Array constructor expects AllocationSite or undefined as feedback.

src/x64/code-stubs-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2193 matching lines @@
   if (NeedsChecks()) {
     // Check that the function really is a JavaScript function.
     __ JumpIfSmi(rdi, &non_function);
 
     // Goto slow case if we do not have a function.
     __ CmpObjectType(rdi, JS_FUNCTION_TYPE, rcx);
     __ j(not_equal, &slow);
 
     if (RecordCallTarget()) {
       GenerateRecordCallTarget(masm);
+      // Type information was updated. Because we may call Array, which
+      // expects either undefined or an AllocationSite in rbx we need
+      // to set rbx to undefined.
+      __ LoadRoot(rbx, Heap::kUndefinedValueRootIndex);
     }
   }
 
   // Fast-case: Just invoke the function.
   ParameterCount actual(argc_);
 
   if (CallAsMethod()) {
     if (NeedsChecks()) {
       // Do not transform the receiver for strict mode functions.
       __ movp(rcx, FieldOperand(rdi, JSFunction::kSharedFunctionInfoOffset));
@@ skipping 88 matching lines @@
   // rdi : constructor function
   Label slow, non_function_call;
 
   // Check that function is not a smi.
   __ JumpIfSmi(rdi, &non_function_call);
   // Check that function is a JSFunction.
   __ CmpObjectType(rdi, JS_FUNCTION_TYPE, rcx);
   __ j(not_equal, &slow);
 
   if (RecordCallTarget()) {
+    Label feedback_register_initialized;
     GenerateRecordCallTarget(masm);
+    // Put the AllocationSite from the feedback vector into rbx, or undefined.
+    __ SmiToInteger32(rdx, rdx);
+    __ movp(rbx, FieldOperand(rbx, rdx, times_pointer_size,
+                              FixedArray::kHeaderSize));
+    __ CompareRoot(FieldOperand(rbx, 0), Heap::kAllocationSiteMapRootIndex);
+    __ j(equal, &feedback_register_initialized);
+    __ LoadRoot(rbx, Heap::kUndefinedValueRootIndex);
+    __ bind(&feedback_register_initialized);
+    __ AssertUndefinedOrAllocationSite(rbx);
   }
 
   // Jump to the function-specific construct stub.
   Register jmp_reg = rcx;
   __ movp(jmp_reg, FieldOperand(rdi, JSFunction::kSharedFunctionInfoOffset));
   __ movp(jmp_reg, FieldOperand(jmp_reg,
                                 SharedFunctionInfo::kConstructStubOffset));
   __ lea(jmp_reg, FieldOperand(jmp_reg, Code::kHeaderSize));
   __ jmp(jmp_reg);
 
@@ skipping 2584 matching lines @@
     CreateArrayDispatch<ArrayNArgumentsConstructorStub>(masm, mode);
   } else {
     UNREACHABLE();
   }
 }
 
 
 void ArrayConstructorStub::Generate(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- rax    : argc
-  //  -- rbx    : feedback vector (fixed array or megamorphic symbol)
-  //  -- rdx    : slot index (if ebx is fixed array)
+  //  -- rbx    : AllocationSite or undefined
   //  -- rdi    : constructor
   //  -- rsp[0] : return address
   //  -- rsp[8] : last argument
   // -----------------------------------
-  Handle<Object> megamorphic_sentinel =
-      TypeFeedbackInfo::MegamorphicSentinel(masm->isolate());
-
   if (FLAG_debug_code) {
     // The array construct code is only set for the global and natives
     // builtin Array functions which always have maps.
 
     // Initial map for the builtin Array function should be a map.
     __ movp(rcx, FieldOperand(rdi, JSFunction::kPrototypeOrInitialMapOffset));
     // Will both indicate a NULL and a Smi.
     STATIC_ASSERT(kSmiTag == 0);
     Condition not_smi = NegateCondition(masm->CheckSmi(rcx));
     __ Check(not_smi, kUnexpectedInitialMapForArrayFunction);
     __ CmpObjectType(rcx, MAP_TYPE, rcx);
     __ Check(equal, kUnexpectedInitialMapForArrayFunction);
 
-    // We should either have the megamorphic symbol in rbx or a valid
-    // fixed array.
-    Label okay_here;
-    Handle<Map> fixed_array_map = masm->isolate()->factory()->fixed_array_map();
-    __ Cmp(rbx, megamorphic_sentinel);
-    __ j(equal, &okay_here);
-    __ Cmp(FieldOperand(rbx, 0), fixed_array_map);
-    __ Assert(equal, kExpectedFixedArrayInRegisterRbx);
-
-    // rdx should be a smi if we don't have the megamorphic symbol in rbx.
-    __ AssertSmi(rdx);
-
-    __ bind(&okay_here);
+    // We should either have undefined in rbx or a valid AllocationSite
+    __ AssertUndefinedOrAllocationSite(rbx);
   }
 
   Label no_info;
   // If the feedback slot is the megamorphic sentinel, or contains anything
   // other than an AllocationSite, call an array constructor that doesn't use
   // AllocationSites.
-  __ Cmp(rbx, megamorphic_sentinel);
+  __ CompareRoot(rbx, Heap::kUndefinedValueRootIndex);
   __ j(equal, &no_info);
-  __ SmiToInteger32(rdx, rdx);
-  __ movp(rbx, FieldOperand(rbx, rdx, times_pointer_size,
-                            FixedArray::kHeaderSize));
-  __ Integer32ToSmi(rdx, rdx);
-  __ Cmp(FieldOperand(rbx, 0),
-         masm->isolate()->factory()->allocation_site_map());
-  __ j(not_equal, &no_info);
 
   // Only look at the lower 16 bits of the transition info.
   __ movp(rdx, FieldOperand(rbx, AllocationSite::kTransitionInfoOffset));
   __ SmiToInteger32(rdx, rdx);
   STATIC_ASSERT(AllocationSite::ElementsKindBits::kShift == 0);
   __ and_(rdx, Immediate(AllocationSite::ElementsKindBits::kMask));
   GenerateDispatchToArrayStub(masm, DONT_OVERRIDE);
 
   __ bind(&no_info);
   GenerateDispatchToArrayStub(masm, DISABLE_ALLOCATION_SITES);
@@ skipping 264 matching lines @@
                               return_value_operand,
                               NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64