From aabbbec67c3c7363ef08c657f2d688ad2e8f7de8 Mon Sep 17 00:00:00 2001
From: bradnelson <bradnelson@chromium.org>
Date: Mon, 12 Dec 2016 06:47:56 -0800
Subject: [PATCH] [wasm] [asmjs] Route asm.js warnings to the dev console.

Generalize Messages to include an error level.
Add a parameter to AddMessageHandler to select which error levels to receive, using a mask (default being just errors, i.e. the current behavior).

BUG=v8:4203
R=dgozman@chromium.org,machenbach@chromium.org,danno@chromium.org,bmeurer@chromium.org,jochen@chromium.org

Review-Url: https://codereview.chromium.org/2526703002
Cr-Commit-Position: refs/heads/master@{#41648}
---
 include/v8.h                        |  32 ++++++++-
 src/api.cc                          |  14 +++-
 src/asmjs/asm-js.cc                 |   5 +-
 src/asmjs/asm-typer.cc              |  54 ++++++--------
 src/asmjs/asm-typer.h               |  18 ++---
 src/d8.cc                           |  44 +++++++++++-
 src/factory.cc                      |   1 +
 src/messages.cc                     | 105 ++++++++++++++++------------
 src/messages.h                      |  12 +++-
 src/objects-inl.h                   |   2 +-
 src/objects.h                       |   6 +-
 test/cctest/asmjs/test-asm-typer.cc |   9 ++-
 test/cctest/test-api.cc             |  73 +++++++++++++++++++
 13 files changed, 275 insertions(+), 100 deletions(-)

diff --git a/include/v8.h b/include/v8.h
index e5ff0c0332..86aa8b7d2d 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -1477,6 +1477,11 @@ class V8_EXPORT Message {
    */
   int GetEndPosition() const;
 
+  /**
+   * Returns the error level of the message.
+   */
+  int ErrorLevel() const;
+
   /**
    * Returns the index within the line of the first character where
    * the error occurred.
@@ -6451,6 +6456,16 @@ class V8_EXPORT Isolate {
     kUseCounterFeatureCount  // This enum value must be last.
   };
 
+  enum MessageErrorLevel {
+    kMessageLog = (1 << 0),
+    kMessageDebug = (1 << 1),
+    kMessageInfo = (1 << 2),
+    kMessageError = (1 << 3),
+    kMessageWarning = (1 << 4),
+    kMessageAll = kMessageLog | kMessageDebug | kMessageInfo | kMessageError |
+                  kMessageWarning,
+  };
+
   typedef void (*UseCounterCallback)(Isolate* isolate,
                                      UseCounterFeature feature);
 
@@ -7055,7 +7070,7 @@ class V8_EXPORT Isolate {
   bool IsDead();
 
   /**
-   * Adds a message listener.
+   * Adds a message listener (errors only).
    *
    * The same message listener can be added more than once and in that
    * case it will be called more than once for each message.
@@ -7066,6 +7081,21 @@ class V8_EXPORT Isolate {
   bool AddMessageListener(MessageCallback that,
                           Local<Value> data = Local<Value>());
 
+  /**
+   * Adds a message listener.
+   *
+   * The same message listener can be added more than once and in that
+   * case it will be called more than once for each message.
+   *
+   * If data is specified, it will be passed to the callback when it is called.
+   * Otherwise, the exception object will be passed to the callback instead.
+   *
+   * A listener can listen for particular error levels by providing a mask.
+   */
+  bool AddMessageListenerWithErrorLevel(MessageCallback that,
+                                        int message_levels,
+                                        Local<Value> data = Local<Value>());
+
   /**
    * Remove all message listeners from the specified callback function.
    */
diff --git a/src/api.cc b/src/api.cc
index 37c289abf4..18de496ecf 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -2667,6 +2667,10 @@ int Message::GetEndPosition() const {
   return self->end_position();
 }
 
