[mach-o] Add support for interposing tuples section

Darwin uses two-level-namespace lookup for symbols which means the static
linker records where each symbol must be found at runtime.  Thus defining a
symbol in a dylib loaded earlier will not effect where symbols needed by
later dylibs will be found.  Instead overriding is done through a section
of type S_INTERPOSING which contains tuples of <interposer, interposee>.

llvm-svn: 221421

1 files changed, 2 insertions, 0 deletions

diff --git a/lld/lib/ReaderWriter/MachO/MachONormalizedFileToAtoms.cpp b/lld/lib/ReaderWriter/MachO/MachONormalizedFileToAtoms.cpp
index 54899b00a0f..ec66d480833 100644
--- a/lld/lib/ReaderWriter/MachO/MachONormalizedFileToAtoms.cpp
+++ b/lld/lib/ReaderWriter/MachO/MachONormalizedFileToAtoms.cpp
@@ -77,6 +77,8 @@ const MachORelocatableSectionToAtomType sectsToAtomType[] = {
   ENTRY("__DATA", "___bss",           S_ZEROFILL,         typeZeroFill),
   ENTRY("",       "",                 S_NON_LAZY_SYMBOL_POINTERS,
                                                           typeGOT),
+  ENTRY("__DATA", "__interposing",    S_INTERPOSING,      typeInterposingTuples),
+  ENTRY("",       "",                 S_INTERPOSING,      typeInterposingTuples),
   ENTRY("__LD",   "__compact_unwind", S_REGULAR,
                                                          typeCompactUnwindInfo),
   ENTRY("",       "",                 S_REGULAR,          typeUnknown)