[ic] Record call counts for monomorphic calls made with an IC.

The idea is that TurboFan can use this information for more intelligent
inlining.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/1201193003

Cr-Commit-Position: refs/heads/master@{#29281}

src/arm/code-stubs-arm.cc

@@ -2706,6 +2706,13 @@ void CallIC_ArrayStub::Generate(MacroAssembler* masm) {
   __ CompareRoot(r5, Heap::kAllocationSiteMapRootIndex);
   __ b(ne, &miss);
 
+  // Increment the call count for monomorphic function calls.
+  __ add(r2, r2, Operand::PointerOffsetFromSmiKey(r3));
+  __ add(r2, r2, Operand(FixedArray::kHeaderSize + kPointerSize));
+  __ ldr(r3, FieldMemOperand(r2, 0));
+  __ add(r3, r3, Operand(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+  __ str(r3, FieldMemOperand(r2, 0));
+
   __ mov(r2, r4);
   __ mov(r3, r1);
   ArrayConstructorStub stub(masm->isolate(), arg_count());
@@ -2765,6 +2772,13 @@ void CallICStub::Generate(MacroAssembler* masm) {
   // convincing us that we have a monomorphic JSFunction.
   __ JumpIfSmi(r1, &extra_checks_or_miss);
 
+  // Increment the call count for monomorphic function calls.
+  __ add(r2, r2, Operand::PointerOffsetFromSmiKey(r3));
+  __ add(r2, r2, Operand(FixedArray::kHeaderSize + kPointerSize));
+  __ ldr(r3, FieldMemOperand(r2, 0));
+  __ add(r3, r3, Operand(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+  __ str(r3, FieldMemOperand(r2, 0));
+
   __ bind(&have_js_function);
   if (CallAsMethod()) {
     EmitContinueIfStrictOrNative(masm, &cont);
@@ -2840,6 +2854,11 @@ void CallICStub::Generate(MacroAssembler* masm) {
   __ add(r4, r4, Operand(Smi::FromInt(1)));
   __ str(r4, FieldMemOperand(r2, with_types_offset));
 
+  // Initialize the call counter.
+  __ Move(r5, Operand(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+  __ add(r4, r2, Operand::PointerOffsetFromSmiKey(r3));
+  __ str(r5, FieldMemOperand(r4, FixedArray::kHeaderSize + kPointerSize));
+
   // Store the function. Use a stub since we need a frame for allocation.
   // r2 - vector
   // r3 - slot

src/arm64/code-stubs-arm64.cc

@@ -3091,10 +3091,18 @@ void CallIC_ArrayStub::Generate(MacroAssembler* masm) {
   __ Ldr(map, FieldMemOperand(scratch, HeapObject::kMapOffset));
   __ JumpIfNotRoot(map, Heap::kAllocationSiteMapRootIndex, &miss);
 
+  // Increment the call count for monomorphic function calls.
+  __ Add(feedback_vector, feedback_vector,
+         Operand::UntagSmiAndScale(index, kPointerSizeLog2));
+  __ Add(feedback_vector, feedback_vector,
+         Operand(FixedArray::kHeaderSize + kPointerSize));
+  __ Ldr(index, FieldMemOperand(feedback_vector, 0));
+  __ Add(index, index, Operand(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+  __ Str(index, FieldMemOperand(feedback_vector, 0));
+
   Register allocation_site = feedback_vector;
+  Register original_constructor = index;
   __ Mov(allocation_site, scratch);
-
-  Register original_constructor = x3;
   __ Mov(original_constructor, function);
   ArrayConstructorStub stub(masm->isolate(), arg_count());
   __ TailCallStub(&stub);
@@ -3160,6 +3168,15 @@ void CallICStub::Generate(MacroAssembler* masm) {
   // convincing us that we have a monomorphic JSFunction.
   __ JumpIfSmi(function, &extra_checks_or_miss);
 
+  // Increment the call count for monomorphic function calls.
+  __ Add(feedback_vector, feedback_vector,
+         Operand::UntagSmiAndScale(index, kPointerSizeLog2));
+  __ Add(feedback_vector, feedback_vector,
+         Operand(FixedArray::kHeaderSize + kPointerSize));
+  __ Ldr(index, FieldMemOperand(feedback_vector, 0));
+  __ Add(index, index, Operand(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+  __ Str(index, FieldMemOperand(feedback_vector, 0));
+
   __ bind(&have_js_function);
   if (CallAsMethod()) {
     EmitContinueIfStrictOrNative(masm, &cont);
@@ -3235,6 +3252,12 @@ void CallICStub::Generate(MacroAssembler* masm) {
   __ Adds(x4, x4, Operand(Smi::FromInt(1)));
   __ Str(x4, FieldMemOperand(feedback_vector, with_types_offset));
 
+  // Initialize the call counter.
+  __ Mov(x5, Smi::FromInt(CallICNexus::kCallCountIncrement));
+  __ Adds(x4, feedback_vector,
+          Operand::UntagSmiAndScale(index, kPointerSizeLog2));
+  __ Str(x5, FieldMemOperand(x4, FixedArray::kHeaderSize + kPointerSize));
+
   // Store the function. Use a stub since we need a frame for allocation.
   // x2 - vector
   // x3 - slot

src/ia32/code-stubs-ia32.cc

@@ -2247,6 +2247,11 @@ void CallIC_ArrayStub::Generate(MacroAssembler* masm) {
          factory->allocation_site_map());
   __ j(not_equal, &miss);
 
+  // Increment the call count for monomorphic function calls.
+  __ add(FieldOperand(ebx, edx, times_half_pointer_size,
+                      FixedArray::kHeaderSize + kPointerSize),
+         Immediate(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+
   __ mov(ebx, ecx);
   __ mov(edx, edi);
   ArrayConstructorStub stub(masm->isolate(), arg_count());
@@ -2306,6 +2311,11 @@ void CallICStub::Generate(MacroAssembler* masm) {
   // convincing us that we have a monomorphic JSFunction.
   __ JumpIfSmi(edi, &extra_checks_or_miss);
 
+  // Increment the call count for monomorphic function calls.
+  __ add(FieldOperand(ebx, edx, times_half_pointer_size,
+                      FixedArray::kHeaderSize + kPointerSize),
+         Immediate(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+
   __ bind(&have_js_function);
   if (CallAsMethod()) {
     EmitContinueIfStrictOrNative(masm, &cont);
@@ -2377,6 +2387,11 @@ void CallICStub::Generate(MacroAssembler* masm) {
   // Update stats.
   __ add(FieldOperand(ebx, with_types_offset), Immediate(Smi::FromInt(1)));
 
+  // Initialize the call counter.
+  __ mov(FieldOperand(ebx, edx, times_half_pointer_size,
+                      FixedArray::kHeaderSize + kPointerSize),
+         Immediate(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+
   // Store the function. Use a stub since we need a frame for allocation.
   // ebx - vector
   // edx - slot

src/mips/code-stubs-mips.cc

@@ -2842,6 +2842,13 @@ void CallIC_ArrayStub::Generate(MacroAssembler* masm) {
   __ LoadRoot(at, Heap::kAllocationSiteMapRootIndex);
   __ Branch(&miss, ne, t1, Operand(at));
 
+  // Increment the call count for monomorphic function calls.
+  __ sll(at, a3, kPointerSizeLog2 - kSmiTagSize);
+  __ Addu(at, a2, Operand(at));
+  __ lw(a3, FieldMemOperand(at, FixedArray::kHeaderSize + kPointerSize));
+  __ Addu(a3, a3, Operand(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+  __ sw(a3, FieldMemOperand(at, FixedArray::kHeaderSize + kPointerSize));
+
   __ mov(a2, t0);
   __ mov(a3, a1);
   ArrayConstructorStub stub(masm->isolate(), arg_count());
@@ -2901,6 +2908,13 @@ void CallICStub::Generate(MacroAssembler* masm) {
   // convincing us that we have a monomorphic JSFunction.
   __ JumpIfSmi(a1, &extra_checks_or_miss);
 
+  // Increment the call count for monomorphic function calls.
+  __ sll(at, a3, kPointerSizeLog2 - kSmiTagSize);
+  __ Addu(at, a2, Operand(at));
+  __ lw(a3, FieldMemOperand(at, FixedArray::kHeaderSize + kPointerSize));
+  __ Addu(a3, a3, Operand(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+  __ sw(a3, FieldMemOperand(at, FixedArray::kHeaderSize + kPointerSize));
+
   __ bind(&have_js_function);
   if (CallAsMethod()) {
     EmitContinueIfStrictOrNative(masm, &cont);
@@ -2976,6 +2990,12 @@ void CallICStub::Generate(MacroAssembler* masm) {
   __ Addu(t0, t0, Operand(Smi::FromInt(1)));
   __ sw(t0, FieldMemOperand(a2, with_types_offset));
 
