Sean Callanan wrote:
1- Agree on a common API and document it in
http://gcc.gnu.org/wiki/GCC_PluginAPI
So to get the ball rolling, here are some comments on the API as
documented:
-
(1) register_callback is an unnecessary API. It's already possible to
use dlsym() to get a pointer to a symbol in a plug-in. A plug-in
could export a function symbol corresponding to each hook it is
interested in; that way a plug-in would simply have things like
void HOOK_PASS_MANAGER_SETUP(...)
instead of needing to register that callback. Equivalently, a global
data structure in the plug-in could map hook UIDs to function
pointers, giving the same effect. This latter approach would provide
very elegant hook versioning.
Sounds good to me.
(2) It would be very nice to be able to store trees between passes;
right now, our custom version of GCC has a separate garbage-collection
root for plug-ins so that they can store data between passes.
Cool, we'd like that too.
(3) The -fplugin-arg argument is one way to do arguments. We do it as
-ftree-plugin=/path/to/plugin.so:arg=value:arg=value:...
We also have a magic argument called FILE that lets you load arguments
from a file.
I think it's a little more convenient to use a separate argument for
plugin arguments. However we still end up having to split that up into
multiple arguments in many case, so you are probably right here too.
(4) We strongly support the user () GCC attribute.
-
As a second note, we have some debugging tools we could contribute as
soon as an API is fixed, including a GIMPLE visualizer with GDB
integration.
We also have a file (called parameter.def) which formalizes the macros
that are valid for each type of GIMPLE tree node. We use this .def
file extensively when handling trees in a generic way (such as for
pretty-printing).
Interesting. I took a completely opposite way of using GTY tags to
reflect GIMPLE into JavaScript, which then pretty-prints GIMPLE(among
other things) by porting the said macros to JS.
https://developer.mozilla.org/en/Treehydra
However any formalization should make my life easier.
Sean, I agree with you and I think others will too, so please go ahead
and make your API modifications on the wiki
Taras
