1 files changed, 747 insertions, 0 deletions

diff --git a/source/Plugins/SymbolFile/DWARF/HashedNameToDIE.cpp b/source/Plugins/SymbolFile/DWARF/HashedNameToDIE.cpp
new file mode 100644
index 0000000000000..0db416054ae8e
--- /dev/null
+++ b/source/Plugins/SymbolFile/DWARF/HashedNameToDIE.cpp
@@ -0,0 +1,747 @@
+//===-- HashedNameToDIE.cpp -------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "HashedNameToDIE.h"
+
+void
+DWARFMappedHash::ExtractDIEArray (const DIEInfoArray &die_info_array, DIEArray &die_offsets)
+{
+    const size_t count = die_info_array.size();
+    for (size_t i=0; i<count; ++i)
+        die_offsets.emplace_back(die_info_array[i].cu_offset, die_info_array[i].offset);
+}
+
+void
+DWARFMappedHash::ExtractDIEArray (const DIEInfoArray &die_info_array,
+                                  const dw_tag_t tag,
+                                  DIEArray &die_offsets)
+{
+    if (tag == 0)
+    {
+        ExtractDIEArray (die_info_array, die_offsets);
+    }
+    else
+    {
+        const size_t count = die_info_array.size();
+        for (size_t i=0; i<count; ++i)
+        {
+            const dw_tag_t die_tag = die_info_array[i].tag;
+            bool tag_matches = die_tag == 0 || tag == die_tag;
+            if (!tag_matches)
+            {
+                if (die_tag == DW_TAG_class_type || die_tag == DW_TAG_structure_type)
+                    tag_matches = tag == DW_TAG_structure_type || tag == DW_TAG_class_type;
+            }
+            if (tag_matches)
+                die_offsets.emplace_back(die_info_array[i].cu_offset, die_info_array[i].offset);
+        }
+    }
+}
+
+void
+DWARFMappedHash::ExtractDIEArray (const DIEInfoArray &die_info_array,
+                                  const dw_tag_t tag,
+                                  const uint32_t qualified_name_hash,
+                                  DIEArray &die_offsets)
+{
+    if (tag == 0)
+    {
+        ExtractDIEArray (die_info_array, die_offsets);
+    }
+    else
+    {
+        const size_t count = die_info_array.size();
+        for (size_t i=0; i<count; ++i)
+        {
+            if (qualified_name_hash != die_info_array[i].qualified_name_hash)
+                continue;
+            const dw_tag_t die_tag = die_info_array[i].tag;
+            bool tag_matches = die_tag == 0 || tag == die_tag;
+            if (!tag_matches)
+            {
+                if (die_tag == DW_TAG_class_type || die_tag == DW_TAG_structure_type)
+                    tag_matches = tag == DW_TAG_structure_type || tag == DW_TAG_class_type;
+            }
+            if (tag_matches)
+                die_offsets.emplace_back(die_info_array[i].cu_offset, die_info_array[i].offset);
+        }
+    }
+}
+
+void
+DWARFMappedHash::ExtractClassOrStructDIEArray (const DIEInfoArray &die_info_array,
+                                               bool return_implementation_only_if_available,
+                                               DIEArray &die_offsets)
+{
+    const size_t count = die_info_array.size();
+    for (size_t i=0; i<count; ++i)
+    {
+        const dw_tag_t die_tag = die_info_array[i].tag;
+        if (die_tag == 0 || die_tag == DW_TAG_class_type || die_tag == DW_TAG_structure_type)
+        {
+            if (die_info_array[i].type_flags & eTypeFlagClassIsImplementation)
+            {
+                if (return_implementation_only_if_available)
+                {
+                    // We found the one true definition for this class, so
+                    // only return that
+                    die_offsets.clear();                        
+                    die_offsets.emplace_back(die_info_array[i].cu_offset, die_info_array[i].offset);
+                    return;
+                }
+                else
+                {
+                    // Put the one true definition as the first entry so it
+                    // matches first
+                    die_offsets.emplace(die_offsets.begin(), die_info_array[i].cu_offset, die_info_array[i].offset);
