Revert "Revert "Remove the darwin gdb option, that version of gdb is now dead and the rest of the compatibility should be done on a dwarf-N level.""

This reverts commit r189913.

Talked with Eric on IRC. I am going to XFAIL the failing test since it
is using what Eric described as "the member hack" which was needed on
that old GDB.

Sorry for the noise!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189914 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 7b38428..517ace6 100644
--- a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -100,7 +100,7 @@
 
 /// addFlag - Add a flag that is true.
 void CompileUnit::addFlag(DIE *Die, uint16_t Attribute) {
-  if (!DD->useDarwinGDBCompat())
+  if (DD->getDwarfVersion() >= 4)
     Die->addValue(Attribute, dwarf::DW_FORM_flag_present,
                   DIEIntegerOne);
   else
@@ -1242,17 +1242,6 @@
   // Add function template parameters.
   addTemplateParams(*SPDie, SP.getTemplateParams());
 
-  // Unfortunately this code needs to stay here instead of below the
-  // AT_specification code in order to work around a bug in older
-  // gdbs that requires the linkage name to resolve multiple template
-  // functions.
-  // TODO: Remove this set of code when we get rid of the old gdb
-  // compatibility.
-  StringRef LinkageName = SP.getLinkageName();
-  if (!LinkageName.empty() && DD->useDarwinGDBCompat())
-    addString(SPDie, dwarf::DW_AT_MIPS_linkage_name,
-              GlobalValue::getRealLinkageName(LinkageName));
-
   // If this DIE is going to refer declaration info using AT_specification
   // then there is no need to add other attributes.
   if (DeclDie) {
@@ -1264,7 +1253,8 @@
   }
 
   // Add the linkage name if we have one.
-  if (!LinkageName.empty() && !DD->useDarwinGDBCompat())
+  StringRef LinkageName = SP.getLinkageName();
+  if (!LinkageName.empty())
     addString(SPDie, dwarf::DW_AT_MIPS_linkage_name,
               GlobalValue::getRealLinkageName(LinkageName));
 
@@ -1459,21 +1449,15 @@
     } else {
       addBlock(VariableDIE, dwarf::DW_AT_location, 0, Block);
     }
-    // Add linkage name.
+    // Add the linkage name.
     StringRef LinkageName = GV.getLinkageName();
-    if (!LinkageName.empty()) {
+    if (!LinkageName.empty())
       // From DWARF4: DIEs to which DW_AT_linkage_name may apply include:
       // TAG_common_block, TAG_constant, TAG_entry_point, TAG_subprogram and
       // TAG_variable.
       addString(IsStaticMember && VariableSpecDIE ?
                 VariableSpecDIE : VariableDIE, dwarf::DW_AT_MIPS_linkage_name,
                 GlobalValue::getRealLinkageName(LinkageName));
-      // In compatibility mode with older gdbs we put the linkage name on both
-      // the TAG_variable DIE and on the TAG_member DIE.
-      if (IsStaticMember && VariableSpecDIE && DD->useDarwinGDBCompat())
-        addString(VariableDIE, dwarf::DW_AT_MIPS_linkage_name,
-                  GlobalValue::getRealLinkageName(LinkageName));
-    }
   } else if (const ConstantInt *CI =
              dyn_cast_or_null<ConstantInt>(GV.getConstant())) {
     // AT_const_value was added when the static member was created. To avoid