Simplify pending message object handling.

This moves the decision whether to report a message or not to when
the pending exception is propagated instead of trying to preserve the
decision in a ThreadLocalTop field.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/998943003

Cr-Commit-Position: refs/heads/master@{#27150}

src/arm/full-codegen-arm.cc

@@ -5324,28 +5324,12 @@ void FullCodeGenerator::EnterFinallyBlock() {
   __ mov(ip, Operand(pending_message_obj));
   __ ldr(r1, MemOperand(ip));
   __ push(r1);
-
-  ExternalReference has_pending_message =
-      ExternalReference::address_of_has_pending_message(isolate());
-  __ mov(ip, Operand(has_pending_message));
-  STATIC_ASSERT(sizeof(bool) == 1);   // NOLINT(runtime/sizeof)
-  __ ldrb(r1, MemOperand(ip));
-  __ SmiTag(r1);
-  __ push(r1);
 }
 
 
 void FullCodeGenerator::ExitFinallyBlock() {
   DCHECK(!result_register().is(r1));
   // Restore pending message from stack.
-  __ pop(r1);
-  __ SmiUntag(r1);
-  ExternalReference has_pending_message =
-      ExternalReference::address_of_has_pending_message(isolate());
-  __ mov(ip, Operand(has_pending_message));
-  STATIC_ASSERT(sizeof(bool) == 1);   // NOLINT(runtime/sizeof)
-  __ strb(r1, MemOperand(ip));
-
   __ pop(r1);
   ExternalReference pending_message_obj =
       ExternalReference::address_of_pending_message_obj(isolate());

src/arm64/full-codegen-arm64.cc

@@ -5345,15 +5345,7 @@ void FullCodeGenerator::EnterFinallyBlock() {
       ExternalReference::address_of_pending_message_obj(isolate());
   __ Mov(x10, pending_message_obj);
   __ Ldr(x10, MemOperand(x10));
-
-  ExternalReference has_pending_message =
-      ExternalReference::address_of_has_pending_message(isolate());
-  STATIC_ASSERT(sizeof(bool) == 1);   // NOLINT(runtime/sizeof)
-  __ Mov(x11, has_pending_message);
-  __ Ldrb(x11, MemOperand(x11));
-  __ SmiTag(x11);
-
-  __ Push(x10, x11);
+  __ Push(x10);
 }
 
 
@@ -5362,18 +5354,11 @@ void FullCodeGenerator::ExitFinallyBlock() {
   DCHECK(!result_register().is(x10));
 
   // Restore pending message from stack.
-  __ Pop(x10, x11);
-  __ SmiUntag(x10);
-  ExternalReference has_pending_message =
-      ExternalReference::address_of_has_pending_message(isolate());
-  __ Mov(x13, has_pending_message);
-  STATIC_ASSERT(sizeof(bool) == 1);   // NOLINT(runtime/sizeof)
-  __ Strb(x10, MemOperand(x13));
-
+  __ Pop(x10);
   ExternalReference pending_message_obj =
       ExternalReference::address_of_pending_message_obj(isolate());
   __ Mov(x13, pending_message_obj);
-  __ Str(x11, MemOperand(x13));
+  __ Str(x10, MemOperand(x13));
 
   // Restore result register and cooked return address from the stack.
   __ Pop(x10, result_register());

src/assembler.cc

@@ -1267,12 +1267,6 @@ ExternalReference ExternalReference::address_of_pending_message_obj(
 }
 
 
-ExternalReference ExternalReference::address_of_has_pending_message(
-    Isolate* isolate) {
-  return ExternalReference(isolate->has_pending_message_address());
-}
-
-
 ExternalReference ExternalReference::address_of_min_int() {
   return ExternalReference(reinterpret_cast<void*>(&double_constants.min_int));
 }

src/assembler.h

@@ -956,7 +956,6 @@ class ExternalReference BASE_EMBEDDED {
 
   static ExternalReference scheduled_exception_address(Isolate* isolate);
   static ExternalReference address_of_pending_message_obj(Isolate* isolate);
-  static ExternalReference address_of_has_pending_message(Isolate* isolate);
 
   // Static variables containing common double constants.
   static ExternalReference address_of_min_int();

src/compiler/ast-graph-builder.cc

@@ -1264,8 +1264,6 @@ void AstGraphBuilder::VisitTryFinallyStatement(TryFinallyStatement* stmt) {
 
   ExternalReference message_object =
       ExternalReference::address_of_pending_message_obj(isolate());
-  ExternalReference message_present =
-      ExternalReference::address_of_has_pending_message(isolate());
 
