[runtime] Mark more Context getters const

- Add Context extension slot verification
- Fix ScriptContextTable printing
- Make Context::scope_info() inlinable

Bug: chromium:1244145
Change-Id: Ide71866885f3f92de6561dfef6911ee52c6094f9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3211578
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77286}

src/diagnostics/objects-debug.cc

@@ -603,6 +603,7 @@ void FixedDoubleArray::FixedDoubleArrayVerify(Isolate* isolate) {
 }
 
 void Context::ContextVerify(Isolate* isolate) {
+  if (has_extension()) VerifyExtensionSlot(extension());
   TorqueGeneratedClassVerifiers::ContextVerify(*this, isolate);
   for (int i = 0; i < length(); i++) {
     VerifyObjectField(isolate, OffsetOfElementAt(i));

src/diagnostics/objects-printer.cc

@@ -123,9 +123,11 @@ void HeapObject::HeapObjectPrint(std::ostream& os) {
     case MODULE_CONTEXT_TYPE:
     case SCRIPT_CONTEXT_TYPE:
     case WITH_CONTEXT_TYPE:
-    case SCRIPT_CONTEXT_TABLE_TYPE:
       Context::cast(*this).ContextPrint(os);
       break;
+    case SCRIPT_CONTEXT_TABLE_TYPE:
+      FixedArray::cast(*this).FixedArrayPrint(os);
+      break;
     case NATIVE_CONTEXT_TYPE:
       NativeContext::cast(*this).NativeContextPrint(os);
       break;

src/objects/contexts-inl.h

@@ -113,9 +113,9 @@ void Context::set_scope_info(ScopeInfo scope_info, WriteBarrierMode mode) {
   set(SCOPE_INFO_INDEX, scope_info, mode);
 }
 
-Object Context::unchecked_previous() { return get(PREVIOUS_INDEX); }
+Object Context::unchecked_previous() const { return get(PREVIOUS_INDEX); }
 
-Context Context::previous() {
+Context Context::previous() const {
   Object result = get(PREVIOUS_INDEX);
   DCHECK(IsBootstrappingOrValidParentContext(result, *this));
   return Context::unchecked_cast(result);
@@ -124,19 +124,28 @@ void Context::set_previous(Context context, WriteBarrierMode mode) {
   set(PREVIOUS_INDEX, context, mode);
 }
 
-Object Context::next_context_link() { return get(Context::NEXT_CONTEXT_LINK); }
+ScopeInfo Context::scope_info() const {
+  return ScopeInfo::cast(get(SCOPE_INFO_INDEX));
+}
+
+Object Context::next_context_link() const {
+  return get(Context::NEXT_CONTEXT_LINK);
+}
 
-bool Context::has_extension() {
+bool Context::has_extension() const {
   return scope_info().HasContextExtensionSlot() && !extension().IsUndefined();
 }
 
-HeapObject Context::extension() {
+HeapObject Context::extension() const {
   DCHECK(scope_info().HasContextExtensionSlot());
   return HeapObject::cast(get(EXTENSION_INDEX));
 }
 
 void Context::set_extension(HeapObject object, WriteBarrierMode mode) {
   DCHECK(scope_info().HasContextExtensionSlot());
+#ifdef VERIFY_HEAP
+  VerifyExtensionSlot(object);
+#endif
   set(EXTENSION_INDEX, object, mode);
 }
 

src/objects/contexts.cc

@@ -65,7 +65,7 @@ bool ScriptContextTable::Lookup(Isolate* isolate, ScriptContextTable table,
   return false;
 }
 
-bool Context::is_declaration_context() {
+bool Context::is_declaration_context() const {
   if (IsFunctionContext() || IsNativeContext() || IsScriptContext() ||
       IsModuleContext()) {
     return true;
@@ -77,7 +77,7 @@ bool Context::is_declaration_context() {
   return scope_info().is_declaration_scope();
 }
 
-Context Context::declaration_context() {
+Context Context::declaration_context() const {
   Context current = *this;
   while (!current.is_declaration_context()) {
     current = current.previous();
@@ -85,7 +85,7 @@ Context Context::declaration_context() {
   return current;
 }
 
-Context Context::closure_context() {
+Context Context::closure_context() const {
   Context current = *this;
   while (!current.IsFunctionContext() && !current.IsScriptContext() &&
          !current.IsModuleContext() && !current.IsNativeContext() &&
@@ -95,7 +95,7 @@ Context Context::closure_context() {
   return current;
 }
 
-JSObject Context::extension_object() {
+JSObject Context::extension_object() const {
   DCHECK(IsNativeContext() || IsFunctionContext() || IsBlockContext() ||
          IsEvalContext() || IsCatchContext());
   HeapObject object = extension();
@@ -105,17 +105,13 @@ JSObject Context::extension_object() {
   return JSObject::cast(object);
 }
 
-JSReceiver Context::extension_receiver() {
+JSReceiver Context::extension_receiver() const {
   DCHECK(IsNativeContext() || IsWithContext() || IsEvalContext() ||
          IsFunctionContext() || IsBlockContext());
   return IsWithContext() ? JSReceiver::cast(extension()) : extension_object();
 }
 
-ScopeInfo Context::scope_info() {
-  return ScopeInfo::cast(get(SCOPE_INFO_INDEX));
-}
-
-SourceTextModule Context::module() {
+SourceTextModule Context::module() const {
   Context current = *this;
   while (!current.IsModuleContext()) {
     current = current.previous();
@@ -123,11 +119,11 @@ SourceTextModule Context::module() {
   return SourceTextModule::cast(current.extension());
 }
 
-JSGlobalObject Context::global_object() {
+JSGlobalObject Context::global_object() const {
   return JSGlobalObject::cast(native_context().extension());
 }
 
-Context Context::script_context() {
+Context Context::script_context() const {
   Context current = *this;
   while (!current.IsScriptContext()) {
     current = current.previous();
@@ -135,7 +131,7 @@ Context Context::script_context() {
   return current;
 }
 
-JSGlobalProxy Context::global_proxy() {
+JSGlobalProxy Context::global_proxy() const {
   return native_context().global_proxy_object();
 }
 
@@ -446,6 +442,23 @@ int Context::IntrinsicIndexForName(const unsigned char* unsigned_string,
 
 #undef COMPARE_NAME
 
+#ifdef VERIFY_HEAP
+void Context::VerifyExtensionSlot(HeapObject extension) {
+  CHECK(scope_info().HasContextExtensionSlot());
+  if (extension.IsUndefined()) return;
+  if (IsModuleContext()) {
+    extension.IsSourceTextModule();
+  } else if (IsDebugEvaluateContext() || IsWithContext()) {
+    extension.IsJSReceiver();
+  } else if (IsNativeContext()) {
+    extension.IsJSGlobalObject();
+  } else if ((IsBlockContext() && scope_info().is_declaration_scope()) ||
+             IsFunctionContext()) {
+    extension.IsJSContextExtensionObject();
+  }
+}
+#endif  // VERIFY_HEAP
+
 #ifdef DEBUG
 
 bool Context::IsBootstrappingOrValidParentContext(Object object,

src/objects/contexts.h

@@ -542,39 +542,39 @@ class Context : public TorqueGeneratedContext<Context, HeapObject> {
   inline void set_scope_info(ScopeInfo scope_info,
                              WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
 
-  inline Object unchecked_previous();
-  inline Context previous();
+  inline Object unchecked_previous() const;
+  inline Context previous() const;
 
-  inline Object next_context_link();
+  inline Object next_context_link() const;
 
-  inline bool has_extension();
-  inline HeapObject extension();
+  inline bool has_extension() const;
+  inline HeapObject extension() const;
   inline void set_extension(HeapObject object,
                             WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
-  JSObject extension_object();
-  JSReceiver extension_receiver();
-  V8_EXPORT_PRIVATE ScopeInfo scope_info();
+  JSObject extension_object() const;
+  JSReceiver extension_receiver() const;
+  V8_EXPORT_PRIVATE inline ScopeInfo scope_info() const;
 
   // Find the module context (assuming there is one) and return the associated
   // module object.
-  SourceTextModule module();
+  SourceTextModule module() const;
 
   // Get the context where var declarations will be hoisted to, which
   // may be the context itself.
-  Context declaration_context();
-  bool is_declaration_context();
+  Context declaration_context() const;
+  bool is_declaration_context() const;
 
   // Get the next closure's context on the context chain.
-  Context closure_context();
+  Context closure_context() const;
 
   // Returns a JSGlobalProxy object or null.
-  V8_EXPORT_PRIVATE JSGlobalProxy global_proxy();
+  V8_EXPORT_PRIVATE JSGlobalProxy global_proxy() const;
 
   // Get the JSGlobalObject object.
-  V8_EXPORT_PRIVATE JSGlobalObject global_object();
+  V8_EXPORT_PRIVATE JSGlobalObject global_object() const;
 
   // Get the script context by traversing the context chain.
-  Context script_context();
+  Context script_context() const;
 
   // Compute the native context.
   inline NativeContext native_context() const;
@@ -652,6 +652,10 @@ class Context : public TorqueGeneratedContext<Context, HeapObject> {
 
   class BodyDescriptor;
 
+#ifdef VERIFY_HEAP
+  void VerifyExtensionSlot(HeapObject extension);
+#endif
+
  private:
 #ifdef DEBUG
   // Bootstrapping-aware type checks.