[llvm] IR: Add !nofpclass metadata (PR #177140)

[Nikita Popov via llvm-commits]

================
@@ -7448,6 +7448,37 @@ Examples:
     !2 = !{ i8 0, i8 2, i8 3, i8 6 }
     !3 = !{ i8 -2, i8 0, i8 3, i8 6 }
 
+
+.. _nofpclass-metadata:
+
+'``nofpclass``' Metadata
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+``nofpclass`` metadata may be attached only to ``load``
+instructions. It asserts floating-point value classes which will not
+be loaded. The representation is an i32 constant integer encoding a
+10-bit bitmask, with the same meaning and format as the
+:ref:`nofpclass <nofpclass>` attribute. If the loaded value is one of
+the specified floating-point classes, a poison value is returned. The
+intrepretation does not depend on the floating-point environment. A
----------------
nikic wrote:

```suggestion
interpretation does not depend on the floating-point environment. A
```

https://github.com/llvm/llvm-project/pull/177140