[heap] Scavenger: Restructure main processing method

- Add scopes
- Rename scopes to fit hierarchy
- Scavenge weak collections before parallel phase
- Remove semi space phase which doesn't exist anymore

Bug: chromium:738865
Change-Id: Id3b72793e764f8d3597917e45185d08675b57f5d
Reviewed-on: https://chromium-review.googlesource.com/593611Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47002}

src/heap/gc-tracer.cc

@@ -459,14 +459,15 @@ void GCTracer::PrintNVP() const {
           "heap.external.prologue=%.2f "
           "heap.external.epilogue=%.2f "
           "heap.external_weak_global_handles=%.2f "
+          "fast_promote=%.2f "
           "scavenge=%.2f "
-          "evacuate=%.2f "
-          "old_new=%.2f "
-          "weak=%.2f "
-          "roots=%.2f "
-          "semispace=%.2f "
-          "steps_count=%d "
-          "steps_took=%.1f "
+          "scavenge.roots=%.2f "
+          "scavenge.weak=%.2f "
+          "scavenge.weak_global_handles.identify=%.2f"
+          "scavenge.weak_global_handles.process=%.2f"
+          "scavenge.parallel=%.2f "
+          "incremental.steps_count=%d "
+          "incremental.steps_took=%.1f "
           "scavenge_throughput=%.f "
           "total_size_before=%" PRIuS
           " "
@@ -498,12 +499,15 @@ void GCTracer::PrintNVP() const {
           current_.scopes[Scope::HEAP_EXTERNAL_PROLOGUE],
           current_.scopes[Scope::HEAP_EXTERNAL_EPILOGUE],
           current_.scopes[Scope::HEAP_EXTERNAL_WEAK_GLOBAL_HANDLES],
+          current_.scopes[Scope::SCAVENGER_FAST_PROMOTE],
           current_.scopes[Scope::SCAVENGER_SCAVENGE],
-          current_.scopes[Scope::SCAVENGER_EVACUATE],
-          current_.scopes[Scope::SCAVENGER_OLD_TO_NEW_POINTERS],
-          current_.scopes[Scope::SCAVENGER_WEAK],
-          current_.scopes[Scope::SCAVENGER_ROOTS],
-          current_.scopes[Scope::SCAVENGER_SEMISPACE],
+          current_.scopes[Scope::SCAVENGER_SCAVENGE_ROOTS],
+          current_.scopes[Scope::SCAVENGER_SCAVENGE_WEAK],
+          current_
+              .scopes[Scope::SCAVENGER_SCAVENGE_WEAK_GLOBAL_HANDLES_IDENTIFY],
+          current_
+              .scopes[Scope::SCAVENGER_SCAVENGE_WEAK_GLOBAL_HANDLES_PROCESS],
+          current_.scopes[Scope::SCAVENGER_SCAVENGE_PARALLEL],
           current_.incremental_marking_scopes[GCTracer::Scope::MC_INCREMENTAL]
               .steps,
           current_.scopes[Scope::MC_INCREMENTAL],

src/heap/gc-tracer.h

@@ -103,12 +103,13 @@ enum ScavengeSpeedMode { kForAllObjects, kForSurvivedObjects };
   F(MINOR_MC_MARKING_DEQUE)                          \
   F(MINOR_MC_RESET_LIVENESS)                         \
   F(MINOR_MC_SWEEPING)                               \
-  F(SCAVENGER_EVACUATE)                             \
-  F(SCAVENGER_OLD_TO_NEW_POINTERS)                  \
-  F(SCAVENGER_ROOTS)                                \
+  F(SCAVENGER_FAST_PROMOTE)                          \
   F(SCAVENGER_SCAVENGE)                              \
-  F(SCAVENGER_SEMISPACE)                            \
-  F(SCAVENGER_WEAK)
+  F(SCAVENGER_SCAVENGE_WEAK_GLOBAL_HANDLES_IDENTIFY) \
+  F(SCAVENGER_SCAVENGE_WEAK_GLOBAL_HANDLES_PROCESS)  \
+  F(SCAVENGER_SCAVENGE_PARALLEL)                     \
+  F(SCAVENGER_SCAVENGE_ROOTS)                        \
+  F(SCAVENGER_SCAVENGE_WEAK)
 
 #define TRACE_GC(tracer, scope_id)                             \
   GCTracer::Scope::ScopeId gc_tracer_scope_id(scope_id);       \

src/heap/heap.cc

@@ -1746,7 +1746,7 @@ class ScavengeWeakObjectRetainer : public WeakObjectRetainer {
 };
 
 void Heap::EvacuateYoungGeneration() {
-  TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_EVACUATE);
+  TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_FAST_PROMOTE);
   base::LockGuard<base::Mutex> guard(relocation_mutex());
   ConcurrentMarking::PauseScope pause_scope(concurrent_marking());
   if (!FLAG_concurrent_marking) {
@@ -1937,36 +1937,40 @@ void Heap::Scavenge() {
 
   RootScavengeVisitor root_scavenge_visitor(this, scavengers[kMainThreadId]);
 
+  {
+    // Identify weak unmodified handles. Requires an unmodified graph.
+    TRACE_GC(tracer(),
+             GCTracer::Scope::SCAVENGER_SCAVENGE_WEAK_GLOBAL_HANDLES_IDENTIFY);
     isolate()->global_handles()->IdentifyWeakUnmodifiedObjects(
         &JSObject::IsUnmodifiedApiObject);
-
+  }
   {
     // Copy roots.
-    TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_ROOTS);
+    TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_SCAVENGE_ROOTS);
     IterateRoots(&root_scavenge_visitor, VISIT_ALL_IN_SCAVENGE);
   }
-
-  {
-    TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_OLD_TO_NEW_POINTERS);
-    job.Run();
-  }
-
   {
-    TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_WEAK);
+    // Weak collections are held strongly by the Scavenger.
+    TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_SCAVENGE_WEAK);
     IterateEncounteredWeakCollections(&root_scavenge_visitor);
   }
-
   {
-    TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_SEMISPACE);
-    scavengers[kMainThreadId]->Process();
+    // Parallel phase scavenging all copied and promoted objects.
+    TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_SCAVENGE_PARALLEL);
+    job.Run();
+    DCHECK(copied_list.IsGlobalEmpty());
+    DCHECK(promotion_list.IsGlobalEmpty());
   }
-
+  {
+    // Scavenge weak global handles.
+    TRACE_GC(tracer(),
+             GCTracer::Scope::SCAVENGER_SCAVENGE_WEAK_GLOBAL_HANDLES_PROCESS);
     isolate()->global_handles()->MarkNewSpaceWeakUnmodifiedObjectsPending(
         &IsUnscavengedHeapObject);
-
     isolate()->global_handles()->IterateNewSpaceWeakUnmodifiedRoots(
         &root_scavenge_visitor);
     scavengers[kMainThreadId]->Process();
+  }
 
   for (int i = 0; i < num_scavenge_tasks; i++) {
     scavengers[i]->Finalize();