Fix infinite recursion in DWO file parsing

Summary:
Since r264316, clang started adding DW_AT_GNU_dwo_name attribute to dwo files (previously, this
attribute was only present in main object files), breaking pretty much every dwo test. The
problem was that we were treating the presence of said attribute as a signal that we should look
for information in an external object file, and caused us to enter an infinite loop. I fix this
by making sure we do not go looking for an external dwo file if we already *are* parsing a dwo
file.

Reviewers: tberghammer, clayborg

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D18547

llvm-svn: 264729

4 files changed, 45 insertions, 37 deletions

diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.cpp
index f8a1043b160..51dcb7c2d73 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.cpp
@@ -311,46 +311,12 @@ DWARFCompileUnit::AddCompileUnitDIE(DWARFDebugInfoEntry& die)
 {
     assert (m_die_array.empty() && "Compile unit DIE already added");
     AddDIE(die);
-    
-    DWARFDebugInfoEntry& cu_die = m_die_array.front();
 
-    const char* dwo_name = cu_die.GetAttributeValueAsString(m_dwarf2Data,
-                                                            this,
-                                                            DW_AT_GNU_dwo_name,
-                                                            nullptr);
-    if (!dwo_name)
+    const DWARFDebugInfoEntry &cu_die = m_die_array.front();
+    std::unique_ptr<SymbolFileDWARFDwo> dwo_symbol_file = m_dwarf2Data->GetDwoSymbolFileForCompileUnit(*this, cu_die);
+    if (!dwo_symbol_file)
         return;
 
-    FileSpec dwo_file(dwo_name, true);
-    if (dwo_file.IsRelative())
-    {
-        const char* comp_dir = cu_die.GetAttributeValueAsString(m_dwarf2Data,
-                                                                this,
-                                                                DW_AT_comp_dir,
-                                                                nullptr);
-        if (!comp_dir)
-            return;
-
-        dwo_file.SetFile(comp_dir, true);
-        dwo_file.AppendPathComponent(dwo_name);
-    }
-
-    if (!dwo_file.Exists())
-        return;
-
-    DataBufferSP dwo_file_data_sp;
-    lldb::offset_t dwo_file_data_offset = 0;
-    ObjectFileSP dwo_obj_file = ObjectFile::FindPlugin(m_dwarf2Data->GetObjectFile()->GetModule(),
-                                                       &dwo_file,
-                                                       0 /* file_offset */,
-                                                       dwo_file.GetByteSize(),
-                                                       dwo_file_data_sp,
-                                                       dwo_file_data_offset);
-    if (dwo_obj_file == nullptr)
-        return;
-
-    std::unique_ptr<SymbolFileDWARFDwo> dwo_symbol_file(new SymbolFileDWARFDwo(dwo_obj_file, this));
-
     DWARFCompileUnit* dwo_cu = dwo_symbol_file->GetCompileUnit();
     if (!dwo_cu)
         return; // Can't fetch the compile unit from the dwo file.
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index 66e3e72999e..e161c08470b 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -1763,6 +1763,38 @@ SymbolFileDWARF::GetDWOModule (ConstString name)
         return lldb::ModuleSP();
 }
 
+std::unique_ptr<SymbolFileDWARFDwo>
+SymbolFileDWARF::GetDwoSymbolFileForCompileUnit(DWARFCompileUnit &dwarf_cu, const DWARFDebugInfoEntry &cu_die)
+{
+    const char *dwo_name = cu_die.GetAttributeValueAsString(this, &dwarf_cu, DW_AT_GNU_dwo_name, nullptr);
+    if (!dwo_name)
+        return nullptr;
+
+    FileSpec dwo_file(dwo_name, true);
+    if (dwo_file.IsRelative())
+    {
+        const char *comp_dir = cu_die.GetAttributeValueAsString(this, &dwarf_cu, DW_AT_comp_dir, nullptr);
+        if (!comp_dir)
+            return nullptr;
+
+        dwo_file.SetFile(comp_dir, true);
+        dwo_file.AppendPathComponent(dwo_name);
+    }
+
+    if (!dwo_file.Exists())
+        return nullptr;
+
+    const lldb::offset_t file_offset = 0;
+    DataBufferSP dwo_file_data_sp;
+    lldb::offset_t dwo_file_data_offset = 0;
+    ObjectFileSP dwo_obj_file = ObjectFile::FindPlugin(GetObjectFile()->GetModule(), &dwo_file, file_offset,
+                                                       dwo_file.GetByteSize(), dwo_file_data_sp, dwo_file_data_offset);
+    if (dwo_obj_file == nullptr)
+        return nullptr;
+
+    return llvm::make_unique<SymbolFileDWARFDwo>(dwo_obj_file, &dwarf_cu);
+}
+
 void
 SymbolFileDWARF::UpdateExternalModuleListIfNeeded()
 {
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
index 2742d459f8d..fa7f12d8417 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
@@ -58,6 +58,7 @@ class DWARFDeclContext;
 class DWARFDIECollection;
 class DWARFFormValue;
 class SymbolFileDWARFDebugMap;
+class SymbolFileDWARFDwo;
 
 #define DIE_IS_BEING_PARSED ((lldb_private::Type*)1)
 
@@ -329,6 +330,9 @@ public:
     lldb::ModuleSP
     GetDWOModule (lldb_private::ConstString name);
 
+    virtual std::unique_ptr<SymbolFileDWARFDwo>
+    GetDwoSymbolFileForCompileUnit(DWARFCompileUnit &dwarf_cu, const DWARFDebugInfoEntry &cu_die);
+
 protected:
     typedef llvm::DenseMap<const DWARFDebugInfoEntry *, lldb_private::Type *> DIEToTypePtr;
     typedef llvm::DenseMap<const DWARFDebugInfoEntry *, lldb::VariableSP> DIEToVariableSP;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
index 39ed6502229..81cbd583492 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
@@ -38,6 +38,12 @@ public:
     lldb_private::TypeSystem*
     GetTypeSystemForLanguage(lldb::LanguageType language) override;
 
+    std::unique_ptr<SymbolFileDWARFDwo>
+    GetDwoSymbolFileForCompileUnit(DWARFCompileUnit &dwarf_cu, const DWARFDebugInfoEntry &cu_die) override
+    {
+        return nullptr;
+    }
+
 protected:
     void
     LoadSectionData (lldb::SectionType sect_type, lldb_private::DWARFDataExtractor& data) override;