[libc-commits] [libc] [libc] Add utility functions for warp-level scan and reduction (PR #84866)

[Matt Arsenault via libc-commits]

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@@ -31,6 +31,25 @@ LIBC_INLINE bool is_first_lane(uint64_t lane_mask) {
   return gpu::get_lane_id() == get_first_lane_id(lane_mask);
 }
 
+/// Gets the sum of all lanes inside the warp or wavefront.
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arsenm wrote:

Also looks like the alternative implementations were never implemented. currently looks like we don't have the bpermute or DPP paths 

https://github.com/llvm/llvm-project/pull/84866