+                }
+            }
+            else
+            {
+                die_offsets.emplace_back(die_info_array[i].cu_offset, die_info_array[i].offset);
+            }
+        }
+    }
+}
+
+void
+DWARFMappedHash::ExtractTypesFromDIEArray (const DIEInfoArray &die_info_array,
+                                           uint32_t type_flag_mask,
+                                           uint32_t type_flag_value,
+                                           DIEArray &die_offsets)
+{
+    const size_t count = die_info_array.size();
+    for (size_t i=0; i<count; ++i)
+    {
+        if ((die_info_array[i].type_flags & type_flag_mask) == type_flag_value)
+            die_offsets.emplace_back(die_info_array[i].cu_offset, die_info_array[i].offset);
+    }
+}
+
+const char *
+DWARFMappedHash::GetAtomTypeName (uint16_t atom)
+{
+    switch (atom)
+    {
+        case eAtomTypeNULL:         return "NULL";
+        case eAtomTypeDIEOffset:    return "die-offset";
+        case eAtomTypeCUOffset:     return "cu-offset";
+        case eAtomTypeTag:          return "die-tag";
+        case eAtomTypeNameFlags:    return "name-flags";
+        case eAtomTypeTypeFlags:    return "type-flags";
+        case eAtomTypeQualNameHash: return "qualified-name-hash";
+    }
+    return "<invalid>";
+}
+
+DWARFMappedHash::DIEInfo::DIEInfo () :
+    cu_offset (DW_INVALID_OFFSET),
+    offset (DW_INVALID_OFFSET),
+    tag (0),
+    type_flags (0),
+    qualified_name_hash (0)
+{
+}
+
+DWARFMappedHash::DIEInfo::DIEInfo (dw_offset_t c,
+                                   dw_offset_t o,
+                                   dw_tag_t t,
+                                   uint32_t f,
+                                   uint32_t h) :
+    cu_offset (c),
+    offset (o),
+    tag (t),
+    type_flags (f),
+    qualified_name_hash (h)
+{
+}
+
+DWARFMappedHash::Prologue::Prologue (dw_offset_t _die_base_offset) :
+    die_base_offset (_die_base_offset),
+    atoms(),
+    atom_mask (0),
+    min_hash_data_byte_size(0),
+    hash_data_has_fixed_byte_size(true)
+{
+    // Define an array of DIE offsets by first defining an array, 
+    // and then define the atom type for the array, in this case
+    // we have an array of DIE offsets
+    AppendAtom (eAtomTypeDIEOffset, DW_FORM_data4);
+}
+
+void
+DWARFMappedHash::Prologue::ClearAtoms ()
+{
+    hash_data_has_fixed_byte_size = true;
+    min_hash_data_byte_size = 0;
+    atom_mask = 0;
+    atoms.clear();
+}
+
+bool
+DWARFMappedHash::Prologue::ContainsAtom (AtomType atom_type) const
+{
+    return (atom_mask & (1u << atom_type)) != 0;
+}
+
+void
+DWARFMappedHash::Prologue::Clear ()
+{
+    die_base_offset = 0;
+    ClearAtoms ();
+}
+
+void
+DWARFMappedHash::Prologue::AppendAtom (AtomType type, dw_form_t form)
+{
+    atoms.push_back ({type, form});
+    atom_mask |= 1u << type;
+    switch (form)
+    {
+        case DW_FORM_indirect:
+        case DW_FORM_exprloc:
+        case DW_FORM_flag_present:
+        case DW_FORM_ref_sig8:
+            assert (!"Unhandled atom form");
+            break;
+
+        case DW_FORM_string:
+        case DW_FORM_block:
+        case DW_FORM_block1:
+        case DW_FORM_sdata:
+        case DW_FORM_udata:
+        case DW_FORM_ref_udata:
+        case DW_FORM_GNU_addr_index:
+        case DW_FORM_GNU_str_index:
+            hash_data_has_fixed_byte_size = false;
+            // Fall through to the cases below...
+        case DW_FORM_flag:
+        case DW_FORM_data1:
+        case DW_FORM_ref1:
+        case DW_FORM_sec_offset:
+            min_hash_data_byte_size += 1; 
+            break;
+
+        case DW_FORM_block2:
+            hash_data_has_fixed_byte_size = false;
+            // Fall through to the cases below...
+        case DW_FORM_data2: 
+        case DW_FORM_ref2:
+            min_hash_data_byte_size += 2; 
+            break;
+
+        case DW_FORM_block4: 
+            hash_data_has_fixed_byte_size = false;
+            // Fall through to the cases below...
