On Nov 24, 2007, at 1:54 PM, Alexandre Oliva wrote:
On Nov 16, 2007, Basile STARYNKEVITCH <[EMAIL PROTECTED]>
wrote:
For example, the "simple" plugin mechanism many people have
implicitly
in mind is just: something give you the ability to call a dlsymed
function inside a dlopened plugin as a pass in a defined (& fixed)
position in passes.c. I tend to believe it is not that difficult to
implement (it seems to me that the issue is to get it accepted in the
trunk). However, this does not guaranty at all that all the internal
representation (e.g. the tree.h and other header files) is stable.
Exactly. And I guess some of this could even be accomplished with
LD_PRELOAD. But how useful would that be, really? How far would this
go into addressing the real needs that are behind the requests for
plugin support?
Full "plugin support" really encompasses more than having GCC just
being able to dlopen a .so file. It means providing (hopefully) well
defined extension points for common operations. For example, it
should be relatively easy to load a plugin that defines a new tree-ssa
pass, and have it get dropped naturally into the pass manager.
Alternatively, you could have an extension point for "gimple
consumers" that don't care about the optimizer or backend, but just
want a way to parse the code and deal with the gimple or generic
trees. Examples of this would be static analysis tools or things like
the "FFI generator" for scripting languages.
To me personally, I'm looking forward to this happening because it
means that "llvm-gcc" could conceptually just become a plugin into a
standard GCC: the llvm-gcc plugin would use exactly the same extension
point as the "static analysis tools" (it doesn't care about the GCC
optimizer or backend, so it just wouldn't use it). This would make it
potentially easier to deploy the llvm-gcc binary (it's a plugin for a
specific gcc, instead of an entire copy of gcc itself), and it would
potentially make it easier to keep the tree up to date as GCC moves
forward. For the record, I'm fine everything being GPL, the license
is not the issue.
-Chris