+int Message::ErrorLevel() const {
+  auto self = Utils::OpenHandle(this);
+  return self->error_level();
+}
 
 Maybe<int> Message::GetStartColumn(Local<Context> context) const {
   auto self = Utils::OpenHandle(this);
@@ -8452,18 +8456,24 @@ bool Isolate::IsDead() {
   return isolate->IsDead();
 }
 
-
 bool Isolate::AddMessageListener(MessageCallback that, Local<Value> data) {
+  return AddMessageListenerWithErrorLevel(that, kMessageError, data);
+}
+
+bool Isolate::AddMessageListenerWithErrorLevel(MessageCallback that,
+                                               int message_levels,
+                                               Local<Value> data) {
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::TemplateList> list = isolate->factory()->message_listeners();
-  i::Handle<i::FixedArray> listener = isolate->factory()->NewFixedArray(2);
+  i::Handle<i::FixedArray> listener = isolate->factory()->NewFixedArray(3);
   i::Handle<i::Foreign> foreign =
       isolate->factory()->NewForeign(FUNCTION_ADDR(that));
   listener->set(0, *foreign);
   listener->set(1, data.IsEmpty() ? isolate->heap()->undefined_value()
                                   : *Utils::OpenHandle(*data));
+  listener->set(2, i::Smi::FromInt(message_levels));
   list = i::TemplateList::Add(isolate, list, listener);
   isolate->heap()->SetMessageListeners(*list);
   return true;
diff --git a/src/asmjs/asm-js.cc b/src/asmjs/asm-js.cc
index 7d00c5fd87..af27beef9a 100644
--- a/src/asmjs/asm-js.cc
+++ b/src/asmjs/asm-js.cc
@@ -160,8 +160,9 @@ MaybeHandle<FixedArray> AsmJs::ConvertAsmToWasm(ParseInfo* info) {
   auto asm_wasm_result = builder.Run(&foreign_globals);
   if (!asm_wasm_result.success) {
     DCHECK(!info->isolate()->has_pending_exception());
-    PrintF("Validation of asm.js module failed: %s\n",
-           builder.typer()->error_message());
+    MessageHandler::ReportMessage(info->isolate(),
+                                  builder.typer()->message_location(),
+                                  builder.typer()->error_message());
     return MaybeHandle<FixedArray>();
   }
   wasm::ZoneBuffer* module = asm_wasm_result.module_bytes;
diff --git a/src/asmjs/asm-typer.cc b/src/asmjs/asm-typer.cc
index 6dbfa87267..ddc8898266 100644
--- a/src/asmjs/asm-typer.cc
+++ b/src/asmjs/asm-typer.cc
@@ -9,6 +9,7 @@
 #include <memory>
 #include <string>
 
+#include "include/v8.h"
 #include "src/v8.h"
 
 #include "src/asmjs/asm-types.h"
@@ -17,21 +18,25 @@
 #include "src/base/bits.h"
 #include "src/codegen.h"
 #include "src/globals.h"
+#include "src/messages.h"
 #include "src/utils.h"
 
-#define FAIL_LINE(line, msg)                                   \
-  do {                                                         \
-    base::OS::SNPrintF(error_message_, sizeof(error_message_), \
-                       "asm: line %d: %s", (line) + 1, msg);   \
-    return AsmType::None();                                    \
+#define FAIL_LOCATION(location, msg)                                      \
+  do {                                                                    \
+    Handle<String> message(isolate_->factory()->InternalizeOneByteString( \
+        STATIC_CHAR_VECTOR(msg)));                                        \
+    error_message_ = MessageHandler::MakeMessageObject(                   \
+        isolate_, MessageTemplate::kAsmJsInvalid, (location), message,    \
+        Handle<JSArray>::null());                                         \
+    error_message_->set_error_level(v8::Isolate::kMessageWarning);        \
+    message_location_ = *(location);                                      \
+    return AsmType::None();                                               \
   } while (false)
 
