jdoerfert added a comment. In D125378#3506383 <https://reviews.llvm.org/D125378#3506383>, @skc7 wrote:
> In D125378#3506215 <https://reviews.llvm.org/D125378#3506215>, @jdoerfert > wrote: > >> In D125378#3506001 <https://reviews.llvm.org/D125378#3506001>, @nikic wrote: >> >>> Please specify the semantics of the new LLVM attribute in LangRef -- though >>> I don't really understand why you need an LLVM-side attribute at all. >> >> +1. I doubt this patch is helpful. >> >>> Shuffle attribute has been added as per suggestions/comments from review: >>> D124158 <https://reviews.llvm.org/D124158> >> >> I failed to see where this was suggested. >> >> --- >> >> My suggestion was and still is summarized in: >> https://reviews.llvm.org/D124158#3486110 > > @jdoerfert I meant to convey that, As a solution to review comments from > D124158 <https://reviews.llvm.org/D124158>, introduced this shuffle attribute > to identify __shfl_sync like APIs. I'm confused. What is the Attribute in IR going to achieve? The problem is during clang codegen. I can see how the C++/Clang attribute part is useful but I would not call it "shuffle". 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: __attribute__((maybe_undef(0))) int __shfl_sync(int var, int src_lane, int width = warpSize); __attribute__((maybe_undef(var))) int __shfl_sync(int var, int src_lane, int width = warpSize); *OR* int __shfl_sync(int __attribute__((maybe_undef)) var, int src_lane, int width = warpSize); And the attribute will cause clang either not to place `noundef` or place `freeze` for the respective argument(s). CHANGES SINCE LAST ACTION https://reviews.llvm.org/D125378/new/ https://reviews.llvm.org/D125378 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
