[clang] [llvm] [clang] [OpenMP] New OpenMP 6.0 self_maps clause - CodeGen (PR #134131)

[via llvm-commits]

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@@ -236,6 +236,8 @@ enum class OpenMPOffloadMappingFlags : uint64_t {
   // dynamic.
   // This is an OpenMP extension for the sake of OpenACC support.
   OMP_MAP_OMPX_HOLD = 0x2000,
+  /// Self directs mapping without creating a separate device copy.
+  OMP_MAP_SELF = 0x4000,
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Ritanya-B-Bharadwaj wrote:

Right, I get that OMP_MAP_LITERAL just passes the pointer(or anything that fits into a register as you mentioned) as is, without changing anything.  But the problem is, it doesn’t guarantee that the memory it points to is actually accessible on the device. OMP_MAP_SELF explicitly states that the memory is already available on the device and avoids unnecessary mappings. The idea was to avoid unnecessary copies, especially for USM. 
If there’s another way to handle this cleanly, I’m open to discussing it. Please let me know. 

https://github.com/llvm/llvm-project/pull/134131