Re: Post-mortem debugging and abort

[David Kastrup]

"Lennart Borgman (gmail)" <address@hidden> writes:

> Richard M Stallman wrote:
>> Perhaps the GCC manual should say more about the importance of
>> -fno-cross-jump for debugging.  If you write a patch to it,
>> then if I like it, I will send it to the GCC maintainers.
>
> Wouldn't it also be good to add some of the thoughts David had to
> etc/DEBUG? That could save time for other people and also be used as a
> source when trying to discuss this with the GCC maintainers.

etc/DEBUG contains

    ** When you are trying to analyze failed assertions, it will be
    essential to compile Emacs either completely without optimizations or
    at least (when using GCC) with the -fno-crossjumping option.  Failure
    to do so may make the compiler recycle the same abort call for all
    assertions in a given function, rendering the stack backtrace useless
    for identifying the specific failed assertion.

It is a bit too weak in that the compiler nowadays will recycle the same
abort call for all assertions in a given _compilation unit_ I think.  So
the stack frame might not even belong at all to the function that called
abort just by proxy.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum