Introduce flag --allocation-site-transitioning

src/ia32/code-stubs-ia32.cc

 // Copyright 2012 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.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_IA32
 
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
@@ skipping 1847 matching lines @@
   __ mov(ecx, FieldOperand(ebx, edx, times_half_pointer_size,
                            FixedArray::kHeaderSize));
 
   // A monomorphic cache hit or an already megamorphic state: invoke the
   // function without changing the state.
   __ cmp(ecx, edi);
   __ j(equal, &done, Label::kFar);
   __ 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
     // AllocationSite. Do a map check on the object in ecx.
     Handle<Map> allocation_site_map = isolate->factory()->allocation_site_map();
     __ cmp(FieldOperand(ecx, 0), Immediate(allocation_site_map));
     __ j(not_equal, &miss);
 
     // Make sure the function is the Array() function
     __ LoadGlobalFunction(Context::ARRAY_FUNCTION_INDEX, ecx);
@@ skipping 12 matching lines @@
   // write-barrier is needed.
   __ bind(&megamorphic);
   __ mov(
       FieldOperand(ebx, edx, times_half_pointer_size, FixedArray::kHeaderSize),
       Immediate(TypeFeedbackVector::MegamorphicSentinel(isolate)));
   __ jmp(&done, Label::kFar);
 
   // 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);
     __ j(not_equal, &not_array_function);
 
     // The target function is the Array constructor,
     // Create an AllocationSite if we don't already have it, store it in the
     // slot.
     {
       FrameScope scope(masm, StackFrame::INTERNAL);
@@ skipping 168 matching lines @@
 
   if (RecordCallTarget()) {
     GenerateRecordCallTarget(masm);
 
     if (FLAG_pretenuring_call_new) {
       // Put the AllocationSite from the feedback vector into ebx.
       // By adding kPointerSize we encode that we know the AllocationSite
       // 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,
                                FixedArray::kHeaderSize));
       Handle<Map> allocation_site_map =
           isolate()->factory()->allocation_site_map();
       __ cmp(FieldOperand(ebx, 0), Immediate(allocation_site_map));
       __ j(equal, &feedback_register_initialized);
       __ mov(ebx, isolate()->factory()->undefined_value());
       __ bind(&feedback_register_initialized);
+    } else {
+      __ mov(ebx, isolate()->factory()->undefined_value());
     }
 
     __ AssertUndefinedOrAllocationSite(ebx);
   }
 
   // Jump to the function-specific construct stub.
   Register jmp_reg = ecx;
   __ mov(jmp_reg, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
   __ mov(jmp_reg, FieldOperand(jmp_reg,
                                SharedFunctionInfo::kConstructStubOffset));
@@ skipping 2322 matching lines @@
     // Will both indicate a NULL and a Smi.
     __ test(ecx, Immediate(kSmiTagMask));
     __ Assert(not_zero, kUnexpectedInitialMapForArrayFunction);
     __ CmpObjectType(ecx, MAP_TYPE, ecx);
     __ Assert(equal, kUnexpectedInitialMapForArrayFunction);
 
     // We should either have undefined in ebx or a valid AllocationSite
     __ 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);
 }
 
 
 void InternalArrayConstructorStub::GenerateCase(
     MacroAssembler* masm, ElementsKind kind) {
   Label not_zero_case, not_one_case;
   Label normal_sequence;
 
   __ test(eax, eax);
@@ skipping 235 matching lines @@
                               Operand(ebp, 7 * kPointerSize),
                               NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32