   // We keep a record of all paths that enter the finally-block to be able to
   // dispatch to the correct continuation point after the statements in the
@@ -1302,7 +1300,6 @@ void AstGraphBuilder::VisitTryFinallyStatement(TryFinallyStatement* stmt) {
   environment()->Push(token);  // TODO(mstarzinger): Cook token!
   environment()->Push(result);
   environment()->Push(BuildLoadExternal(message_object, kMachAnyTagged));
-  environment()->Push(BuildLoadExternal(message_present, kMachBool));
 
   // Evaluate the finally-block.
   Visit(stmt->finally_block());
@@ -1310,7 +1307,6 @@ void AstGraphBuilder::VisitTryFinallyStatement(TryFinallyStatement* stmt) {
 
   // The result value, dispatch token and message is restored from the operand
   // stack (this is in sync with FullCodeGenerator::ExitFinallyBlock).
-  BuildStoreExternal(message_present, kMachBool, environment()->Pop());
   BuildStoreExternal(message_object, kMachAnyTagged, environment()->Pop());
   result = environment()->Pop();
   token = environment()->Pop();  // TODO(mstarzinger): Uncook token!

src/full-codegen.h

@@ -249,7 +249,7 @@ class FullCodeGenerator: public AstVisitor {
   // The finally block of a try/finally statement.
   class Finally : public NestedStatement {
    public:
-    static const int kElementCount = 4;
+    static const int kElementCount = 3;
 
     explicit Finally(FullCodeGenerator* codegen) : NestedStatement(codegen) { }
     virtual ~Finally() {}

src/ia32/full-codegen-ia32.cc

@@ -5252,24 +5252,12 @@ void FullCodeGenerator::EnterFinallyBlock() {
       ExternalReference::address_of_pending_message_obj(isolate());
   __ mov(edx, Operand::StaticVariable(pending_message_obj));
   __ push(edx);
-
-  ExternalReference has_pending_message =
-      ExternalReference::address_of_has_pending_message(isolate());
-  __ mov(edx, Operand::StaticVariable(has_pending_message));
-  __ SmiTag(edx);
-  __ push(edx);
 }
 
 
 void FullCodeGenerator::ExitFinallyBlock() {
   DCHECK(!result_register().is(edx));
   // Restore pending message from stack.
-  __ pop(edx);
-  __ SmiUntag(edx);
-  ExternalReference has_pending_message =
-      ExternalReference::address_of_has_pending_message(isolate());
-  __ mov(Operand::StaticVariable(has_pending_message), edx);
-
   __ pop(edx);
   ExternalReference pending_message_obj =
       ExternalReference::address_of_pending_message_obj(isolate());

src/isolate.cc

@@ -87,7 +87,6 @@ void ThreadLocalTop::InitializeInternal() {
   // These members are re-initialized later after deserialization
   // is complete.
   pending_exception_ = NULL;
-  has_pending_message_ = false;
   rethrowing_message_ = false;
   pending_message_obj_ = NULL;
   scheduled_exception_ = NULL;
@@ -1000,9 +999,6 @@ Object* Isolate::Throw(Object* exception, MessageLocation* location) {
     }
   }
 
-  // Save the message for reporting if the the exception remains uncaught.
-  thread_local_top()->has_pending_message_ = report_exception;
-
   // Set the exception being thrown.
   set_pending_exception(*exception_handle);
   return heap()->exception();
@@ -1405,30 +1401,38 @@ bool Isolate::IsFinallyOnTop() {
 
 
 void Isolate::ReportPendingMessages() {
-  DCHECK(has_pending_exception());
-  bool can_clear_message = PropagatePendingExceptionToExternalTryCatch();
+  Object* exception = pending_exception();
 
-  HandleScope scope(this);
-  if (thread_local_top_.pending_exception_ == heap()->termination_exception()) {
+  // Try to propagate the exception to an external v8::TryCatch handler. If
+  // propagation was unsuccessful, then we will get another chance at reporting
+  // the pending message if the exception is re-thrown.
+  bool has_been_propagated = PropagatePendingExceptionToExternalTryCatch();
+  if (!has_been_propagated) return;
+
+  // Clear the pending message object early to avoid endless recursion.
+  Object* message_obj = thread_local_top_.pending_message_obj_;
+  clear_pending_message();
+
+  bool can_be_caught_externally = false;
+  bool catchable_by_javascript = is_catchable_by_javascript(exception);
+  bool should_report_exception =
+      ShouldReportException(&can_be_caught_externally, catchable_by_javascript);
+
+  if (!catchable_by_javascript) {
     // Do nothing: if needed, the exception has been already propagated to
     // v8::TryCatch.
   } else {
-    if (thread_local_top_.has_pending_message_) {
-      thread_local_top_.has_pending_message_ = false;
-      if (!thread_local_top_.pending_message_obj_->IsTheHole()) {
-        HandleScope scope(this);
-        Handle<JSMessageObject> message_obj(
-            JSMessageObject::cast(thread_local_top_.pending_message_obj_));
-        Handle<JSValue> script_wrapper(JSValue::cast(message_obj->script()));
-        Handle<Script> script(Script::cast(script_wrapper->value()));
-        int start_pos = message_obj->start_position();
-        int end_pos = message_obj->end_position();
-        MessageLocation location(script, start_pos, end_pos);
-        MessageHandler::ReportMessage(this, &location, message_obj);
-      }
+    if (!message_obj->IsTheHole() && should_report_exception) {
+      HandleScope scope(this);
+      Handle<JSMessageObject> message(JSMessageObject::cast(message_obj));
+      Handle<JSValue> script_wrapper(JSValue::cast(message->script()));
+      Handle<Script> script(Script::cast(script_wrapper->value()));
+      int start_pos = message->start_position();
+      int end_pos = message->end_position();
+      MessageLocation location(script, start_pos, end_pos);
+      MessageHandler::ReportMessage(this, &location, message);
     }
   }
-  if (can_clear_message) clear_pending_message();
 }
 
 
@@ -1436,7 +1440,6 @@ MessageLocation Isolate::GetMessageLocation() {
   DCHECK(has_pending_exception());
 
   if (thread_local_top_.pending_exception_ != heap()->termination_exception() &&
-      thread_local_top_.has_pending_message_ &&
       !thread_local_top_.pending_message_obj_->IsTheHole()) {
     Handle<JSMessageObject> message_obj(
         JSMessageObject::cast(thread_local_top_.pending_message_obj_));

src/isolate.h

@@ -282,7 +282,6 @@ class ThreadLocalTop BASE_EMBEDDED {
   Address pending_handler_sp_;
 
   // Communication channel between Isolate::Throw and message consumers.
-  bool has_pending_message_;
   bool rethrowing_message_;
   Object* pending_message_obj_;
 
@@ -604,7 +603,6 @@ class Isolate {
   THREAD_LOCAL_TOP_ACCESSOR(bool, external_caught_exception)
 
   void clear_pending_message() {
-    thread_local_top_.has_pending_message_ = false;
     thread_local_top_.pending_message_obj_ = heap_.the_hole_value();
   }
   v8::TryCatch* try_catch_handler() {
@@ -623,10 +621,6 @@ class Isolate {
     return reinterpret_cast<Address>(&thread_local_top_.pending_message_obj_);
   }
 
-  Address has_pending_message_address() {
-    return reinterpret_cast<Address>(&thread_local_top_.has_pending_message_);
-  }
-
   Object* scheduled_exception() {
     DCHECK(has_scheduled_exception());
     DCHECK(!thread_local_top_.scheduled_exception_->IsException());

src/serialize.cc

@@ -102,8 +102,6 @@ ExternalReferenceTable::ExternalReferenceTable(Isolate* isolate) {
       "date_cache_stamp");
   Add(ExternalReference::address_of_pending_message_obj(isolate).address(),
       "address_of_pending_message_obj");
-  Add(ExternalReference::address_of_has_pending_message(isolate).address(),
-      "address_of_has_pending_message");
   Add(ExternalReference::get_make_code_young_function(isolate).address(),
       "Code::MakeCodeYoung");
   Add(ExternalReference::cpu_features().address(), "cpu_features");

src/x64/full-codegen-x64.cc

@@ -5272,12 +5272,6 @@ void FullCodeGenerator::EnterFinallyBlock() {
       ExternalReference::address_of_pending_message_obj(isolate());
   __ Load(rdx, pending_message_obj);
   __ Push(rdx);
-
-  ExternalReference has_pending_message =
-      ExternalReference::address_of_has_pending_message(isolate());
-  __ Load(rdx, has_pending_message);
-  __ Integer32ToSmi(rdx, rdx);
-  __ Push(rdx);
 }
 
 
@@ -5285,12 +5279,6 @@ void FullCodeGenerator::ExitFinallyBlock() {
   DCHECK(!result_register().is(rdx));
   DCHECK(!result_register().is(rcx));
   // Restore pending message from stack.
-  __ Pop(rdx);
-  __ SmiToInteger32(rdx, rdx);
-  ExternalReference has_pending_message =
-      ExternalReference::address_of_has_pending_message(isolate());
-  __ Store(has_pending_message, rdx);
-
   __ Pop(rdx);
   ExternalReference pending_message_obj =
       ExternalReference::address_of_pending_message_obj(isolate());