Chris,
LLVM is an excellent piece of work,
LLVM is one of the few project I know that has used the
mysterious GCC front-end. I think it will be a great
contribution to the community if you could writeup and document how to
interface to
the GCC front-end data-structures (like LLVM has done). Specifically:
a) detail the gcc front-end tree data-structures
b) how to go about interfacing to them
c) what are changes that LLVM did to the gcc front end
My interest is to interface to gcc data-structures to produce an
open-source language
independent IL in Ocaml -- like LLVM but at a higher level suitable for program
analysis in Ocaml (like the CIL effort at berkeley -- note CIL folks developed
their C frontend from scratch -- a waste of effort when they could
have leveraged the gcc frontend)
Unfortunately there is very little documentation for the gcc front
end interface.
I have to spend a lot of time code-browsing the gcc code trying to
understand the
gcc code and data-structures. Since you have done this already,
I will really appreciate if you could document your efforts.
This will be a valuable contribution to the community since gcc is
the ONLY (and defacto standard) open-source compiler for C,C++,
and at the same time its front end interface is very poorly documented.
Thanks and Regards
On Sat, 10 Jul 2004, Ramu Ramamurthy wrote:> LLVM is an excellent piece of work,Thanks!> LLVM is one of the few project I know that has used the mysterious GCC > front-end. I think it will be a great contribution to the community if > you could writeup and document how to interface to the GCC front-end > data-structures (like LLVM has done). Specifically: > > a) detail the gcc front-end tree data-structures > b) how to go about interfacing to them > c) what are changes that LLVM did to the gcc front endWhile that would be a useful document, I don't think that anyone will be jumping to write it unfortunately. We all have plenty of other interesting things to do, and writing docs that makes it easier for people to not use LLVM is not a high-priority. :)> My interest is to interface to gcc data-structures to produce an > open-source language independent IL in Ocaml -- like LLVM but at a > higher level suitable for program analysis in Ocaml (like the CIL effort > at berkeley -- note CIL folks developed their C frontend from scratch -- > a waste of effort when they could have leveraged the gcc frontend)Ok.> Unfortunately there is very little documentation for the gcc front end > interface. I have to spend a lot of time code-browsing the gcc code > trying to understand the gcc code and data-structures. Since you have > done this already, I will really appreciate if you could document your > efforts.You could look a the llvmgcc source, or you could build on what we already have with LLVM. I'm not sure exactly what you hope to gain with a OCaml-like CIL, but I suspect that you can get 95% or more of the benefit by writing an OCaml backend for LLVM. Please read up on LLVM and get a clear understanding of what we can and can not do, you might be suprised. -Chris -- http://llvm.cs.uiuc.edu/ http://nondot.org/sabre/
Ramu, Let me second what Chris said. It's far easier to write an LLVM-to-NewIL translator (or LLVM-to-OCaml back-end), than a GCC-to-NewIL front-end. And that is if you have a compelling reason to invent a new IL and write new analyses and transformations for it, rather than using an existing IL and compiler system. --Vikram http://www.cs.uiuc.edu/~vadve http://llvm.cs.uiuc.edu/ On Jul 10, 2004, at 1:07 PM, Chris Lattner wrote:> On Sat, 10 Jul 2004, Ramu Ramamurthy wrote: > >> LLVM is an excellent piece of work, > > Thanks! > >> LLVM is one of the few project I know that has used the mysterious GCC >> front-end. I think it will be a great contribution to the community if >> you could writeup and document how to interface to the GCC front-end >> data-structures (like LLVM has done). Specifically: >> >> a) detail the gcc front-end tree data-structures >> b) how to go about interfacing to them >> c) what are changes that LLVM did to the gcc front end > > While that would be a useful document, I don't think that anyone will > be > jumping to write it unfortunately. We all have plenty of other > interesting things to do, and writing docs that makes it easier for > people > to not use LLVM is not a high-priority. :) > >> My interest is to interface to gcc data-structures to produce an >> open-source language independent IL in Ocaml -- like LLVM but at a >> higher level suitable for program analysis in Ocaml (like the CIL >> effort >> at berkeley -- note CIL folks developed their C frontend from scratch >> -- >> a waste of effort when they could have leveraged the gcc frontend) > > Ok. > >> Unfortunately there is very little documentation for the gcc front end >> interface. I have to spend a lot of time code-browsing the gcc code >> trying to understand the gcc code and data-structures. Since you have >> done this already, I will really appreciate if you could document your >> efforts. > > You could look a the llvmgcc source, or you could build on what we > already > have with LLVM. I'm not sure exactly what you hope to gain with a > OCaml-like CIL, but I suspect that you can get 95% or more of the > benefit > by writing an OCaml backend for LLVM. Please read up on LLVM and get a > clear understanding of what we can and can not do, you might be > suprised. > > -Chris > > -- > http://llvm.cs.uiuc.edu/ > http://nondot.org/sabre/ > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev
Ramu Ramamurthy wrote:> the GCC front-end data-structures (like LLVM has done). Specifically: > > a) detail the gcc front-end tree data-structuresEhm... I'm not sure that's reasonable because, 1. I might be mistaken, but LLVM uses gcc state from before merge of the tree-ssa branch, which has considerably changed internal representation 2. There's http://gcc.gnu.org/onlinedocs/gccint/ already. I don't know how good it is, but improving it is not something LLVM folks can do - Volodya