-#define FAIL(node, msg)                                        \
-  do {                                                         \
-    int line = node->position() == kNoSourcePosition           \
-                   ? -1                                        \
-                   : script_->GetLineNumber(node->position()); \
-    FAIL_LINE(line, msg);                                      \
+#define FAIL(node, msg)                                                    \
+  do {                                                                     \
+    MessageLocation location(script_, node->position(), node->position()); \
+    FAIL_LOCATION(&location, msg);                                         \
   } while (false)
 
 #define RECURSE(call)                                             \
@@ -164,8 +169,8 @@ AsmTyper::VariableInfo* AsmTyper::VariableInfo::Clone(Zone* zone) const {
   return new_var_info;
 }
 
-void AsmTyper::VariableInfo::SetFirstForwardUse(int source_location) {
-  DCHECK(source_location_ == -1);
+void AsmTyper::VariableInfo::SetFirstForwardUse(
+    const MessageLocation& source_location) {
   missing_definition_ = true;
   source_location_ = source_location;
 }
@@ -400,7 +405,8 @@ AsmTyper::VariableInfo* AsmTyper::Lookup(Variable* variable) const {
 }
 
 void AsmTyper::AddForwardReference(VariableProxy* proxy, VariableInfo* info) {
-  info->SetFirstForwardUse(proxy->position());
+  MessageLocation location(script_, proxy->position(), proxy->position());
+  info->SetFirstForwardUse(location);
   forward_definitions_.push_back(info);
 }
 
@@ -738,11 +744,8 @@ AsmType* AsmTyper::ValidateModuleAfterFunctionsPhase(FunctionLiteral* fun) {
 
   for (auto* forward_def : forward_definitions_) {
     if (forward_def->missing_definition()) {
-      int position = forward_def->source_location();
-      int line =
-          position == kNoSourcePosition ? -1 : script_->GetLineNumber(position);
-
-      FAIL_LINE(line, "Missing definition for forward declared identifier.");
+      FAIL_LOCATION(forward_def->source_location(),
+                    "Missing definition for forward declared identifier.");
     }
   }
 
@@ -2911,19 +2914,6 @@ AsmType* AsmTyper::NewHeapView(CallNew* new_heap_view) {
   return heap_view_info->type();
 }
 
-bool IsValidAsm(Isolate* isolate, Zone* zone, Handle<Script> script,
-                FunctionLiteral* root, std::string* error_message) {
-  error_message->clear();
-
-  AsmTyper typer(isolate, zone, script, root);
-  if (typer.Validate()) {
-    return true;
-  }
-
-  *error_message = typer.error_message();
-  return false;
-}
-
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8
diff --git a/src/asmjs/asm-typer.h b/src/asmjs/asm-typer.h
index 33ba39e7cc..723731bcdd 100644
--- a/src/asmjs/asm-typer.h
+++ b/src/asmjs/asm-typer.h
@@ -16,6 +16,7 @@
 #include "src/ast/ast-types.h"
 #include "src/ast/ast.h"
 #include "src/effects.h"
+#include "src/messages.h"
 #include "src/type-info.h"
 #include "src/zone/zone-containers.h"
 #include "src/zone/zone.h"
@@ -78,7 +79,8 @@ class AsmTyper final {
   bool ValidateAfterFunctionsPhase();
   void ClearFunctionNodeTypes();
 
-  const char* error_message() const { return error_message_; }
+  Handle<JSMessageObject> error_message() const { return error_message_; }
+  const MessageLocation* message_location() const { return &message_location_; }
 
   AsmType* TypeOf(AstNode* node) const;
   AsmType* TypeOf(Variable* v) const;
@@ -138,7 +140,7 @@ class AsmTyper final {
     bool IsHeap() const { return standard_member_ == kHeap; }
 
     void MarkDefined() { missing_definition_ = false; }
-    void SetFirstForwardUse(int source_location);
+    void SetFirstForwardUse(const MessageLocation& source_location);
 
