On Sat, 11 Sep 2010 22:19:06 +0800 (CST)
"Thinker K.F. Li" <thin...@codemud.net> wrote:
> Hi,
>
> I am try to make a plugin to analyze GIMPLE before genericize. It
> will insert some code defined by user into the tree. I want the user
> to specify the inserted code in C. For example,
>
> --------------------------------------------------
> {
> static int i=0;
>
> printf("Hello %d\n", i++);
> }
> --------------------------------------------------
>
> I try to find a way to make C language parser of GCC to compile it for
> me, and I will insert the code into the tree created from the main
> source. But, it seems provide only functions to parse a complete C
> source file, and I try to push a buffer to the reader of libcpp. But,
> it does not work.
I am not sure that there exist enough plugin hooks to do that (I am not sure
even if there are plugin hooks to front-ends in GCC). However, I do see some
way to perhaps implement what you suggest even in 4.5
First, don't think of your problem as adding C code. Think of it as adding
Gimple stuff into some Gimple representation.
(I believe it is a case of aspect oriented programming, see
http://en.wikipedia.org/wiki/Aspect-oriented_programming for more). But you
want the user to specify the added code, using the already accepted C syntax of
GCC (i.e. without hacking GCC parser).
So you could use attributes & pragmas or builtins for that purpose.
First, your user define its code snipped to insert as a C function with a
special attribute, e.g.
void say_hello(void) __attribute__((added_chunk));
void say_hello(void)
{
static int i;
printf("Hello %d\n", i++);
}
Then, your user would mark with another attribute every function into which
your chunk should be added, perhaps
int some_complex_function(int a, void*b)
__attribute((insert_chunk(say_hello)));
Or perhaps have a pragram asking this to insert the chunk in every function
whose name start with some_
#pragma GCCMELT insert_chunk_prefix(say_hello, some_)
The point here is that with the tricks above, you don't have to change GCC
parser! and you could implement that using a plugin coded in C (this is not so
simple, you have to filter Gimple). Better yet, you could implement that using
GCC MELT http://gcc.gnu.org/wiki/MELT which provides pattern matching
facilities on Gimple to make such tasks much simpler.
You still have to understand Gimple & Tree in detail and find a good position
in the pass machinery to insert your new pass or passes.
If you succeed in making such a plugin please tell us. I would be delighted if
you coded it in MELT, as a MELT extension.
Good luck.
--
Basile STARYNKEVITCH http://starynkevitch.net/Basile/
email: basile<at>starynkevitch<dot>net mobile: +33 6 8501 2359
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*** opinions {are only mine, sont seulement les miennes} ***
