Perf: Put in a portable std::hash that works with the pool. This turns on the 10-15% perf gain.

glslang/Include/Common.h

@@ -86,16 +86,37 @@
 
 namespace glslang {
 
-//
-// Pool version of string.
-//
-typedef pool_allocator<char> TStringAllocator;
-typedef std::basic_string <char, std::char_traits<char>, TStringAllocator> TString;
+    //
+    // Pool version of string.
+    //
+    typedef pool_allocator<char> TStringAllocator;
+    typedef std::basic_string <char, std::char_traits<char>, TStringAllocator> TString;
+
+} // end namespace glslang
 
 // Repackage the std::hash for use by unordered map/set with a TString key.
-//struct TStringHash {
-//    size_t operator()(const TString& string) const { return std::hash<TString>()(string); }
-//};
+namespace std {
+
+    template<> struct hash<glslang::TString> {
+        std::size_t operator()(const glslang::TString& s) const
+        {
+            const unsigned _FNV_offset_basis = 2166136261U;
+            const unsigned _FNV_prime = 16777619U;
+            unsigned _Val = _FNV_offset_basis;
+            unsigned _Count = s.size();
+            const char* _First = s.c_str();
+            for (unsigned _Next = 0; _Next < _Count; ++_Next)
+            {
+                _Val ^= (unsigned)_First[_Next];
+                _Val *= _FNV_prime;
+            }
+
+            return _Val;
+        }
+    };
+}
+
+namespace glslang {
 
 inline TString* NewPoolTString(const char* s)
 {

glslang/MachineIndependent/ParseHelper.h

@@ -306,8 +306,7 @@ protected:
     TInputScanner* currentScanner;
     int numErrors;               // number of compile-time errors encountered
     bool parsingBuiltins;        // true if parsing built-in symbols/functions
-//  need portable TStringHash  TUnorderedMap<TString, TExtensionBehavior, TStringHash> extensionBehavior;    // for each extension string, what its current behavior is set to
-    TMap<TString, TExtensionBehavior> extensionBehavior;    // for each extension string, what its current behavior is set to
+    TUnorderedMap<TString, TExtensionBehavior> extensionBehavior;    // for each extension string, what its current behavior is set to
     static const int maxSamplerIndex = EsdNumDims * (EbtNumTypes * (2 * 2 * 2)); // see computeSamplerTypeIndex()
     TPrecisionQualifier defaultSamplerPrecision[maxSamplerIndex];
     bool afterEOF;

glslang/MachineIndependent/preprocessor/PpContext.h

@@ -192,7 +192,6 @@ public:
     };
 
     MemoryPool *pool;
-    // need portable hash typedef TUnorderedMap<int, Symbol*> TSymbolMap;
     typedef TMap<int, Symbol*> TSymbolMap;
     TSymbolMap symbols; // this has light use... just defined macros
 
@@ -437,8 +436,7 @@ protected:
     //
     // From PpAtom.cpp
     //
-    // need portable TStringHash typedef TUnorderedMap<const TString, int, TStringHash> TAtomMap;
-    typedef TMap<const TString, int> TAtomMap;
+    typedef TUnorderedMap<TString, int> TAtomMap;
     typedef TVector<const TString*> TStringMap;
     TAtomMap atomMap;
     TStringMap stringMap;