[objects] Move deopt_count to FeedbackVector

Since any deopt-count-based heuristics should be native context
dependent, it belongs in the feedback vector rather than the SFI.

Bug: v8:6402
Change-Id: I30804d58bc1dec9150558e6ee21ee5b4dbd36c8d
Reviewed-on: https://chromium-review.googlesource.com/593661
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47014}

src/deoptimizer.cc

@@ -243,13 +243,12 @@ void Deoptimizer::DeoptimizeMarkedCodeForContext(Context* context) {
       if (!code->marked_for_deoptimization()) return;
 
       // Unlink this function.
-      SharedFunctionInfo* shared = function->shared();
       if (!code->deopt_already_counted()) {
-        shared->increment_deopt_count();
+        function->feedback_vector()->increment_deopt_count();
         code->set_deopt_already_counted(true);
       }
 
-      function->set_code(shared->code());
+      function->set_code(function->shared()->code());
 
       if (FLAG_trace_deopt) {
         CodeTracer::Scope scope(code->GetHeap()->isolate()->GetCodeTracer());
@@ -535,7 +534,7 @@ Deoptimizer::Deoptimizer(Isolate* isolate, JSFunction* function,
       // that can eventually lead to disabling optimization for a function.
       isolate->counters()->soft_deopts_executed()->Increment();
     } else if (function != nullptr) {
-      function->shared()->increment_deopt_count();
+      function->feedback_vector()->increment_deopt_count();
     }
   }
   if (compiled_code_->kind() == Code::OPTIMIZED_FUNCTION) {

src/feedback-vector-inl.h

@@ -100,6 +100,7 @@ ACCESSORS(FeedbackVector, optimized_code_cell, Object, kOptimizedCodeOffset)
 INT32_ACCESSORS(FeedbackVector, length, kLengthOffset)
 INT32_ACCESSORS(FeedbackVector, invocation_count, kInvocationCountOffset)
 INT32_ACCESSORS(FeedbackVector, profiler_ticks, kProfilerTicksOffset)
+INT32_ACCESSORS(FeedbackVector, deopt_count, kDeoptCountOffset)
 
 bool FeedbackVector::is_empty() const { return length() == 0; }
 
@@ -109,6 +110,13 @@ FeedbackMetadata* FeedbackVector::metadata() const {
 
 void FeedbackVector::clear_invocation_count() { set_invocation_count(0); }
 
+void FeedbackVector::increment_deopt_count() {
+  int count = deopt_count();
+  if (count < std::numeric_limits<int32_t>::max()) {
+    set_deopt_count(count + 1);
+  }
+}
+
 Code* FeedbackVector::optimized_code() const {
   Object* slot = optimized_code_cell();
   if (slot->IsSmi()) return nullptr;

src/feedback-vector.cc

@@ -206,6 +206,7 @@ Handle<FeedbackVector> FeedbackVector::New(Isolate* isolate,
             Smi::FromEnum(OptimizationMarker::kNone));
   DCHECK_EQ(vector->invocation_count(), 0);
   DCHECK_EQ(vector->profiler_ticks(), 0);
+  DCHECK_EQ(vector->deopt_count(), 0);
 
   // Ensure we can skip the write barrier
   Handle<Object> uninitialized_sentinel = UninitializedSentinel(isolate);
@@ -334,7 +335,7 @@ void FeedbackVector::EvictOptimizedCodeMarkedForDeoptimization(
       PrintF("]\n");
     }
     if (!code->deopt_already_counted()) {
-      shared->increment_deopt_count();
+      increment_deopt_count();
       code->set_deopt_already_counted(true);
     }
     ClearOptimizedCode();

src/feedback-vector.h

@@ -148,7 +148,11 @@ class FeedbackVector : public HeapObject {
   // runtime profiler.
   DECL_INT32_ACCESSORS(profiler_ticks)
 
+  // [deopt_count]: The number of times this function has deoptimized.
+  DECL_INT32_ACCESSORS(deopt_count)
+
   inline void clear_invocation_count();
+  inline void increment_deopt_count();
 
   inline Code* optimized_code() const;
   inline OptimizationMarker optimization_marker() const;
@@ -243,6 +247,7 @@ class FeedbackVector : public HeapObject {
   V(kLengthOffset, kInt32Size)               \
   V(kInvocationCountOffset, kInt32Size)      \
   V(kProfilerTicksOffset, kInt32Size)        \
+  V(kDeoptCountOffset, kInt32Size)           \
   V(kUnalignedHeaderSize, 0)
 
   DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize, FEEDBACK_VECTOR_FIELDS)

src/heap/heap.cc

@@ -4228,9 +4228,10 @@ AllocationResult Heap::CopyFeedbackVector(FeedbackVector* src) {
 
