Add support for allowing us to create uniquely identified "COMDAT" or "ELF
Group" sections while lowering. In particular, for ELF sections this is
useful for creating function-specific groups that get merged into the
same named section.

Also use const Twine& instead of StringRef for the getELF functions
while we're here.

Differential Revision: http://reviews.llvm.org/D21743

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274336 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed