[symbol-as-weakmap-key] Add tests to check weak collection size

... after gc.

This CL also adds a runtime test function GetWeakCollectionSize
to get the weak collection size.

Bug: v8:12947
Change-Id: I4aff39165a54b63b3d690bfea71c2a439da01d00
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3905071
Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: 王澳 <wangao.james@bytedance.com>
Cr-Commit-Position: refs/heads/main@{#83464}

src/runtime/runtime-test.cc

@@ -23,6 +23,7 @@
 #include "src/heap/heap-inl.h"  // For ToBoolean. TODO(jkummerow): Drop.
 #include "src/heap/heap-write-barrier-inl.h"
 #include "src/ic/stub-cache.h"
+#include "src/objects/js-collection-inl.h"
 #ifdef V8_ENABLE_MAGLEV
 #include "src/maglev/maglev-concurrent-dispatcher.h"
 #endif  // V8_ENABLE_MAGLEV
@@ -1764,5 +1765,14 @@ RUNTIME_FUNCTION(Runtime_AtomicsConditionNumWaitersForTesting) {
   return cv->NumWaitersForTesting(isolate);
 }
 
+RUNTIME_FUNCTION(Runtime_GetWeakCollectionSize) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(1, args.length());
+  Handle<JSWeakCollection> collection = args.at<JSWeakCollection>(0);
+
+  return Smi::FromInt(
+      EphemeronHashTable::cast(collection->table()).NumberOfElements());
+}
+
 }  // namespace internal
 }  // namespace v8

src/runtime/runtime.h

@@ -513,6 +513,7 @@ namespace internal {
   F(GetInitializerFunction, 1, 1)             \
   F(GetOptimizationStatus, 1, 1)              \
   F(GetUndetectable, 0, 1)                    \
+  F(GetWeakCollectionSize, 1, 1)              \
   F(GlobalPrint, 1, 1)                        \
   F(HasDictionaryElements, 1, 1)              \
   F(HasDoubleElements, 1, 1)                  \

test/mjsunit/harmony/symbol-as-weakmap-key.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --harmony-symbol-as-weakmap-key --expose-gc
+// Flags: --harmony-symbol-as-weakmap-key --expose-gc --allow-natives-syntax --noincremental-marking
 
 (function TestWeakMapWithNonRegisteredSymbolKey() {
   const key = Symbol('123');
@@ -28,16 +28,17 @@
   const outerKey = Symbol('234');
   const outerValue = 1;
   map.set(outerKey, outerValue);
-  {
+  (function () {
     const innerKey = Symbol('123');
     const innerValue = 1;
     map.set(innerKey, innerValue);
     assertTrue(map.has(innerKey));
     assertSame(innerValue, map.get(innerKey));
-  }
+  })();
   gc();
   assertTrue(map.has(outerKey));
   assertSame(outerValue, map.get(outerKey));
+  assertEquals(1, %GetWeakCollectionSize(map));
 })();
 
 (function TestWeakMapWithRegisteredSymbolKey() {
@@ -74,13 +75,14 @@
   const set = new WeakSet();
   const outerKey = Symbol('234');
   set.add(outerKey);
-  {
+  (function () {
     const innerKey = Symbol('123');
     set.add(innerKey);
     assertTrue(set.has(innerKey));
-  }
-  gc();
+  })();
   assertTrue(set.has(outerKey));
+  gc();
+  assertEquals(1, %GetWeakCollectionSize(set));
 })();
 
 (function TestWeakSetWithRegisteredSymbolKey() {

test/unittests/objects/weakmaps-unittest.cc

@@ -83,14 +83,22 @@ TEST_F(WeakMapsTest, Weakness) {
     int32_t object_hash = object->GetOrCreateHash(isolate).value();
     JSWeakCollection::Set(weakmap, object, smi, object_hash);
   }
-  CHECK_EQ(2, EphemeronHashTable::cast(weakmap->table()).NumberOfElements());
+  // Put a symbol key into weak map.
+  {
+    HandleScope inner_scope(isolate);
+    Handle<Symbol> symbol = factory->NewSymbol();
+    Handle<Smi> smi(Smi::FromInt(23), isolate);
+    JSWeakCollection::Set(weakmap, symbol, smi, symbol->hash());
+  }
+  CHECK_EQ(3, EphemeronHashTable::cast(weakmap->table()).NumberOfElements());
 
   // Force a full GC.
   PreciseCollectAllGarbage();
   CHECK_EQ(0, NumberOfWeakCalls);
+  // Symbol key should be deleted.
   CHECK_EQ(2, EphemeronHashTable::cast(weakmap->table()).NumberOfElements());
   CHECK_EQ(
-      0, EphemeronHashTable::cast(weakmap->table()).NumberOfDeletedElements());
+      1, EphemeronHashTable::cast(weakmap->table()).NumberOfDeletedElements());
 
   // Make the global reference to the key weak.
   std::pair<Handle<Object>*, int> handle_and_id(&key, 1234);
@@ -103,7 +111,7 @@ TEST_F(WeakMapsTest, Weakness) {
   CHECK_EQ(1, NumberOfWeakCalls);
   CHECK_EQ(0, EphemeronHashTable::cast(weakmap->table()).NumberOfElements());
   CHECK_EQ(
-      2, EphemeronHashTable::cast(weakmap->table()).NumberOfDeletedElements());
+      3, EphemeronHashTable::cast(weakmap->table()).NumberOfDeletedElements());
 }
 
 TEST_F(WeakMapsTest, Shrinking) {