[fpc-devel] Exceptions on wiki

[Sven Barth]

Kirinn <kirinn at mooncore.eu> schrieb am Mi., 1. Aug. 2018, 23:30:

> Hi all,
>
> Inspired by Gareth aka. Kit's infectious enthusiasm, and the recent long
> discussion on exceptions on this list, I wrote up an article on
> Exceptions on the FPC wiki. (Strangely enough we didn't have one before.)
>
> http://wiki.freepascal.org/Exceptions
>
> I hope it'll be useful, and not entirely inaccurate! Particularly the
> part about performance. If a programmer knows exactly what each
> exception statement inserts in the code, that should help in deciding
> when to worry about the performance, and when to embrace the convenience.
>

Please note that you can't generalize the performance impact as it depends
on the used exception handling mechanism. By default FPC uses
setjmp/longjmp which exhibit the behavior you described. On Win64 however
SEH is used which - in that platform - relies on metadata inside the binary
to mark the areas for a protected block (no matter whether it's for
"except" or "finally"). On Win32 with SEH enabled (which isn't the default
currently) it is again different. And should we decide to support DWARF
exception frames that would again be different.

Regards,
Sven

>
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