Dedup stackmaps.

runtime/vm/precompiler.h

Index: runtime/vm/precompiler.h
diff --git a/runtime/vm/precompiler.h b/runtime/vm/precompiler.h
index 3106984a178f95d30e37ea31d9c4b0a78deaf43b..e0e008bddbf4ce063ad0e41bdd820b6fa6df62b0 100644
--- a/runtime/vm/precompiler.h
+++ b/runtime/vm/precompiler.h
@@ -24,17 +24,18 @@ class SymbolPair {
  public:
   // Typedefs needed for the DirectChainedHashMap template.
   typedef const String* Key;
-  typedef bool Value;
+  typedef const String* Value;
   typedef SymbolPair Pair;
 
-  SymbolPair() : key_(NULL), value_(false) {}
-  SymbolPair(Key key, Value value) : key_(key), value_(value) {
+  SymbolPair() : key_(NULL) {}
+  SymbolPair(Key key, Value value) : key_(key) {
     ASSERT(key->IsNotTemporaryScopedHandle());
+    ASSERT(key == value);
   }
 
   static Key KeyOf(Pair kv) { return kv.key_; }
 
-  static Value ValueOf(Pair kv) { return kv.value_; }
+  static Value ValueOf(Pair kv) { return kv.key_; }
 
   static inline intptr_t Hashcode(Key key) {
     return key->Hash();
@@ -46,7 +47,6 @@ class SymbolPair {
 
  private:
   Key key_;

[Florian Schneider, 2015/10/07 10:40:07]

No need for key_ either.

This is basicaly the same as PointerKeyValueTrait - modulo IsKeyEqual, which
invokes Equals, instead of comparing the raw-ptr. Actually, PointerKeyValueTrait
may just work as a drop-in replacement.

[rmacnak, 2015/10/07 22:19:06]

Oh, I misunderstood this to be used as the backing storage of the map.

-  Value value_;
 };
 
 
@@ -57,17 +57,18 @@ class SymbolSet : public ValueObject {
   void Add(const String& symbol) {
     ASSERT(symbol.IsSymbol());
     if (symbol.IsNotTemporaryScopedHandle()) {
-      SymbolPair pair(&symbol, true);
+      SymbolPair pair(&symbol, &symbol);
       map_.Insert(pair);
     } else {
-      SymbolPair pair(&String::ZoneHandle(zone_, symbol.raw()), true);
+      const String* zone_symbol = &String::ZoneHandle(zone_, symbol.raw());
+      SymbolPair pair(zone_symbol, zone_symbol);
       map_.Insert(pair);
     }
   }
 
   bool Includes(const String& symbol) {
     ASSERT(symbol.IsSymbol());
-    return map_.Lookup(&symbol);
+    return map_.Lookup(&symbol) != NULL;
   }
 
  private:
@@ -76,6 +77,55 @@ class SymbolSet : public ValueObject {
 };
 
 
+class StackmapPair {
+ public:
+  // Typedefs needed for the DirectChainedHashMap template.
+  typedef const Stackmap* Key;
+  typedef const Stackmap* Value;
+  typedef StackmapPair Pair;
+
+  StackmapPair() : key_(NULL) {}
+  StackmapPair(Key key, Value value) : key_(key) {
+    ASSERT(key->IsNotTemporaryScopedHandle());
+    ASSERT(key == value);
+  }
+
+  static Key KeyOf(Pair kv) { return kv.key_; }
+
+  static Value ValueOf(Pair kv) { return kv.key_; }
+
+  static inline intptr_t Hashcode(Key key) {

[Florian Schneider, 2015/10/07 10:40:07]

Can you avoid this class and use PointerKeyValueTrait instead, if you add a
corresponding Hashcode method to Stackmap?

[rmacnak, 2015/10/07 22:19:06]

Not quite. It wants Stackmap::Equals(Stackmap*&) instead of
Stackmap::Equals(Stackmap&)

+    return key->PcOffset();
+  }
+
+  static inline bool IsKeyEqual(Pair pair, Key key) {
+    return pair.key_->Equals(*key);
+  }
+
+ private:
+  Key key_;
+};
+
+
+class StackmapSet : public ValueObject {

[Florian Schneider, 2015/10/07 10:40:07]

typedef DirectChainedHashmap<PointerKeyValueTrait<Stackmap> > StackmapSet;

[rmacnak, 2015/10/07 22:19:06]

Dropped StackmapSet and SymbolsSet for typedefs.

+ public:
+  explicit StackmapSet(Zone* zone) : zone_(zone), map_() {}
+
+  void Add(const Stackmap& stackmap) {
+    StackmapPair pair(&stackmap, &stackmap);
+    map_.Insert(pair);
+  }
+
+  const Stackmap* Lookup(const Stackmap& stackmap) {
+    return map_.Lookup(&stackmap);
+  }
+
+ private:
+  Zone* zone_;
+  DirectChainedHashMap<StackmapPair> map_;
+};
+
+
 class Precompiler : public ValueObject {
  public:
   static RawError* CompileAll(
@@ -106,6 +156,9 @@ class Precompiler : public ValueObject {
   void DropUncompiledFunctions();
   void BindStaticCalls();
   void BindStaticCalls(const Function& function);
+  void DedupStackmaps();
+  void DedupStackmaps(const Function& function);
+  RawStackmap* DedupStackmap(const Stackmap& stackmap);
 
   Thread* thread() const { return thread_; }
   Zone* zone() const { return zone_; }
@@ -127,6 +180,7 @@ class Precompiler : public ValueObject {
   const GrowableObjectArray& pending_functions_;
   const GrowableObjectArray& collected_closures_;
   SymbolSet sent_selectors_;
+  StackmapSet stackmaps_;
   Error& error_;
 };