[obj2yaml] [yaml2obj] Support for MachO nlist and string table

This commit adds round tripping for MachO symbol data. Symbols are entries in the name list, that contain offsets into the string table which is at the end of the __LINKEDIT segment.

llvm-svn: 271604

5 files changed, 610 insertions, 7 deletions

diff --git a/llvm/include/llvm/ObjectYAML/MachOYAML.h b/llvm/include/llvm/ObjectYAML/MachOYAML.h
index ee11055b972..dee1bec3af3 100644
--- a/llvm/include/llvm/ObjectYAML/MachOYAML.h
+++ b/llvm/include/llvm/ObjectYAML/MachOYAML.h
@@ -57,6 +57,13 @@ struct LoadCommand {
   uint64_t ZeroPadBytes;
 };
 
+struct NListEntry {
+  uint32_t n_strx;
+  uint8_t n_type;
+  uint8_t n_sect;
+  uint16_t n_desc;
+  uint64_t n_value;
+};
 struct RebaseOpcode {
   MachO::RebaseOpcode Opcode;
   uint8_t Imm;
@@ -91,6 +98,8 @@ struct LinkEditData {
   std::vector<MachOYAML::BindOpcode> WeakBindOpcodes;
   std::vector<MachOYAML::BindOpcode> LazyBindOpcodes;
   MachOYAML::ExportEntry ExportTrie;
+  std::vector<NListEntry> NameList;
+  std::vector<StringRef> StringTable;
 };
 
 struct Object {
@@ -111,6 +120,8 @@ LLVM_YAML_IS_SEQUENCE_VECTOR(int64_t)
 LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::MachOYAML::RebaseOpcode)
 LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::MachOYAML::BindOpcode)
 LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::MachOYAML::ExportEntry)
+LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::MachOYAML::NListEntry)
+LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::StringRef)
 
 namespace llvm {
 namespace yaml {
@@ -147,6 +158,10 @@ template <> struct MappingTraits<MachOYAML::Section> {
   static void mapping(IO &IO, MachOYAML::Section &Section);
 };
 
+template <> struct MappingTraits<MachOYAML::NListEntry> {
+  static void mapping(IO &IO, MachOYAML::NListEntry &NListEntry);
+};
+
 #define HANDLE_LOAD_COMMAND(LCName, LCValue, LCStruct)                         \
   io.enumCase(value, #LCName, MachO::LCName);
 
diff --git a/llvm/lib/ObjectYAML/MachOYAML.cpp b/llvm/lib/ObjectYAML/MachOYAML.cpp
index 6fe137215cf..b4e808552df 100644
--- a/llvm/lib/ObjectYAML/MachOYAML.cpp
+++ b/llvm/lib/ObjectYAML/MachOYAML.cpp
@@ -104,6 +104,8 @@ void MappingTraits<MachOYAML::LinkEditData>::mapping(
   IO.mapOptional("WeakBindOpcodes", LinkEditData.WeakBindOpcodes);
   IO.mapOptional("LazyBindOpcodes", LinkEditData.LazyBindOpcodes);
   IO.mapOptional("ExportTrie", LinkEditData.ExportTrie);
+  IO.mapOptional("NameList", LinkEditData.NameList);
+  IO.mapOptional("StringTable", LinkEditData.StringTable);
 }
 
 void MappingTraits<MachOYAML::RebaseOpcode>::mapping(
@@ -134,6 +136,15 @@ void MappingTraits<MachOYAML::ExportEntry>::mapping(
   IO.mapOptional("Children", ExportEntry.Children);
 }
 
+void MappingTraits<MachOYAML::NListEntry>::mapping(
+    IO &IO, MachOYAML::NListEntry &NListEntry) {
+  IO.mapRequired("n_strx", NListEntry.n_strx);
+  IO.mapRequired("n_type", NListEntry.n_type);
+  IO.mapRequired("n_sect", NListEntry.n_sect);
+  IO.mapRequired("n_desc", NListEntry.n_desc);
+  IO.mapRequired("n_value", NListEntry.n_value);
+}
+
 template <typename StructType>
 void mapLoadCommandData(IO &IO, MachOYAML::LoadCommand &LoadCommand) {}
 
