[debugger] handle stack overflow. Fail silently.

R=jgruber@chromium.org
BUG=v8:5654

Review-Url: https://codereview.chromium.org/2511733002
Cr-Commit-Position: refs/heads/master@{#41139}

src/d8.cc

@@ -1806,7 +1806,22 @@ class InspectorFrontend final : public v8_inspector::V8Inspector::Channel {
       Local<Value> args[] = {message};
       MaybeLocal<Value> result = Local<Function>::Cast(callback)->Call(
           context, Undefined(isolate_), 1, args);
-      CHECK(!result.IsEmpty());  // Listeners may not throw.
+#ifdef DEBUG
+      if (try_catch.HasCaught()) {
+        Local<Object> exception = Local<Object>::Cast(try_catch.Exception());
+        Local<String> key = v8::String::NewFromUtf8(isolate_, "message",
+                                                    v8::NewStringType::kNormal)
+                                .ToLocalChecked();
+        Local<String> expected =
+            v8::String::NewFromUtf8(isolate_,
+                                    "Maximum call stack size exceeded",
+                                    v8::NewStringType::kNormal)
+                .ToLocalChecked();
+        CHECK(exception->Get(context, key)
+                  .ToLocalChecked()
+                  ->StrictEquals(expected));
+      }
+#endif
     }
   }
 

src/debug/debug-evaluate.cc

@@ -158,8 +158,8 @@ DebugEvaluate::ContextBuilder::ContextBuilder(Isolate* isolate,
   //  - Look up in the original context.
   //  - Check the whitelist to find out whether to skip contexts during lookup.
   const ScopeIterator::Option option = ScopeIterator::COLLECT_NON_LOCALS;
-  for (ScopeIterator it(isolate, &frame_inspector, option);
-       !it.Failed() && !it.Done(); it.Next()) {
+  for (ScopeIterator it(isolate, &frame_inspector, option); !it.Done();
+       it.Next()) {
     ScopeIterator::ScopeType scope_type = it.Type();
     if (scope_type == ScopeIterator::ScopeTypeLocal) {
       DCHECK_EQ(FUNCTION_SCOPE, it.CurrentScopeInfo()->scope_type());

src/debug/debug-scopes.cc

@@ -23,8 +23,7 @@ ScopeIterator::ScopeIterator(Isolate* isolate, FrameInspector* frame_inspector,
     : isolate_(isolate),
       frame_inspector_(frame_inspector),
       nested_scope_chain_(4),
-      seen_script_scope_(false),
-      failed_(false) {
+      seen_script_scope_(false) {
   if (!frame_inspector->GetContext()->IsContext()) {
     // Optimized frame, context or function cannot be materialized. Give up.
     return;
@@ -119,26 +118,26 @@ ScopeIterator::ScopeIterator(Isolate* isolate, FrameInspector* frame_inspector,
       DeclarationScope::Analyze(info.get(), AnalyzeMode::kDebugger);
       RetrieveScopeChain(scope);
     }
-  } else if (!ignore_nested_scopes) {
+  } else {
     // A failed reparse indicates that the preparser has diverged from the
     // parser or that the preparse data given to the initial parse has been
     // faulty. We fail in debug mode but in release mode we only provide the
     // information we get from the context chain but nothing about
     // completely stack allocated scopes or stack allocated locals.
     // Or it could be due to stack overflow.
-    DCHECK(isolate_->has_pending_exception());
-    failed_ = true;
+    // Silently fail by presenting an empty context chain.
+    CHECK(isolate_->has_pending_exception());
+    isolate_->clear_pending_exception();
+    context_ = Handle<Context>();
   }
   UnwrapEvaluationContext();
 }
 
