On MachO platforms that use subsections-via-symbols dead code stripping will
drop prefix data. Unfortunately there is no great way to convey the relationship
between a function and its prefix data to the linker. We are forced to use a bit
of a hack: we give the prefix data it’s own symbol, and mark the actual function
entry an .alt_entry.
Patch by Moritz Angermann!
Differential Revision: https://reviews.llvm.org/D30770
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297804 91177308-0d34-0410-b5e6-96231b3b80d8
Peter Collingbourne