diff --git a/llvm/test/ObjectYAML/MachO/symtab.yaml b/llvm/test/ObjectYAML/MachO/symtab.yaml
new file mode 100644
index 00000000000..7472d4462d3
--- /dev/null
+++ b/llvm/test/ObjectYAML/MachO/symtab.yaml
@@ -0,0 +1,511 @@
+# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+
+--- !mach-o
+FileHeader:      
+  magic:           0xFEEDFACF
+  cputype:         0x01000007
+  cpusubtype:      0x80000003
+  filetype:        0x00000002
+  ncmds:           16
+  sizeofcmds:      1408
+  flags:           0x00218085
+  reserved:        0x00000000
+LoadCommands:    
+  - cmd:             LC_SEGMENT_64
+    cmdsize:         72
+    segname:         __PAGEZERO
+    vmaddr:          0
+    vmsize:          4294967296
+    fileoff:         0
+    filesize:        0
+    maxprot:         0
+    initprot:        0
+    nsects:          0
+    flags:           0
+  - cmd:             LC_SEGMENT_64
+    cmdsize:         552
+    segname:         __TEXT
+    vmaddr:          4294967296
+    vmsize:          8192
+    fileoff:         0
+    filesize:        8192
+    maxprot:         7
+    initprot:        5
+    nsects:          6
+    flags:           0
+    Sections:        
+  - cmd:             LC_SEGMENT_64
+    cmdsize:         312
+    segname:         __DATA
+    vmaddr:          4294975488
+    vmsize:          4096
+    fileoff:         8192
+    filesize:        4096
+    maxprot:         7
+    initprot:        3
+    nsects:          3
+    flags:           0
+    Sections:        
+  - cmd:             LC_SEGMENT_64
+    cmdsize:         72
+    segname:         __LINKEDIT
+    vmaddr:          4294979584
+    vmsize:          4096
+    fileoff:         12288
+    filesize:        2508
+    maxprot:         7
+    initprot:        1
+    nsects:          0
+    flags:           0
+  - cmd:             LC_DYLD_INFO_ONLY
+    cmdsize:         48
+    rebase_off:      12288
+    rebase_size:     8
+    bind_off:        12296
+    bind_size:       96
+    weak_bind_off:   0
+    weak_bind_size:  0
+    lazy_bind_off:   12392
+    lazy_bind_size:  624
+    export_off:      13016
+    export_size:     48
+  - cmd:             LC_SYMTAB
+    cmdsize:         24
+    symoff:          13080
+    nsyms:           30
+    stroff:          13700
+    strsize:         1096
+  - cmd:             LC_DYSYMTAB
+    cmdsize:         80
+    ilocalsym:       0
+    nlocalsym:       9
+    iextdefsym:      9
+    nextdefsym:      2
+    iundefsym:       11
+    nundefsym:       19
+    tocoff:          0
+    ntoc:            0
+    modtaboff:       0
+    nmodtab:         0
+    extrefsymoff:    0
+    nextrefsyms:     0
+    indirectsymoff:  13560
+    nindirectsyms:   35
+    extreloff:       0
+    nextrel:         0
+    locreloff:       0
+    nlocrel:         0
+  - cmd:             LC_LOAD_DYLINKER
+    cmdsize:         32
+    name:            12
+    PayloadString:   /usr/lib/dyld
+    ZeroPadBytes:    7
+  - cmd:             LC_UUID
+    cmdsize:         24
+    uuid:            461A1B28-822F-3F38-B670-645419E636F5
+  - cmd:             LC_VERSION_MIN_MACOSX
+    cmdsize:         16
+    version:         658176
+    sdk:             658176
+  - cmd:             LC_SOURCE_VERSION
+    cmdsize:         16
+    version:         0
+  - cmd:             LC_MAIN
+    cmdsize:         24
+    entryoff:        4448
+    stacksize:       0
+  - cmd:             LC_LOAD_DYLIB
+    cmdsize:         48
+    dylib:           
+      name:            24
+      timestamp:       2
+      current_version: 7864576
+      compatibility_version: 65536
+    PayloadString:   '/usr/lib/libc++.1.dylib'
+    ZeroPadBytes:    1
+  - cmd:             LC_LOAD_DYLIB
+    cmdsize:         56
+    dylib:           
+      name:            24
+      timestamp:       2
+      current_version: 80349697
+      compatibility_version: 65536
+    PayloadString:   /usr/lib/libSystem.B.dylib
+    ZeroPadBytes:    6
+  - cmd:             LC_FUNCTION_STARTS
+    cmdsize:         16
+    dataoff:         13064
+    datasize:        16
+  - cmd:             LC_DATA_IN_CODE
+    cmdsize:         16
+    dataoff:         13080
+    datasize:        0
+LinkEditData:    
+  NameList:        
+    - n_strx:          2
+      n_type:          30
+      n_sect:          1
+      n_desc:          128
+      n_value:         4294971808
+    - n_strx:          69
+      n_type:          30
+      n_sect:          1
+      n_desc:          128
+      n_value:         4294971888
+    - n_strx:          166
+      n_type:          30
+      n_sect:          1
+      n_desc:          128
+      n_value:         4294973024
+    - n_strx:          204
+      n_type:          30
+      n_sect:          1
+      n_desc:          128
+      n_value:         4294973056
+    - n_strx:          320
+      n_type:          30
+      n_sect:          1
+      n_desc:          128
+      n_value:         4294974784
+    - n_strx:          344
+      n_type:          30
+      n_sect:          1
+      n_desc:          128
+      n_value:         4294974800
+    - n_strx:          387
+      n_type:          30
+      n_sect:          1
+      n_desc:          128
+      n_value:         4294974832
+    - n_strx:          420
+      n_type:          14
+      n_sect:          4
+      n_desc:          0
+      n_value:         4294975104
+    - n_strx:          438
+      n_type:          14
+      n_sect:          4
+      n_desc:          0
+      n_value:         4294975280
+    - n_strx:          456
+      n_type:          15
+      n_sect:          1
+      n_desc:          16
+      n_value:         4294967296
+    - n_strx:          476
+      n_type:          15
+      n_sect:          1
+      n_desc:          0
+      n_value:         4294971744
+    - n_strx:          482
+      n_type:          1
+      n_sect:          0
+      n_desc:          512
+      n_value:         0
+    - n_strx:          498
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          537
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          567
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          642
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          711
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          774
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          834
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          851
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          875
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          897
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          954
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          982
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          999
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          1018
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          1035
+      n_type:          1
+      n_sect:          0
+      n_desc:          256
+      n_value:         0
+    - n_strx:          1057
+      n_type:          1
+      n_sect:          0
+      n_desc:          512
+      n_value:         0
+    - n_strx:          1065
+      n_type:          1
+      n_sect:          0
+      n_desc:          512
+      n_value:         0
+    - n_strx:          1073
+      n_type:          1
+      n_sect:          0
+      n_desc:          512
+      n_value:         0
+  StringTable:     
+    - ' '
+    - __ZNSt3__1lsINS_11char_traitsIcEEEERNS_13basic_ostreamIcT_EES6_PKc
+    - __ZNSt3__124__put_character_sequenceIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_PKS4_m
+    - __ZNSt3__111char_traitsIcE6lengthEPKc
+    - __ZNSt3__116__pad_and_outputIcNS_11char_traitsIcEEEENS_19ostreambuf_iteratorIT_T0_EES6_PKS4_S8_S8_RNS_8ios_baseES4_
+    - ___clang_call_terminate
+    - __ZNSt3__111char_traitsIcE11eq_int_typeEii
+    - __ZNSt3__111char_traitsIcE3eofEv
+    - GCC_except_table2
+    - GCC_except_table4
+    - __mh_execute_header
+    - _main
+    - __Unwind_Resume
+    - __ZNKSt3__16locale9use_facetERNS0_2idE
+    - __ZNKSt3__18ios_base6getlocEv
+    - __ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE6__initEmc
+    - __ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEED1Ev
+    - __ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE6sentryC1ERS3_
+    - __ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE6sentryD1Ev
+    - __ZNSt3__14coutE
+    - __ZNSt3__15ctypeIcE2idE
+    - __ZNSt3__16localeD1Ev
+    - __ZNSt3__18ios_base33__set_badbit_and_consider_rethrowEv
+    - __ZNSt3__18ios_base5clearEj
+    - __ZSt9terminatev
+    - ___cxa_begin_catch
+    - ___cxa_end_catch
+    - ___gxx_personality_v0
+    - _memset
+    - _strlen
+    - dyld_stub_binder
+...
+
+#CHECK:   NameList:        
+#CHECK:     - n_strx:          2
+#CHECK:       n_type:          30
+#CHECK:       n_sect:          1
+#CHECK:       n_desc:          128
+#CHECK:       n_value:         4294971808
+#CHECK:     - n_strx:          69
+#CHECK:       n_type:          30
+#CHECK:       n_sect:          1
+#CHECK:       n_desc:          128
+#CHECK:       n_value:         4294971888
+#CHECK:     - n_strx:          166
+#CHECK:       n_type:          30
+#CHECK:       n_sect:          1
+#CHECK:       n_desc:          128
+#CHECK:       n_value:         4294973024
+#CHECK:     - n_strx:          204
+#CHECK:       n_type:          30
+#CHECK:       n_sect:          1
+#CHECK:       n_desc:          128
+#CHECK:       n_value:         4294973056
+#CHECK:     - n_strx:          320
+#CHECK:       n_type:          30
+#CHECK:       n_sect:          1
+#CHECK:       n_desc:          128
+#CHECK:       n_value:         4294974784
