Use [[likely]] and [[unlikely]] in //chrome/

as discussed in this thread: https://groups.google.com/a/chromium.org/g/cxx/c/bk9YC5qSDF8/m/LLzo7uS8AgAJ?utm_medium=email&utm_source=footer

Bug: 40256217
Change-Id: I99b56f03952457dfb6ba9cc2f2fe9aac3698efbd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5496820
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Punith Nayak <punithbnayak@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1294753}

PRESUBMIT.py

@@ -1332,15 +1332,6 @@ _BANNED_CPP_FUNCTIONS : Sequence[BanRule] = (
       True,
       [_THIRD_PARTY_EXCEPT_BLINK],  # Don't warn in third_party folders.
     ),
-    BanRule(
-      r'/\[\[(un)?likely\]\]',
-      (
-        '[[likely]] and [[unlikely]] are not yet allowed ',
-        '(https://crbug.com/1414620). Use [UN]LIKELY instead.',
-      ),
-      True,
-      [_THIRD_PARTY_EXCEPT_BLINK],  # Don't warn in third_party folders.
-    ),
     BanRule(
       r'/\[\[(\w*::)?no_unique_address\]\]',
       (

chrome/browser/accessibility/media_app/ax_media_app_untrusted_handler.cc

@@ -90,7 +90,7 @@ void AXMediaAppUntrustedHandler::OnOCRServiceInitialized(bool successful) {
   if (!dirty_page_ids_.empty()) {
     OcrNextDirtyPageIfAny();
   }
-  if (UNLIKELY(media_app_)) {
+  if (media_app_) [[unlikely]] {
     // `media_app_` is only used for testing.
     CHECK_IS_TEST();
     media_app_->OcrServiceEnabledChanged(true);
@@ -128,7 +128,7 @@ void AXMediaAppUntrustedHandler::PerformAction(
           ax::mojom::IntAttribute::kScrollYMin));
       viewport_box_.set_y(
           std::max(viewport_box_.y() - viewport_box_.height(), y_min));
-      if (UNLIKELY(media_app_)) {
+      if (media_app_) [[unlikely]] {
         // `media_app_` is only used for testing.
         CHECK_IS_TEST();
         media_app_->SetViewport(viewport_box_);
@@ -143,7 +143,7 @@ void AXMediaAppUntrustedHandler::PerformAction(
           ax::mojom::IntAttribute::kScrollYMax));
       viewport_box_.set_y(
           std::min(viewport_box_.y() + viewport_box_.height(), y_max));
-      if (UNLIKELY(media_app_)) {
+      if (media_app_) [[unlikely]] {
         // `media_app_` is only used for testing.
         CHECK_IS_TEST();
         media_app_->SetViewport(viewport_box_);
@@ -157,7 +157,7 @@ void AXMediaAppUntrustedHandler::PerformAction(
           ax::mojom::IntAttribute::kScrollXMin));
       viewport_box_.set_x(
           std::max(viewport_box_.x() - viewport_box_.width(), x_min));
-      if (UNLIKELY(media_app_)) {
+      if (media_app_) [[unlikely]] {
         // `media_app_` is only used for testing.
         CHECK_IS_TEST();
         media_app_->SetViewport(viewport_box_);
@@ -171,7 +171,7 @@ void AXMediaAppUntrustedHandler::PerformAction(
           ax::mojom::IntAttribute::kScrollXMax));
       viewport_box_.set_x(
           std::min(viewport_box_.x() + viewport_box_.width(), x_max));
-      if (UNLIKELY(media_app_)) {
+      if (media_app_) [[unlikely]] {
         // `media_app_` is only used for testing.
         CHECK_IS_TEST();
         media_app_->SetViewport(viewport_box_);
@@ -224,7 +224,7 @@ void AXMediaAppUntrustedHandler::PerformAction(
         }
         break;
       }
-      if (UNLIKELY(media_app_)) {
+      if (media_app_) [[unlikely]] {
         // `media_app_` is only used for testing.
         CHECK_IS_TEST();
         media_app_->SetViewport(viewport_box_);
@@ -266,7 +266,7 @@ void AXMediaAppUntrustedHandler::PerformAction(
 }
 
 void AXMediaAppUntrustedHandler::OnAXModeAdded(ui::AXMode mode) {
-  if (UNLIKELY(media_app_)) {
+  if (media_app_) [[unlikely]] {
     // `media_app_` is only used for testing.
     CHECK_IS_TEST();
     media_app_->AccessibilityEnabledChanged(
@@ -652,7 +652,7 @@ void AXMediaAppUntrustedHandler::OcrNextDirtyPageIfAny() {
   const std::string dirty_page_id = PopDirtyPage();
   // TODO(b/289012145): Refactor this code to support things happening
   // asynchronously - i.e. `RequestBitmap` will be async.
-  if (UNLIKELY(media_app_)) {
+  if (media_app_) [[unlikely]] {
     // `media_app_` is only used for testing.
     CHECK_IS_TEST();
     SkBitmap page_bitmap = media_app_->RequestBitmap(dirty_page_id);

chrome/browser/ash/attestation/tpm_challenge_key.cc

@@ -29,7 +29,7 @@ TpmChallengeKey* TpmChallengeKeyFactory::next_result_for_testing_ = nullptr;
 
