[LLVMdev] Supporting heterogeneous computing in llvm.

[Christos Margiolas]

Hi Gerolf,

Thanks for the interest. I agree that this project may help in different
directions and this is the reason I tried to keep it modular and
independent of particular use cases.

--chris

On Fri, Jun 5, 2015 at 3:14 PM, Gerolf Hoflehner <ghoflehner at apple.com>
wrote:

> Hi Christos,
>
> your idea can certainly go very far, and the capability of extracting and
> executing one loop nest at a time should enable progress in multiple
> directions, among them fast performance evaluation of loop transformations
> and benefits of accelerators. It could also be useful for measuring and
> tuning off-loading overhead.
>
> Cheers
> Gerolf
>
> On Jun 5, 2015, at 3:01 AM, Christos Margiolas <chrmargiolas at gmail.com>
> wrote:
>
> Hi Gerolf,
>
> LLVM already has a Utility class for extracting loops to functions.
> However extracting code to a different module is something that is missing
> I think. Supporting a homogeneous variant is something I have considered
> and in fact the debug plugin I have written is a homogeneous variant. I
> "offload" to the same architecture. The idea could be further extended in a
> scheme where the offloaded code is loaded in a third process and the main
> process performs remote process calls. This would probably require
> extensive data transfers across the address spaces or a Memory Allocator
> that operates across the processes by using Inter-process shared memory.
>
> --chris
>
>
>
> On Thu, Jun 4, 2015 at 5:57 PM, Gerolf Hoflehner <ghoflehner at apple.com>
> wrote:
>
>> Hi,
>>
>> I can see even the homogenous variant of this to be useful. Just having
>> the capability of extracting loops and wrapping them into functions and/or
>> modules could help speeding up performance analysis and experiments. It
>> would also help with testing the basic infrastructure + heterogenous
>> environments.
>>
>>
>> Cheers
>> Gerolf
>>
>> On Jun 4, 2015, at 5:35 PM, Christos Margiolas <chrmargiolas at gmail.com>
>> wrote:
>>
>> Hello All,
>>
>> The last two months I have been working on the design and implementation
>> of a heterogeneous execution engine for LLVM. I started this project as an
>> intern at the Qualcomm Innovation Center and I believe it can be useful to
>> different people and use cases. I am planning to share more details and a
>> set of patches in the next
>> days. However, I would first like to see if there is an interest for
>> this.
>>
>> The project is about providing compiler and runtime support for the
>> automatic and transparent offloading of loop or function workloads to
>> accelerators.
>>
>> It is composed of the following:
>> a) Compiler and Transformation Passes for extracting loops or functions
>> for offloading.
>> b) A runtime library that handles scheduling, data sharing and coherency
>> between the
>> host and accelerator sides.
>> c) A modular codebase and design. Adaptors specialize the code
>> transformations for the target accelerators. Runtime plugins manage the
>> interaction with the different accelerator environments.
>>
>> So far, this work so far supports the Qualcomm DSP accelerator  but I am
>> planning to extend it to support OpenCL accelerators. I have also developed
>> a debug port where I can test the passes and the runtime without requiring
>> an accelerator.
>>
>>
>> The project is still in early R&D stage and I am looking forward for
>> feedback and to gauge  the interest level. I am willing to continue working
>> on this as an open source project and bring it to the right shape so it can
>> be merged with the LLVM tree.
>>
>>
>> Regards,
>> Chris
>>
>> P.S. I intent to join the llvm social in Bay Area tonight and I will be
>> more than happy to talk about it.
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>>
>>
>>
>
>
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