[debug] Report optimized out and certain TDZ values as unavailable.

This adds a new --experimental-value-unavailable flag, which is disabled
for now. When enabled the debugger reports values that are optimized out
by TurboFan and values of certain variables in Temporal Dead Zones (TDZ)
as unavailable. Internally we use a special `value_unavailable` accessor
info to represent these values, and on the debugger boundary we report
these properties with `value`, `get`, or `set`.

Doc: https://goo.gle/devtools-value-unavailable
Bug: chromium:1328681
Demo: devtools-dbg-stories.netlify.app/crbug-1328681-value-unavailable
Change-Id: Idb09a4a148335a950deae60f7c07caecc48826ba
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3627510
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81509}

src/builtins/accessors.cc

@@ -808,6 +808,24 @@ Handle<AccessorInfo> Accessors::MakeWrappedFunctionLengthInfo(
                       &WrappedFunctionLengthGetter, &ReconfigureToDataProperty);
 }
 
+//
+// Accessors::ValueUnavailable
+//
+
+void Accessors::ValueUnavailableGetter(
+    v8::Local<v8::Name> name, const v8::PropertyCallbackInfo<v8::Value>& info) {
+  Isolate* isolate = reinterpret_cast<Isolate*>(info.GetIsolate());
+  HandleScope scope(isolate);
+  isolate->Throw(*isolate->factory()->NewReferenceError(
+      MessageTemplate::kAccessedUnavailableVariable, Utils::OpenHandle(*name)));
+  isolate->OptionalRescheduleException(false);
+}
+
+Handle<AccessorInfo> Accessors::MakeValueUnavailableInfo(Isolate* isolate) {
+  return MakeAccessor(isolate, isolate->factory()->empty_string(),
+                      &ValueUnavailableGetter, &ReconfigureToDataProperty);
+}
+
 //
 // Accessors::WrappedFunctionName
 //

src/builtins/accessors.h

@@ -48,6 +48,8 @@ class JavaScriptFrame;
     kHasSideEffectToReceiver)                                                 \
   V(_, string_length, StringLength, kHasNoSideEffect,                         \
     kHasSideEffectToReceiver)                                                 \
+  V(_, value_unavailable, ValueUnavailable, kHasNoSideEffect,                 \
+    kHasSideEffectToReceiver)                                                 \
   V(_, wrapped_function_length, WrappedFunctionLength, kHasNoSideEffect,      \
     kHasSideEffectToReceiver)                                                 \
   V(_, wrapped_function_name, WrappedFunctionName, kHasNoSideEffect,          \

src/common/message-template.h

@@ -340,6 +340,7 @@ namespace internal {
   T(SuperAlreadyCalled, "Super constructor may only be called once")           \
   T(AccessedUninitializedVariable, "Cannot access '%' before initialization")  \
   T(UnsupportedSuper, "Unsupported reference to 'super'")                      \
+  T(AccessedUnavailableVariable, "Cannot access '%' from debugger")            \
   /* RangeError */                                                             \
   T(BigIntDivZero, "Division by zero")                                         \
   T(BigIntNegativeExponent, "Exponent must be positive")                       \

src/debug/debug-interface.h

@@ -565,7 +565,8 @@ void SetReturnValue(v8::Isolate* isolate, v8::Local<v8::Value> value);
 enum class NativeAccessorType {
   None = 0,
   HasGetter = 1 << 0,
-  HasSetter = 1 << 1
+  HasSetter = 1 << 1,
+  IsValueUnavailable = 1 << 2
 };
 
 int64_t GetNextRandomInt64(v8::Isolate* isolate);

src/debug/debug-property-iterator.cc

@@ -223,6 +223,9 @@ base::Flags<debug::NativeAccessorType, int> GetNativeAccessorDescriptorInternal(
   Handle<Object> structure = it.GetAccessors();
   if (!structure->IsAccessorInfo()) return debug::NativeAccessorType::None;
   base::Flags<debug::NativeAccessorType, int> result;
+  if (*structure == *isolate->factory()->value_unavailable_accessor()) {
+    return debug::NativeAccessorType::IsValueUnavailable;
+  }
 #define IS_BUILTIN_ACCESSOR(_, name, ...)                   \
   if (*structure == *isolate->factory()->name##_accessor()) \
     return debug::NativeAccessorType::None;

src/debug/debug-scopes.cc

@@ -563,14 +563,31 @@ Handle<JSObject> ScopeIterator::ScopeObject(Mode mode) {
   Handle<JSObject> scope = isolate_->factory()->NewSlowJSObjectWithNullProto();
   auto visitor = [=](Handle<String> name, Handle<Object> value,
                      ScopeType scope_type) {
-    if (value->IsTheHole(isolate_)) {
-      // Reflect variables under TDZ as undefined in scope object.
+    if (value->IsOptimizedOut(isolate_)) {
+      if (FLAG_experimental_value_unavailable) {
+        JSObject::SetAccessor(scope, name,
+                              isolate_->factory()->value_unavailable_accessor(),
+                              NONE)
+            .Check();
+        return false;
+      }
+      // Reflect optimized out variables as undefined in scope object.
+      value = isolate_->factory()->undefined_value();
+    } else if (value->IsTheHole(isolate_)) {
       if (scope_type == ScopeTypeScript &&
           JSReceiver::HasOwnProperty(isolate_, scope, name).FromMaybe(true)) {
         // We also use the hole to represent overridden let-declarations via
         // REPL mode in a script context. Catch this case.
         return false;
       }
+      if (FLAG_experimental_value_unavailable) {
+        JSObject::SetAccessor(scope, name,
+                              isolate_->factory()->value_unavailable_accessor(),
+                              NONE)
+            .Check();
+        return false;
+      }
+      // Reflect variables under TDZ as undefined in scope object.
       value = isolate_->factory()->undefined_value();
     }
     // Overwrite properties. Sometimes names in the same scope can collide, e.g.
@@ -804,12 +821,8 @@ bool ScopeIterator::VisitLocals(const Visitor& visitor, Mode mode,
     Handle<Object> receiver =
         this_var->location() == VariableLocation::CONTEXT
             ? handle(context_->get(this_var->index()), isolate_)
-            : frame_inspector_ == nullptr
-                  ? handle(generator_->receiver(), isolate_)
+        : frame_inspector_ == nullptr ? handle(generator_->receiver(), isolate_)
                                       : frame_inspector_->GetReceiver();
-    if (receiver->IsOptimizedOut(isolate_)) {
-      receiver = isolate_->factory()->undefined_value();
-    }
     if (visitor(isolate_->factory()->this_string(), receiver, scope_type))
       return true;
   }
@@ -850,10 +863,6 @@ bool ScopeIterator::VisitLocals(const Visitor& visitor, Mode mode,
           value = handle(parameters_and_registers.get(index), isolate_);
         } else {
           value = frame_inspector_->GetParameter(index);
-
-          if (value->IsOptimizedOut(isolate_)) {
-            value = isolate_->factory()->undefined_value();
-          }
         }
         break;
       }
@@ -877,7 +886,6 @@ bool ScopeIterator::VisitLocals(const Visitor& visitor, Mode mode,
                 current_scope_->AsDeclarationScope()->arguments() == var) {
               continue;
             }
-            value = isolate_->factory()->undefined_value();
           }
         }
         break;

src/flags/flag-definitions.h

@@ -1652,6 +1652,8 @@ DEFINE_BOOL(hard_abort, true, "abort by crashing")
 
 DEFINE_BOOL(experimental_async_stack_tagging_api, false,
             "enable experimental async stacks tagging API")
+DEFINE_BOOL(experimental_value_unavailable, false,
+            "enable experimental <value unavailable> in scopes")
 