+        case DW_FORM_data4:
+        case DW_FORM_ref4:
+        case DW_FORM_addr:
+        case DW_FORM_ref_addr:
+        case DW_FORM_strp:
+            min_hash_data_byte_size += 4; 
+            break;
+
+        case DW_FORM_data8:
+        case DW_FORM_ref8:
+            min_hash_data_byte_size += 8; 
+            break;
+            
+    }
+}
+
+lldb::offset_t
+DWARFMappedHash::Prologue::Read (const lldb_private::DataExtractor &data,
+      lldb::offset_t offset)
+{
+    ClearAtoms ();
+    
+    die_base_offset = data.GetU32 (&offset);
+    
+    const uint32_t atom_count = data.GetU32 (&offset);
+    if (atom_count == 0x00060003u)
+    {
+        // Old format, deal with contents of old pre-release format
+        while (data.GetU32(&offset))
+            /* do nothing */;
+
+        // Hardcode to the only known value for now.
+        AppendAtom (eAtomTypeDIEOffset, DW_FORM_data4);
+    }
+    else
+    {
+        for (uint32_t i=0; i<atom_count; ++i)
+        {
+            AtomType type = (AtomType)data.GetU16 (&offset);
+            dw_form_t form = (dw_form_t)data.GetU16 (&offset);                    
+            AppendAtom (type, form);
+        }
+    }
+    return offset;
+}
+
+size_t
+DWARFMappedHash::Prologue::GetByteSize () const
+{
+    // Add an extra count to the atoms size for the zero termination Atom that gets
+    // written to disk
+    return sizeof(die_base_offset) + sizeof(uint32_t) + atoms.size() * sizeof(Atom);
+}
+
+size_t
+DWARFMappedHash::Prologue::GetMinimumHashDataByteSize () const
+{
+    return min_hash_data_byte_size;
+}
+
+bool
+DWARFMappedHash::Prologue::HashDataHasFixedByteSize() const
+{
+    return hash_data_has_fixed_byte_size;
+}
+
+size_t
+DWARFMappedHash::Header::GetByteSize (const HeaderData &header_data)
+{
+    return header_data.GetByteSize();
+}
+
+lldb::offset_t
+DWARFMappedHash::Header::Read (lldb_private::DataExtractor &data, lldb::offset_t offset)
+{
+    offset = MappedHash::Header<Prologue>::Read (data, offset);
+    if (offset != UINT32_MAX)
+    {
+        offset = header_data.Read (data, offset);
+    }
+    return offset;
+}
+
+bool
+DWARFMappedHash::Header::Read (const lldb_private::DWARFDataExtractor &data, 
+                               lldb::offset_t *offset_ptr, 
+                               DIEInfo &hash_data) const
+{
+    const size_t num_atoms = header_data.atoms.size();
+    if (num_atoms == 0)
+        return false;
+    
+    for (size_t i=0; i<num_atoms; ++i)
+    {
+        DWARFFormValue form_value (NULL, header_data.atoms[i].form);
+        
+        if (!form_value.ExtractValue(data, offset_ptr))
+            return false;
+        
+        switch (header_data.atoms[i].type)
+        {
+            case eAtomTypeDIEOffset:    // DIE offset, check form for encoding
+                hash_data.offset = (dw_offset_t)form_value.Reference (header_data.die_base_offset);
+                break;
+
+            case eAtomTypeTag:          // DW_TAG value for the DIE
+                hash_data.tag = (dw_tag_t)form_value.Unsigned ();
+                
+            case eAtomTypeTypeFlags:    // Flags from enum TypeFlags
+                hash_data.type_flags = (uint32_t)form_value.Unsigned ();
+                break;
+
+            case eAtomTypeQualNameHash:    // Flags from enum TypeFlags
+                hash_data.qualified_name_hash = form_value.Unsigned ();
+                break;
+
+            default:
+                // We can always skip atoms we don't know about
+                break;
+        }
+    }
+    return true;
+}
+
+void
+DWARFMappedHash::Header::Dump (lldb_private::Stream& strm, const DIEInfo &hash_data) const
+{
+    const size_t num_atoms = header_data.atoms.size();
+    for (size_t i=0; i<num_atoms; ++i)
+    {
+        if (i > 0)
+            strm.PutCString (", ");
+        
+        DWARFFormValue form_value (NULL, header_data.atoms[i].form);
+        switch (header_data.atoms[i].type)
+        {
+            case eAtomTypeDIEOffset:    // DIE offset, check form for encoding
+                strm.Printf ("{0x%8.8x}", hash_data.offset);
+                break;
+
+            case eAtomTypeTag:          // DW_TAG value for the DIE
+                {
+                    const char *tag_cstr = lldb_private::DW_TAG_value_to_name (hash_data.tag);
+                    if (tag_cstr)
+                        strm.PutCString (tag_cstr);
+                    else
+                        strm.Printf ("DW_TAG_(0x%4.4x)", hash_data.tag);
+                }
+                break;
+
+            case eAtomTypeTypeFlags:    // Flags from enum TypeFlags
+                strm.Printf ("0x%2.2x", hash_data.type_flags);
+                if (hash_data.type_flags)
+                {
+                    strm.PutCString (" (");
+                    if (hash_data.type_flags & eTypeFlagClassIsImplementation)
+                        strm.PutCString (" implementation");
+                    strm.PutCString (" )");
+                }
+                break;
+
+            case eAtomTypeQualNameHash:    // Flags from enum TypeFlags
+                strm.Printf ("0x%8.8x", hash_data.qualified_name_hash);
+                break;
+
+            default:
+                strm.Printf ("AtomType(0x%x)", header_data.atoms[i].type);
+                break;
+        }
+    }
+}
+
+DWARFMappedHash::MemoryTable::MemoryTable (lldb_private::DWARFDataExtractor &table_data, 
+                                           const lldb_private::DWARFDataExtractor &string_table,
+                                           const char *name) :
+    MappedHash::MemoryTable<uint32_t, Header, DIEInfoArray> (table_data),
+    m_data (table_data),
+    m_string_table (string_table),
+    m_name (name)
+{
+}
+
+const char *
+DWARFMappedHash::MemoryTable::GetStringForKeyType (KeyType key) const
+{
+    // The key in the DWARF table is the .debug_str offset for the string
+    return m_string_table.PeekCStr (key);
+}
+
+bool
+DWARFMappedHash::MemoryTable::ReadHashData (uint32_t hash_data_offset, HashData &hash_data) const
+{
+    lldb::offset_t offset = hash_data_offset;
+    offset += 4; // Skip string table offset that contains offset of hash name in .debug_str
+    const uint32_t count = m_data.GetU32 (&offset);
+    if (count > 0)
+    {
+        hash_data.resize(count);
+        for (uint32_t i=0; i<count; ++i)
+        {
+            if (!m_header.Read(m_data, &offset, hash_data[i]))
+                return false;
+        }
+    }
+    else
+        hash_data.clear();
+    return true;
+}
+
+DWARFMappedHash::MemoryTable::Result
+DWARFMappedHash::MemoryTable::GetHashDataForName (const char *name,
+                                                  lldb::offset_t* hash_data_offset_ptr,
+                                                  Pair &pair) const
+{
+    pair.key = m_data.GetU32 (hash_data_offset_ptr);
+    pair.value.clear();
+
+    // If the key is zero, this terminates our chain of HashData objects
+    // for this hash value.
+    if (pair.key == 0)
+        return eResultEndOfHashData;
+
+    // There definitely should be a string for this string offset, if
+    // there isn't, there is something wrong, return and error
+    const char *strp_cstr = m_string_table.PeekCStr (pair.key);
+    if (strp_cstr == NULL)
+    {
+        *hash_data_offset_ptr = UINT32_MAX;
+        return eResultError;
+    }
+
+    const uint32_t count = m_data.GetU32 (hash_data_offset_ptr);
+    const size_t min_total_hash_data_size = count * m_header.header_data.GetMinimumHashDataByteSize();
+    if (count > 0 && m_data.ValidOffsetForDataOfSize (*hash_data_offset_ptr, min_total_hash_data_size))
+    {
+        // We have at least one HashData entry, and we have enough
+        // data to parse at least "count" HashData entries.
+        
+        // First make sure the entire C string matches...
+        const bool match = strcmp (name, strp_cstr) == 0;
+        
+        if (!match && m_header.header_data.HashDataHasFixedByteSize())
+        {
+            // If the string doesn't match and we have fixed size data,
+            // we can just add the total byte size of all HashData objects
+            // to the hash data offset and be done...
+            *hash_data_offset_ptr += min_total_hash_data_size;
+        }
+        else
+        {
+            // If the string does match, or we don't have fixed size data
+            // then we need to read the hash data as a stream. If the
+            // string matches we also append all HashData objects to the
+            // value array.
+            for (uint32_t i=0; i<count; ++i)
+            {
+                DIEInfo die_info;
+                if (m_header.Read(m_data, hash_data_offset_ptr, die_info))
+                {
+                    // Only happened if the HashData of the string matched...
