Add a __LD,__compact_unwind section.

If the linker supports it, this will hold the CIE and FDE information in a
compact format. The implementation of the compact unwinding emission is coming
soon.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133658 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -605,6 +605,12 @@ void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
   // Exception Handling.
   LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
                                              SectionKind::getReadOnlyWithRel());
+
+  CompactUnwindSection =
+    getContext().getMachOSection("__LD", "__compact_unwind",
+                                 MCSectionMachO::S_ATTR_DEBUG,
+                                 SectionKind::getReadOnly());
+
   // Debug Information.
   DwarfAbbrevSection =
     getContext().getMachOSection("__DWARF", "__debug_abbrev",