[runtime][api] Fix tracking of entered contexts

The entered contexts stack must be in sync with the flags stack.

Bug: chromium:1269225
Change-Id: Ibb522286b47866d5f13aaec1a0a02914c13a5545
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3279680
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Auto-Submit: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77882}

src/api/api-inl.h

@@ -318,6 +318,7 @@ inline bool V8_EXPORT TryToCopyAndConvertArrayToCppBuffer(Local<Array> src,
 namespace internal {
 
 Handle<Context> HandleScopeImplementer::LastEnteredContext() {
+  DCHECK_EQ(entered_contexts_.capacity(), is_microtask_context_.capacity());
   DCHECK_EQ(entered_contexts_.size(), is_microtask_context_.size());
 
   for (size_t i = 0; i < entered_contexts_.size(); ++i) {

src/api/api.cc

@@ -10451,6 +10451,11 @@ void HandleScopeImplementer::IterateThis(RootVisitor* v) {
     v->VisitRootPointers(Root::kHandleScope, nullptr, start,
                          start + static_cast<int>(context_lists[i]->size()));
   }
+  // The shape of |entered_contexts_| and |is_microtask_context_| stacks must
+  // be in sync.
+  is_microtask_context_.shrink_to_fit();
+  DCHECK_EQ(entered_contexts_.capacity(), is_microtask_context_.capacity());
+  DCHECK_EQ(entered_contexts_.size(), is_microtask_context_.size());
 }
 
 void HandleScopeImplementer::Iterate(RootVisitor* v) {

src/api/api.h

@@ -468,6 +468,7 @@ bool HandleScopeImplementer::HasSavedContexts() {
 }
 
 void HandleScopeImplementer::EnterContext(Context context) {
+  DCHECK_EQ(entered_contexts_.capacity(), is_microtask_context_.capacity());
   DCHECK_EQ(entered_contexts_.size(), is_microtask_context_.size());
   entered_contexts_.push_back(context);
   is_microtask_context_.push_back(0);
@@ -475,6 +476,7 @@ void HandleScopeImplementer::EnterContext(Context context) {
 
 void HandleScopeImplementer::LeaveContext() {
   DCHECK(!entered_contexts_.empty());
+  DCHECK_EQ(entered_contexts_.capacity(), is_microtask_context_.capacity());
   DCHECK_EQ(entered_contexts_.size(), is_microtask_context_.size());
   entered_contexts_.pop_back();
   is_microtask_context_.pop_back();
@@ -485,6 +487,7 @@ bool HandleScopeImplementer::LastEnteredContextWas(Context context) {
 }
 
 void HandleScopeImplementer::EnterMicrotaskContext(Context context) {
+  DCHECK_EQ(entered_contexts_.capacity(), is_microtask_context_.capacity());
   DCHECK_EQ(entered_contexts_.size(), is_microtask_context_.size());
   entered_contexts_.push_back(context);
   is_microtask_context_.push_back(1);

src/builtins/builtins-microtask-queue-gen.cc

@@ -413,14 +413,23 @@ void MicrotaskQueueBuiltinsAssembler::EnterMicrotaskContext(
     TNode<IntPtrT> flag_data_offset =
         IntPtrConstant(HandleScopeImplementer::kIsMicrotaskContextOffset +
                        FlagStack::kDataOffset);
+    TNode<IntPtrT> flag_capacity_offset =
+        IntPtrConstant(HandleScopeImplementer::kIsMicrotaskContextOffset +
+                       FlagStack::kCapacityOffset);
+    TNode<IntPtrT> flag_size_offset =
+        IntPtrConstant(HandleScopeImplementer::kIsMicrotaskContextOffset +
+                       FlagStack::kSizeOffset);
+    // Ensure both stacks are in sync.
+    USE(flag_capacity_offset);
+    CSA_DCHECK(this,
+               WordEqual(capacity, Load<IntPtrT>(hsi, flag_capacity_offset)));
+    CSA_DCHECK(this, WordEqual(size, Load<IntPtrT>(hsi, flag_size_offset)));
+
     TNode<RawPtrT> flag_data = Load<RawPtrT>(hsi, flag_data_offset);
     StoreNoWriteBarrier(MachineRepresentation::kWord8, flag_data, size,
                         BoolConstant(true));
-    StoreNoWriteBarrier(
-        MachineType::PointerRepresentation(), hsi,
-        IntPtrConstant(HandleScopeImplementer::kIsMicrotaskContextOffset +
-                       FlagStack::kSizeOffset),
-        new_size);
+    StoreNoWriteBarrier(MachineType::PointerRepresentation(), hsi,
+                        flag_size_offset, new_size);
 
     Goto(&done);
   }
@@ -449,13 +458,11 @@ void MicrotaskQueueBuiltinsAssembler::RewindEnteredContext(
       IntPtrConstant(HandleScopeImplementer::kEnteredContextsOffset +
                      ContextStack::kSizeOffset);
 
-#ifdef ENABLE_VERIFY_CSA
-  {
+  if (DEBUG_BOOL) {
     TNode<IntPtrT> size = Load<IntPtrT>(hsi, size_offset);
     CSA_CHECK(this, IntPtrLessThan(IntPtrConstant(0), size));
     CSA_CHECK(this, IntPtrLessThanOrEqual(saved_entered_context_count, size));
   }
-#endif
 
   StoreNoWriteBarrier(MachineType::PointerRepresentation(), hsi, size_offset,
                       saved_entered_context_count);