 DEFINE_BOOL(
     live_edit_top_frame, true,

test/inspector/debugger/value-unavailable-scopes-expected.txt

+Test scopes with unavailable values
+
+Running test: testTemporalDeadZone
+variable y correctly reported as <value_unavailable>
+
+Running test: testOptimizedOut
+variable y correctly reported as <value_unavailable>

test/inspector/debugger/value-unavailable-scopes.js

+// Copyright 2022 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --experimental-value-unavailable
+
+let {session, contextGroup, Protocol} =
+    InspectorTest.start('Test scopes with unavailable values');
+
+contextGroup.addScript(`
+function tdz() {
+  debugger;
+  const x = 2 ?? y + x;
+  let y = x + 1;
+  return y;
+}
+
+function opt() {
+  function optimizedOut(x, stop) {
+    let y = x + 1;
+    let z = y + 1;
+    if (stop) {
+      debugger;
+    }
+    return z;
+  }
+
+  %PrepareFunctionForOptimization(optimizedOut);
+  optimizedOut(1, false);
+  optimizedOut(2, false);
+  %OptimizeFunctionOnNextCall(optimizedOut);
+  optimizedOut(3, false);
+
+  return optimizedOut(1, true);
+}
+`);
+
+Protocol.Debugger.onPaused(async ({params: {callFrames: [{scopeChain}]}}) => {
+  for (const scope of scopeChain) {
+    if (scope.type !== 'local') continue;
+    const {result: {result: variables}} =
+        await Protocol.Runtime.getProperties({objectId: scope.object.objectId});
+    for (const variable of variables) {
+      if (variable.name !== 'y') continue;
+      if ('value' in variable || 'get' in variable || 'set' in variable) {
+        InspectorTest.log(
+            'FAIL: variable y was expected to be reported as <value_unavailable>');
+      } else {
+        InspectorTest.log(
+            'variable y correctly reported as <value_unavailable>');
+      }
+    }
+  }
+  await Protocol.Debugger.resume();
+});
+
+InspectorTest.runAsyncTestSuite([
+  async function testTemporalDeadZone() {
+    await Promise.all([
+      Protocol.Runtime.enable(),
+      Protocol.Debugger.enable(),
+    ]);
+    await Protocol.Runtime.evaluate({expression: 'tdz()'});
+    await Promise.all([
+      Protocol.Runtime.disable(),
+      Protocol.Debugger.disable(),
+    ]);
+  },
+
+  async function testOptimizedOut() {
+    await Promise.all([
+      Protocol.Runtime.enable(),
+      Protocol.Debugger.enable(),
+    ]);
+    await Protocol.Runtime.evaluate({expression: 'opt()'});
+    await Promise.all([
+      Protocol.Runtime.disable(),
+      Protocol.Debugger.disable(),
+    ]);
+  },
+]);

test/inspector/inspector.status

@@ -542,6 +542,7 @@
 ['lite_mode or variant in (nooptimization, jitless, assert_types)', {
   # Test relies on TurboFan being enabled.
   'debugger/restart-frame/restart-inlined-frame': [SKIP],
+  'debugger/value-unavailable-scopes': [SKIP],
 }], # lite_mode or variant in (nooptimization, jitless, assert_types)
 
 ]

test/unittests/interpreter/bytecode_expectations/PrivateAccessorAccess.golden

@@ -83,7 +83,7 @@ bytecodes: [
   /*   48 E> */ B(DefineKeyedOwnProperty), R(this), R(0), U8(0),
   /*   53 S> */ B(LdaImmutableCurrentContextSlot), U8(3),
   /*   58 E> */ B(GetKeyedProperty), R(this), U8(2),
-                B(Wide), B(LdaSmi), I16(302),
+                B(Wide), B(LdaSmi), I16(303),
                 B(Star2),
                 B(LdaConstant), U8(0),
                 B(Star3),
@@ -115,7 +115,7 @@ bytecodes: [
   /*   41 E> */ B(DefineKeyedOwnProperty), R(this), R(0), U8(0),
   /*   46 S> */ B(LdaImmutableCurrentContextSlot), U8(3),
   /*   51 E> */ B(GetKeyedProperty), R(this), U8(2),
-                B(Wide), B(LdaSmi), I16(301),
+                B(Wide), B(LdaSmi), I16(302),
                 B(Star2),
                 B(LdaConstant), U8(0),
                 B(Star3),
@@ -149,7 +149,7 @@ bytecodes: [
                 B(Star2),
                 B(LdaImmutableCurrentContextSlot), U8(3),
   /*   58 E> */ B(GetKeyedProperty), R(this), U8(2),
-                B(Wide), B(LdaSmi), I16(302),
+                B(Wide), B(LdaSmi), I16(303),
                 B(Star3),
                 B(LdaConstant), U8(0),
                 B(Star4),
@@ -181,7 +181,7 @@ bytecodes: [
   /*   41 E> */ B(DefineKeyedOwnProperty), R(this), R(0), U8(0),
   /*   46 S> */ B(LdaImmutableCurrentContextSlot), U8(3),
   /*   51 E> */ B(GetKeyedProperty), R(this), U8(2),
-                B(Wide), B(LdaSmi), I16(301),
+                B(Wide), B(LdaSmi), I16(302),
                 B(Star2),
                 B(LdaConstant), U8(0),
                 B(Star3),

test/unittests/interpreter/bytecode_expectations/PrivateMethodAccess.golden

@@ -58,7 +58,7 @@ bytecodes: [
                 B(Star2),
                 B(LdaImmutableCurrentContextSlot), U8(3),
   /*   54 E> */ B(GetKeyedProperty), R(this), U8(2),
-                B(Wide), B(LdaSmi), I16(300),
+                B(Wide), B(LdaSmi), I16(301),
                 B(Star3),
                 B(LdaConstant), U8(0),
                 B(Star4),
@@ -91,7 +91,7 @@ bytecodes: [
   /*   44 E> */ B(DefineKeyedOwnProperty), R(this), R(0), U8(0),
   /*   49 S> */ B(LdaImmutableCurrentContextSlot), U8(3),
   /*   54 E> */ B(GetKeyedProperty), R(this), U8(2),
-                B(Wide), B(LdaSmi), I16(300),
+                B(Wide), B(LdaSmi), I16(301),
                 B(Star2),
                 B(LdaConstant), U8(0),
                 B(Star3),

test/unittests/interpreter/bytecode_expectations/StaticPrivateMethodAccess.golden

@@ -24,7 +24,7 @@ bytecodes: [
                 B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(1),
                 B(JumpIfTrue), U8(16),
-                B(Wide), B(LdaSmi), I16(294),
+                B(Wide), B(LdaSmi), I16(295),
                 B(Star2),
                 B(LdaConstant), U8(0),
                 B(Star3),
@@ -61,13 +61,13 @@ bytecodes: [
                 B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(0),
                 B(JumpIfTrue), U8(16),
-                B(Wide), B(LdaSmi), I16(294),
+                B(Wide), B(LdaSmi), I16(295),
                 B(Star2),
                 B(LdaConstant), U8(0),
                 B(Star3),
   /*   61 E> */ B(CallRuntime), U16(Runtime::kNewTypeError), R(2), U8(2),
                 B(Throw),
-                B(Wide), B(LdaSmi), I16(300),
+                B(Wide), B(LdaSmi), I16(301),
                 B(Star2),
                 B(LdaConstant), U8(1),
                 B(Star3),
@@ -99,13 +99,13 @@ bytecodes: [
                 B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(0),
                 B(JumpIfTrue), U8(16),
-                B(Wide), B(LdaSmi), I16(294),
+                B(Wide), B(LdaSmi), I16(295),
                 B(Star1),
                 B(LdaConstant), U8(0),
                 B(Star2),
   /*   61 E> */ B(CallRuntime), U16(Runtime::kNewTypeError), R(1), U8(2),
                 B(Throw),
-                B(Wide), B(LdaSmi), I16(300),
+                B(Wide), B(LdaSmi), I16(301),
                 B(Star1),
                 B(LdaConstant), U8(1),
                 B(Star2),
@@ -145,7 +145,7 @@ bytecodes: [
                 B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(0),
                 B(JumpIfTrue), U8(16),
-                B(Wide), B(LdaSmi), I16(294),
+                B(Wide), B(LdaSmi), I16(295),
                 B(Star2),
                 B(LdaConstant), U8(0),
                 B(Star3),
@@ -167,7 +167,7 @@ bytecodes: [
                 B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(0),
                 B(JumpIfTrue), U8(16),
-                B(Wide), B(LdaSmi), I16(294),
+                B(Wide), B(LdaSmi), I16(295),
                 B(Star3),
                 B(LdaConstant), U8(0),
                 B(Star4),
@@ -182,7 +182,7 @@ bytecodes: [
                 B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(0),
                 B(JumpIfTrue), U8(16),
-                B(Wide), B(LdaSmi), I16(294),
+                B(Wide), B(LdaSmi), I16(295),
                 B(Star2),
                 B(LdaConstant), U8(0),
                 B(Star3),
@@ -216,13 +216,13 @@ bytecodes: [
                 B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(0),
                 B(JumpIfTrue), U8(16),
-                B(Wide), B(LdaSmi), I16(294),
+                B(Wide), B(LdaSmi), I16(295),
                 B(Star1),
                 B(LdaConstant), U8(0),
                 B(Star2),
   /*   65 E> */ B(CallRuntime), U16(Runtime::kNewTypeError), R(1), U8(2),
                 B(Throw),
-                B(Wide), B(LdaSmi), I16(302),
+                B(Wide), B(LdaSmi), I16(303),
                 B(Star1),
                 B(LdaConstant), U8(1),
                 B(Star2),
@@ -253,13 +253,13 @@ bytecodes: [
                 B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(0),
                 B(JumpIfTrue), U8(16),
-                B(Wide), B(LdaSmi), I16(294),
+                B(Wide), B(LdaSmi), I16(295),
                 B(Star1),
                 B(LdaConstant), U8(0),
                 B(Star2),
   /*   58 E> */ B(CallRuntime), U16(Runtime::kNewTypeError), R(1), U8(2),
                 B(Throw),
-                B(Wide), B(LdaSmi), I16(301),
+                B(Wide), B(LdaSmi), I16(302),
                 B(Star1),
                 B(LdaConstant), U8(1),
                 B(Star2),
@@ -292,13 +292,13 @@ bytecodes: [
                 B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(0),
                 B(JumpIfTrue), U8(16),
-                B(Wide), B(LdaSmi), I16(294),
+                B(Wide), B(LdaSmi), I16(295),
                 B(Star2),
                 B(LdaConstant), U8(0),
                 B(Star3),
   /*   65 E> */ B(CallRuntime), U16(Runtime::kNewTypeError), R(2), U8(2),
                 B(Throw),
-                B(Wide), B(LdaSmi), I16(302),
+                B(Wide), B(LdaSmi), I16(303),
                 B(Star2),
                 B(LdaConstant), U8(1),
                 B(Star3),
@@ -327,7 +327,7 @@ bytecode array length: 19
 bytecodes: [
   /*   46 S> */ B(LdaImmutableCurrentContextSlot), U8(3),
   /*   51 E> */ B(GetKeyedProperty), R(this), U8(0),
-                B(Wide), B(LdaSmi), I16(301),
+                B(Wide), B(LdaSmi), I16(302),
                 B(Star1),
                 B(LdaConstant), U8(0),
                 B(Star2),

tools/v8heapconst.py

@@ -514,56 +514,57 @@ KNOWN_OBJECTS = {
   ("old_space", 0x04399): "FunctionPrototypeAccessor",
   ("old_space", 0x043c1): "SharedArrayLengthAccessor",
   ("old_space", 0x043e9): "StringLengthAccessor",
-  ("old_space", 0x04411): "WrappedFunctionLengthAccessor",
-  ("old_space", 0x04439): "WrappedFunctionNameAccessor",
-  ("old_space", 0x04461): "InvalidPrototypeValidityCell",
-  ("old_space", 0x04469): "EmptyScript",
-  ("old_space", 0x044ad): "ManyClosuresCell",
-  ("old_space", 0x044b9): "ArrayConstructorProtector",
-  ("old_space", 0x044cd): "NoElementsProtector",
-  ("old_space", 0x044e1): "MegaDOMProtector",
-  ("old_space", 0x044f5): "IsConcatSpreadableProtector",
-  ("old_space", 0x04509): "ArraySpeciesProtector",
-  ("old_space", 0x0451d): "TypedArraySpeciesProtector",
-  ("old_space", 0x04531): "PromiseSpeciesProtector",
-  ("old_space", 0x04545): "RegExpSpeciesProtector",
-  ("old_space", 0x04559): "StringLengthProtector",
-  ("old_space", 0x0456d): "ArrayIteratorProtector",
-  ("old_space", 0x04581): "ArrayBufferDetachingProtector",
-  ("old_space", 0x04595): "PromiseHookProtector",
-  ("old_space", 0x045a9): "PromiseResolveProtector",
-  ("old_space", 0x045bd): "MapIteratorProtector",
-  ("old_space", 0x045d1): "PromiseThenProtector",
-  ("old_space", 0x045e5): "SetIteratorProtector",
-  ("old_space", 0x045f9): "StringIteratorProtector",
-  ("old_space", 0x0460d): "SingleCharacterStringCache",
-  ("old_space", 0x04a15): "StringSplitCache",
-  ("old_space", 0x04e1d): "RegExpMultipleCache",
-  ("old_space", 0x05225): "BuiltinsConstantsTable",
-  ("old_space", 0x05669): "AsyncFunctionAwaitRejectSharedFun",
-  ("old_space", 0x0568d): "AsyncFunctionAwaitResolveSharedFun",
-  ("old_space", 0x056b1): "AsyncGeneratorAwaitRejectSharedFun",
-  ("old_space", 0x056d5): "AsyncGeneratorAwaitResolveSharedFun",
-  ("old_space", 0x056f9): "AsyncGeneratorYieldResolveSharedFun",
-  ("old_space", 0x0571d): "AsyncGeneratorReturnResolveSharedFun",
-  ("old_space", 0x05741): "AsyncGeneratorReturnClosedRejectSharedFun",
-  ("old_space", 0x05765): "AsyncGeneratorReturnClosedResolveSharedFun",
-  ("old_space", 0x05789): "AsyncIteratorValueUnwrapSharedFun",
-  ("old_space", 0x057ad): "PromiseAllResolveElementSharedFun",
-  ("old_space", 0x057d1): "PromiseAllSettledResolveElementSharedFun",
-  ("old_space", 0x057f5): "PromiseAllSettledRejectElementSharedFun",
-  ("old_space", 0x05819): "PromiseAnyRejectElementSharedFun",
-  ("old_space", 0x0583d): "PromiseCapabilityDefaultRejectSharedFun",
-  ("old_space", 0x05861): "PromiseCapabilityDefaultResolveSharedFun",
-  ("old_space", 0x05885): "PromiseCatchFinallySharedFun",
-  ("old_space", 0x058a9): "PromiseGetCapabilitiesExecutorSharedFun",
-  ("old_space", 0x058cd): "PromiseThenFinallySharedFun",
-  ("old_space", 0x058f1): "PromiseThrowerFinallySharedFun",
-  ("old_space", 0x05915): "PromiseValueThunkFinallySharedFun",
-  ("old_space", 0x05939): "ProxyRevokeSharedFun",
-  ("old_space", 0x0595d): "ShadowRealmImportValueFulfilledSFI",
-  ("old_space", 0x05981): "SourceTextModuleExecuteAsyncModuleFulfilledSFI",
-  ("old_space", 0x059a5): "SourceTextModuleExecuteAsyncModuleRejectedSFI",
+  ("old_space", 0x04411): "ValueUnavailableAccessor",
+  ("old_space", 0x04439): "WrappedFunctionLengthAccessor",
+  ("old_space", 0x04461): "WrappedFunctionNameAccessor",
+  ("old_space", 0x04489): "InvalidPrototypeValidityCell",
+  ("old_space", 0x04491): "EmptyScript",
+  ("old_space", 0x044d5): "ManyClosuresCell",
+  ("old_space", 0x044e1): "ArrayConstructorProtector",
+  ("old_space", 0x044f5): "NoElementsProtector",
+  ("old_space", 0x04509): "MegaDOMProtector",
+  ("old_space", 0x0451d): "IsConcatSpreadableProtector",
+  ("old_space", 0x04531): "ArraySpeciesProtector",
+  ("old_space", 0x04545): "TypedArraySpeciesProtector",
+  ("old_space", 0x04559): "PromiseSpeciesProtector",
+  ("old_space", 0x0456d): "RegExpSpeciesProtector",
+  ("old_space", 0x04581): "StringLengthProtector",
+  ("old_space", 0x04595): "ArrayIteratorProtector",
+  ("old_space", 0x045a9): "ArrayBufferDetachingProtector",
+  ("old_space", 0x045bd): "PromiseHookProtector",
+  ("old_space", 0x045d1): "PromiseResolveProtector",
+  ("old_space", 0x045e5): "MapIteratorProtector",
+  ("old_space", 0x045f9): "PromiseThenProtector",
+  ("old_space", 0x0460d): "SetIteratorProtector",
+  ("old_space", 0x04621): "StringIteratorProtector",
+  ("old_space", 0x04635): "SingleCharacterStringCache",
+  ("old_space", 0x04a3d): "StringSplitCache",
+  ("old_space", 0x04e45): "RegExpMultipleCache",
+  ("old_space", 0x0524d): "BuiltinsConstantsTable",
+  ("old_space", 0x05691): "AsyncFunctionAwaitRejectSharedFun",
+  ("old_space", 0x056b5): "AsyncFunctionAwaitResolveSharedFun",
+  ("old_space", 0x056d9): "AsyncGeneratorAwaitRejectSharedFun",
+  ("old_space", 0x056fd): "AsyncGeneratorAwaitResolveSharedFun",
+  ("old_space", 0x05721): "AsyncGeneratorYieldResolveSharedFun",
+  ("old_space", 0x05745): "AsyncGeneratorReturnResolveSharedFun",
+  ("old_space", 0x05769): "AsyncGeneratorReturnClosedRejectSharedFun",
+  ("old_space", 0x0578d): "AsyncGeneratorReturnClosedResolveSharedFun",
+  ("old_space", 0x057b1): "AsyncIteratorValueUnwrapSharedFun",
+  ("old_space", 0x057d5): "PromiseAllResolveElementSharedFun",
+  ("old_space", 0x057f9): "PromiseAllSettledResolveElementSharedFun",
+  ("old_space", 0x0581d): "PromiseAllSettledRejectElementSharedFun",
+  ("old_space", 0x05841): "PromiseAnyRejectElementSharedFun",
+  ("old_space", 0x05865): "PromiseCapabilityDefaultRejectSharedFun",
+  ("old_space", 0x05889): "PromiseCapabilityDefaultResolveSharedFun",
+  ("old_space", 0x058ad): "PromiseCatchFinallySharedFun",
+  ("old_space", 0x058d1): "PromiseGetCapabilitiesExecutorSharedFun",
+  ("old_space", 0x058f5): "PromiseThenFinallySharedFun",
+  ("old_space", 0x05919): "PromiseThrowerFinallySharedFun",
+  ("old_space", 0x0593d): "PromiseValueThunkFinallySharedFun",
+  ("old_space", 0x05961): "ProxyRevokeSharedFun",
+  ("old_space", 0x05985): "ShadowRealmImportValueFulfilledSFI",
+  ("old_space", 0x059a9): "SourceTextModuleExecuteAsyncModuleFulfilledSFI",
+  ("old_space", 0x059cd): "SourceTextModuleExecuteAsyncModuleRejectedSFI",
 }
 
 # Lower 32 bits of first page addresses for various heap spaces.