+                    if (match)
+                        pair.value.push_back (die_info);
+                }
+                else
+                {
+                    // Something went wrong while reading the data
+                    *hash_data_offset_ptr = UINT32_MAX;
+                    return eResultError;
+                }
+            }
+        }
+        // Return the correct response depending on if the string matched
+        // or not...
+        if (match)
+            return eResultKeyMatch;     // The key (cstring) matches and we have lookup results!
+        else
+            return eResultKeyMismatch;  // The key doesn't match, this function will get called 
+                                        // again for the next key/value or the key terminator
+                                        // which in our case is a zero .debug_str offset.
+    }
+    else
+    {
+        *hash_data_offset_ptr = UINT32_MAX;
+        return eResultError;
+    }
+}
+
+DWARFMappedHash::MemoryTable::Result
+DWARFMappedHash::MemoryTable::AppendHashDataForRegularExpression (
+        const lldb_private::RegularExpression& regex,
+        lldb::offset_t* hash_data_offset_ptr, 
+        Pair &pair) const
+{
+    pair.key = m_data.GetU32 (hash_data_offset_ptr);
+    // If the key is zero, this terminates our chain of HashData objects
+    // for this hash value.
+    if (pair.key == 0)
+        return eResultEndOfHashData;
+    
+    // There definitely should be a string for this string offset, if
+    // there isn't, there is something wrong, return and error
+    const char *strp_cstr = m_string_table.PeekCStr (pair.key);
+    if (strp_cstr == NULL)
+        return eResultError;
+    
+    const uint32_t count = m_data.GetU32 (hash_data_offset_ptr);
+    const size_t min_total_hash_data_size = count * m_header.header_data.GetMinimumHashDataByteSize();
+    if (count > 0 && m_data.ValidOffsetForDataOfSize (*hash_data_offset_ptr, min_total_hash_data_size))
+    {
+        const bool match = regex.Execute(strp_cstr);
+        
+        if (!match && m_header.header_data.HashDataHasFixedByteSize())
+        {
+            // If the regex doesn't match and we have fixed size data,
+            // we can just add the total byte size of all HashData objects
+            // to the hash data offset and be done...
+            *hash_data_offset_ptr += min_total_hash_data_size;
+        }
+        else
+        {
+            // If the string does match, or we don't have fixed size data
+            // then we need to read the hash data as a stream. If the
+            // string matches we also append all HashData objects to the
+            // value array.
+            for (uint32_t i=0; i<count; ++i)
+            {
+                DIEInfo die_info;
+                if (m_header.Read(m_data, hash_data_offset_ptr, die_info))
+                {
+                    // Only happened if the HashData of the string matched...
+                    if (match)
+                        pair.value.push_back (die_info);
+                }
+                else
+                {
+                    // Something went wrong while reading the data
+                    *hash_data_offset_ptr = UINT32_MAX;
+                    return eResultError;
+                }
+            }
+        }
+        // Return the correct response depending on if the string matched
+        // or not...
+        if (match)
+            return eResultKeyMatch;     // The key (cstring) matches and we have lookup results!
+        else
+            return eResultKeyMismatch;  // The key doesn't match, this function will get called 
+                                        // again for the next key/value or the key terminator
+                                        // which in our case is a zero .debug_str offset.
+    }
+    else
+    {
+        *hash_data_offset_ptr = UINT32_MAX;
+        return eResultError;
+    }
+}
+
+size_t
+DWARFMappedHash::MemoryTable::AppendAllDIEsThatMatchingRegex (
+        const lldb_private::RegularExpression& regex, 
+        DIEInfoArray &die_info_array) const
+{
+    const uint32_t hash_count = m_header.hashes_count;
+    Pair pair;
+    for (uint32_t offset_idx=0; offset_idx<hash_count; ++offset_idx)
+    {
+        lldb::offset_t hash_data_offset = GetHashDataOffset (offset_idx);
+        while (hash_data_offset != UINT32_MAX)
+        {
+            const lldb::offset_t prev_hash_data_offset = hash_data_offset;
+            Result hash_result = AppendHashDataForRegularExpression (regex, &hash_data_offset, pair);
+            if (prev_hash_data_offset == hash_data_offset)
+                break;
+
+            // Check the result of getting our hash data
+            switch (hash_result)
+            {
+                case eResultKeyMatch:
+                case eResultKeyMismatch:
+                    // Whether we matches or not, it doesn't matter, we
+                    // keep looking.
