gfx940 and gfx941 are no longer supported. This is one of a series of
PRs to remove them from the code base.
This PR removes all non-documentation occurrences of gfx940/gfx941 from
the llvm directory, and the remaining occurrences in clang.
Documentation changes will follow.
For SWDEV-512631
The verifier ensures function !dbg metadata is unique across the module,
so ensure the old nameless function we leave behind doesn't violate
this invariant.
Removing the function via e.g. eraseFromParent seems like a better
option, but doesn't seem to be legal from a FunctionPass.