+#CHECK:     - n_strx:          344
+#CHECK:       n_type:          30
+#CHECK:       n_sect:          1
+#CHECK:       n_desc:          128
+#CHECK:       n_value:         4294974800
+#CHECK:     - n_strx:          387
+#CHECK:       n_type:          30
+#CHECK:       n_sect:          1
+#CHECK:       n_desc:          128
+#CHECK:       n_value:         4294974832
+#CHECK:     - n_strx:          420
+#CHECK:       n_type:          14
+#CHECK:       n_sect:          4
+#CHECK:       n_desc:          0
+#CHECK:       n_value:         4294975104
+#CHECK:     - n_strx:          438
+#CHECK:       n_type:          14
+#CHECK:       n_sect:          4
+#CHECK:       n_desc:          0
+#CHECK:       n_value:         4294975280
+#CHECK:     - n_strx:          456
+#CHECK:       n_type:          15
+#CHECK:       n_sect:          1
+#CHECK:       n_desc:          16
+#CHECK:       n_value:         4294967296
+#CHECK:     - n_strx:          476
+#CHECK:       n_type:          15
+#CHECK:       n_sect:          1
+#CHECK:       n_desc:          0
+#CHECK:       n_value:         4294971744
+#CHECK:     - n_strx:          482
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          512
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          498
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          537
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          567
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          642
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          711
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          774
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          834
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          851
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          875
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          897
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          954
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          982
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          999
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          1018
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          1035
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          256
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          1057
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          512
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          1065
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          512
+#CHECK:       n_value:         0
+#CHECK:     - n_strx:          1073
+#CHECK:       n_type:          1
+#CHECK:       n_sect:          0
+#CHECK:       n_desc:          512
+#CHECK:       n_value:         0
+#CHECK:   StringTable:     
+#CHECK:     - ' '
+#CHECK:     - __ZNSt3__1lsINS_11char_traitsIcEEEERNS_13basic_ostreamIcT_EES6_PKc
+#CHECK:     - __ZNSt3__124__put_character_sequenceIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_PKS4_m
+#CHECK:     - __ZNSt3__111char_traitsIcE6lengthEPKc
+#CHECK:     - __ZNSt3__116__pad_and_outputIcNS_11char_traitsIcEEEENS_19ostreambuf_iteratorIT_T0_EES6_PKS4_S8_S8_RNS_8ios_baseES4_
+#CHECK:     - ___clang_call_terminate
+#CHECK:     - __ZNSt3__111char_traitsIcE11eq_int_typeEii
+#CHECK:     - __ZNSt3__111char_traitsIcE3eofEv
+#CHECK:     - GCC_except_table2
+#CHECK:     - GCC_except_table4
+#CHECK:     - __mh_execute_header
+#CHECK:     - _main
+#CHECK:     - __Unwind_Resume
+#CHECK:     - __ZNKSt3__16locale9use_facetERNS0_2idE
+#CHECK:     - __ZNKSt3__18ios_base6getlocEv
+#CHECK:     - __ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE6__initEmc
+#CHECK:     - __ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEED1Ev
+#CHECK:     - __ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE6sentryC1ERS3_
+#CHECK:     - __ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE6sentryD1Ev
+#CHECK:     - __ZNSt3__14coutE
+#CHECK:     - __ZNSt3__15ctypeIcE2idE
+#CHECK:     - __ZNSt3__16localeD1Ev
+#CHECK:     - __ZNSt3__18ios_base33__set_badbit_and_consider_rethrowEv
+#CHECK:     - __ZNSt3__18ios_base5clearEj
+#CHECK:     - __ZSt9terminatev
+#CHECK:     - ___cxa_begin_catch
+#CHECK:     - ___cxa_end_catch
+#CHECK:     - ___gxx_personality_v0
+#CHECK:     - _memset
+#CHECK:     - _strlen
+#CHECK:     - dyld_stub_binder
diff --git a/llvm/tools/obj2yaml/macho2yaml.cpp b/llvm/tools/obj2yaml/macho2yaml.cpp
index be584f2ffe7..24bd6a60da4 100644
--- a/llvm/tools/obj2yaml/macho2yaml.cpp
+++ b/llvm/tools/obj2yaml/macho2yaml.cpp
@@ -33,6 +33,7 @@ class MachODumper {
   void dumpBindOpcodes(std::vector<MachOYAML::BindOpcode> &BindOpcodes,
                        ArrayRef<uint8_t> OpcodeBuffer, bool Lazy = false);
   void dumpExportTrie(std::unique_ptr<MachOYAML::Object> &Y);
+  void dumpSymbols(std::unique_ptr<MachOYAML::Object> &Y);
 