+  // Initialize the call counter.
+  __ sll(at, a3, kPointerSizeLog2 - kSmiTagSize);
+  __ Addu(at, a2, Operand(at));
+  __ li(t0, Operand(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+  __ sw(t0, FieldMemOperand(at, FixedArray::kHeaderSize + kPointerSize));
+
   // Store the function. Use a stub since we need a frame for allocation.
   // a2 - vector
   // a3 - slot

src/mips64/code-stubs-mips64.cc

@@ -2918,6 +2918,13 @@ void CallIC_ArrayStub::Generate(MacroAssembler* masm) {
   __ LoadRoot(at, Heap::kAllocationSiteMapRootIndex);
   __ Branch(&miss, ne, a5, Operand(at));
 
+  // Increment the call count for monomorphic function calls.
+  __ dsrl(t0, a3, 32 - kPointerSizeLog2);
+  __ Daddu(a3, a2, Operand(t0));
+  __ ld(t0, FieldMemOperand(a3, FixedArray::kHeaderSize + kPointerSize));
+  __ Daddu(t0, t0, Operand(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+  __ sd(t0, FieldMemOperand(a3, FixedArray::kHeaderSize + kPointerSize));
+
   __ mov(a2, a4);
   __ mov(a3, a1);
   ArrayConstructorStub stub(masm->isolate(), arg_count());
@@ -2977,6 +2984,13 @@ void CallICStub::Generate(MacroAssembler* masm) {
   // convincing us that we have a monomorphic JSFunction.
   __ JumpIfSmi(a1, &extra_checks_or_miss);
 
+  // Increment the call count for monomorphic function calls.
+  __ dsrl(t0, a3, 32 - kPointerSizeLog2);
+  __ Daddu(a3, a2, Operand(t0));
+  __ ld(t0, FieldMemOperand(a3, FixedArray::kHeaderSize + kPointerSize));
+  __ Daddu(t0, t0, Operand(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+  __ sd(t0, FieldMemOperand(a3, FixedArray::kHeaderSize + kPointerSize));
+
   __ bind(&have_js_function);
   if (CallAsMethod()) {
     EmitContinueIfStrictOrNative(masm, &cont);
@@ -3052,6 +3066,12 @@ void CallICStub::Generate(MacroAssembler* masm) {
   __ Daddu(a4, a4, Operand(Smi::FromInt(1)));
   __ sd(a4, FieldMemOperand(a2, with_types_offset));
 
+  // Initialize the call counter.
+  __ dsrl(at, a3, 32 - kPointerSizeLog2);
+  __ Daddu(at, a2, Operand(at));
+  __ li(t0, Operand(Smi::FromInt(CallICNexus::kCallCountIncrement)));
+  __ sd(t0, FieldMemOperand(at, FixedArray::kHeaderSize + kPointerSize));
+
   // Store the function. Use a stub since we need a frame for allocation.
   // a2 - vector
   // a3 - slot

src/type-feedback-vector-inl.h

@@ -30,12 +30,6 @@ Handle<Object> TypeFeedbackVector::PremonomorphicSentinel(Isolate* isolate) {
 }
 
 
-Handle<Object> TypeFeedbackVector::MonomorphicArraySentinel(
-    Isolate* isolate, ElementsKind elements_kind) {
-  return Handle<Object>(Smi::FromInt(static_cast<int>(elements_kind)), isolate);
-}
-
-
 Object* TypeFeedbackVector::RawUninitializedSentinel(Heap* heap) {
   return heap->uninitialized_symbol();
 }

src/type-feedback-vector.cc

@@ -262,11 +262,11 @@ InlineCacheState LoadICNexus::StateFromFeedback() const {
   Isolate* isolate = GetIsolate();
   Object* feedback = GetFeedback();
 
