Array constructor expects AllocationSite or undefined as feedback.

src/ia32/code-stubs-ia32.cc

 // Copyright 2012 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 2356 matching lines @@
   if (NeedsChecks()) {
     // Check that the function really is a JavaScript function.
     __ JumpIfSmi(edi, &non_function);
 
     // Goto slow case if we do not have a function.
     __ CmpObjectType(edi, JS_FUNCTION_TYPE, ecx);
     __ 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 ebx we need
+      // to set ebx to undefined.
+      __ mov(ebx, Immediate(isolate->factory()->undefined_value()));
     }
   }
 
   // Fast-case: Just invoke the function.
   ParameterCount actual(argc_);
 
   if (CallAsMethod()) {
     if (NeedsChecks()) {
       // Do not transform the receiver for strict mode functions.
       __ mov(ecx, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
@@ skipping 83 matching lines @@
   // edi : constructor function
   Label slow, non_function_call;
 
   // Check that function is not a smi.
   __ JumpIfSmi(edi, &non_function_call);
   // Check that function is a JSFunction.
   __ CmpObjectType(edi, JS_FUNCTION_TYPE, ecx);
   __ j(not_equal, &slow);
 
   if (RecordCallTarget()) {
+    Label feedback_register_initialized;
     GenerateRecordCallTarget(masm);
+
+    // 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 =
+        masm->isolate()->factory()->allocation_site_map();
+    __ cmp(FieldOperand(ebx, 0), Immediate(allocation_site_map));
+    __ j(equal, &feedback_register_initialized);
+    __ mov(ebx, masm->isolate()->factory()->undefined_value());
+    __ bind(&feedback_register_initialized);
+    __ 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));
   __ 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 -------------
   //  -- eax : argc (only if argument_count_ == ANY)
-  //  -- ebx : feedback vector (fixed array or megamorphic symbol)
-  //  -- edx : slot index (if ebx is fixed array)
+  //  -- ebx : AllocationSite or undefined
   //  -- edi : constructor
   //  -- esp[0] : return address
   //  -- esp[4] : 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.
     __ mov(ecx, FieldOperand(edi, JSFunction::kPrototypeOrInitialMapOffset));
     // 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 the megamorphic symbol in ebx or a valid
-    // fixed array.
-    Label okay_here;
-    Handle<Map> fixed_array_map = masm->isolate()->factory()->fixed_array_map();
-    __ cmp(ebx, Immediate(megamorphic_sentinel));
-    __ j(equal, &okay_here);
-    __ cmp(FieldOperand(ebx, 0), Immediate(fixed_array_map));
-    __ Assert(equal, kExpectedFixedArrayInRegisterEbx);
-
-    // edx should be a smi if we don't have the megamorphic symbol in ebx.
-    __ AssertSmi(edx);
-
-    __ bind(&okay_here);
+    // We should either have undefined in ebx or a valid AllocationSite
+    __ AssertUndefinedOrAllocationSite(ebx);
   }
 
   Label no_info;
-  // If the feedback vector is the megamorphic sentinel, or contains anything
-  // other than an AllocationSite, call an array constructor that doesn't use
-  // AllocationSites.
-  __ cmp(ebx, Immediate(megamorphic_sentinel));
+  // If the feedback vector is the undefined value call an array constructor
+  // that doesn't use AllocationSites.
+  __ cmp(ebx, masm->isolate()->factory()->undefined_value());
   __ j(equal, &no_info);
-  __ mov(ebx, FieldOperand(ebx, edx, times_half_pointer_size,
-                           FixedArray::kHeaderSize));
-  __ cmp(FieldOperand(ebx, 0), Immediate(
-      masm->isolate()->factory()->allocation_site_map()));
-  __ j(not_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);
 
   __ bind(&no_info);
   GenerateDispatchToArrayStub(masm, DISABLE_ALLOCATION_SITES);
@@ skipping 244 matching lines @@
                               Operand(ebp, 7 * kPointerSize),
                               NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32