Date: Thu, 31 Jan 2002 14:36:11 -0800 From: Bakul Shah <bakul@bitblocks.com> To: Jeroen Ruigrok/asmodai <asmodai@wxs.nl> Cc: arch@FreeBSD.ORG Subject: A C dialect called GCC C (was Re: __P macro question) Message-ID: <200201312236.RAA00395@renown.cnchost.com> In-Reply-To: Your message of "Thu, 31 Jan 2002 08:34:30 %2B0100." <20020131073430.GR22384@daemon.ninth-circle.org>
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> -On [20020130 20:45], Bakul Shah (bakul@bitblocks.com) wrote:
> >Similarly, if Terry were to make the changes to the FreeBSD
> >kernel to compile it with TenDRA (and make it work) at least
> >I would be very grateful to him -- I do think relying so much
> >on GCC is a bad idea but I am realistic (and lazy) enough to
> >not want to fix that on my own.
>
> As someone who has been hacking TenDRA for a while now and trying to get
> it up-to-date a bit, I can tell you FreeBSD is written in a C dialect
> called GCC C.
Yeah, I am well aware of it; which is why I raised this issue
+ the fact this is a much more serious issue than to __P or
not to __P!
I'd be interested to know what you found from your TenDRA
hacking. From what I know, the GCC-isms used are:
long long -- this is already in the C9x standard
__attribute -- the common use seems to be for better
type checking. I think one can live without this.
asm() -- this is different for different processors in
any case. But I agree some sort of asm support
will most likely be needed. Also, the ability
to mix C expressions as operands
inline -- needed for performance. Already in C9x.
typeof -- handy especially in macros but we can
live without this with an extra macro arg
where the type is passed in.
({...}) -- this is a way to declare local temp vars in an
expression. There is no need for this given
inline functions (though a bit more verbose)
int array[n] -- variable length array. This is in C9x.
// comments -- in C9x.
I am not sure the following extensions are used in the kernel:
alignment -- not sure if specifying alignment is needed in .c files
int x = y; -- non constant initializers. Need an _init() section
to deal with this.
a?:b -- lazy conditional. Handy but can do without
vararg macros -- this is in C9x in a slightly different form
computed goto -- labels as lvalues. Improves interpreter performance
but I doubt this is used in the kernel.
global registers
cast to unions
etc.
I am sure I have missed quite a few things but on first
glance it seems the work needed to use TenDRA for compiling
the kernel will also take it in the direction of C9x
compliance, which is a good thing. Until TenDRA comes close
to compiling the kernel there is no incentive for people to
not use gccisms let alone remove the existing ones.
-- bakul
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