[llvm] [NVPTX] Add Intrinsics for discard.* (PR #128404)

[Artem Belevich via llvm-commits]

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@@ -5043,6 +5043,15 @@ def int_nvvm_prefetch_global_L2_evict_last: Intrinsic<[], [llvm_global_ptr_ty],
 def int_nvvm_prefetchu_L1 : Intrinsic<[], [llvm_ptr_ty],
   [IntrArgMemOnly, ReadOnly<ArgIndex<0>>, NoCapture<ArgIndex<0>>]>;
 
+// Intrinsics for discard
+def int_nvvm_discard_global_L2 : DefaultAttrsIntrinsic<[], 
+    [llvm_global_ptr_ty, llvm_i64_ty], [IntrArgMemOnly, ReadOnly<ArgIndex<0>>, 
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Artem-B wrote:

I believe my original phrasing is correct.

If LLVM does track the size of data accessed by the pointer (e.g. we're pointing at an i32), then it would only consider those 4 bytes changed and we need additional constraint saying that we're changing more data than LLVM assumes.

If it does not make an assumption about the size of the affected data (and therefore assumes that anything in the same AS is affected), then reads-memory/writes-memory is sufficient.



https://github.com/llvm/llvm-project/pull/128404