Hi all,
I'm pretty new to LLVM and am slowly learning the code-base and
architecture, mostly as a result of my efforts to implement a target
backend.
There are a number of resources (read: documents) available which deal
with some parts of backend development (and LLVM development in
general), but sadly they are not at all comprehensive.
I'd like to propose that a wiki be made available so that people who
work out how to do stuff can document their findings. I'd like to see
sections devoted to frontend, backend and misc. pass implementation,
with both explanations of how LLVM works under the hood, and 'recipes'
for common tasks/issues.
For example, I would be more than happy to write up a set of howtos
for the various questions and tasks I've encountered during my backend
development, ranging from a 'What's the bare minimum?' to more complex
issues like 'Implementing conditional branching' and 'calling
conventions', 'emitting binary (object) code' etc.
Thoughts?
someguy
I endorse. The current docs are far from complete, getting better though. An open wiki would enourage informal note writing of various issues, and those notes could later be cleaned and moved to the official docs if so wanted.
Hi all,
I'm pretty new to LLVM and am slowly learning the code-base and
architecture, mostly as a result of my efforts to implement a target
backend.
There are a number of resources (read: documents) available which deal
with some parts of backend development (and LLVM development in
general), but sadly they are not at all comprehensive.
I'd like to propose that a wiki be made available so that people who
work out how to do stuff can document their findings. I'd like to see
sections devoted to frontend, backend and misc. pass implementation,
with both explanations of how LLVM works under the hood, and 'recipes'
for common tasks/issues.
..
Thoughts?
I think it's a great idea, and I'm sure I can find some things to add as well.
We've had to go in and read the source code to LLVM many times during
the development of LDC (the D compiler), and lots of this have been
fairly simple stuff, where a few notes in a wiki could have saved us
time. It all adds up.
Especially one feature of LLVM that's extremely underdocumented,
inline assembler, has been very important for LDC, which needs inline
asm as it is part of the language specification. I've tried writing a
document proposal before but I didn't really find the time, and there
was still a lot of things I didn't (and don't) know how worked, so it
never got done. I can easily imagining starting a small wiki page to
collect some reference information though.
Cheers
-Tomas
I agree too. I'm working on an analysis pass and I could be adding info to a wiki as I discover how to do things.
Anthony
Glad to see there is support 
I'd love to get it up as soon as possible, so I can note the stuff I'm
doing now.
Who maintains the llvm servers?
Reid Spencer had set one up at one point, but it never got much traction. It seems to be broken at the moment:
http://wiki.llvm.org/
In principle, having a Wiki like this would be valuable. In practice, I think there will need to be some sanity checking to make sure incorrect or misleading information is not added to it.
The old Wiki below isn't up any more. We can set one up on llvm.org.
--Vikram
Associate Professor, Computer Science
University of Illinois at Urbana-Champaign
http://llvm.org/~vadve
Yes, I think a Wiki would be extremely valuable. I would particularly like to
see information on which aspects of LLVM have problems and what conflicts
exist (e.g. the first-class structs vs tail calls thing). I'm not sure how
such information could be organised though...
Probably there should be an "unreliable" section for those of us who want
to contribute but are newbies and might have understood something wrong.
Or at least a way to label something as "try this at your own risk" so to speak.
Anthony
I agree. Being a newbie myself, I can relate to what problems someone new to llvm would have.
While I think most of the stuff I have tried will be useful, I wouldn’t be entirely sure if its the best way to go about it.
Thanks
Nipun Arora
Columbia University
If we get the blessing of one of the old-timers who is willing to
spend a little time reviewing postings, we can deal with the
'misleading information' issue.
In addition, it might be _useful_ to understand why people were misled.
I don't consider the possibility of "misleading" information to be a big worry. It is no worse than having out of date "official" docs.
Ideally, useful sections of the wiki will periodically be merged back into the main docs.
-Chris
Except that official docs are written by people who really know what they are doing ("experts") whereas the whole point of this Wiki is for any user to contribute tips. Still, I'm happy to give it a try.
One procedural concern is how we can authenticate Wiki contributors since I've been told UI prohibits hosting Wiki pages with anonymous content (which is understandable). We will get back to you all on that. Unless of course someone else wants to volunteer to set one up.
--Vikram
Associate Professor, Computer Science
University of Illinois at Urbana-Champaign
http://llvm.org/~vadve
Except that official docs are written by people who really know what
they are doing ("experts") whereas the whole point of this Wiki is for
any user to contribute tips. Still, I'm happy to give it a try.
Just add a big banner to the top of the wiki. I think the internet world at large understands the caveats on relying on a wiki.
One procedural concern is how we can authenticate Wiki contributors
since I've been told UI prohibits hosting Wiki pages with anonymous
content (which is understandable). We will get back to you all on
that. Unless of course someone else wants to volunteer to set one up.
Ugh, that is annoying.
-Chris
Can't it just be hosted elsewhere if that's an issue?
As I said, I don't have a problem with that. We can just link it of the LLVM pages. But we need a volunteer with a reliable system.
--Vikram
Associate Professor, Computer Science
University of Illinois at Urbana-Champaign
http://llvm.org/~vadve
One more vote for an LLVM wiki! I really like that idea!
Anthony Danalis wrote:
Probably there should be an "unreliable" section for those of us who
want
to contribute but are newbies and might have understood something wrong.
Or at least a way to label something as "try this at your own risk" so
to speak.
I think a public/unmoderated wiki is always kind of unreliable. If a
section has been reviewed it should somehow find its way into the
official documentation (Tutorials/HowTos/etc). I would like to see a
wiki as a pre stage for the docs so that the community can discuss the
content of a topic and change it if necessary.
The wiki should be "try this at your own risk" at all.
Just my 2 cents.
Josef
Ugh, that is annoying.
Yeah, I think there were only 3 accounts in the past wiki: John's, Reid's and mine. The procedure of obtaining an account for non-UIUC person was not so easy, afair...
I can set it up on google1.osuosl.org if you guys want.
It's reliable (racked in a data center), etc.
If you wanted to cname it to wiki.llvm.org i can set up the apache
file to virtual host it.
Just name the wiki software you think we should use 
Anton Korobeynikov wrote:
Ugh, that is annoying.
Yeah, I think there were only 3 accounts in the past wiki: John's,
Reid's and mine. The procedure of obtaining an account for non-UIUC
person was not so easy, afair...
There's always wikispaces. Very easy to use. Or LLVM could have a shell
presence at Google Code and just have the wiki there. Also very easy to
operate (requires signup with a gmail account, though).