Modifying gcc.

[Niko Matsakis <niko@xxxxxxxxxxxx>]

I am trying to write a modification to gcc to support native 
coroutines; this is mostly for my own amusement, but if it works out 
well perhaps it will be useful to other people as well.

I have a couple of questions maybe people here can help me with:

- Is there a switch to dump the IR from the compiler between passes / 
enable debug out?  I remember I found one a long time ago, but I've 
forgotten where.

- The only guide to gcc internals I have found is

	http://gcc.gnu.org/onlinedocs/gccint/

Are there other documents I should be looking at?  I am hoping for 
something that shows each pass of the compiler, explains which IR is in 
use at that time, etc.

That guide brings up a few questions for me though:

- It mentions GENERIC, GIMPLE, C/C++ Trees, and RTL as various IRs of 
the gcc compiler.  I cannot find anything in the source that references 
GIMPLE or GENERIC; I just did "find . -name '*.[ch]' | xargs grep -i 
GIMPLE" and nothing came up.  Am I missing something?

Let me know if this is not the right list for these kind of questions, 
'cause I'm sure I'll have a bunch more. :)


Niko