[LLVMdev] C Backend Ressurected

[Eric Christopher]

I can't see why you'd want to do this, no.

-eric


On Tue, Aug 19, 2014 at 8:02 PM, Isaac Dupree <
ml at isaac.cedarswampstudios.org> wrote:

> Is the C backend at all suitable to be adapted to emit OpenCL code?  Or
> do the target-dependence, and/or things that C can do but OpenCL can't,
> make that hopeless?
> -Isaac
>
> On 08/19/2014 03:08 PM, Carback, Richard T., III wrote:
> > It provides a useful starting point, but I agree with Jim that it is not
> > a complete solution and requires rework of the results in a lot cases. I
> > think we could improve it further to address these issues but that work
> > is nontrivial.
> >
> >
> >
> > If you are deciding between a quick and dirty implementation of a custom
> > backend vs. the C backend, then the C backend is sometimes preferable in
> > my experience although it depends on the complexity of the code you are
> > trying to run and how often you need to change it.
> >
> >
> >
> > *From:*llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu]
> > *On Behalf Of *Jim Grosbach
> > *Sent:* Tuesday, August 19, 2014 2:12 PM
> > *To:* Bruce Hoult
> > *Cc:* llvmdev at cs.uiuc.edu
> > *Subject:* Re: [LLVMdev] C Backend Ressurected
> >
> >
> >
> > This is part of the problem with the C backend. This is very much not
> > what it’s useful for, yet it very much looks like it is. The LLVM IR is
> > target dependent, including things like structure layout, pointer size,
> > and other ABI issues. Even with a resurrected C backend, you can’t use
> > it as a substitute for real target support.
> >
> >
> >
> > -Jim
> >
> >
> >
> >     On Aug 18, 2014, at 7:02 PM, Bruce Hoult <bruce at hoult.org
> >     <mailto:bruce at hoult.org>> wrote:
> >
> >
> >
> >     I don't know how good it is, but the applications seem obvious. e.g.
> >     compiling programs in any of a number of original formats to run
> >     natively on CPUs that have a working simple C compiler (maybe only
> >     K&R or C89) but don't have an LLVM back end.
> >
> >
> >
> >     The source program could be in modern C, C++, or any other high
> >     level language or assembly language with a translator to LLVM.
> >
> >
> >
> >     On Tue, Aug 19, 2014 at 1:40 PM, Jun Koi <junkoi2004 at gmail.com
> >     <mailto:junkoi2004 at gmail.com>> wrote:
> >
> >
> >
> >
> >
> >     On Mon, Aug 18, 2014 at 9:18 PM, Carback, Richard T., III
> >     <rcarback at draper.com <mailto:rcarback at draper.com>> wrote:
> >
> >         Hi All,
> >
> >
> >
> >         2 of my summer interns (Aimee Dipietro and Greg Simpson) used
> >         their time over the summer to resurrect the LLVM C Backend:
> >
> >
> >
> >         https://github.com/draperlaboratory/llvm-cbe
> >
> >
> >
> >         Improvements include recovery of simple for/while loops (instead
> >         of goto), better variable naming, inline asm support, and making
> >         it work on a more recent version of llvm. I believe they used
> >         the repository here as a starting point:
> >
> >
> >
> >         https://github.com/glycerine/llvm/tree/cbe_revival
> >
> >
> >
> >         Feedback is welcomed. I would like to see this feature put back
> >         into LLVM, and any help on how to make that happen would be
> >         appreciated.
> >
> >
> >
> >     would you mind explaining what this backend is for, and its
> >     applications?
> >
> >     i guess it is to get the C code at the output of the backend, but
> >     dont get why we need it.
> >
> >     thanks,
> >
> >     Jun
> >
> >
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> >
> >
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> >
> >
> >
> >
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