Introduce flag --allocation-site-transitioning

src/ia32/code-stubs-ia32.cc

Index: src/ia32/code-stubs-ia32.cc
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index 39bef3065b422f9188ed3696ea154f9404468f12..05739adaf0e73431349581d39e27d577d4268736 100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -1865,7 +1865,7 @@ static void GenerateRecordCallTarget(MacroAssembler* masm) {
   __ cmp(ecx, Immediate(TypeFeedbackVector::MegamorphicSentinel(isolate)));
   __ j(equal, &done, Label::kFar);
 
-  if (!FLAG_pretenuring_call_new) {
+  if (!FLAG_pretenuring_call_new && FLAG_allocation_site_transitioning) {
     // If we came here, we need to see if we are the array function.
     // If we didn't have a matching function, and we didn't find the megamorph
     // sentinel, then we have in the slot either some other function or an
@@ -1898,7 +1898,7 @@ static void GenerateRecordCallTarget(MacroAssembler* masm) {
   // An uninitialized cache is patched with the function or sentinel to
   // indicate the ElementsKind if function is the Array constructor.
   __ bind(&initialize);
-  if (!FLAG_pretenuring_call_new) {
+  if (!FLAG_pretenuring_call_new && FLAG_allocation_site_transitioning) {
     // Make sure the function is the Array() function
     __ LoadGlobalFunction(Context::ARRAY_FUNCTION_INDEX, ecx);
     __ cmp(edi, ecx);
@@ -2087,7 +2087,7 @@ void CallConstructStub::Generate(MacroAssembler* masm) {
       // entry is at the feedback vector slot given by edx + 1.
       __ mov(ebx, FieldOperand(ebx, edx, times_half_pointer_size,
                                FixedArray::kHeaderSize + kPointerSize));
-    } else {
+    } else if (FLAG_allocation_site_transitioning) {
       Label feedback_register_initialized;
       // Put the AllocationSite from the feedback vector into ebx, or undefined.
       __ mov(ebx, FieldOperand(ebx, edx, times_half_pointer_size,
@@ -2098,6 +2098,8 @@ void CallConstructStub::Generate(MacroAssembler* masm) {
       __ j(equal, &feedback_register_initialized);
       __ mov(ebx, isolate()->factory()->undefined_value());
       __ bind(&feedback_register_initialized);
+    } else {
+      __ mov(ebx, isolate()->factory()->undefined_value());
     }
 
     __ AssertUndefinedOrAllocationSite(ebx);
@@ -4440,20 +4442,23 @@ void ArrayConstructorStub::Generate(MacroAssembler* masm) {
     __ AssertUndefinedOrAllocationSite(ebx);
   }
 
-  Label no_info;
-  // If the feedback vector is the undefined value call an array constructor
-  // that doesn't use AllocationSites.
-  __ cmp(ebx, isolate()->factory()->undefined_value());
-  __ j(equal, &no_info);
+  if (FLAG_allocation_site_transitioning) {
+    Label no_info;
+    // If the feedback vector is the undefined value call an array constructor
+    // that doesn't use AllocationSites.
+    __ cmp(ebx, isolate()->factory()->undefined_value());
+    __ j(equal, &no_info);
 
-  // Only look at the lower 16 bits of the transition info.
-  __ mov(edx, FieldOperand(ebx, AllocationSite::kTransitionInfoOffset));
-  __ SmiUntag(edx);
-  STATIC_ASSERT(AllocationSite::ElementsKindBits::kShift == 0);
-  __ and_(edx, Immediate(AllocationSite::ElementsKindBits::kMask));
-  GenerateDispatchToArrayStub(masm, DONT_OVERRIDE);
+    // Only look at the lower 16 bits of the transition info.
+    __ mov(edx, FieldOperand(ebx, AllocationSite::kTransitionInfoOffset));
+    __ SmiUntag(edx);
+    STATIC_ASSERT(AllocationSite::ElementsKindBits::kShift == 0);
+    __ and_(edx, Immediate(AllocationSite::ElementsKindBits::kMask));
+    GenerateDispatchToArrayStub(masm, DONT_OVERRIDE);
+
+    __ bind(&no_info);
+  }
 
-  __ bind(&no_info);
   GenerateDispatchToArrayStub(masm, DISABLE_ALLOCATION_SITES);
 }