-
 ScopeIterator::ScopeIterator(Isolate* isolate, Handle<JSFunction> function)
     : isolate_(isolate),
       frame_inspector_(NULL),
       context_(function->context()),
-      seen_script_scope_(false),
-      failed_(false) {
+      seen_script_scope_(false) {
   if (!function->shared()->IsSubjectToDebugging()) context_ = Handle<Context>();
   UnwrapEvaluationContext();
 }
@@ -148,8 +147,7 @@ ScopeIterator::ScopeIterator(Isolate* isolate,
     : isolate_(isolate),
       frame_inspector_(NULL),
       context_(generator->context()),
-      seen_script_scope_(false),
-      failed_(false) {
+      seen_script_scope_(false) {
   if (!generator->function()->shared()->IsSubjectToDebugging()) {
     context_ = Handle<Context>();
   }
@@ -212,7 +210,7 @@ MUST_USE_RESULT MaybeHandle<JSObject> ScopeIterator::MaterializeScopeDetails() {
 
 
 void ScopeIterator::Next() {
-  DCHECK(!failed_);
+  DCHECK(!Done());
   ScopeType scope_type = Type();
   if (scope_type == ScopeTypeGlobal) {
     // The global scope is always the last in the chain.
@@ -249,7 +247,7 @@ void ScopeIterator::Next() {
 
 // Return the type of the current scope.
 ScopeIterator::ScopeType ScopeIterator::Type() {
-  DCHECK(!failed_);
+  DCHECK(!Done());
   if (!nested_scope_chain_.is_empty()) {
     Handle<ScopeInfo> scope_info = nested_scope_chain_.last().scope_info;
     switch (scope_info->scope_type()) {
@@ -304,7 +302,7 @@ ScopeIterator::ScopeType ScopeIterator::Type() {
 
 
 MaybeHandle<JSObject> ScopeIterator::ScopeObject() {
-  DCHECK(!failed_);
+  DCHECK(!Done());
   switch (Type()) {
     case ScopeIterator::ScopeTypeGlobal:
       return Handle<JSObject>(CurrentContext()->global_proxy());
@@ -346,7 +344,7 @@ bool ScopeIterator::HasContext() {
 
 bool ScopeIterator::SetVariableValue(Handle<String> variable_name,
                                      Handle<Object> new_value) {
-  DCHECK(!failed_);
+  DCHECK(!Done());
   switch (Type()) {
     case ScopeIterator::ScopeTypeGlobal:
       break;
@@ -372,7 +370,7 @@ bool ScopeIterator::SetVariableValue(Handle<String> variable_name,
 
 
 Handle<ScopeInfo> ScopeIterator::CurrentScopeInfo() {
-  DCHECK(!failed_);
+  DCHECK(!Done());
   if (!nested_scope_chain_.is_empty()) {
     return nested_scope_chain_.last().scope_info;
   } else if (context_->IsBlockContext()) {
@@ -385,7 +383,7 @@ Handle<ScopeInfo> ScopeIterator::CurrentScopeInfo() {
 
 
 Handle<Context> ScopeIterator::CurrentContext() {
-  DCHECK(!failed_);
+  DCHECK(!Done());
   if (Type() == ScopeTypeGlobal || Type() == ScopeTypeScript ||
       nested_scope_chain_.is_empty()) {
     return context_;
@@ -402,7 +400,7 @@ Handle<StringSet> ScopeIterator::GetNonLocals() { return non_locals_; }
 // Debug print of the content of the current scope.
 void ScopeIterator::DebugPrint() {
   OFStream os(stdout);
-  DCHECK(!failed_);
+  DCHECK(!Done());
   switch (Type()) {
     case ScopeIterator::ScopeTypeGlobal:
       os << "Global:\n";

src/debug/debug-scopes.h

@@ -50,12 +50,7 @@ class ScopeIterator {
   MUST_USE_RESULT MaybeHandle<JSObject> MaterializeScopeDetails();
 
   // More scopes?
-  bool Done() {
-    DCHECK(!failed_);
-    return context_.is_null();
-  }
-
-  bool Failed() { return failed_; }
+  bool Done() { return context_.is_null(); }
 
   // Move to the next scope.
   void Next();
@@ -103,7 +98,6 @@ class ScopeIterator {
   List<ExtendedScopeInfo> nested_scope_chain_;
   Handle<StringSet> non_locals_;
   bool seen_script_scope_;
-  bool failed_;
 
   inline JavaScriptFrame* GetFrame() {
     return frame_inspector_->GetArgumentsFrame();