[llvm] [AMDGPU] Improve the description of asyncmark semantics (PR #202579)

[Sameer Sahasrabuddhe via llvm-commits]

================
@@ -57,49 +55,54 @@ memory and LDS memory.
   void @llvm.amdgcn.tensor.load.to.lds(...)
   void @llvm.amdgcn.tensor.store.from.lds(...)
 
-Asyncmark Operations
----------------------
+Asyncmarks
+----------
 
 An *asyncmark* in the abstract machine tracks all the async operations that
-are *program-ordered* before that asyncmark. An asyncmark M is said to be *completed*
-only when all async operations *program-ordered* before M are reported by the
-implementation as having finished, and it is said to be *outstanding* otherwise.
-
-Thus we have the following sufficient condition:
-
-  An async operation X is *completed* at a program point P if there exists an
-  asyncmark M such that X is *program-ordered* before M, M is *program-ordered* before
-  P, and M is completed. X is said to be *outstanding* at P otherwise.
+are *program-ordered* before that asyncmark.
----------------
ssahasra wrote:

Thanks for catching that! I was being very inconsistent with `po`. Now replaced that with appropriate `hb` edges.

https://github.com/llvm/llvm-project/pull/202579