gin: Add features for code flushing

Bug: v8:13842
Change-Id: Ifb9398bc55e9039c4ac13c789e76f9ab07b08ef2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4598010
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1154607}

gin/gin_features.cc

@@ -34,6 +34,18 @@ BASE_FEATURE(kV8FlushBaselineCode,
              "V8FlushBaselineCode",
              base::FEATURE_DISABLED_BY_DEFAULT);
 
+// Enables code flushing based on tab visibility.
+BASE_FEATURE(kV8FlushCodeBasedOnTabVisibility,
+             "V8FlushCodeBasedOnTabVisibility",
+             base::FEATURE_DISABLED_BY_DEFAULT);
+
+// Enables code flushing based on time.
+BASE_FEATURE(kV8FlushCodeBasedOnTime,
+             "V8FlushCodeBasedOnTime",
+             base::FEATURE_DISABLED_BY_DEFAULT);
+const base::FeatureParam<int> kV8FlushCodeOldTime{&kV8FlushCodeBasedOnTime,
+                                                  "V8FlushCodeOldTime", 30};
+
 // Enables finalizing streaming JS compilations on a background thread.
 BASE_FEATURE(kV8OffThreadFinalization,
              "V8OffThreadFinalization",

gin/gin_features.h

@@ -25,6 +25,9 @@ GIN_EXPORT BASE_DECLARE_FEATURE(kV8ExperimentalRegexpEngine);
 GIN_EXPORT extern const base::FeatureParam<int> kV8FlushBytecodeOldAge;
 GIN_EXPORT BASE_DECLARE_FEATURE(kV8FlushBaselineCode);
 GIN_EXPORT BASE_DECLARE_FEATURE(kV8FlushBytecode);
+GIN_EXPORT BASE_DECLARE_FEATURE(kV8FlushCodeBasedOnTabVisibility);
+GIN_EXPORT BASE_DECLARE_FEATURE(kV8FlushCodeBasedOnTime);
+GIN_EXPORT extern const base::FeatureParam<int> kV8FlushCodeOldTime;
 GIN_EXPORT BASE_DECLARE_FEATURE(kV8FlushEmbeddedBlobICache);
 GIN_EXPORT BASE_DECLARE_FEATURE(kV8IgnitionElideRedundantTdzChecks);
 GIN_EXPORT BASE_DECLARE_FEATURE(kV8LazyFeedbackAllocation);

gin/v8_initializer.cc

@@ -249,6 +249,12 @@ void SetFlags(IsolateHolder::ScriptMode mode,
                          "--no-flush-bytecode");
   SetV8FlagsIfOverridden(features::kV8FlushBaselineCode,
                          "--flush-baseline-code", "--no-flush-baseline-code");
+  SetV8FlagsIfOverridden(features::kV8FlushCodeBasedOnTabVisibility,
+                         "--flush-code-based-on-tab-visibility",
+                         "--no-flush-code-based-on-tab-visibility");
+  SetV8FlagsIfOverridden(features::kV8FlushCodeBasedOnTime,
+                         "--flush-code-based-on-time",
+                         "--no-flush-code-based-on-time");
   SetV8FlagsIfOverridden(features::kV8OffThreadFinalization,
                          "--finalize-streaming-on-background",
                          "--no-finalize-streaming-on-background");
@@ -320,6 +326,12 @@ void SetFlags(IsolateHolder::ScriptMode mode,
     }
   }
 
+  if (base::FeatureList::IsEnabled(features::kV8FlushCodeBasedOnTime)) {
+    if (int old_time = features::kV8FlushCodeOldTime.Get()) {
+      SetV8FlagsFormatted("--bytecode-old-time=%i", old_time);
+    }
+  }
+
   // Make sure aliases of kV8SlowHistograms only enable the feature to
   // avoid contradicting settings between multiple finch experiments.
   bool any_slow_histograms_alias =