[offthread] Enable off-thread logging

Enable logging script events and code position events during a
background compile. This isn't technically thread-safe, but neither
are the existing logger accesses in the parser, so something has to
be done here in general.

Bug: chromium:1011762
Change-Id: I3b610c3bb146880ef826928b6f341f402ca6247e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2162853
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69426}

BUILD.gn

@@ -2710,6 +2710,7 @@ v8_source_set("v8_base_without_compiler") {
     "src/logging/counters-inl.h",
     "src/logging/counters.cc",
     "src/logging/counters.h",
+    "src/logging/local-logger.cc",
     "src/logging/local-logger.h",
     "src/logging/log-inl.h",
     "src/logging/log-utils.cc",

src/execution/local-isolate.cc

@@ -16,7 +16,7 @@ LocalIsolate::LocalIsolate(Isolate* isolate)
     : HiddenLocalFactory(isolate),
       heap_(isolate->heap()),
       isolate_(isolate),
-      logger_(new LocalLogger()),
+      logger_(new LocalLogger(isolate)),
       thread_id_(ThreadId::Current()) {}
 
 LocalIsolate::~LocalIsolate() = default;

src/logging/local-logger.cc

@@ -0,0 +1,31 @@
+// Copyright 2020 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.
+
+#include "src/logging/local-logger.h"
+
+#include "src/execution/isolate.h"
+
+namespace v8 {
+namespace internal {
+
+// TODO(leszeks): Add support for logging from off-thread.
+LocalLogger::LocalLogger(Isolate* isolate)
+    : logger_(isolate->logger()),
+      is_logging_(isolate->logger()->is_logging()),
+      is_listening_to_code_events_(
+          isolate->logger()->is_listening_to_code_events()) {}
+
+void LocalLogger::ScriptDetails(Script script) {
+  logger_->ScriptDetails(script);
+}
+void LocalLogger::ScriptEvent(Logger::ScriptEventType type, int script_id) {
+  logger_->ScriptEvent(type, script_id);
+}
+void LocalLogger::CodeLinePosInfoRecordEvent(Address code_start,
+                                             ByteArray source_position_table) {
+  logger_->CodeLinePosInfoRecordEvent(code_start, source_position_table);
+}
+
+}  // namespace internal
+}  // namespace v8

src/logging/local-logger.h

@@ -14,16 +14,21 @@ namespace internal {
 // TODO(leszeks): Add support for logging from off-thread.
 class LocalLogger {
  public:
-  bool is_logging() const { return false; }
-  bool is_listening_to_code_events() const { return false; }
-  void ScriptEvent(Logger::ScriptEventType type, int script_id) {
-    UNREACHABLE();
+  explicit LocalLogger(Isolate* isolate);
+
+  bool is_logging() const { return is_logging_; }
+  bool is_listening_to_code_events() const {
+    return is_listening_to_code_events_;
   }
-  void ScriptDetails(Script script) { UNREACHABLE(); }
+  void ScriptDetails(Script script);
+  void ScriptEvent(Logger::ScriptEventType type, int script_id);
   void CodeLinePosInfoRecordEvent(Address code_start,
-                                  ByteArray source_position_table) {
-    UNREACHABLE();
-  }
+                                  ByteArray source_position_table);
+
+ private:
+  Logger* logger_;
+  bool is_logging_;
+  bool is_listening_to_code_events_;
 };
 
 }  // namespace internal