[PATCH] D80932: [SYCL] Make default address space a superset of OpenCL address spaces.

Wed Jun 10 12:13:42 PDT 2020

Anastasia added a subscriber: rjmccall.
Anastasia added a comment.

In D80932#2083185 <https://reviews.llvm.org/D80932#2083185>, @bader wrote:

> In D80932#2080631 <https://reviews.llvm.org/D80932#2080631>, @Anastasia wrote:
>
> > > @Anastasia, if we make this change specific to SYCL mode, will it address your concerns?
> >
> > I can't answer this question for the reasons I have explained above.
>
>
> Sorry, I'm not sure that I get your concern correctly, so let me clarify: is it allowing conversion between pointers w/ and w/o address space annotation in non-SYCL mode or using OpenCL address space attributes in SYCL mode?
>
> Just to help you to understand the proposed design, I created the full patch for address space handling in SYCL: https://github.com/bader/llvm/pull/18. There are few CodeGen tests validating LLVM IR for SPIR target. Fee free to ask any questions on this PR.

Thanks! This is good but it is only an implementation of the design. Deducing the design from an implementation is time-consuming and not sure it is even feasible. I don't want to waste our time to provide you detailed feedback based on my interpretation of your design and invalid assumptions. I don't want to bind you to any particular format and we don't have any strict requirement for this in LLVM either, but I would encourage you to take a look at some of RFC threads sent to cfe-dev that explain new design concepts. Perhaps, they can help you to understand what information can be provided as a starting point to new design discussions.

Particularly I would suggest covering these two points:

- SYCL specifies address spaces as classes and it is not very obvious how did you come from libraries classes to modifications in Clang? I believe there are a number of design choices that you could make. One might think that you can just implement address space classes using existing Clang functionality. But if it is not sufficient it is important to understand what modifications are required and why.

- Other aspects that are important to highlight whether your design has any limitations. For example, I don't quite understand your need for `SPIR*SYCLDeviceTargetInfo`. Is there anything in your design that limits compilation to one particular target?

Overall, I see that there are a lot of changes in CodeGen that are related to the language semantic. I believe that CodeGen is supposed to be dialing primarily with target-specific logic and I don't know if you should change them to query target specific details instead. Also most of your CodeGen changes are not related to OpenCL so I would make sure to loop @rjmccall in this thread.

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https://reviews.llvm.org/D80932