     StandardMember standard_member() const { return standard_member_; }
     void set_standard_member(StandardMember standard_member) {
@@ -153,7 +155,7 @@ class AsmTyper final {
 
     bool missing_definition() const { return missing_definition_; }
 
-    int source_location() const { return source_location_; }
+    const MessageLocation* source_location() { return &source_location_; }
 
     static VariableInfo* ForSpecialSymbol(Zone* zone,
                                           StandardMember standard_member);
@@ -165,11 +167,8 @@ class AsmTyper final {
     // missing_definition_ is set to true for forward definition - i.e., use
     // before definition.
     bool missing_definition_ = false;
-    // source_location_ holds the line number that first referenced this
-    // VariableInfo. Used for error messages.
-    // TODO(bradnelson): When merged with console change, this should
-    // become a source location.
-    int source_location_ = -1;
+    // Used for error messages.
+    MessageLocation source_location_;
   };
 
   // RAII-style manager for the in_function_ member variable.
@@ -397,7 +396,8 @@ class AsmTyper final {
   static const int kErrorMessageLimit = 128;
   AsmType* fround_type_;
   AsmType* ffi_type_;
-  char error_message_[kErrorMessageLimit];
+  Handle<JSMessageObject> error_message_;
+  MessageLocation message_location_;
   StdlibSet stdlib_uses_;
 
   SourceLayoutTracker source_layout_;
diff --git a/src/d8.cc b/src/d8.cc
index f1b9d6c31b..e3178faeab 100644
--- a/src/d8.cc
+++ b/src/d8.cc
@@ -1579,9 +1579,43 @@ Local<ObjectTemplate> Shell::CreateGlobalTemplate(Isolate* isolate) {
   return global_template;
 }
 
-static void EmptyMessageCallback(Local<Message> message, Local<Value> error) {
-  // Nothing to be done here, exceptions thrown up to the shell will be reported
+static void PrintNonErrorsMessageCallback(Local<Message> message,
+                                          Local<Value> error) {
+  // Nothing to do here for errors, exceptions thrown up to the shell will be
+  // reported
   // separately by {Shell::ReportException} after they are caught.
+  // Do print other kinds of messages.
+  switch (message->ErrorLevel()) {
+    case v8::Isolate::kMessageWarning:
+    case v8::Isolate::kMessageLog:
+    case v8::Isolate::kMessageInfo:
+    case v8::Isolate::kMessageDebug: {
+      break;
+    }
+
+    case v8::Isolate::kMessageError: {
+      // Ignore errors, printed elsewhere.
+      return;
+    }
+
+    default: {
+      UNREACHABLE();
+      break;
+    }
+  }
+  // Converts a V8 value to a C string.
+  auto ToCString = [](const v8::String::Utf8Value& value) {
+    return *value ? *value : "<string conversion failed>";
+  };
+  Isolate* isolate = Isolate::GetCurrent();
+  v8::String::Utf8Value msg(message->Get());
+  const char* msg_string = ToCString(msg);
+  // Print (filename):(line number): (message).
+  v8::String::Utf8Value filename(message->GetScriptOrigin().ResourceName());
+  const char* filename_string = ToCString(filename);
+  Maybe<int> maybeline = message->GetLineNumber(isolate->GetCurrentContext());
+  int linenum = maybeline.IsJust() ? maybeline.FromJust() : -1;
+  printf("%s:%i: %s\n", filename_string, linenum, msg_string);
 }
 
 void Shell::Initialize(Isolate* isolate) {
@@ -1589,7 +1623,11 @@ void Shell::Initialize(Isolate* isolate) {
   if (i::StrLength(i::FLAG_map_counters) != 0)
     MapCounters(isolate, i::FLAG_map_counters);
   // Disable default message reporting.
-  isolate->AddMessageListener(EmptyMessageCallback);
+  isolate->AddMessageListenerWithErrorLevel(
+      PrintNonErrorsMessageCallback,
+      v8::Isolate::kMessageError | v8::Isolate::kMessageWarning |
+          v8::Isolate::kMessageInfo | v8::Isolate::kMessageDebug |
+          v8::Isolate::kMessageLog);
 }
 
