Added a special stack guard to deopt marked allocation sites.

BUG=
R=mvstanton@chromium.org, ulan@chromium.org

Review URL: https://codereview.chromium.org/169563002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19404 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/execution.cc

@@ -516,15 +516,15 @@ void StackGuard::FullDeopt() {
 }
 
 
-bool StackGuard::IsDeoptMarkedCode() {
+bool StackGuard::IsDeoptMarkedAllocationSites() {
   ExecutionAccess access(isolate_);
-  return (thread_local_.interrupt_flags_ & DEOPT_MARKED_CODE) != 0;
+  return (thread_local_.interrupt_flags_ & DEOPT_MARKED_ALLOCATION_SITES) != 0;
 }
 
 
-void StackGuard::DeoptMarkedCode() {
+void StackGuard::DeoptMarkedAllocationSites() {
   ExecutionAccess access(isolate_);
-  thread_local_.interrupt_flags_ |= DEOPT_MARKED_CODE;
+  thread_local_.interrupt_flags_ |= DEOPT_MARKED_ALLOCATION_SITES;
   set_interrupt_limits(access);
 }
 
@@ -1040,9 +1040,9 @@ MaybeObject* Execution::HandleStackGuardInterrupt(Isolate* isolate) {
     stack_guard->Continue(FULL_DEOPT);
     Deoptimizer::DeoptimizeAll(isolate);
   }
-  if (stack_guard->IsDeoptMarkedCode()) {
-    stack_guard->Continue(DEOPT_MARKED_CODE);
-    Deoptimizer::DeoptimizeMarkedCode(isolate);
+  if (stack_guard->IsDeoptMarkedAllocationSites()) {
+    stack_guard->Continue(DEOPT_MARKED_ALLOCATION_SITES);
+    isolate->heap()->DeoptMarkedAllocationSites();
   }
   if (stack_guard->IsInstallCodeRequest()) {
     ASSERT(isolate->concurrent_recompilation_enabled());

src/execution.h

@@ -45,7 +45,7 @@ enum InterruptFlag {
   FULL_DEOPT = 1 << 6,
   INSTALL_CODE = 1 << 7,
   API_INTERRUPT = 1 << 8,
-  DEOPT_MARKED_CODE = 1 << 9
+  DEOPT_MARKED_ALLOCATION_SITES = 1 << 9
 };
 
 
@@ -223,8 +223,8 @@ class StackGuard {
   void RequestInstallCode();
   bool IsFullDeopt();
   void FullDeopt();
-  bool IsDeoptMarkedCode();
-  void DeoptMarkedCode();
+  bool IsDeoptMarkedAllocationSites();
+  void DeoptMarkedAllocationSites();
   void Continue(InterruptFlag after_what);
 
   void RequestInterrupt(InterruptCallback callback, void* data);

src/heap.cc

@@ -545,7 +545,9 @@ void Heap::ProcessPretenuringFeedback() {
       }
     }
 
-    if (trigger_deoptimization) isolate_->stack_guard()->DeoptMarkedCode();
+    if (trigger_deoptimization) {
+      isolate_->stack_guard()->DeoptMarkedAllocationSites();
+    }
 
     FlushAllocationSitesScratchpad();
 
@@ -567,6 +569,25 @@ void Heap::ProcessPretenuringFeedback() {
 }
 
 
+void Heap::DeoptMarkedAllocationSites() {
+  // TODO(hpayer): If iterating over the allocation sites list becomes a
+  // performance issue, use a cache heap data structure instead (similar to the
+  // allocation sites scratchpad).
+  Object* list_element = allocation_sites_list();
+  while (list_element->IsAllocationSite()) {
+    AllocationSite* site = AllocationSite::cast(list_element);
+    if (site->deopt_dependent_code()) {
+      site->dependent_code()->MarkCodeForDeoptimization(
+          isolate_,
+          DependentCode::kAllocationSiteTenuringChangedGroup);
+      site->set_deopt_dependent_code(false);
+    }
+    list_element = site->weak_next();
+  }
+  Deoptimizer::DeoptimizeMarkedCode(isolate_);
+}
+
+
 void Heap::GarbageCollectionEpilogue() {
   store_buffer()->GCEpilogue();
 
@@ -2000,14 +2021,12 @@ void Heap::ResetAllAllocationSitesDependentCode(PretenureFlag flag) {
     AllocationSite* casted = AllocationSite::cast(cur);
     if (casted->GetPretenureMode() == flag) {
       casted->ResetPretenureDecision();
-      bool got_marked = casted->dependent_code()->MarkCodeForDeoptimization(
-          isolate_,
-          DependentCode::kAllocationSiteTenuringChangedGroup);
-      if (got_marked) marked = true;
+      casted->set_deopt_dependent_code(true);
+      marked = true;
     }
     cur = casted->weak_next();
   }
-  if (marked) isolate_->stack_guard()->DeoptMarkedCode();
+  if (marked) isolate_->stack_guard()->DeoptMarkedAllocationSites();
 }
 
 

src/heap.h

@@ -1847,6 +1847,8 @@ class Heap {
     return amount_of_external_allocated_memory_;
   }
 
+  void DeoptMarkedAllocationSites();
+
   // ObjectStats are kept in two arrays, counts and sizes. Related stats are
   // stored in a contiguous linear buffer. Stats groups are stored one after
   // another.

src/objects-inl.h

@@ -1554,9 +1554,7 @@ inline bool AllocationSite::DigestPretenuringFeedback() {
     set_pretenure_decision(result);
     if (current_mode != GetPretenureMode()) {
       decision_changed = true;
-      dependent_code()->MarkCodeForDeoptimization(
-          GetIsolate(),
-          DependentCode::kAllocationSiteTenuringChangedGroup);
+      set_deopt_dependent_code(true);
     }
   }
 

src/objects.h

@@ -8256,8 +8256,9 @@ class AllocationSite: public Struct {
   class DoNotInlineBit:         public BitField<bool,         29,  1> {};
 
   // Bitfields for pretenure_data
-  class MementoFoundCountBits:  public BitField<int,          0, 28> {};
-  class PretenureDecisionBits:  public BitField<PretenureDecision, 28, 2> {};
+  class MementoFoundCountBits:  public BitField<int,               0, 27> {};
+  class PretenureDecisionBits:  public BitField<PretenureDecision, 27, 2> {};
+  class DeoptDependentCodeBit:  public BitField<bool,              29, 1> {};
   STATIC_ASSERT(PretenureDecisionBits::kMax >= kLastPretenureDecisionValue);
 
   // Increments the mementos found counter and returns true when the first
@@ -8282,6 +8283,18 @@ class AllocationSite: public Struct {
         SKIP_WRITE_BARRIER);
   }
 
+  bool deopt_dependent_code() {
+    int value = pretenure_data()->value();
+    return DeoptDependentCodeBit::decode(value);
+  }
+
+  void set_deopt_dependent_code(bool deopt) {
+    int value = pretenure_data()->value();
+    set_pretenure_data(
+        Smi::FromInt(DeoptDependentCodeBit::update(value, deopt)),
+        SKIP_WRITE_BARRIER);
+  }
+
   int memento_found_count() {
     int value = pretenure_data()->value();
     return MementoFoundCountBits::decode(value);