 public:
   MachODumper(const object::MachOObjectFile &O) : Obj(O) {}
@@ -210,6 +211,7 @@ void MachODumper::dumpLinkEdit(std::unique_ptr<MachOYAML::Object> &Y) {
   dumpBindOpcodes(Y->LinkEdit.LazyBindOpcodes, Obj.getDyldInfoLazyBindOpcodes(),
                   true);
   dumpExportTrie(Y);
+  dumpSymbols(Y);
 }
 
 void MachODumper::dumpRebaseOpcodes(std::unique_ptr<MachOYAML::Object> &Y) {
@@ -424,6 +426,41 @@ void MachODumper::dumpExportTrie(std::unique_ptr<MachOYAML::Object> &Y) {
   processExportNode(ExportsTrie.begin(), ExportsTrie.end(), LEData.ExportTrie);
 }
 
+template <typename nlist_t>
+MachOYAML::NListEntry constructNameList(const nlist_t &nlist) {
+  MachOYAML::NListEntry NL;
+  NL.n_strx = nlist.n_strx;
+  NL.n_type = nlist.n_type;
+  NL.n_sect = nlist.n_sect;
+  NL.n_desc = nlist.n_desc;
+  NL.n_value = nlist.n_value;
+  return NL;
+}
+
+void MachODumper::dumpSymbols(std::unique_ptr<MachOYAML::Object> &Y) {
+  MachOYAML::LinkEditData &LEData = Y->LinkEdit;
+
+  for (auto Symbol : Obj.symbols()) {
+    MachOYAML::NListEntry NLE =
+        Obj.is64Bit() ? constructNameList<MachO::nlist_64>(
+                            *reinterpret_cast<const MachO::nlist_64 *>(
+                                Symbol.getRawDataRefImpl().p))
+                      : constructNameList<MachO::nlist>(
+                            *reinterpret_cast<const MachO::nlist *>(
+                                Symbol.getRawDataRefImpl().p));
+    LEData.NameList.push_back(NLE);
+  }
+
+  StringRef RemainingTable = Obj.getStringTableData();
+  while (RemainingTable.size() > 0) {
+    auto SymbolPair = RemainingTable.split('\0');
+    RemainingTable = SymbolPair.second;
+    if (SymbolPair.first.empty())
+      break;
+    LEData.StringTable.push_back(SymbolPair.first);
+  }
+}
+
 Error macho2yaml(raw_ostream &Out, const object::MachOObjectFile &Obj) {
   MachODumper Dumper(Obj);
   Expected<std::unique_ptr<MachOYAML::Object>> YAML = Dumper.dump();
diff --git a/llvm/tools/yaml2obj/yaml2macho.cpp b/llvm/tools/yaml2obj/yaml2macho.cpp
index b825c9a3494..d65aabc5c86 100644
--- a/llvm/tools/yaml2obj/yaml2macho.cpp
+++ b/llvm/tools/yaml2obj/yaml2macho.cpp
@@ -165,7 +165,7 @@ size_t writeLoadCommandData<MachO::dylinker_command>(MachOYAML::LoadCommand &LC,
 