-  if (feedback == *vector()->UninitializedSentinel(isolate)) {
+  if (feedback == *TypeFeedbackVector::UninitializedSentinel(isolate)) {
     return UNINITIALIZED;
-  } else if (feedback == *vector()->MegamorphicSentinel(isolate)) {
+  } else if (feedback == *TypeFeedbackVector::MegamorphicSentinel(isolate)) {
     return MEGAMORPHIC;
-  } else if (feedback == *vector()->PremonomorphicSentinel(isolate)) {
+  } else if (feedback == *TypeFeedbackVector::PremonomorphicSentinel(isolate)) {
     return PREMONOMORPHIC;
   } else if (feedback->IsFixedArray()) {
     // Determine state purely by our structure, don't check if the maps are
@@ -285,11 +285,11 @@ InlineCacheState KeyedLoadICNexus::StateFromFeedback() const {
   Isolate* isolate = GetIsolate();
   Object* feedback = GetFeedback();
 
-  if (feedback == *vector()->UninitializedSentinel(isolate)) {
+  if (feedback == *TypeFeedbackVector::UninitializedSentinel(isolate)) {
     return UNINITIALIZED;
-  } else if (feedback == *vector()->PremonomorphicSentinel(isolate)) {
+  } else if (feedback == *TypeFeedbackVector::PremonomorphicSentinel(isolate)) {
     return PREMONOMORPHIC;
-  } else if (feedback == *vector()->MegamorphicSentinel(isolate)) {
+  } else if (feedback == *TypeFeedbackVector::MegamorphicSentinel(isolate)) {
     return MEGAMORPHIC;
   } else if (feedback->IsFixedArray()) {
     // Determine state purely by our structure, don't check if the maps are
@@ -311,25 +311,39 @@ InlineCacheState KeyedLoadICNexus::StateFromFeedback() const {
 InlineCacheState CallICNexus::StateFromFeedback() const {
   Isolate* isolate = GetIsolate();
   Object* feedback = GetFeedback();
-  DCHECK(GetFeedbackExtra() == *vector()->UninitializedSentinel(isolate) ||
-         GetFeedbackExtra() == Smi::FromInt(kHasReturnedMinusZeroSentinel));
+  DCHECK(GetFeedbackExtra() ==
+             *TypeFeedbackVector::UninitializedSentinel(isolate) ||
+         GetFeedbackExtra()->IsSmi());
 
-  if (feedback == *vector()->MegamorphicSentinel(isolate)) {
+  if (feedback == *TypeFeedbackVector::MegamorphicSentinel(isolate)) {
     return GENERIC;
   } else if (feedback->IsAllocationSite() || feedback->IsWeakCell()) {
     return MONOMORPHIC;
   }
 
-  CHECK(feedback == *vector()->UninitializedSentinel(isolate));
+  CHECK(feedback == *TypeFeedbackVector::UninitializedSentinel(isolate));
   return UNINITIALIZED;
 }
 
 
+int CallICNexus::ExtractCallCount() {
+  Object* call_count = GetFeedbackExtra();
+  if (call_count->IsSmi()) {
+    int value = Smi::cast(call_count)->value() / 2;
+    return value;
+  }
+  return -1;
+}
+
+
 void CallICNexus::Clear(Code* host) { CallIC::Clear(GetIsolate(), host, this); }
 
 
 void CallICNexus::ConfigureGeneric() {
-  SetFeedback(*vector()->MegamorphicSentinel(GetIsolate()), SKIP_WRITE_BARRIER);
+  SetFeedback(*TypeFeedbackVector::MegamorphicSentinel(GetIsolate()),
+              SKIP_WRITE_BARRIER);
+  SetFeedbackExtra(*TypeFeedbackVector::UninitializedSentinel(GetIsolate()),
+                   SKIP_WRITE_BARRIER);
 }
 