 
diff --git a/src/factory.cc b/src/factory.cc
index 407ddd8cc3..8b08b426d3 100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -2295,6 +2295,7 @@ Handle<JSMessageObject> Factory::NewJSMessageObject(
   message_obj->set_end_position(end_position);
   message_obj->set_script(*script);
   message_obj->set_stack_frames(*stack_frames);
+  message_obj->set_error_level(v8::Isolate::kMessageError);
   return message_obj;
 }
 
diff --git a/src/messages.cc b/src/messages.cc
index a5597e2257..ca09b1a66a 100644
--- a/src/messages.cc
+++ b/src/messages.cc
@@ -47,10 +47,9 @@ void MessageHandler::DefaultMessageReport(Isolate* isolate,
   }
 }
 
-
 Handle<JSMessageObject> MessageHandler::MakeMessageObject(
     Isolate* isolate, MessageTemplate::Template message,
-    MessageLocation* location, Handle<Object> argument,
+    const MessageLocation* location, Handle<Object> argument,
     Handle<JSArray> stack_frames) {
   Factory* factory = isolate->factory();
 
@@ -75,50 +74,63 @@ Handle<JSMessageObject> MessageHandler::MakeMessageObject(
   return message_obj;
 }
 
-
-void MessageHandler::ReportMessage(Isolate* isolate, MessageLocation* loc,
+void MessageHandler::ReportMessage(Isolate* isolate, const MessageLocation* loc,
                                    Handle<JSMessageObject> message) {
-  // We are calling into embedder's code which can throw exceptions.
-  // Thus we need to save current exception state, reset it to the clean one
-  // and ignore scheduled exceptions callbacks can throw.
-
-  // We pass the exception object into the message handler callback though.
-  Object* exception_object = isolate->heap()->undefined_value();
-  if (isolate->has_pending_exception()) {
-    exception_object = isolate->pending_exception();
-  }
-  Handle<Object> exception(exception_object, isolate);
-
-  Isolate::ExceptionScope exception_scope(isolate);
-  isolate->clear_pending_exception();
-  isolate->set_external_caught_exception(false);
-
-  // Turn the exception on the message into a string if it is an object.
-  if (message->argument()->IsJSObject()) {
-    HandleScope scope(isolate);
-    Handle<Object> argument(message->argument(), isolate);
-
-    MaybeHandle<Object> maybe_stringified;
-    Handle<Object> stringified;
-    // Make sure we don't leak uncaught internally generated Error objects.
-    if (argument->IsJSError()) {
-      maybe_stringified = Object::NoSideEffectsToString(isolate, argument);
-    } else {
-      v8::TryCatch catcher(reinterpret_cast<v8::Isolate*>(isolate));
-      catcher.SetVerbose(false);
-      catcher.SetCaptureMessage(false);
-
-      maybe_stringified = Object::ToString(isolate, argument);
-    }
-
-    if (!maybe_stringified.ToHandle(&stringified)) {
-      stringified = isolate->factory()->NewStringFromAsciiChecked("exception");
-    }
-    message->set_argument(*stringified);
-  }
-
   v8::Local<v8::Message> api_message_obj = v8::Utils::MessageToLocal(message);
-  v8::Local<v8::Value> api_exception_obj = v8::Utils::ToLocal(exception);
+
+  if (api_message_obj->ErrorLevel() == v8::Isolate::kMessageError) {
+    // We are calling into embedder's code which can throw exceptions.
+    // Thus we need to save current exception state, reset it to the clean one
+    // and ignore scheduled exceptions callbacks can throw.
+
+    // We pass the exception object into the message handler callback though.
+    Object* exception_object = isolate->heap()->undefined_value();
+    if (isolate->has_pending_exception()) {
+      exception_object = isolate->pending_exception();
+    }
+    Handle<Object> exception(exception_object, isolate);
+
+    Isolate::ExceptionScope exception_scope(isolate);
+    isolate->clear_pending_exception();
+    isolate->set_external_caught_exception(false);
+
+    // Turn the exception on the message into a string if it is an object.
+    if (message->argument()->IsJSObject()) {
+      HandleScope scope(isolate);
+      Handle<Object> argument(message->argument(), isolate);
+
+      MaybeHandle<Object> maybe_stringified;
+      Handle<Object> stringified;
+      // Make sure we don't leak uncaught internally generated Error objects.
+      if (argument->IsJSError()) {
+        maybe_stringified = Object::NoSideEffectsToString(isolate, argument);
+      } else {
+        v8::TryCatch catcher(reinterpret_cast<v8::Isolate*>(isolate));
+        catcher.SetVerbose(false);
+        catcher.SetCaptureMessage(false);
+
+        maybe_stringified = Object::ToString(isolate, argument);
+      }
+
+      if (!maybe_stringified.ToHandle(&stringified)) {
+        stringified =
+            isolate->factory()->NewStringFromAsciiChecked("exception");
+      }
+      message->set_argument(*stringified);
+    }
+
+    v8::Local<v8::Value> api_exception_obj = v8::Utils::ToLocal(exception);
+    ReportMessageNoExceptions(isolate, loc, message, api_exception_obj);
+  } else {
+    ReportMessageNoExceptions(isolate, loc, message, v8::Local<v8::Value>());
+  }
+}
+
+void MessageHandler::ReportMessageNoExceptions(
+    Isolate* isolate, const MessageLocation* loc, Handle<Object> message,
+    v8::Local<v8::Value> api_exception_obj) {
+  v8::Local<v8::Message> api_message_obj = v8::Utils::MessageToLocal(message);
+  int error_level = api_message_obj->ErrorLevel();
 
   Handle<TemplateList> global_listeners =
       isolate->factory()->message_listeners();
@@ -134,6 +146,11 @@ void MessageHandler::ReportMessage(Isolate* isolate, MessageLocation* loc,
       if (global_listeners->get(i)->IsUndefined(isolate)) continue;
       FixedArray* listener = FixedArray::cast(global_listeners->get(i));
       Foreign* callback_obj = Foreign::cast(listener->get(0));
+      int32_t message_levels =
+          static_cast<int32_t>(Smi::cast(listener->get(2))->value());
+      if (!(message_levels & error_level)) {
+        continue;
+      }
       v8::MessageCallback callback =
           FUNCTION_CAST<v8::MessageCallback>(callback_obj->foreign_address());
       Handle<Object> callback_data(listener->get(1), isolate);
diff --git a/src/messages.h b/src/messages.h
index cbec757d6f..153c01964b 100644
--- a/src/messages.h
+++ b/src/messages.h
@@ -669,6 +669,8 @@ class ErrorUtils : public AllStatic {
   T(WasmTrapFuncSigMismatch, "function signature mismatch")                    \
   T(WasmTrapInvalidIndex, "invalid index into function table")                 \
   T(WasmTrapTypeError, "invalid type")                                         \
+  /* Asm.js validation warnings */                                             \
+  T(AsmJsInvalid, "Invalid asm.js: %")                                         \
   /* DataCloneError messages */                                                \
   T(DataCloneError, "% could not be cloned.")                                  \
   T(DataCloneErrorNeuteredArrayBuffer,                                         \
@@ -709,11 +711,11 @@ class MessageHandler {
   // Returns a message object for the API to use.
   static Handle<JSMessageObject> MakeMessageObject(
       Isolate* isolate, MessageTemplate::Template type,
-      MessageLocation* location, Handle<Object> argument,
+      const MessageLocation* location, Handle<Object> argument,
       Handle<JSArray> stack_frames);
 
