VM: Make precompiler process constants/fields only once, avoid using pool.InfoAt()

runtime/vm/precompiler.cc

Index: runtime/vm/precompiler.cc
diff --git a/runtime/vm/precompiler.cc b/runtime/vm/precompiler.cc
index ce07486c707488878bde0cd3312493e488848a53..9f8cbca6f794e9939def5c4e67c1a55388c9f351 100644
--- a/runtime/vm/precompiler.cc
+++ b/runtime/vm/precompiler.cc
@@ -830,6 +830,7 @@ void Precompiler::AddCalleesOf(const Function& function) {
 #endif
 
   const ObjectPool& pool = ObjectPool::Handle(Z, code.GetObjectPool());
+  ObjectPoolInfo pool_info(pool);
   ICData& call_site = ICData::Handle(Z);
   MegamorphicCache& cache = MegamorphicCache::Handle(Z);
   String& selector = String::Handle(Z);
@@ -838,7 +839,7 @@ void Precompiler::AddCalleesOf(const Function& function) {
   Instance& instance = Instance::Handle(Z);
   Code& target_code = Code::Handle(Z);
   for (intptr_t i = 0; i < pool.Length(); i++) {
-    if (pool.InfoAt(i) == ObjectPool::kTaggedObject) {
+    if (pool_info.InfoAt(i) == ObjectPool::kTaggedObject) {
       entry = pool.ObjectAt(i);
       if (entry.IsICData()) {
         // A dynamic call.
@@ -1032,6 +1033,9 @@ void Precompiler::AddConstObject(const Instance& instance) {
   // argument descriptors.
   if (!instance.IsCanonical()) return;
 
+  // Constants are canonicalized and we avoid repeated processing of them.
+  if (consts_to_retain_.Lookup(&instance) != NULL) return;
+
   consts_to_retain_.Insert(&Instance::ZoneHandle(Z, instance.raw()));
 
   if (cls.NumTypeArguments() > 0) {
@@ -1077,6 +1081,8 @@ void Precompiler::AddClosureCall(const Array& arguments_descriptor) {
 
 
 void Precompiler::AddField(const Field& field) {
+  if (fields_to_retain_.Lookup(&field) != NULL) return;
+
   fields_to_retain_.Insert(&Field::ZoneHandle(Z, field.raw()));
 
   if (field.is_static()) {
@@ -2095,6 +2101,7 @@ void Precompiler::SwitchICCalls() {
           code_(Code::Handle(zone)),
           pool_(ObjectPool::Handle(zone)),
           entry_(Object::Handle(zone)),
+          info_array_(TypedData::Handle(zone)),
           ic_(ICData::Handle(zone)),
           target_name_(String::Handle(zone)),
           args_descriptor_(Array::Handle(zone)),
@@ -2109,8 +2116,10 @@ void Precompiler::SwitchICCalls() {
 
       code_ = function.CurrentCode();
       pool_ = code_.object_pool();
+      info_array_ = pool_.info_array();
+      ObjectPoolInfo pool_info(info_array_);
       for (intptr_t i = 0; i < pool_.Length(); i++) {
-        if (pool_.InfoAt(i) != ObjectPool::kTaggedObject) continue;
+        if (pool_info.InfoAt(i) != ObjectPool::kTaggedObject) continue;
         entry_ = pool_.ObjectAt(i);
         if (entry_.IsICData()) {
           // The only IC calls generated by precompilation are for switchable
@@ -2150,6 +2159,7 @@ void Precompiler::SwitchICCalls() {
     Code& code_;
     ObjectPool& pool_;
     Object& entry_;
+    TypedData& info_array_;
     ICData& ic_;
     String& target_name_;
     Array& args_descriptor_;