[json] Postpone stack operation

This CL can improve micro case in Bug: v8:13955 by ~5.5%. Bug: v8:13955 Change-Id: I01dad874d85453b941c477e2c7e0b84d5b26da9a Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4728921 Reviewed-by: Jakob Kummerow <[email protected]> Commit-Queue: Tao Pan <[email protected]> Cr-Commit-Position: refs/heads/main@{#89690}
hexagon-geo-surv · Aug 30, 2023 · 79330c6 · 79330c6
1 parent edb8673
commit 79330c6
Showing 1 changed file with 35 additions and 5 deletions.
diff --git a/src/json/json-stringifier.cc b/src/json/json-stringifier.cc
@@ -35,7 +35,7 @@ class JsonStringifier {
                                                       Handle<Object> gap);
 
  private:
-  enum Result { UNCHANGED, SUCCESS, EXCEPTION };
+  enum Result { UNCHANGED, SUCCESS, EXCEPTION, NEED_STACK };
 
   bool InitializeReplacer(Handle<Object> replacer);
   bool InitializeGap(Handle<Object> gap);
@@ -345,7 +345,9 @@ class JsonStringifier {
   int indent_;
   int part_length_;
   int current_index_;
+  int stack_nesting_level_;
   bool overflowed_;
+  bool need_stack_;
 
   using KeyObject = std::pair<Handle<Object>, Handle<Object>>;
   std::vector<KeyObject> stack_;
@@ -439,7 +441,9 @@ JsonStringifier::JsonStringifier(Isolate* isolate)
       indent_(0),
       part_length_(kInitialPartLength),
       current_index_(0),
+      stack_nesting_level_(0),
       overflowed_(false),
+      need_stack_(false),
       stack_(),
       key_cache_(isolate) {
   one_byte_ptr_ = one_byte_array_;
@@ -458,6 +462,11 @@ MaybeHandle<Object> JsonStringifier::Stringify(Handle<Object> object,
     return MaybeHandle<Object>();
   }
   Result result = SerializeObject(object);
+  if (result == NEED_STACK) {
+    indent_ = 0;
+    current_index_ = 0;
+    result = SerializeObject(object);
+  }
   if (result == UNCHANGED) return factory()->undefined_value();
   if (result == SUCCESS) {
     if (overflowed_ || current_index_ > String::kMaxLength) {
@@ -619,6 +628,14 @@ Handle<JSReceiver> JsonStringifier::CurrentHolder(
 
 JsonStringifier::Result JsonStringifier::StackPush(Handle<Object> object,
                                                    Handle<Object> key) {
+  if (!need_stack_) {
+    ++stack_nesting_level_;
+    if V8_UNLIKELY (stack_nesting_level_ > 10) {
+      need_stack_ = true;
+      return NEED_STACK;
+    }
+    return SUCCESS;
+  }
   StackLimitCheck check(isolate_);
   if (check.HasOverflowed()) {
     isolate_->StackOverflow();
@@ -645,7 +662,13 @@ JsonStringifier::Result JsonStringifier::StackPush(Handle<Object> object,
   return SUCCESS;
 }
 
-void JsonStringifier::StackPop() { stack_.pop_back(); }
+void JsonStringifier::StackPop() {
+  if V8_LIKELY (!need_stack_) {
+    --stack_nesting_level_;
+    return;
+  }
+  stack_.pop_back();
+}
 
 class CircularStructureMessageBuilder {
  public:
@@ -761,8 +784,9 @@ Handle<String> JsonStringifier::ConstructCircularStructureErrorMessage(
 bool MayHaveInterestingProperties(Isolate* isolate, JSReceiver object) {
   for (PrototypeIterator iter(isolate, object, kStartAtReceiver);
        !iter.IsAtEnd(); iter.Advance()) {
-    if (iter.GetCurrent()->map()->may_have_interesting_properties())
+    if (iter.GetCurrent()->map()->may_have_interesting_properties()) {
       return true;
+    }
   }
   return false;
 }
@@ -785,11 +809,17 @@ JsonStringifier::Result JsonStringifier::Serialize_(Handle<Object> object,
     if ((InstanceTypeChecker::IsJSReceiver(instance_type) &&
          MayHaveInterestingProperties(isolate_, JSReceiver::cast(*object))) ||
         InstanceTypeChecker::IsBigInt(instance_type)) {
+      if (!need_stack_ && stack_nesting_level_ > 0) {
+        need_stack_ = true;
+        return NEED_STACK;
+      }
+      need_stack_ = true;
       ASSIGN_RETURN_ON_EXCEPTION_VALUE(
           isolate_, object, ApplyToJsonFunction(object, key), EXCEPTION);
     }
   }
   if (!replacer_function_.is_null()) {
+    need_stack_ = true;
     ASSIGN_RETURN_ON_EXCEPTION_VALUE(
         isolate_, object, ApplyReplacerFunction(object, key, initial_value),
         EXCEPTION);
@@ -1141,7 +1171,7 @@ JsonStringifier::Result JsonStringifier::SerializeJSObject(
     }
     Result result = SerializeProperty(property, comma, key_name);
     if (!comma && result == SUCCESS) comma = true;
-    if (result == EXCEPTION) return result;
+    if (result == EXCEPTION || result == NEED_STACK) return result;
   }
   Unindent();
   if (comma) NewLine();
@@ -1172,7 +1202,7 @@ JsonStringifier::Result JsonStringifier::SerializeJSReceiverSlow(
         EXCEPTION);
     Result result = SerializeProperty(property, comma, key);
     if (!comma && result == SUCCESS) comma = true;
-    if (result == EXCEPTION) return result;
+    if (result == EXCEPTION || result == NEED_STACK) return result;
   }
   Unindent();
   if (comma) NewLine();