Index: src/analyze/gui/locationdata.h
===================================================================
--- src/analyze/gui/locationdata.h
+++ src/analyze/gui/locationdata.h
@@ -28,12 +28,15 @@
 
 #include <KLocalizedString>
 
+using SymbolId = long;
+
 struct Symbol
 {
-    Symbol(const QString& symbol = {}, const QString& binary = {}, const QString& path = {})
+    Symbol(const QString& symbol = {}, const QString& binary = {}, const QString& path = {}, SymbolId symbolId = 0)
         : symbol(symbol)
         , binary(binary)
         , path(path)
+        , symbolId(symbolId)
     {
     }
 
@@ -43,10 +46,12 @@
     QString binary;
     // path to dso / executable
     QString path;
+    // ID
+    SymbolId symbolId;
 
     bool operator==(const Symbol& rhs) const
     {
-        return std::tie(symbol, binary, path) == std::tie(rhs.symbol, rhs.binary, rhs.path);
+        return symbolId == rhs.symbolId;
     }
 
     bool operator!=(const Symbol& rhs) const
@@ -56,12 +61,12 @@
 
     bool operator<(const Symbol& rhs) const
     {
-        return std::tie(symbol, binary, path) < std::tie(rhs.symbol, rhs.binary, rhs.path);
+        return symbolId < rhs.symbolId;
     }
 
     bool isValid() const
     {
-        return !symbol.isEmpty() || !binary.isEmpty() || !path.isEmpty();
+        return symbolId > 0;
     }
 };
 
@@ -99,11 +104,7 @@
 
 inline uint qHash(const Symbol& symbol, uint seed_ = 0)
 {
-    size_t seed = seed_;
-    boost::hash_combine(seed, qHash(symbol.symbol));
-    boost::hash_combine(seed, qHash(symbol.binary));
-    boost::hash_combine(seed, qHash(symbol.path));
-    return seed;
+    return qHash(symbol.symbolId, seed_);
 }
 
 inline uint qHash(const FileLine& location, uint seed_ = 0)
Index: src/analyze/gui/parser.cpp
===================================================================
--- src/analyze/gui/parser.cpp
+++ src/analyze/gui/parser.cpp
@@ -77,20 +77,33 @@
         if (binaryIt == m_pathToBinaries.end()) {
             binaryIt = m_pathToBinaries.insert(module, Util::basename(module));
         }
-        return {{func(frame), *binaryIt, module}, {file(frame), frame.line}};
+        const SymbolId id = ++m_nextSymbolId;
+        auto symbol = Symbol{func(frame), *binaryIt, module, id};
+        const auto it = m_symbols.emplace(std::make_pair(std::move(symbol), id)).first;
+        return {it->first, {file(frame), frame.line}};
     }
 
     void update(const vector<string>& strings)
     {
         transform(strings.begin() + m_strings.size(), strings.end(), back_inserter(m_strings),
                   [](const string& str) { return QString::fromStdString(str); });
     }
 
+    struct SymbolCompare {
+        bool operator()(const Symbol &lhs, const Symbol &rhs) {
+            return std::tie(lhs.symbol, lhs.binary, lhs.path) < std::tie(rhs.symbol, rhs.binary, rhs.path);
+        }
+    };
+
     vector<QString> m_strings;
     // interned module basenames
     mutable QHash<QString, QString> m_pathToBinaries;
+    // existing symbols
+    mutable std::map<Symbol, SymbolId, SymbolCompare> m_symbols;
 
     bool diffMode = false;
+
+    mutable SymbolId m_nextSymbolId = 0;
 };
 
 struct ChartMergeData