 
@@ -340,48 +354,55 @@ void CallICNexus::ConfigureMonomorphicArray() {
         GetIsolate()->factory()->NewAllocationSite();
     SetFeedback(*new_site);
   }
+  SetFeedbackExtra(Smi::FromInt(kCallCountIncrement), SKIP_WRITE_BARRIER);
 }
 
 
 void CallICNexus::ConfigureUninitialized() {
-  SetFeedback(*vector()->UninitializedSentinel(GetIsolate()),
+  SetFeedback(*TypeFeedbackVector::UninitializedSentinel(GetIsolate()),
               SKIP_WRITE_BARRIER);
+  SetFeedbackExtra(*TypeFeedbackVector::UninitializedSentinel(GetIsolate()),
+                   SKIP_WRITE_BARRIER);
 }
 
 
 void CallICNexus::ConfigureMonomorphic(Handle<JSFunction> function) {
   Handle<WeakCell> new_cell = GetIsolate()->factory()->NewWeakCell(function);
   SetFeedback(*new_cell);
+  SetFeedbackExtra(Smi::FromInt(kCallCountIncrement), SKIP_WRITE_BARRIER);
 }
 
 
 void KeyedLoadICNexus::ConfigureMegamorphic() {
   Isolate* isolate = GetIsolate();
-  SetFeedback(*vector()->MegamorphicSentinel(isolate), SKIP_WRITE_BARRIER);
-  SetFeedbackExtra(*vector()->UninitializedSentinel(isolate),
+  SetFeedback(*TypeFeedbackVector::MegamorphicSentinel(isolate),
+              SKIP_WRITE_BARRIER);
+  SetFeedbackExtra(*TypeFeedbackVector::UninitializedSentinel(isolate),
                    SKIP_WRITE_BARRIER);
 }
 
 
 void LoadICNexus::ConfigureMegamorphic() {
-  SetFeedback(*vector()->MegamorphicSentinel(GetIsolate()), SKIP_WRITE_BARRIER);
-  SetFeedbackExtra(*vector()->UninitializedSentinel(GetIsolate()),
+  SetFeedback(*TypeFeedbackVector::MegamorphicSentinel(GetIsolate()),
+              SKIP_WRITE_BARRIER);
+  SetFeedbackExtra(*TypeFeedbackVector::UninitializedSentinel(GetIsolate()),
                    SKIP_WRITE_BARRIER);
 }
 
 
 void LoadICNexus::ConfigurePremonomorphic() {
-  SetFeedback(*vector()->PremonomorphicSentinel(GetIsolate()),
+  SetFeedback(*TypeFeedbackVector::PremonomorphicSentinel(GetIsolate()),
               SKIP_WRITE_BARRIER);
-  SetFeedbackExtra(*vector()->UninitializedSentinel(GetIsolate()),
+  SetFeedbackExtra(*TypeFeedbackVector::UninitializedSentinel(GetIsolate()),
                    SKIP_WRITE_BARRIER);
 }
 
 
 void KeyedLoadICNexus::ConfigurePremonomorphic() {
   Isolate* isolate = GetIsolate();
-  SetFeedback(*vector()->PremonomorphicSentinel(isolate), SKIP_WRITE_BARRIER);
-  SetFeedbackExtra(*vector()->UninitializedSentinel(isolate),
+  SetFeedback(*TypeFeedbackVector::PremonomorphicSentinel(isolate),
+              SKIP_WRITE_BARRIER);
+  SetFeedbackExtra(*TypeFeedbackVector::UninitializedSentinel(isolate),
                    SKIP_WRITE_BARRIER);
 }
 
@@ -416,7 +437,7 @@ void LoadICNexus::ConfigurePolymorphic(MapHandleList* maps,
   int receiver_count = maps->length();
   Handle<FixedArray> array = EnsureArrayOfSize(receiver_count * 2);
   InstallHandlers(array, maps, handlers);
-  SetFeedbackExtra(*vector()->UninitializedSentinel(isolate),
+  SetFeedbackExtra(*TypeFeedbackVector::UninitializedSentinel(isolate),
                    SKIP_WRITE_BARRIER);
 }
 
@@ -429,7 +450,7 @@ void KeyedLoadICNexus::ConfigurePolymorphic(Handle<Name> name,
   Handle<FixedArray> array;
   if (name.is_null()) {
     array = EnsureArrayOfSize(receiver_count * 2);
-    SetFeedbackExtra(*vector()->UninitializedSentinel(GetIsolate()),
+    SetFeedbackExtra(*TypeFeedbackVector::UninitializedSentinel(GetIsolate()),
                      SKIP_WRITE_BARRIER);
   } else {
     SetFeedback(*name);

src/type-feedback-vector.h

@@ -214,11 +214,6 @@ class TypeFeedbackVector : public FixedArray {
   // The object that indicates a premonomorphic state.
   static inline Handle<Object> PremonomorphicSentinel(Isolate* isolate);
 
