Ladybird+LibWebView: Add -P/--enable-callgrind-profiling option

This adds a -P option to run Ladybird under callgrind. It starts with
instrumentation disabled. To start capturing a profile (once Ladybird
has launched) run `callgrind_control -i on` and to stop it again run
`callgrind_control -i off`.

P.s. This is pretty much stolen from Andreas (and is based on the patch
everyone [that wants a profile] have been manually applying).

5 files changed, 34 insertions, 13 deletions

diff --git a/Userland/Libraries/LibWebView/OutOfProcessWebView.cpp b/Userland/Libraries/LibWebView/OutOfProcessWebView.cpp
index cee2b51ba1..52a1185550 100644
--- a/Userland/Libraries/LibWebView/OutOfProcessWebView.cpp
+++ b/Userland/Libraries/LibWebView/OutOfProcessWebView.cpp
@@ -59,7 +59,7 @@ void OutOfProcessWebView::handle_web_content_process_crash()
     load_html(builder.to_deprecated_string(), m_url);
 }
 
-void OutOfProcessWebView::create_client()
+void OutOfProcessWebView::create_client(EnableCallgrindProfiling)
 {
     m_client_state = {};
 
diff --git a/Userland/Libraries/LibWebView/OutOfProcessWebView.h b/Userland/Libraries/LibWebView/OutOfProcessWebView.h
index e521b29751..1e66ecd62c 100644
--- a/Userland/Libraries/LibWebView/OutOfProcessWebView.h
+++ b/Userland/Libraries/LibWebView/OutOfProcessWebView.h
@@ -121,7 +121,7 @@ private:
     virtual void did_scroll() override;
 
     // ^WebView::ViewImplementation
-    virtual void create_client() override;
+    virtual void create_client(EnableCallgrindProfiling = EnableCallgrindProfiling::No) override;
     virtual void update_zoom() override;
     virtual void notify_server_did_layout(Badge<WebContentClient>, Gfx::IntSize content_size) override;
     virtual void notify_server_did_paint(Badge<WebContentClient>, i32 bitmap_id) override;
diff --git a/Userland/Libraries/LibWebView/ViewImplementation.cpp b/Userland/Libraries/LibWebView/ViewImplementation.cpp
index c77b8c27f9..0686544921 100644
--- a/Userland/Libraries/LibWebView/ViewImplementation.cpp
+++ b/Userland/Libraries/LibWebView/ViewImplementation.cpp
@@ -126,7 +126,7 @@ void ViewImplementation::run_javascript(StringView js_source)
 
 #if !defined(AK_OS_SERENITY)
 
-ErrorOr<NonnullRefPtr<WebView::WebContentClient>> ViewImplementation::launch_web_content_process(ReadonlySpan<String> candidate_web_content_paths)
+ErrorOr<NonnullRefPtr<WebView::WebContentClient>> ViewImplementation::launch_web_content_process(ReadonlySpan<String> candidate_web_content_paths, EnableCallgrindProfiling enable_callgrind_profiling)
 {
     int socket_fds[2] {};
     TRY(Core::System::socketpair(AF_LOCAL, SOCK_STREAM, 0, socket_fds));
@@ -149,15 +149,22 @@ ErrorOr<NonnullRefPtr<WebView::WebContentClient>> ViewImplementation::launch_web
 
         auto webcontent_fd_passing_socket_string = TRY(String::number(wc_fd_passing_fd));
 
-        auto arguments = Array {
-            "WebContent"sv,
-            "--webcontent-fd-passing-socket"sv,
-            webcontent_fd_passing_socket_string
-        };
-
         ErrorOr<void> result;
         for (auto const& path : candidate_web_content_paths) {
-            result = Core::System::exec(path, arguments, Core::System::SearchInPath::Yes);
+            constexpr auto callgrind_prefix_length = 3;
+            auto arguments_with_callgrind_prefix = Array {
+                "valgrind"sv,
+                "--tool=callgrind"sv,
+                "--instr-atstart=no"sv,
+                path.bytes_as_string_view(),
+                "--webcontent-fd-passing-socket"sv,
+                webcontent_fd_passing_socket_string
+            };
+            auto arguments = arguments_with_callgrind_prefix.span();
+            if (enable_callgrind_profiling == EnableCallgrindProfiling::No)
+                arguments = arguments.slice(callgrind_prefix_length);
+
+            result = Core::System::exec(arguments[0], arguments, Core::System::SearchInPath::Yes);
             if (!result.is_error())
                 break;
         }
@@ -176,6 +183,13 @@ ErrorOr<NonnullRefPtr<WebView::WebContentClient>> ViewImplementation::launch_web
     auto new_client = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) WebView::WebContentClient(move(socket), *this)));
     new_client->set_fd_passing_socket(TRY(Core::LocalSocket::adopt_fd(ui_fd_passing_fd)));
 
+    if (enable_callgrind_profiling == EnableCallgrindProfiling::Yes) {
+        dbgln();
+        dbgln("\033[1;45mLaunched WebContent process under callgrind!\033[0m");
+        dbgln("\033[100mRun `\033[4mcallgrind_control -i on\033[24m` to start instrumentation and `\033[4mcallgrind_control -i off\033[24m` stop it again.\033[0m");
+        dbgln();
+    }
+
     return new_client;
 }
 
diff --git a/Userland/Libraries/LibWebView/ViewImplementation.h b/Userland/Libraries/LibWebView/ViewImplementation.h
index 0aa276da80..a7342a3cb8 100644
--- a/Userland/Libraries/LibWebView/ViewImplementation.h
+++ b/Userland/Libraries/LibWebView/ViewImplementation.h
@@ -18,6 +18,12 @@
 
 namespace WebView {
 
+// Note: This only exists inside Serenity to avoid #ifdefs in all implementors of ViewImplementation.
+enum class EnableCallgrindProfiling {
+    No,
+    Yes
+};
+
 class ViewImplementation {
 public:
     virtual ~ViewImplementation() { }
@@ -120,11 +126,12 @@ protected:
 
     WebContentClient& client();
     WebContentClient const& client() const;
-    virtual void create_client() = 0;
     virtual void update_zoom() = 0;
 
+    virtual void create_client(EnableCallgrindProfiling = EnableCallgrindProfiling::No) {};
+
 #if !defined(AK_OS_SERENITY)
-    ErrorOr<NonnullRefPtr<WebView::WebContentClient>> launch_web_content_process(ReadonlySpan<String> candidate_web_content_paths);
+    ErrorOr<NonnullRefPtr<WebView::WebContentClient>> launch_web_content_process(ReadonlySpan<String> candidate_web_content_paths, EnableCallgrindProfiling = EnableCallgrindProfiling::No);
 #endif
 
     struct SharedBitmap {
diff --git a/Userland/Utilities/headless-browser.cpp b/Userland/Utilities/headless-browser.cpp
index 2dfca6f1ee..8c6420aca6 100644
--- a/Userland/Utilities/headless-browser.cpp
+++ b/Userland/Utilities/headless-browser.cpp
@@ -157,7 +157,7 @@ private:
 
     void notify_server_did_finish_handling_input_event(bool) override { }
     void update_zoom() override { }
-    void create_client() override { }
+    void create_client(WebView::EnableCallgrindProfiling) override { }
 };
 
 static ErrorOr<NonnullRefPtr<Core::Timer>> load_page_for_screenshot_and_exit(Core::EventLoop& event_loop, HeadlessWebContentView& view, int screenshot_timeout)