Re: [MinGW-dvlpr] _alloca/_chkstk??

[Luke D. <cod...@ho...>]

----- Original Message ----- 
From: "Danny Smith" <dan...@cl...>
To: "mingw-dvlpr" <min...@li...>
Sent: Tuesday, October 07, 2003 6:08 PM
Subject: [MinGW-dvlpr] _alloca/_chkstk??


> Does any one really know why GCC (and other windows compilers) insert
> code for checking stack when allocating more than a page?
>
> I can see where it would be useful with SEH exceptions (the OS throws an
> 0x80010001 exception if stack cannot be grown) but how else is needed?
>
> Danny

http://msdn.microsoft.com/library/en-us/vccore98/HTML/_core_.2f.gs.asp

I guess it is for efficiency to make page faults more predictable but it's
hard to imagine that it would have a significant effect. A number of smaller
stack frames could also cause a fault so I can't see that it would actually
be *needed* for correctness. Is there a particular reason to remove it
though, apart from when statically linking GCC-compiled objects with MSVC
programs or vice versa? (I'm thinking of the undefined references to
__alloca). It could be useful to have a GCC equivalent of "/Gs" to
optionally disable this feature, if there isn't one already.

Luke