Support reading GNU symbol versions in ELFObjectFile

include/llvm/Support/ELF.h

 //===-- llvm/Support/ELF.h - ELF constants and data structures --*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This header contains common, non-processor-specific data structures and
@@ skipping 716 matching lines @@
   SHT_NOBITS        = 8,  // Data occupies no space in the file.
   SHT_REL           = 9,  // Relocation entries; no explicit addends.
   SHT_SHLIB         = 10, // Reserved.
   SHT_DYNSYM        = 11, // Symbol table.
   SHT_INIT_ARRAY    = 14, // Pointers to initialization functions.
   SHT_FINI_ARRAY    = 15, // Pointers to termination functions.
   SHT_PREINIT_ARRAY = 16, // Pointers to pre-init functions.
   SHT_GROUP         = 17, // Section group.
   SHT_SYMTAB_SHNDX  = 18, // Indices for SHN_XINDEX entries.
   SHT_LOOS          = 0x60000000, // Lowest operating system-specific type.
+  SHT_GNU_verdef    = 0x6ffffffd, // GNU version definitions.
+  SHT_GNU_verneed   = 0x6ffffffe, // GNU version references.
+  SHT_GNU_versym    = 0x6fffffff, // GNU symbol versions table.
   SHT_HIOS          = 0x6fffffff, // Highest operating system-specific type.
   SHT_LOPROC        = 0x70000000, // Lowest processor architecture-specific type.
   // Fixme: All this is duplicated in MCSectionELF. Why??
   // Exception Index table
   SHT_ARM_EXIDX           = 0x70000001U,
   // BPABI DLL dynamic linking pre-emption map
   SHT_ARM_PREEMPTMAP      = 0x70000002U,
   //  Object file compatibility attributes
   SHT_ARM_ATTRIBUTES      = 0x70000003U,
   SHT_ARM_DEBUGOVERLAY    = 0x70000004U,
@@ skipping 348 matching lines @@
 
 // DT_FLAGS values.
 enum {
   DF_ORIGIN     = 0x01, // The object may reference $ORIGIN.
   DF_SYMBOLIC   = 0x02, // Search the shared lib before searching the exe.
   DF_TEXTREL    = 0x04, // Relocations may modify a non-writable segment.
   DF_BIND_NOW   = 0x08, // Process all relocations on load.
   DF_STATIC_TLS = 0x10  // Reject attempts to load dynamically.
 };
 
+// ElfXX_VerDef structure version (GNU versioning)
+enum {
+  VER_DEF_NONE    = 0,
+  VER_DEF_CURRENT = 1
+};
+
+// VerDef Flags (ElfXX_VerDef::vd_flags)
+enum {
+  VER_FLG_BASE = 0x1,
+  VER_FLG_WEAK = 0x2,
+  VER_FLG_INFO = 0x4
+};
+
+// Special constants for the version table. (SHT_GNU_versym/.gnu.version)
+enum {
+  VER_NDX_LOCAL  = 0,      // Unversioned local symbol
+  VER_NDX_GLOBAL = 1,      // Unversioned global symbol
+  VERSYM_VERSION = 0x7fff, // Version Index mask
+  VERSYM_HIDDEN  = 0x8000  // Hidden bit (non-default version)
+};
+
+// ElfXX_VerNeed structure version (GNU versioning)
+enum {
+  VER_NEED_NONE = 0,
+  VER_NEED_CURRENT = 1
+};
+
 } // end namespace ELF
 
 } // end namespace llvm
 
 #endif