[clang] [Clang][C++23] Implement P1774R8: Portable assumptions (PR #81014)

[via cfe-commits]

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@@ -1996,6 +1996,30 @@ Here is an example:
   }];
 }
 
+def AssumeDocs : Documentation {
+  let Category = DocCatStmt;
+  let Heading = "assume";
+  let Content = [{
+The ``assume`` attribute is used to indicate to the optimizer that a
+certain condition can be assumed to be true at a certain point in the
+program. If this condition is violated at runtime, the behavior is
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cor3ntin wrote:

Do we want to add some caveat to the docs?

"Note that due to the way the optimizer works, [[assume]] can affect performance negatively. It should be used with parsimony and care"

https://github.com/llvm/llvm-project/pull/81014