Parse function name from DWARF DW_AT_abstract_origin

[tberghammer]

Summary

Parse function name from DWARF DW_AT_abstract_origin

A DW_TAG_subprogram entry can contain a reference to a
DW_AT_abstract_origin entry instead of duplicating the information
from it (e.g.: name) when the same function is inlined in some case
and not inlined in other cases.

This CL fixes name parsing for the case when the DW_TAG_subprogram
for the non inlined version contains just a reference to the
DW_AT_abstract_origin entry instead of the full information.

[ovyalov]

LGTM

[clayborg]

Looks good.

lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp

 (
     SymbolFileDWARF* dwarf2Data,
     const DWARFCompileUnit* cu
 ) const
 {
     DWARFFormValue form_value;
     if (GetAttributeValue(dwarf2Data, cu, DW_AT_name, form_value))
         return form_value.AsCString(&dwarf2Data->get_debug_str_data());
-    else
-    {
-        if (GetAttributeValue(dwarf2Data, cu, DW_AT_specification, form_value))
-        {
-            DWARFCompileUnitSP cu_sp_ptr;
-            const DWARFDebugInfoEntry* die = const_cast<SymbolFileDWARF*>(dwarf2Data)->DebugInfo()->GetDIEPtr(form_value.Reference(), &cu_sp_ptr);
-            if (die)
-                return die->GetName(dwarf2Data, cu_sp_ptr.get());
-        }
+    else if (GetAttributeValue(dwarf2Data, cu, DW_AT_specification, form_value))
+    else if (GetAttributeValue(dwarf2Data, cu, DW_AT_abstract_origin, form_value))
+    {
+        DWARFCompileUnitSP cu_sp_ptr;
+        const DWARFDebugInfoEntry* die = const_cast<SymbolFileDWARF*>(dwarf2Data)->DebugInfo()->GetDIEPtr(form_value.Reference(), &cu_sp_ptr);
+        if (die)
+            return die->GetName(dwarf2Data, cu_sp_ptr.get());
     }
-    return NULL;
+    return nullptr;
 }
 
 
 //----------------------------------------------------------------------
 // GetMangledName
 //
 // Get value of the DW_AT_MIPS_linkage_name attribute and return it if
 // one exists, else return the value of the DW_AT_name attribute