[llvm] [IR] Initial introduction of memset_pattern (PR #97583)

[Nikita Popov via llvm-commits]

================
@@ -15230,6 +15230,64 @@ The behavior of '``llvm.memset.inline.*``' is equivalent to the behavior of
 '``llvm.memset.*``', but the generated code is guaranteed not to call any
 external functions.
 
+.. _int_memset_pattern:
+
+'``llvm.memset.pattern``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+This is an overloaded intrinsic. You can use ``llvm.memset_pattern`` on
+any integer bit width that is an integral number of bytes and for different
+address spaces. Not all targets support all bit widths however.
+
+::
+
+      declare void @llvm.memset.pattern.p0.i64.i128(ptr <dest>, i128 <val>,
----------------
nikic wrote:

```suggestion
      declare void @llvm.memset.pattern.p0.i128.i64(ptr <dest>, i128 <val>,
```
I think the right mangling order is this?

https://github.com/llvm/llvm-project/pull/97583