[Libclc-dev] Beignet wants to apply libclc

[He Junyan]

On 二, 2014-09-16 at 10:33 -0400, Tom Stellard wrote:
> On Tue, Sep 16, 2014 at 09:26:27PM +0800, He Junyan wrote:
> > hi,
> > 
> > I am a developer of Intel's open source CL stack, which name is Beignet.
> > We used to include all the CL built-ins in one huge header file and
> > compile it as a PCH.
> > We find some disadvantages of that manner and switched to the same
> > manner as libclc recently. We now have a internal lib, which play the
> > same role as the libclc, and we are attempting to apply the libclc to
> > replace it in the near future.
> > But I find some problems when I try to integrate the libclc:
> > 1. There is no support for Image related functions in it now. Is that on
> > your plan?
> 
> libclc only supports GPU targets and these targets require target-specific
> implementations of the image functions, which is why there are no
> generic image functions.  If you were to use libclc for Intel GPUs, you
> would need to implement your own target specific image functions.
> 
OK, get it. The image module is really specific for each vendor and some
of them do not want to expose the HW details to the public.

> > 2. I find it is not compatible with OpenCL1.2, which Beignet must
> > support, are you going to implement it?
> 
> In what way is it not compatible?  The goal is to implement everything,
> but as far as I know no one has spent much time on OpenCL 1.2 features.
> 
The beignet has declared the full support for 1.2, but if we use clc, we
have to fallback to 1.1, this seems weird. 
So far as I know, there are really some changes for CL APIs between 1.1
and 1.2, but for the builtin functions and defines, the changes are not
so big. The major changes are: adding 1d image and sampler-less image
read functions, adding printf function, and adding extern and static
keyword support. And the image module is even not included in clc, so I
think this is not a big task to support 1.2, and I can do that job if
you do not mind.

> > 3. Because beignet as a backend does not completely follow the PTX or
> > NVPTX framework, it has a lot of internal implementations for the
> > builtin functions. We may need to add a lot of files for it, is that
> > acceptable?
> 
> Yes, if you are adding a new target with a lot of target specific
> implementations, then it is not a problem if there are a lot of files.
> 
OK, I will consider how to integrate our implementation and maximize the
use of the clc's code.

> -Tom
> 
> > 
> > 
> > Thanks
> > 
> > 
> > 
> > 
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