[clang] [llvm] [AMDGPU] Introduce asyncmark/wait intrinsics (PR #180467)

[via cfe-commits]

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@@ -975,6 +999,14 @@ class WaitcntBrackets {
   // Store representative LDS DMA operations. The only useful info here is
   // alias info. One store is kept per unique AAInfo.
   SmallVector<const MachineInstr *> LDSDMAStores;
+
+  // State of all counters at each async mark encountered so far.
+  SmallVector<CounterValueArray> AsyncMarks;
+  static constexpr unsigned MaxAsyncMarks = 16;
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vporpo wrote:

1. It looks like AsyncMarks is size-limited in some cases and the size limit is MaxAsyncMarks. Please use a data structure that enforces the size limit internally instead of using a SmallVector and handling this manually.
2. Why 16? Please explain in a comment.

https://github.com/llvm/llvm-project/pull/180467