Attempts to fix bugs introduced in 8b6fcf50e85d.

runtime/vm/scavenger.cc

Index: runtime/vm/scavenger.cc
diff --git a/runtime/vm/scavenger.cc b/runtime/vm/scavenger.cc
index 32d62e000906025ed067aaa6032adfd2f326b1a0..3d40c23bcf6e030e6658ee4ba067cdf9a0d55fd4 100644
--- a/runtime/vm/scavenger.cc
+++ b/runtime/vm/scavenger.cc
@@ -394,13 +394,6 @@ SemiSpace* Scavenger::Prologue(Isolate* isolate, bool invoke_api_callbacks) {
   resolved_top_ = top_;
   end_ = to_->end();
 
-  // Throw out the old information about the from space
-  if (isolate->IsMutatorThreadScheduled()) {
-    Thread* mutator_thread = isolate->mutator_thread();
-    mutator_thread->set_top(top_);
-    mutator_thread->set_end(end_);
-  }
-
   return from;
 }
 
@@ -410,12 +403,11 @@ void Scavenger::Epilogue(Isolate* isolate,
   // All objects in the to space have been copied from the from space at this
   // moment.
 
-  // Ensure the mutator thread now has the up-to-date top_ and end_ of the
-  // semispace
+  // Ensure the mutator thread will fail the next allocation. This will force
+  // mutator to allocate a new TLAB
   if (isolate->IsMutatorThreadScheduled()) {
-    Thread* thread = isolate->mutator_thread();
-    thread->set_top(top_);
-    thread->set_end(end_);
+    Thread* mutator_thread = isolate->mutator_thread();
+    ASSERT(!mutator_thread->HasActiveTLAB());
   }
 
   double avg_frac = stats_history_.Get(0).PromoCandidatesSuccessFraction();
@@ -722,16 +714,20 @@ void Scavenger::ProcessWeakReferences() {
   }
 }
 
-void Scavenger::FlushTLS() const {
+void Scavenger::MakeNewSpaceIterable() const {
   ASSERT(heap_ != NULL);
-  if (heap_->isolate()->IsMutatorThreadScheduled()) {
+  if (heap_->isolate()->IsMutatorThreadScheduled() && !scavenging_) {
     Thread* mutator_thread = heap_->isolate()->mutator_thread();
-    mutator_thread->heap()->new_space()->set_top(mutator_thread->top());
+    if (mutator_thread->HasActiveTLAB()) {
+      ASSERT(mutator_thread->top() <=
+             mutator_thread->heap()->new_space()->top());
+      heap_->FillRemainingTLAB(mutator_thread);
+    }
   }
 }
 
 void Scavenger::VisitObjectPointers(ObjectPointerVisitor* visitor) const {
-  FlushTLS();
+  MakeNewSpaceIterable();
   uword cur = FirstObjectStart();
   while (cur < top_) {
     RawObject* raw_obj = RawObject::FromAddr(cur);
@@ -740,7 +736,7 @@ void Scavenger::VisitObjectPointers(ObjectPointerVisitor* visitor) const {
 }
 
 void Scavenger::VisitObjects(ObjectVisitor* visitor) const {
-  FlushTLS();
+  MakeNewSpaceIterable();
   uword cur = FirstObjectStart();
   while (cur < top_) {
     RawObject* raw_obj = RawObject::FromAddr(cur);
@@ -755,7 +751,7 @@ void Scavenger::AddRegionsToObjectSet(ObjectSet* set) const {
 
 RawObject* Scavenger::FindObject(FindObjectVisitor* visitor) const {
   ASSERT(!scavenging_);
-  FlushTLS();
+  MakeNewSpaceIterable();
   uword cur = FirstObjectStart();
   if (visitor->VisitRange(cur, top_)) {
     while (cur < top_) {
@@ -802,6 +798,13 @@ void Scavenger::Scavenge(bool invoke_api_callbacks) {
   int64_t post_safe_point = OS::GetCurrentMonotonicMicros();
   heap_->RecordTime(kSafePoint, post_safe_point - pre_safe_point);
 
+  if (isolate->IsMutatorThreadScheduled()) {
+    Thread* mutator_thread = isolate->mutator_thread();
+    if (mutator_thread->HasActiveTLAB()) {
+      heap_->AbandonRemainingTLAB(mutator_thread);
+    }
+  }
+
   // TODO(koda): Make verification more compatible with concurrent sweep.
   if (FLAG_verify_before_gc && !FLAG_concurrent_sweep) {
     OS::PrintErr("Verifying before Scavenge...");
@@ -913,11 +916,6 @@ void Scavenger::Evacuate() {
   // Forces the next scavenge to promote all the objects in the new space.
   survivor_end_ = top_;
 
-  if (heap_->isolate()->IsMutatorThreadScheduled()) {
-    Thread* mutator_thread = heap_->isolate()->mutator_thread();
-    survivor_end_ = mutator_thread->top();
-  }
-
   Scavenge();
 
   // It is possible for objects to stay in the new space
@@ -925,4 +923,9 @@ void Scavenger::Evacuate() {
   ASSERT((UsedInWords() == 0) || failed_to_promote_);
 }
 
+int64_t Scavenger::UsedInWords() const {
+  int64_t used_in_words = (top_ - FirstObjectStart()) >> kWordSizeLog2;
+  return used_in_words;
+}
+
 }  // namespace dart