 template <>
 size_t writeLoadCommandData<MachO::rpath_command>(MachOYAML::LoadCommand &LC,
-                                                     raw_ostream &OS) {
+                                                  raw_ostream &OS) {
   return writePayloadString(LC, OS);
 }
 
@@ -295,23 +295,23 @@ void MachOWriter::writeBindOpcodes(
   }
 }
 
-void MachOWriter::dumpExportEntry(raw_ostream &OS, MachOYAML::ExportEntry &Entry) {
+void MachOWriter::dumpExportEntry(raw_ostream &OS,
+                                  MachOYAML::ExportEntry &Entry) {
   encodeSLEB128(Entry.TerminalSize, OS);
   if (Entry.TerminalSize > 0) {
     encodeSLEB128(Entry.Flags, OS);
-    if ( Entry.Flags & MachO::EXPORT_SYMBOL_FLAGS_REEXPORT ) {
+    if (Entry.Flags & MachO::EXPORT_SYMBOL_FLAGS_REEXPORT) {
       encodeSLEB128(Entry.Other, OS);
       OS << Entry.ImportName;
       OS.write('\0');
-    }
-    else {
+    } else {
       encodeSLEB128(Entry.Address, OS);
       if (Entry.Flags & MachO::EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER)
         encodeSLEB128(Entry.Other, OS);
     }
   }
   OS.write(static_cast<uint8_t>(Entry.Children.size()));
-  for (auto EE : Entry.Children){
+  for (auto EE : Entry.Children) {
     OS << EE.Name;
     OS.write('\0');
     encodeSLEB128(EE.NodeOffset, OS);
@@ -325,6 +325,17 @@ Error MachOWriter::writeExportTrie(raw_ostream &OS) {
   return Error::success();
 }
 
+template <typename NListType>
+void writeNListEntry(MachOYAML::NListEntry &NLE, raw_ostream &OS) {
+  NListType ListEntry;
+  ListEntry.n_strx = NLE.n_strx;
+  ListEntry.n_type = NLE.n_type;
+  ListEntry.n_sect = NLE.n_sect;
+  ListEntry.n_desc = NLE.n_desc;
+  ListEntry.n_value = NLE.n_value;
+  OS.write(reinterpret_cast<const char *>(&ListEntry), sizeof(NListType));
+}
+
 Error MachOWriter::writeLinkEditData(raw_ostream &OS) {
   MachOYAML::LinkEditData &LinkEdit = Obj.LinkEdit;
   MachO::dyld_info_command *DyldInfoOnlyCmd = 0;
@@ -357,9 +368,27 @@ Error MachOWriter::writeLinkEditData(raw_ostream &OS) {
                    LinkEdit.LazyBindOpcodes);
 
   ZeroToOffset(OS, DyldInfoOnlyCmd->export_off);
-  if(auto Err = writeExportTrie(OS))
+  if (auto Err = writeExportTrie(OS))
     return Err;
 
+  ZeroToOffset(OS, SymtabCmd->symoff);
+  
+  for (auto NLE : LinkEdit.NameList) {
+    if (is64Bit)
+      writeNListEntry<MachO::nlist_64>(NLE, OS);
+    else
+      writeNListEntry<MachO::nlist>(NLE, OS);
+  }
+
+  auto currOffset = OS.tell() - fileStart;
+  if (currOffset < SymtabCmd->stroff)
+    Fill(OS, SymtabCmd->stroff - currOffset, 0xDEADBEEFu);
+
+  for (auto Str : LinkEdit.StringTable) {
+    OS.write(Str.data(), Str.size());
+    OS.write('\0');
+  }
+
   // Fill to the end of the string table
   ZeroToOffset(OS, SymtabCmd->stroff + SymtabCmd->strsize);