-  // The object that indicates a monomorphic state of Array with
-  // ElementsKind
-  static inline Handle<Object> MonomorphicArraySentinel(
-      Isolate* isolate, ElementsKind elements_kind);
-
   // A raw version of the uninitialized sentinel that's safe to read during
   // garbage collection (e.g., for patching the cache).
   static inline Object* RawUninitializedSentinel(Heap* heap);
@@ -339,6 +334,10 @@ class FeedbackNexus {
 
 class CallICNexus : public FeedbackNexus {
  public:
+  // Monomorphic call ics store call counts. Platform code needs to increment
+  // the count appropriately (ie, by 2).
+  static const int kCallCountIncrement = 2;
+
   CallICNexus(Handle<TypeFeedbackVector> vector, FeedbackVectorICSlot slot)
       : FeedbackNexus(vector, slot) {
     DCHECK(vector->GetKind(slot) == Code::CALL_IC);
@@ -368,6 +367,8 @@ class CallICNexus : public FeedbackNexus {
                             int length = -1) const override {
     return length == 0;
   }
+
+  int ExtractCallCount();
 };
 
 

src/x64/code-stubs-x64.cc

@@ -2130,6 +2130,11 @@ void CallIC_ArrayStub::Generate(MacroAssembler* masm) {
          factory->allocation_site_map());
   __ j(not_equal, &miss);
 
+  // Increment the call count for monomorphic function calls.
+  __ SmiAddConstant(FieldOperand(rbx, rdx, times_pointer_size,
+                                 FixedArray::kHeaderSize + kPointerSize),
+                    Smi::FromInt(CallICNexus::kCallCountIncrement));
+
   __ movp(rbx, rcx);
   __ movp(rdx, rdi);
   ArrayConstructorStub stub(masm->isolate(), arg_count());
@@ -2191,6 +2196,11 @@ void CallICStub::Generate(MacroAssembler* masm) {
   // convincing us that we have a monomorphic JSFunction.
   __ JumpIfSmi(rdi, &extra_checks_or_miss);
 
+  // Increment the call count for monomorphic function calls.
+  __ SmiAddConstant(FieldOperand(rbx, rdx, times_pointer_size,
+                                 FixedArray::kHeaderSize + kPointerSize),
+                    Smi::FromInt(CallICNexus::kCallCountIncrement));
+
   __ bind(&have_js_function);
   if (CallAsMethod()) {
     EmitContinueIfStrictOrNative(masm, &cont);
@@ -2261,6 +2271,11 @@ void CallICStub::Generate(MacroAssembler* masm) {
   // Update stats.
   __ SmiAddConstant(FieldOperand(rbx, with_types_offset), Smi::FromInt(1));
 
+  // Initialize the call counter.
+  __ Move(FieldOperand(rbx, rdx, times_pointer_size,
+                       FixedArray::kHeaderSize + kPointerSize),
+          Smi::FromInt(CallICNexus::kCallCountIncrement));
+
   // Store the function. Use a stub since we need a frame for allocation.
   // rbx - vector
   // rdx - slot (needs to be in smi form)

test/mjsunit/call-counts.js

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --noalways-opt
+
+// Locations in the type feedback vector where call counts are maintained for
+// the two calls made from bar();
+const kFooCallExtraIndex = 5;
+const kArrayCallExtraIndex = 9;
+
+function GetCallCount(func, slot) {
+  var vector = %GetTypeFeedbackVector(func);
+  // Call counts are recorded doubled.
+  var value = %FixedArrayGet(vector, slot);
+  return Math.floor(value / 2);
+}
+
+function foo(a) { return a[3] * 16; }
+
+function bar(a) {
+  var result = 0;
+  for (var i = 0; i < 10; i++) {
+    result = foo(a);
+    if (i % 2 === 0) {
+      var r = Array();
+      r[0] = 1;
+      result += r[0];
+    }
+  }
+  return result;
+}
+
+var a = [1, 2, 3];
+bar(a);
+assertEquals(10, GetCallCount(bar, kFooCallExtraIndex));
+assertEquals(5, GetCallCount(bar, kArrayCallExtraIndex));
+
+%OptimizeFunctionOnNextCall(bar);
+bar(a);