[lld][MachO] Add debug info support for MachO.

This patch causes LLD to build stabs debugging symbols for files containing
DWARF debug info, and to propagate existing stabs symbols for object files
built using '-r' mode. This enables debugging of binaries generated by LLD
from MachO objects.

llvm-svn: 276921

1 files changed, 14 insertions, 7 deletions

diff --git a/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp b/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp
index f3e159684e1..ed58d92a80b 100644
--- a/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp
+++ b/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp
@@ -789,8 +789,8 @@ llvm::Error MachOFileLayout::writeLoadCommands() {
     st->cmd     = LC_SYMTAB;
     st->cmdsize = sizeof(symtab_command);
     st->symoff  = _startOfSymbols;
-    st->nsyms   = _file.localSymbols.size() + _file.globalSymbols.size()
-                                            + _file.undefinedSymbols.size();
+    st->nsyms   = _file.stabsSymbols.size() + _file.localSymbols.size() +
+                  _file.globalSymbols.size() + _file.undefinedSymbols.size();
     st->stroff  = _startOfSymbolStrings;
     st->strsize = _endOfSymbolStrings - _startOfSymbolStrings;
     if (_swap)
@@ -876,8 +876,8 @@ llvm::Error MachOFileLayout::writeLoadCommands() {
     st->cmd     = LC_SYMTAB;
     st->cmdsize = sizeof(symtab_command);
     st->symoff  = _startOfSymbols;
-    st->nsyms   = _file.localSymbols.size() + _file.globalSymbols.size()
-                                            + _file.undefinedSymbols.size();
+    st->nsyms   = _file.stabsSymbols.size() + _file.localSymbols.size() +
+                  _file.globalSymbols.size() + _file.undefinedSymbols.size();
     st->stroff  = _startOfSymbolStrings;
     st->strsize = _endOfSymbolStrings - _startOfSymbolStrings;
     if (_swap)
@@ -890,7 +890,8 @@ llvm::Error MachOFileLayout::writeLoadCommands() {
       dst->cmd            = LC_DYSYMTAB;
       dst->cmdsize        = sizeof(dysymtab_command);
       dst->ilocalsym      = _symbolTableLocalsStartIndex;
-      dst->nlocalsym      = _file.localSymbols.size();
+      dst->nlocalsym      = _file.stabsSymbols.size() +
+                            _file.localSymbols.size();
       dst->iextdefsym     = _symbolTableGlobalsStartIndex;
       dst->nextdefsym     = _file.globalSymbols.size();
       dst->iundefsym      = _symbolTableUndefinesStartIndex;
@@ -1102,6 +1103,7 @@ void MachOFileLayout::writeSymbolTable() {
   uint32_t symOffset = _startOfSymbols;
   uint32_t strOffset = _startOfSymbolStrings;
   _buffer[strOffset++] = '\0'; // Reserve n_strx offset of zero to mean no name.
+  appendSymbols(_file.stabsSymbols, symOffset, strOffset);
   appendSymbols(_file.localSymbols, symOffset, strOffset);
   appendSymbols(_file.globalSymbols, symOffset, strOffset);
   appendSymbols(_file.undefinedSymbols, symOffset, strOffset);
@@ -1414,10 +1416,14 @@ void MachOFileLayout::buildExportTrie() {
 void MachOFileLayout::computeSymbolTableSizes() {
   // MachO symbol tables have three ranges: locals, globals, and undefines
   const size_t nlistSize = (_is64 ? sizeof(nlist_64) : sizeof(nlist));
-  _symbolTableSize = nlistSize * (_file.localSymbols.size()
+  _symbolTableSize = nlistSize * (_file.stabsSymbols.size()
+                                + _file.localSymbols.size()
                                 + _file.globalSymbols.size()
                                 + _file.undefinedSymbols.size());
   _symbolStringPoolSize = 1; // Always reserve 1-byte for the empty string.
+  for (const Symbol &sym : _file.stabsSymbols) {
+    _symbolStringPoolSize += (sym.name.size()+1);
+  }
   for (const Symbol &sym : _file.localSymbols) {
     _symbolStringPoolSize += (sym.name.size()+1);
   }
@@ -1428,7 +1434,8 @@ void MachOFileLayout::computeSymbolTableSizes() {
     _symbolStringPoolSize += (sym.name.size()+1);
   }
   _symbolTableLocalsStartIndex = 0;
-  _symbolTableGlobalsStartIndex = _file.localSymbols.size();
+  _symbolTableGlobalsStartIndex = _file.stabsSymbols.size() +
+                                  _file.localSymbols.size();
   _symbolTableUndefinesStartIndex = _symbolTableGlobalsStartIndex
                                     + _file.globalSymbols.size();