Use llvm::DenseSet/Map<InternedString>

Speeds up the interpreter by about 10-15% when the higher tiers are disabled

src/analysis/scoping_analysis.cpp

@@ -14,6 +14,8 @@
 
 #include "analysis/scoping_analysis.h"
 
+#include "llvm/ADT/DenseSet.h"
+
 #include "core/ast.h"
 #include "core/common.h"
 #include "core/util.h"
@@ -112,7 +114,7 @@ struct ScopingAnalysis::ScopeNameUsage {
     const std::string* private_name;
     ScopingAnalysis* scoping;
 
-    typedef std::unordered_set<InternedString> StrSet;
+    typedef llvm::DenseSet<InternedString> StrSet;
 
     // Properties determined from crawling the scope:
     StrSet read;

src/core/stringpool.h

@@ -19,6 +19,7 @@
 #include <cstdio>
 #include <sys/time.h>
 
+#include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/StringRef.h"
 
@@ -78,6 +79,7 @@ public:
     friend class InternedStringPool;
     friend struct std::hash<InternedString>;
     friend struct std::less<InternedString>;
+    friend struct llvm::DenseMapInfo<pyston::InternedString>;
 };
 
 class InternedStringPool {
@@ -130,4 +132,18 @@ template <> struct less<pyston::InternedString> {
 };
 }
 
+template <> struct llvm::DenseMapInfo<pyston::InternedString> {
+    static inline pyston::InternedString getEmptyKey() { return pyston::InternedString(); }
+    static inline pyston::InternedString getTombstoneKey() {
+        pyston::InternedString str;
+        str._str = (const std::string*)-1;
+        return str;
+    }
+    static unsigned getHashValue(const pyston::InternedString& val) { return std::hash<pyston::InternedString>()(val); }
+    static bool isEqual(const pyston::InternedString& lhs, const pyston::InternedString& rhs) {
+        // Have to reimplement InternedString comparison otherwise asserts would trigger because of the empty keys.
+        return lhs._str == rhs._str;
+    }
+};
+
 #endif