[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:

The `ReadOnly<ArgIndex<0>` part is still wrong as discarding dirty cache is technically a write.
hasSideEffects may supercede it, but I would not bet on it.

Considering that we do not have a good way to express exactly how this intrinsic affects the memory, I would remove the `IntrArgMemOnly, ReadOnly<ArgIndex<0>>` altogether.



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