This adds a Darwin x86_64 relocation encoding for a subtraction expression
where both symbols are "local", that is non-external symbols, and there is
no "base" for the symbols used in the expression, that is the section has
no non-temporary symbols. This case looks like this:
% cat local_reloc_A-B.s
.long 0
LB: .long 1
.long LA - LB - 4
.long 2
LA: .long 3
which llvm-mc will not encode without this patch, generates a "unsupported
local relocations in difference" error, but the Darwin assembler will
encode with relocation entries like this:
% otool -rv a.out l.out
a.out:
Relocation information (__TEXT,__text) 2 entries
address pcrel length extern type scattered symbolnum/value
00000008 False long False SUB False 1 (__TEXT,__text)
00000008 False long False UNSIGND False 1 (__TEXT,__text)
which is very similar to what is encoded when the symbols don't have the
leading 'L' and they are not temporary symbols. Which llvm-mc and the
Darwin assembler will encoded like this:
Relocation information (__TEXT,__text) 2 entries
address pcrel length extern type scattered symbolnum/value
00000008 False long True SUB False B
00000008 False long True UNSIGND False A
This is the missing relocation encoding needed to allow the Mach-O x86
Dwarf file and line table to be emitted. So this patch also removes the
TODO from the if() statement in MCMachOStreamer::Finish() that didn't
call MCDwarfFileTable::Emit() for 64-bit targets.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115389
91177308-0d34-0410-b5e6-
96231b3b80d8