 // static
 std::unique_ptr<TpmChallengeKey> TpmChallengeKeyFactory::Create() {
-  if (UNLIKELY(next_result_for_testing_)) {
+  if (next_result_for_testing_) [[unlikely]] {
     std::unique_ptr<TpmChallengeKey> result(next_result_for_testing_);
     next_result_for_testing_ = nullptr;
     return result;

chrome/browser/ash/attestation/tpm_challenge_key_subtle.cc

@@ -56,7 +56,7 @@ TpmChallengeKeySubtle* TpmChallengeKeySubtleFactory::next_result_for_testing_ =
 
 // static
 std::unique_ptr<TpmChallengeKeySubtle> TpmChallengeKeySubtleFactory::Create() {
-  if (UNLIKELY(next_result_for_testing_)) {
+  if (next_result_for_testing_) [[unlikely]] {
     std::unique_ptr<TpmChallengeKeySubtle> result(next_result_for_testing_);
     next_result_for_testing_ = nullptr;
     return result;

chrome/browser/ash/cert_provisioning/cert_provisioning_worker.cc

@@ -29,7 +29,7 @@ CertProvisioningWorkerFactory* CertProvisioningWorkerFactory::test_factory_ =
 
 // static
 CertProvisioningWorkerFactory* CertProvisioningWorkerFactory::Get() {
-  if (UNLIKELY(test_factory_)) {
+  if (test_factory_) [[unlikely]] {
     return test_factory_;
   }
 

chrome/browser/chromeos/platform_keys/extension_platform_keys_service.cc

@@ -910,7 +910,7 @@ void ExtensionPlatformKeysService::GenerateRSAKey(
     GenerateKeyCallback callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
-  if (UNLIKELY(!keystore_service_)) {
+  if (!keystore_service_) [[unlikely]] {
     std::move(callback).Run(/*public_key_spki_der=*/std::vector<uint8_t>(),
                             crosapi::mojom::KeystoreError::kMojoUnavailable);
     return;
@@ -946,7 +946,7 @@ void ExtensionPlatformKeysService::GenerateECKey(
     GenerateKeyCallback callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
-  if (UNLIKELY(!keystore_service_)) {
+  if (!keystore_service_) [[unlikely]] {
     std::move(callback).Run(/*public_key_spki_der=*/std::vector<uint8_t>(),
                             crosapi::mojom::KeystoreError::kMojoUnavailable);
     return;
@@ -978,7 +978,7 @@ void ExtensionPlatformKeysService::SignDigest(
     SignCallback callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
-  if (UNLIKELY(!keystore_service_)) {
+  if (!keystore_service_) [[unlikely]] {
     std::move(callback).Run(/*signature=*/std::vector<uint8_t>(),
                             crosapi::mojom::KeystoreError::kMojoUnavailable);
     return;
@@ -997,7 +997,7 @@ void ExtensionPlatformKeysService::SignRSAPKCS1Raw(
     SignCallback callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
-  if (UNLIKELY(!keystore_service_)) {
+  if (!keystore_service_) [[unlikely]] {
     std::move(callback).Run(/*signature=*/std::vector<uint8_t>(),
                             crosapi::mojom::KeystoreError::kMojoUnavailable);
     return;
@@ -1019,7 +1019,7 @@ void ExtensionPlatformKeysService::SelectClientCertificates(
     content::WebContents* web_contents) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
-  if (UNLIKELY(!keystore_service_)) {
+  if (!keystore_service_) [[unlikely]] {
     std::move(callback).Run(/*matches=*/nullptr,
                             crosapi::mojom::KeystoreError::kMojoUnavailable);
     return;

chrome/browser/privacy_budget/identifiability_study_state.cc

@@ -95,7 +95,7 @@ int IdentifiabilityStudyState::generation() const {
 bool IdentifiabilityStudyState::ShouldRecordSurface(
     blink::IdentifiableSurface surface) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
-  if (LIKELY(!settings_.enabled() && !meta_experiment_active_)) {
+  if (!settings_.enabled() && !meta_experiment_active_) [[unlikely]] {
     return false;
   }
 
@@ -103,7 +103,7 @@ bool IdentifiabilityStudyState::ShouldRecordSurface(
   if (surface.GetType() == blink::IdentifiableSurface::Type::kReservedInternal)
     return true;
 
-  if (LIKELY(!settings_.enabled())) {
+  if (!settings_.enabled()) [[unlikely]] {
     return false;
   }
 
@@ -165,8 +165,9 @@ void IdentifiabilityStudyState::InitializeRenderer(
 bool IdentifiabilityStudyState::DecideInclusionForNewSurface(
     blink::IdentifiableSurface new_surface) {
   DCHECK(settings_.IsUsingRandomSampling());
-  if (UNLIKELY(seen_surfaces_.size() > kMaxSelectedSurfaceOffset + 1))
+  if (seen_surfaces_.size() > kMaxSelectedSurfaceOffset + 1) [[unlikely]] {
     return false;
+  }
 
   MaybeUpdateSelectedOffsets();
 
@@ -547,7 +548,7 @@ bool IdentifiabilityStudyState::IsMetaExperimentActive() {
 }
 
 void IdentifiabilityStudyState::InitFromPrefs() {
-  if (LIKELY(!settings_.enabled())) {
+  if (!settings_.enabled()) [[unlikely]] {
     // Nothing to do if the study is not active. However it is possible that
     // this client has switched from active to inactive, in which case we should
     // nuke any persisted data.