This revision adds comdat support to functions. Additionally,
it ensures only comdats that have uses are imported/exported and
only non-empty global comdat operations are created.
Reviewed By: Dinistro
Differential Revision: https://reviews.llvm.org/D153739
The LLVM comdat operation specifies how to deduplicate globals with the
same key in two different object files. This is necessary on Windows
where e.g. two object files with linkonce globals will not link unless
a comdat for those globals is specified. It is also supported in the ELF
format.
Differential Revision: https://reviews.llvm.org/D150796