ForIn loop_statement(this, stmt);
increment_loop_depth();
+ // Load null value as it is used several times below.
+ Register null_value = r5;
+ __ LoadRoot(null_value, Heap::kNullValueRootIndex);
+
// Get the object to enumerate over. Both SpiderMonkey and JSC
// ignore null and undefined in contrast to the specification; see
// ECMA-262 section 12.6.4.
__ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
__ cmp(r0, ip);
__ b(eq, &exit);
- __ LoadRoot(ip, Heap::kNullValueRootIndex);
- __ cmp(r0, ip);
+ __ cmp(r0, null_value);
__ b(eq, &exit);
// Convert the object to a JS object.
__ bind(&done_convert);
__ push(r0);
- // BUG(867): Check cache validity in generated code. This is a fast
- // case for the JSObject::IsSimpleEnum cache validity checks. If we
- // cannot guarantee cache validity, call the runtime system to check
- // cache validity or get the property names in a fixed array.
+ // Check cache validity in generated code. This is a fast case for
+ // the JSObject::IsSimpleEnum cache validity checks. If we cannot
+ // guarantee cache validity, call the runtime system to check cache
+ // validity or get the property names in a fixed array.
+ Label next, call_runtime;
+ // Preload a couple of values used in the loop.
+ Register empty_fixed_array_value = r6;
+ __ LoadRoot(empty_fixed_array_value, Heap::kEmptyFixedArrayRootIndex);
+ Register empty_descriptor_array_value = r7;
+ __ LoadRoot(empty_descriptor_array_value,
+ Heap::kEmptyDescriptorArrayRootIndex);
+ __ mov(r1, r0);
+ __ bind(&next);
+
+ // Check that there are no elements. Register r1 contains the
+ // current JS object we've reached through the prototype chain.
+ __ ldr(r2, FieldMemOperand(r1, JSObject::kElementsOffset));
+ __ cmp(r2, empty_fixed_array_value);
+ __ b(ne, &call_runtime);
+
+ // Check that instance descriptors are not empty so that we can
+ // check for an enum cache. Leave the map in r2 for the subsequent
+ // prototype load.
+ __ ldr(r2, FieldMemOperand(r1, HeapObject::kMapOffset));
+ __ ldr(r3, FieldMemOperand(r2, Map::kInstanceDescriptorsOffset));
+ __ cmp(r3, empty_descriptor_array_value);
+ __ b(eq, &call_runtime);
+
+ // Check that there is an enum cache in the non-empty instance
+ // descriptors (r3). This is the case if the next enumeration
+ // index field does not contain a smi.
+ __ ldr(r3, FieldMemOperand(r3, DescriptorArray::kEnumerationIndexOffset));
+ __ JumpIfSmi(r3, &call_runtime);
+
+ // For all objects but the receiver, check that the cache is empty.
+ Label check_prototype;
+ __ cmp(r1, r0);
+ __ b(eq, &check_prototype);
+ __ ldr(r3, FieldMemOperand(r3, DescriptorArray::kEnumCacheBridgeCacheOffset));
+ __ cmp(r3, empty_fixed_array_value);
+ __ b(ne, &call_runtime);
+
+ // Load the prototype from the map and loop if non-null.
+ __ bind(&check_prototype);
+ __ ldr(r1, FieldMemOperand(r2, Map::kPrototypeOffset));
+ __ cmp(r1, null_value);
+ __ b(ne, &next);
+
+ // The enum cache is valid. Load the map of the object being
+ // iterated over and use the cache for the iteration.
+ Label use_cache;
+ __ ldr(r0, FieldMemOperand(r0, HeapObject::kMapOffset));
+ __ b(&use_cache);
// Get the set of properties to enumerate.
+ __ bind(&call_runtime);
__ push(r0); // Duplicate the enumerable object on the stack.
__ CallRuntime(Runtime::kGetPropertyNamesFast, 1);
__ b(ne, &fixed_array);
// We got a map in register r0. Get the enumeration cache from it.
+ __ bind(&use_cache);
__ ldr(r1, FieldMemOperand(r0, Map::kInstanceDescriptorsOffset));
__ ldr(r1, FieldMemOperand(r1, DescriptorArray::kEnumerationIndexOffset));
__ ldr(r2, FieldMemOperand(r1, DescriptorArray::kEnumCacheBridgeCacheOffset));