llvm dev - Oct 2012 - [LLVMdev] Atomic ops cannot be built from C/OCaml bindings

Forgive me if I'm missing something obvious, but it seems that a
number of core instructions—I'm specifically running in to
`atomicrmw`, `fence`, and `cmpxchg` at the moment—cannot be
constructed from the C bindings, and are therefore also inaccessible
to the OCaml bindings. There are opcodes for each of these in the
llvm-c/Core.h, but there seems to be no way to construct them.

Is there a reason these should be omitted?

(I am currently running into this trying to use NVPTX, where CUDA
atomics are largely built from the native atomic instructions, in a
compiler written in OCaml.)

Thanks.

On Sep 14, 2012, at 4:53 PM, Jonathan Ragan-Kelley <jrk at csail.mit.edu>
wrote:
> Is there a reason these should be omitted?
Not in particular. Things are added to the C API as needed and usually on
demand.

-eric

How soon would I need to submit a patch for this for it to have a comfortable
shot at making it into the 3.2 release?


On Sep 14, 2012, at 8:05 PM, Eric Christopher <echristo at apple.com>
wrote:
> 
> On Sep 14, 2012, at 4:53 PM, Jonathan Ragan-Kelley <jrk at
csail.mit.edu> wrote:
> 
>> Is there a reason these should be omitted?
> 
> Not in particular. Things are added to the C API as needed and usually on
demand.
> 
> -eric

I finally got around to adding these.

The patch is posted in a pull request on my copy of llvm.git:

  https://github.com/jrk/llvm/pull/3

and a simple test with OCaml is here:

  https://gist.github.com/3948460

Feedback welcome.

On Sep 14, 2012, at 7:53 PM, Jonathan Ragan-Kelley <jrk at csail.mit.edu>
wrote:
> Forgive me if I'm missing something obvious, but it seems that a
> number of core instructions—I'm specifically running in to
> `atomicrmw`, `fence`, and `cmpxchg` at the moment—cannot be
> constructed from the C bindings, and are therefore also inaccessible
> to the OCaml bindings. There are opcodes for each of these in the
> llvm-c/Core.h, but there seems to be no way to construct them.
> 
> Is there a reason these should be omitted?
> 
> (I am currently running into this trying to use NVPTX, where CUDA
> atomics are largely built from the native atomic instructions, in a
> compiler written in OCaml.)
> 
> Thanks.

Take two, since I didn't hear anything last time I posted about this.

I have rebased the patch onto the trunk as of a few minutes ago and am
attaching it here as a patch. I'd really like to see this go in before
3.2.

test_llvm_atom.ml is a standalone OCaml program which uses the new
interface to generate a bunch of atomic ops. It need not be included
in the repository, I'm just adding it here to help anyone who wants to
sanity check the bindings.

Thanks!

On Wed, Oct 24, 2012 at 4:02 PM, Jonathan Ragan-Kelley
<jrk at csail.mit.edu> wrote:
> I finally got around to adding these.
>
> The patch is posted in a pull request on my copy of llvm.git:
>
>   https://github.com/jrk/llvm/pull/3
>
> and a simple test with OCaml is here:
>
>   https://gist.github.com/3948460
>
> Feedback welcome.
>
> On Sep 14, 2012, at 7:53 PM, Jonathan Ragan-Kelley <jrk at
csail.mit.edu> wrote:
>
>> Forgive me if I'm missing something obvious, but it seems that a
>> number of core instructions—I'm specifically running in to
>> `atomicrmw`, `fence`, and `cmpxchg` at the moment—cannot be
>> constructed from the C bindings, and are therefore also inaccessible
>> to the OCaml bindings. There are opcodes for each of these in the
>> llvm-c/Core.h, but there seems to be no way to construct them.
>>
>> Is there a reason these should be omitted?
>>
>> (I am currently running into this trying to use NVPTX, where CUDA
>> atomics are largely built from the native atomic instructions, in a
>> compiler written in OCaml.)
>>
>> Thanks.
>
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