[clang] [llvm] [Clang] Add __builtin_assume_dereferenceable to encode deref assumption. (PR #121789)

[Johannes Doerfert via llvm-commits]

================
@@ -2761,6 +2761,47 @@ etc.).
 
 Query for this feature with ``__has_builtin(__builtin_assume_separate_storage)``.
 
+``__builtin_assume_dereferenceable``
+-------------------------------------
+
+``__builtin_assume_dereferenceable`` is used to provide the optimizer with the
+knowledge that the pointer argument P is dereferenceable up to the specified
----------------
jdoerfert wrote:

```suggestion
knowledge that the pointer argument P is dereferenceable at least up to the specified
```

https://github.com/llvm/llvm-project/pull/121789