link is stored
- glibc's backtrace () likewise
(The latter looks easy; not sure about the former ...)
Mit freundlichen Gruessen / Best Regards
Dr. Ulrich Weigand
Linux for S/390 Design & Development
IBM Deutschland Entwicklung GmbH, Schoenaicher Str. 220, 71032 Boeblingen
Phone: +49-7031/16-3727 --- Email: Ulrich.Weigand@de.ibm.com
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