[PATCH] D125378: [Attribute] Introduce shuffle attribute to be used for __shfl_sync like cross-lane APIs

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added a comment.

In D125378#3506446 <https://reviews.llvm.org/D125378#3506446>, @jdoerfert wrote:

> What I would suggest, if you want to use C/C++ attributes (which makes sense to me), is an attribute that avoids undef or introduces frozen:

I would prefer to avoid this approach for the moment. Such an attribute is highly focused on how the backend works and I'm not convinced that users in general would know when or how to properly use it. I believe all of the functions which need to be marked are known, and so we can keep an internal list of "interesting" functions that need special attention during clang codegen. If we later find that there's a wider need that cannot be handled transparently like this, we can reevaluate what to expose to users via an attribute at that point.


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https://reviews.llvm.org/D125378