[PATCH] D29110: LangRef: Document the allowed metadata dropping transforms.

[Mehdi AMINI via Phabricator via llvm-commits]

mehdi_amini added inline comments.


================
Comment at: llvm/docs/LangRef.rst:3959
+It is valid for a pass to drop metadata if it is attached to an instruction,
+but metadata attached to a module using named metadata may not be dropped,
+and metadata attached to a function or a global variable may only be dropped
----------------
What about writing:

```
A transformation is required to drop any metadata attachment that it does not know or know it can't preserve.
Currently there is an exception for metadata attachment to globals for '!type' and '!absolute_symbol' which can't be unconditionally dropped unless the global is itself deleted.
```



https://reviews.llvm.org/D29110