+                    break;
+                    
+                case eResultEndOfHashData:
+                case eResultError:
+                    hash_data_offset = UINT32_MAX;
+                    break;
+            }
+        }
+    }
+    die_info_array.swap (pair.value);
+    return die_info_array.size();
+}
+
+size_t
+DWARFMappedHash::MemoryTable::AppendAllDIEsInRange (const uint32_t die_offset_start, 
+                                                    const uint32_t die_offset_end, 
+                                                    DIEInfoArray &die_info_array) const
+{
+    const uint32_t hash_count = m_header.hashes_count;
+    for (uint32_t offset_idx=0; offset_idx<hash_count; ++offset_idx)
+    {
+        bool done = false;
+        lldb::offset_t hash_data_offset = GetHashDataOffset (offset_idx);
+        while (!done && hash_data_offset != UINT32_MAX)
+        {
+            KeyType key = m_data.GetU32 (&hash_data_offset);
+            // If the key is zero, this terminates our chain of HashData objects
+            // for this hash value.
+            if (key == 0)
+                break;
+            
+            const uint32_t count = m_data.GetU32 (&hash_data_offset);
+            for (uint32_t i=0; i<count; ++i)
+            {
+                DIEInfo die_info;
+                if (m_header.Read(m_data, &hash_data_offset, die_info))
+                {
+                    if (die_info.offset == 0)
+                        done = true;
+                    if (die_offset_start <= die_info.offset && die_info.offset < die_offset_end)
+                        die_info_array.push_back(die_info);
+                }
+            }
+        }
+    }
+    return die_info_array.size();
+}
+
+size_t
+DWARFMappedHash::MemoryTable::FindByName (const char *name, DIEArray &die_offsets)
+{
+    DIEInfoArray die_info_array;
+    if (FindByName(name, die_info_array))
+        DWARFMappedHash::ExtractDIEArray (die_info_array, die_offsets);
+    return die_info_array.size();
+}
+
+size_t
+DWARFMappedHash::MemoryTable::FindByNameAndTag (const char *name,
+                                                const dw_tag_t tag,
+                                                DIEArray &die_offsets)
+{
+    DIEInfoArray die_info_array;
+    if (FindByName(name, die_info_array))
+        DWARFMappedHash::ExtractDIEArray (die_info_array, tag, die_offsets);
+    return die_info_array.size();
+}
+
+size_t
+DWARFMappedHash::MemoryTable::FindByNameAndTagAndQualifiedNameHash (const char *name,
+                                                                    const dw_tag_t tag,
+                                                                    const uint32_t qualified_name_hash,
+                                                                    DIEArray &die_offsets)
+{
+    DIEInfoArray die_info_array;
+    if (FindByName(name, die_info_array))
+        DWARFMappedHash::ExtractDIEArray (die_info_array, tag, qualified_name_hash, die_offsets);
+    return die_info_array.size();
+}
+
+size_t
+DWARFMappedHash::MemoryTable::FindCompleteObjCClassByName (const char *name,
+                                                           DIEArray &die_offsets,
+                                                           bool must_be_implementation)
+{
+    DIEInfoArray die_info_array;
+    if (FindByName(name, die_info_array))
+    {
+        if (must_be_implementation && GetHeader().header_data.ContainsAtom (eAtomTypeTypeFlags))
+        {
+            // If we have two atoms, then we have the DIE offset and
+            // the type flags so we can find the objective C class
+            // efficiently.
+            DWARFMappedHash::ExtractTypesFromDIEArray (die_info_array, 
+                                                       UINT32_MAX,
+                                                       eTypeFlagClassIsImplementation,
+                                                       die_offsets);
+        }
+        else
+        {
+            // We don't only want the one true definition, so try and see
+            // what we can find, and only return class or struct DIEs.
+            // If we do have the full implementation, then return it alone,
+            // else return all possible matches.
+            const bool return_implementation_only_if_available = true;
+            DWARFMappedHash::ExtractClassOrStructDIEArray (die_info_array, 
+                                                           return_implementation_only_if_available,
+                                                           die_offsets);
+        }
+    }
+    return die_offsets.size();
+}
+
+size_t 
+DWARFMappedHash::MemoryTable::FindByName (const char *name, DIEInfoArray &die_info_array)
+{
+    Pair kv_pair;
+    size_t old_size = die_info_array.size();
+    if (Find (name, kv_pair))
+    {
+        die_info_array.swap(kv_pair.value);
+        return die_info_array.size() - old_size;
+    }
+    return 0;
+}