MachO: Add comments describing section flags/attrs

When pruning superfluous MachO structure definitions, I chose to keep
the most generically useful which is why Support's definitions won over
the ones in MC.

However, the MC copy had some useful comments describing some of the
field values.

Bring these back to the copy in Support.  While doing this, fill in some
of the underdocumented definitions as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209066 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 48 insertions, 0 deletions

diff --git a/include/llvm/Support/MachO.h b/include/llvm/Support/MachO.h
index ef06a41392..2a0fc7bfe0 100644
--- a/include/llvm/Support/MachO.h
+++ b/include/llvm/Support/MachO.h
@@ -153,27 +153,59 @@ namespace llvm {
     enum SectionType : uint32_t {
       // Constant masks for the "flags[7:0]" field in llvm::MachO::section and
       // llvm::MachO::section_64 (mask "flags" with SECTION_TYPE)
+
+      /// S_REGULAR - Regular section.
       S_REGULAR                             = 0x00u,
+      /// S_ZEROFILL - Zero fill on demand section.
       S_ZEROFILL                            = 0x01u,
+      /// S_CSTRING_LITERALS - Section with literal C strings.
       S_CSTRING_LITERALS                    = 0x02u,
+      /// S_4BYTE_LITERALS - Section with 4 byte literals.
       S_4BYTE_LITERALS                      = 0x03u,
+      /// S_8BYTE_LITERALS - Section with 8 byte literals.
       S_8BYTE_LITERALS                      = 0x04u,
+      /// S_LITERAL_POINTERS - Section with pointers to literals.
       S_LITERAL_POINTERS                    = 0x05u,
+      /// S_NON_LAZY_SYMBOL_POINTERS - Section with non-lazy symbol pointers.
       S_NON_LAZY_SYMBOL_POINTERS            = 0x06u,
+      /// S_LAZY_SYMBOL_POINTERS - Section with lazy symbol pointers.
       S_LAZY_SYMBOL_POINTERS                = 0x07u,
+      /// S_SYMBOL_STUBS - Section with symbol stubs, byte size of stub in
+      /// the Reserved2 field.
       S_SYMBOL_STUBS                        = 0x08u,
+      /// S_MOD_INIT_FUNC_POINTERS - Section with only function pointers for
+      /// initialization.
       S_MOD_INIT_FUNC_POINTERS              = 0x09u,
+      /// S_MOD_TERM_FUNC_POINTERS - Section with only function pointers for
+      /// termination.
       S_MOD_TERM_FUNC_POINTERS              = 0x0au,
+      /// S_COALESCED - Section contains symbols that are to be coalesced.
       S_COALESCED                           = 0x0bu,
+      /// S_GB_ZEROFILL - Zero fill on demand section (that can be larger than 4
+      /// gigabytes).
       S_GB_ZEROFILL                         = 0x0cu,
+      /// S_INTERPOSING - Section with only pairs of function pointers for
+      /// interposing.
       S_INTERPOSING                         = 0x0du,
+      /// S_16BYTE_LITERALS - Section with only 16 byte literals.
       S_16BYTE_LITERALS                     = 0x0eu,
+      /// S_DTRACE_DOF - Section contains DTrace Object Format.
       S_DTRACE_DOF                          = 0x0fu,
+      /// S_LAZY_DYLIB_SYMBOL_POINTERS - Section with lazy symbol pointers to
+      /// lazy loaded dylibs.
       S_LAZY_DYLIB_SYMBOL_POINTERS          = 0x10u,
+      /// S_THREAD_LOCAL_REGULAR - Thread local data section.
       S_THREAD_LOCAL_REGULAR                = 0x11u,
+      /// S_THREAD_LOCAL_ZEROFILL - Thread local zerofill section.
       S_THREAD_LOCAL_ZEROFILL               = 0x12u,
+      /// S_THREAD_LOCAL_VARIABLES - Section with thread local variable
+      /// structure data.
       S_THREAD_LOCAL_VARIABLES              = 0x13u,
+      /// S_THREAD_LOCAL_VARIABLE_POINTERS - Section with pointers to thread
+      /// local structures.
       S_THREAD_LOCAL_VARIABLE_POINTERS      = 0x14u,
+      /// S_THREAD_LOCAL_INIT_FUNCTION_POINTERS - Section with thread local
+      /// variable initialization pointers to functions.
       S_THREAD_LOCAL_INIT_FUNCTION_POINTERS = 0x15u,
 
       LAST_KNOWN_SECTION_TYPE = S_THREAD_LOCAL_INIT_FUNCTION_POINTERS
@@ -182,18 +214,34 @@ namespace llvm {
     enum : uint32_t {
       // Constant masks for the "flags[31:24]" field in llvm::MachO::section and
       // llvm::MachO::section_64 (mask "flags" with SECTION_ATTRIBUTES_USR)
+
+      /// S_ATTR_PURE_INSTRUCTIONS - Section contains only true machine
+      /// instructions.
       S_ATTR_PURE_INSTRUCTIONS   = 0x80000000u,
+      /// S_ATTR_NO_TOC - Section contains coalesced symbols that are not to be
+      /// in a ranlib table of contents.
       S_ATTR_NO_TOC              = 0x40000000u,
+      /// S_ATTR_STRIP_STATIC_SYMS - Ok to strip static symbols in this section
+      /// in files with the MY_DYLDLINK flag.
       S_ATTR_STRIP_STATIC_SYMS   = 0x20000000u,
+      /// S_ATTR_NO_DEAD_STRIP - No dead stripping.
       S_ATTR_NO_DEAD_STRIP       = 0x10000000u,
+      /// S_ATTR_LIVE_SUPPORT - Blocks are live if they reference live blocks.
       S_ATTR_LIVE_SUPPORT        = 0x08000000u,
+      /// S_ATTR_SELF_MODIFYING_CODE - Used with i386 code stubs written on by
+      /// dyld.
       S_ATTR_SELF_MODIFYING_CODE = 0x04000000u,
+      /// S_ATTR_DEBUG - A debug section.
       S_ATTR_DEBUG               = 0x02000000u,
 
       // Constant masks for the "flags[23:8]" field in llvm::MachO::section and
       // llvm::MachO::section_64 (mask "flags" with SECTION_ATTRIBUTES_SYS)
+
+      /// S_ATTR_SOME_INSTRUCTIONS - Section contains some machine instructions.
       S_ATTR_SOME_INSTRUCTIONS   = 0x00000400u,
+      /// S_ATTR_EXT_RELOC - Section has external relocation entries.
       S_ATTR_EXT_RELOC           = 0x00000200u,
+      /// S_ATTR_LOC_RELOC - Section has local relocation entries.
       S_ATTR_LOC_RELOC           = 0x00000100u,
 
       // Constant masks for the value of an indirect symbol in an indirect