SkSL performance improvements

src/sksl/ir/SkSLSymbolTable.h

Index: src/sksl/ir/SkSLSymbolTable.h
diff --git a/src/sksl/ir/SkSLSymbolTable.h b/src/sksl/ir/SkSLSymbolTable.h
index 151475d6423690d3024d322c2c3968f0a21a9066..2c9598253fc181bc0820d97150b45d2b4faf5dd2 100644
--- a/src/sksl/ir/SkSLSymbolTable.h
+++ b/src/sksl/ir/SkSLSymbolTable.h
@@ -23,23 +23,38 @@ namespace SkSL {
 class SymbolTable {
 public:
     SymbolTable(ErrorReporter& errorReporter)
-    : fErrorReporter(errorReporter) {}
+    : fOwner(true)

[dogben, 2016/07/08 19:56:40]

Would it be simpler for Block and FunctionDeclaration to own the SymbolTable
that owns their symbols? This would eliminate the need for fOwner. (We would
still need addWithoutOwnership for the global symbols and to add function
parameters to the function body block.)

+    , fErrorReporter(errorReporter) {}
 
-    SymbolTable(std::shared_ptr<SymbolTable> parent, ErrorReporter& errorReporter)
+    SymbolTable(std::shared_ptr<SymbolTable> parent, ErrorReporter& errorReporter, 
+                bool owner = false)
     : fParent(parent)
+    , fOwner(owner)
     , fErrorReporter(errorReporter) {}
 
-    std::shared_ptr<Symbol> operator[](const std::string& name);
+    ~SymbolTable();
+
+    const Symbol* operator[](const std::string& name);
+
+    // SymbolTable will take ownership of the pointer, deleting it when it is destroyed
+    void add(const std::string& name, Symbol* symbol);

[dogben, 2016/07/08 19:56:40]

nit: use std::unique_ptr to transfer ownership

 
-    void add(const std::string& name, std::shared_ptr<Symbol> symbol);
+    void addWithoutOwnership(const std::string& name, const Symbol* symbol);
+
+    void takeOwnership(Symbol* s);
 
     const std::shared_ptr<SymbolTable> fParent;
 
 private:
-    static std::vector<std::shared_ptr<FunctionDeclaration>> GetFunctions(
-                                                                  const std::shared_ptr<Symbol>& s);
+    static std::vector<const FunctionDeclaration*> GetFunctions(const Symbol& s);
+
+    // true if this symbol should directly own the pointers it contains, false to delegate ownership
+    // to its parent
+    const bool fOwner;
+
+    std::vector<Symbol*> fOwnedPointers;

[dogben, 2016/07/08 19:56:40]

nit: std::vector<std::unique_ptr<Symbol>> eliminates the destructor

 
-    std::unordered_map<std::string, std::shared_ptr<Symbol>> fSymbols;
+    std::unordered_map<std::string, const Symbol*> fSymbols;
 
     ErrorReporter& fErrorReporter;
 };