   // Report a formatted message (needs JS allocation).
-  static void ReportMessage(Isolate* isolate, MessageLocation* loc,
+  static void ReportMessage(Isolate* isolate, const MessageLocation* loc,
                             Handle<JSMessageObject> message);
 
   static void DefaultMessageReport(Isolate* isolate, const MessageLocation* loc,
@@ -721,6 +723,12 @@ class MessageHandler {
   static Handle<String> GetMessage(Isolate* isolate, Handle<Object> data);
   static std::unique_ptr<char[]> GetLocalizedMessage(Isolate* isolate,
                                                      Handle<Object> data);
+
+ private:
+  static void ReportMessageNoExceptions(Isolate* isolate,
+                                        const MessageLocation* loc,
+                                        Handle<Object> message_obj,
+                                        v8::Local<v8::Value> api_exception_obj);
 };
 
 
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 2fb23342ee..d6822a6d09 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -6808,7 +6808,7 @@ ACCESSORS(JSMessageObject, script, Object, kScriptOffset)
 ACCESSORS(JSMessageObject, stack_frames, Object, kStackFramesOffset)
 SMI_ACCESSORS(JSMessageObject, start_position, kStartPositionOffset)
 SMI_ACCESSORS(JSMessageObject, end_position, kEndPositionOffset)
-
+SMI_ACCESSORS(JSMessageObject, error_level, kErrorLevelOffset)
 
 INT_ACCESSORS(Code, instruction_size, kInstructionSizeOffset)
 INT_ACCESSORS(Code, prologue_offset, kPrologueOffset)
diff --git a/src/objects.h b/src/objects.h
index c254431f61..ab8c5db8dd 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -8887,6 +8887,9 @@ class JSMessageObject: public JSObject {
   // position, or the empty string if the position is invalid.
   Handle<String> GetSourceLine() const;
 
+  inline int error_level() const;
+  inline void set_error_level(int level);
+
   DECLARE_CAST(JSMessageObject)
 
   // Dispatched behavior.
@@ -8900,7 +8903,8 @@ class JSMessageObject: public JSObject {
   static const int kStackFramesOffset = kScriptOffset + kPointerSize;
   static const int kStartPositionOffset = kStackFramesOffset + kPointerSize;
   static const int kEndPositionOffset = kStartPositionOffset + kPointerSize;
-  static const int kSize = kEndPositionOffset + kPointerSize;
+  static const int kErrorLevelOffset = kEndPositionOffset + kPointerSize;
+  static const int kSize = kErrorLevelOffset + kPointerSize;
 
   typedef FixedBodyDescriptor<HeapObject::kMapOffset,
                               kStackFramesOffset + kPointerSize,
diff --git a/test/cctest/asmjs/test-asm-typer.cc b/test/cctest/asmjs/test-asm-typer.cc
index 3f6eeafa5a..873e937420 100644
--- a/test/cctest/asmjs/test-asm-typer.cc
+++ b/test/cctest/asmjs/test-asm-typer.cc
@@ -126,7 +126,8 @@ class AsmTyperHarnessBuilder {
     WithGlobal(var_name, type);
     auto* var_info = typer_->Lookup(DeclareVariable(var_name));
     CHECK(var_info);
-    var_info->SetFirstForwardUse(-1);
+    MessageLocation location;
+    var_info->SetFirstForwardUse(location);
     return this;
   }
 
@@ -260,12 +261,14 @@ class AsmTyperHarnessBuilder {
       return false;
     }
 
-    if (std::strstr(typer_->error_message(), error_message) == nullptr) {
+    std::unique_ptr<char[]> msg = i::MessageHandler::GetLocalizedMessage(
+        isolate_, typer_->error_message());
+    if (std::strstr(msg.get(), error_message) == nullptr) {
       std::cerr << "Asm validation failed with the wrong error message:\n"
                    "Expected to contain '"
                 << error_message << "'\n"
                                     "       Actually is  '"
-                << typer_->error_message() << "'\n";
+                << msg.get() << "'\n";
       return false;
     }
 
