[GD-Windows] Re : Strange prolog function issue

[Emmanuel A. <e_a...@ya...>]

Hi,=20
=20
It only happens in release build. And as you said, I suspect a compiler bug=
.
=20
Actually, I don't understand when the compiler decide to switch to a differ=
ent prolog for the function, where ebp doesn't have the same meaning.
It is all fine as the function code knows the different ebp meaning, and ha=
s no trouble accessing local vars, but the exception handler seems not to b=
e aware of the change in the ebp meaning.
=20
Thanks for your help,=20
we send a mail to microsoft, we will wait for their anwser...
=20
Emmanuel

Ps : Kent, replying to your mails only replies to you, not to the list...=
=20

----- Message d'origine ----
De : Kent Quirk <ken...@co...>
=C3=80 : Emmanuel Astier <e_a...@ya...>; Game Development for MS Windo=
ws <gam...@li...>
Envoy=C3=A9 le : Mardi, 25 Juillet 2006, 6h09mn 40s
Objet : Re: [GD-Windows] Strange prolog function issue


Emmanuel Astier wrote:
> Hi all,=20
> =20
> =20
> I have here a very strange issue.
> =20
> We have a function using a local std::string, exceptions, and a alloca.
> =20
> When the exception is thrown, the unwind mecanism tries to delete the std=
::string, but it deletes it at a wrong address( there is a 0x590 offset ).
> =20
> <snip>=20
> =20
> I could not reproduce this ebp offset that makes the exception handler fa=
il in a small sample.=20
> So do you know in which case the compiler does not put esp in ebp, but pu=
t an offset in it ?
> And do you know how to fix it ( other than what we're doing : stopping us=
ing alloca with exceptions ), if it is a kind a known issue ?=20
>  =20

Does the bug occur in both debug and release builds? Have you tried=20
setting the optimization manually for that file?  In any large project,=20
I usually find a couple of files that drive some form of compiler bug=20
under full optimization, and I have to manually turn down the=20
optimization on that particular file or do some sort of special (heavily=20
commented!) adaptation, such as moving a function's location in the=20
source file, or in the header file. You might also try playing with a=20
couple of exception-related compiler switches. Compilers are complicated=20
beasts, and any project of a significant size is likely to drive a bug=20
or two.