[LLVMdev] LLD improvement plan

[Joerg Sonnenberger]

On Mon, May 04, 2015 at 12:52:55PM -0700, Chris Lattner wrote:
> I think the problem here is that these lead to natural and inescapable
> tensions, and Alex summarized how Camp B has been steering LLD away
> from what Camp A people want.  This isn’t bad in and of itself, because
> what Camp B wants is clearly and unarguably good for LLVM.  However,
> it is also not sufficient, and while innovation in the linker space
> (e.g. a new “native” object file format generated directly from
> compiler structures) may or may not actually “work” or be “worth it”,
> we won’t know unless we try, and that won’t fulfill its promise if
> there are compromises to Camp B.

It has been said in this thread before, but I fail to see how the atom
model is an actual improvement over the fine grained section model. It
seems to be artifically restricted for no good reasons.

> Lets stop thinking about lld as one linker, and instead think of it is
> two different ones.  We’ll build a Camp B linker which is the best of
> breed section based linker.  It will support linker scripts and do
> everything better than any existing section based linker.  The first
> step of this is to do what Rui proposes and rip atoms out of the model.

This is another item that has been irritating me. While it is a very
laudable goal to not depend on linker scripts for the common case, not
having the functionality of fine grained output control is certainly a
problem. They are crucial for embedded developers and also at least
significant for anything near a system kernel.

> We will also build a no-holds-barred awesome atom based linker that
> takes advantage of everything it can from LLVM’s architecture to enable
> innovative new tools without worrying too much about backwards
> compatibility.

I'd say that a good justificatiton for way an atom based linker is/can
be better would be a good start...

Joerg