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index 487c1a1575..1fb5e5620a 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -17349,6 +17349,79 @@ TEST(CaptureStackTraceForUncaughtExceptionAndSetters) {
   isolate->SetCaptureStackTraceForUncaughtExceptions(false);
 }
 
+static int asm_warning_triggered = 0;
+
+static void AsmJsWarningListener(v8::Local<v8::Message> message,
+                                 v8::Local<Value>) {
+  DCHECK_EQ(v8::Isolate::kMessageWarning, message->ErrorLevel());
+  asm_warning_triggered = 1;
+}
+
+TEST(AsmJsWarning) {
+  i::FLAG_validate_asm = true;
+
+  LocalContext env;
+  v8::Isolate* isolate = env->GetIsolate();
+  v8::HandleScope scope(isolate);
+
+  asm_warning_triggered = 0;
+  isolate->AddMessageListenerWithErrorLevel(AsmJsWarningListener,
+                                            v8::Isolate::kMessageAll);
+  CompileRun(
+      "function module() {\n"
+      "  'use asm';\n"
+      "  var x = 'hi';\n"
+      "  return {};\n"
+      "}\n"
+      "module();");
+  DCHECK_EQ(1, asm_warning_triggered);
+  isolate->RemoveMessageListeners(AsmJsWarningListener);
+}
+
+static int error_level_message_count = 0;
+static int expected_error_level = 0;
+
+static void ErrorLevelListener(v8::Local<v8::Message> message,
+                               v8::Local<Value>) {
+  DCHECK_EQ(expected_error_level, message->ErrorLevel());
+  ++error_level_message_count;
+}
+
+TEST(ErrorLevelWarning) {
+  LocalContext env;
+  v8::Isolate* isolate = env->GetIsolate();
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  v8::HandleScope scope(isolate);
+
+  const char* source = "fake = 1;";
+  v8::Local<v8::Script> lscript = CompileWithOrigin(source, "test");
+  i::Handle<i::SharedFunctionInfo> obj = i::Handle<i::SharedFunctionInfo>::cast(
+      v8::Utils::OpenHandle(*lscript->GetUnboundScript()));
+  CHECK(obj->script()->IsScript());
+  i::Handle<i::Script> script(i::Script::cast(obj->script()));
+
+  int levels[] = {
+      v8::Isolate::kMessageLog, v8::Isolate::kMessageInfo,
+      v8::Isolate::kMessageDebug, v8::Isolate::kMessageWarning,
+  };
+  error_level_message_count = 0;
+  isolate->AddMessageListenerWithErrorLevel(ErrorLevelListener,
+                                            v8::Isolate::kMessageAll);
+  for (size_t i = 0; i < arraysize(levels); i++) {
+    i::MessageLocation location(script, 0, 0);
+    i::Handle<i::String> msg(i_isolate->factory()->InternalizeOneByteString(
+        STATIC_CHAR_VECTOR("test")));
+    i::Handle<i::JSMessageObject> message =
+        i::MessageHandler::MakeMessageObject(
+            i_isolate, i::MessageTemplate::kAsmJsInvalid, &location, msg,
+            i::Handle<i::JSArray>::null());
+    message->set_error_level(levels[i]);
+    expected_error_level = levels[i];
+    i::MessageHandler::ReportMessage(i_isolate, &location, message);
+  }
+  isolate->RemoveMessageListeners(ErrorLevelListener);
+  DCHECK_EQ(arraysize(levels), error_level_message_count);
+}
 
 static void StackTraceFunctionNameListener(v8::Local<v8::Message> message,
                                            v8::Local<Value>) {