   // Slow case: Just copy the content one-by-one.
   result->set_shared_function_info(src->shared_function_info());
+  result->set_optimized_code_cell(src->optimized_code_cell());
   result->set_invocation_count(src->invocation_count());
   result->set_profiler_ticks(src->profiler_ticks());
-  result->set_optimized_code_cell(src->optimized_code_cell());
+  result->set_deopt_count(src->deopt_count());
   for (int i = 0; i < len; i++) result->set(i, src->get(i), mode);
   return result;
 }
@@ -4373,6 +4374,7 @@ AllocationResult Heap::AllocateFeedbackVector(SharedFunctionInfo* shared,
   vector->set_length(length);
   vector->set_invocation_count(0);
   vector->set_profiler_ticks(0);
+  vector->set_deopt_count(0);
   // TODO(leszeks): Initialize based on the feedback metadata.
   MemsetPointer(vector->slots_start(), undefined_value(), length);
   return vector;

src/objects.cc

@@ -13852,7 +13852,6 @@ void Map::StartInobjectSlackTracking() {
 
 void SharedFunctionInfo::ResetForNewContext(int new_ic_age) {
   set_ic_age(new_ic_age);
-  set_deopt_count(0);
 }
 
 void ObjectVisitor::VisitCodeTarget(Code* host, RelocInfo* rinfo) {

src/objects/shared-function-info-inl.h

@@ -358,23 +358,10 @@ void SharedFunctionInfo::set_inferred_name(String* inferred_name) {
 BIT_FIELD_ACCESSORS(SharedFunctionInfo, counters_and_bailout_reason, ic_age,
                     SharedFunctionInfo::ICAgeBits)
 
-BIT_FIELD_ACCESSORS(SharedFunctionInfo, counters_and_bailout_reason,
-                    deopt_count, SharedFunctionInfo::DeoptCountBits)
-
 BIT_FIELD_ACCESSORS(SharedFunctionInfo, counters_and_bailout_reason,
                     disable_optimization_reason,
                     SharedFunctionInfo::DisabledOptimizationReasonBits)
 
-void SharedFunctionInfo::increment_deopt_count() {
-  int value = counters_and_bailout_reason();
-  int deopt_count = DeoptCountBits::decode(value);
-  // Saturate the deopt count when incrementing, rather than overflowing.
-  if (deopt_count < DeoptCountBits::kMax) {
-    set_counters_and_bailout_reason(
-        DeoptCountBits::update(value, deopt_count + 1));
-  }
-}
-
 bool SharedFunctionInfo::IsUserJavaScript() {
   Object* script_obj = script();
   if (script_obj->IsUndefined(GetIsolate())) return false;

src/objects/shared-function-info.h

@@ -337,10 +337,6 @@ class SharedFunctionInfo : public HeapObject {
   Handle<Object> GetSourceCode();
   Handle<Object> GetSourceCodeHarmony();
 
-  // Number of times the function was deoptimized.
-  DECL_INT_ACCESSORS(deopt_count)
-  inline void increment_deopt_count();
-
   // Stores deopt_count, ic_age and bailout_reason as bit-fields.
   DECL_INT_ACCESSORS(counters_and_bailout_reason)
 
@@ -515,7 +511,6 @@ class SharedFunctionInfo : public HeapObject {
 
 // Bit fields in |counters_and_bailout_reason|.
 #define COUNTERS_AND_BAILOUT_REASON_BIT_FIELDS(V, _) \
-  V(DeoptCountBits, int, 4, _)                       \
   V(ICAgeBits, int, 8, _)                            \
   V(DisabledOptimizationReasonBits, BailoutReason, 8, _)
 

src/runtime/runtime-test.cc

@@ -417,7 +417,9 @@ RUNTIME_FUNCTION(Runtime_GetDeoptCount) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);
-  return Smi::FromInt(function->shared()->deopt_count());
+  // Functions without a feedback vector have never deoptimized.
+  if (!function->has_feedback_vector()) return Smi::kZero;
+  return Smi::FromInt(function->feedback_vector()->deopt_count());
 }
 
 static void ReturnThis(const v8::FunctionCallbackInfo<v8::Value>& args) {

test/cctest/heap/test-heap.cc

@@ -2265,8 +2265,6 @@ TEST(ResetSharedFunctionInfoCountersDuringIncrementalMarking) {
   CcTest::CollectAllGarbage();
 
   CHECK_EQ(CcTest::heap()->global_ic_age(), f->shared()->ic_age());
-  CHECK_EQ(0, f->shared()->deopt_count());
-  CHECK_EQ(0, f->feedback_vector()->profiler_ticks());
 }
 
 
@@ -2308,8 +2306,6 @@ TEST(ResetSharedFunctionInfoCountersDuringMarkSweep) {
   CcTest::CollectAllGarbage();
 
   CHECK_EQ(CcTest::heap()->global_ic_age(), f->shared()->ic_age());
-  CHECK_EQ(0, f->shared()->deopt_count());
-  CHECK_EQ(0, f->feedback_vector()->profiler_ticks());
 }