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1 /*
2  * Copyright (C) 2018 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include "intrinsic_objects.h"
18 
19 #include "art_field-inl.h"
20 #include "base/logging.h"
21 #include "class_root.h"
22 #include "handle.h"
23 #include "obj_ptr-inl.h"
24 #include "mirror/object_array-alloc-inl.h"
25 #include "mirror/object_array-inl.h"
26 
27 namespace art {
28 
LookupIntegerCache(Thread * self,ClassLinker * class_linker)29 static ObjPtr<mirror::ObjectArray<mirror::Object>> LookupIntegerCache(Thread* self,
30                                                                       ClassLinker* class_linker)
31     REQUIRES_SHARED(Locks::mutator_lock_) {
32   ObjPtr<mirror::Class> integer_cache_class = class_linker->LookupClass(
33       self, "Ljava/lang/Integer$IntegerCache;", /* class_loader= */ nullptr);
34   if (integer_cache_class == nullptr || !integer_cache_class->IsInitialized()) {
35     return nullptr;
36   }
37   ArtField* cache_field =
38       integer_cache_class->FindDeclaredStaticField("cache", "[Ljava/lang/Integer;");
39   CHECK(cache_field != nullptr);
40   ObjPtr<mirror::ObjectArray<mirror::Object>> integer_cache =
41       ObjPtr<mirror::ObjectArray<mirror::Object>>::DownCast(
42           cache_field->GetObject(integer_cache_class));
43   CHECK(integer_cache != nullptr);
44   return integer_cache;
45 }
46 
AllocateBootImageLiveObjects(Thread * self,ClassLinker * class_linker)47 ObjPtr<mirror::ObjectArray<mirror::Object>> IntrinsicObjects::AllocateBootImageLiveObjects(
48     Thread* self,
49     ClassLinker* class_linker) REQUIRES_SHARED(Locks::mutator_lock_) {
50   // The objects used for the Integer.valueOf() intrinsic must remain live even if references
51   // to them are removed using reflection. Image roots are not accessible through reflection,
52   // so the array we construct here shall keep them alive.
53   StackHandleScope<1> hs(self);
54   Handle<mirror::ObjectArray<mirror::Object>> integer_cache =
55       hs.NewHandle(LookupIntegerCache(self, class_linker));
56   size_t live_objects_size =
57       (integer_cache != nullptr) ? (/* cache */ 1u + integer_cache->GetLength()) : 0u;
58   ObjPtr<mirror::ObjectArray<mirror::Object>> live_objects =
59       mirror::ObjectArray<mirror::Object>::Alloc(
60           self, GetClassRoot<mirror::ObjectArray<mirror::Object>>(class_linker), live_objects_size);
61   int32_t index = 0;
62   if (integer_cache != nullptr) {
63     live_objects->Set(index++, integer_cache.Get());
64     for (int32_t i = 0, length = integer_cache->GetLength(); i != length; ++i) {
65       live_objects->Set(index++, integer_cache->Get(i));
66     }
67   }
68   CHECK_EQ(index, live_objects->GetLength());
69 
70   if (kIsDebugBuild && integer_cache != nullptr) {
71     CHECK_EQ(integer_cache.Get(), GetIntegerValueOfCache(live_objects));
72     for (int32_t i = 0, len = integer_cache->GetLength(); i != len; ++i) {
73       CHECK_EQ(integer_cache->GetWithoutChecks(i), GetIntegerValueOfObject(live_objects, i));
74     }
75   }
76   return live_objects;
77 }
78 
GetIntegerValueOfCache(ObjPtr<mirror::ObjectArray<mirror::Object>> boot_image_live_objects)79 ObjPtr<mirror::ObjectArray<mirror::Object>> IntrinsicObjects::GetIntegerValueOfCache(
80     ObjPtr<mirror::ObjectArray<mirror::Object>> boot_image_live_objects) {
81   DCHECK(boot_image_live_objects != nullptr);
82   if (boot_image_live_objects->GetLength() == 0u) {
83     return nullptr;  // No intrinsic objects.
84   }
85   // No need for read barrier for boot image object or for verifying the value that was just stored.
86   ObjPtr<mirror::Object> result =
87       boot_image_live_objects->GetWithoutChecks<kVerifyNone, kWithoutReadBarrier>(0);
88   DCHECK(result != nullptr);
89   DCHECK(result->IsObjectArray());
90   DCHECK(result->GetClass()->DescriptorEquals("[Ljava/lang/Integer;"));
91   return ObjPtr<mirror::ObjectArray<mirror::Object>>::DownCast(result);
92 }
93 
GetIntegerValueOfObject(ObjPtr<mirror::ObjectArray<mirror::Object>> boot_image_live_objects,uint32_t index)94 ObjPtr<mirror::Object> IntrinsicObjects::GetIntegerValueOfObject(
95     ObjPtr<mirror::ObjectArray<mirror::Object>> boot_image_live_objects,
96     uint32_t index) {
97   DCHECK(boot_image_live_objects != nullptr);
98   DCHECK_NE(boot_image_live_objects->GetLength(), 0);
99   DCHECK_LT(index,
100             static_cast<uint32_t>(GetIntegerValueOfCache(boot_image_live_objects)->GetLength()));
101 
102   // No need for read barrier for boot image object or for verifying the value that was just stored.
103   ObjPtr<mirror::Object> result =
104       boot_image_live_objects->GetWithoutChecks<kVerifyNone, kWithoutReadBarrier>(
105           /* skip the IntegerCache.cache */ 1u + index);
106   DCHECK(result != nullptr);
107   DCHECK(result->GetClass()->DescriptorEquals("Ljava/lang/Integer;"));
108   return result;
109 }
110 
GetIntegerValueOfArrayDataOffset(ObjPtr<mirror::ObjectArray<mirror::Object>> boot_image_live_objects)111 MemberOffset IntrinsicObjects::GetIntegerValueOfArrayDataOffset(
112     ObjPtr<mirror::ObjectArray<mirror::Object>> boot_image_live_objects) {
113   DCHECK_NE(boot_image_live_objects->GetLength(), 0);
114   MemberOffset result = mirror::ObjectArray<mirror::Object>::OffsetOfElement(1u);
115   DCHECK_EQ(GetIntegerValueOfObject(boot_image_live_objects, 0u),
116             (boot_image_live_objects
117                  ->GetFieldObject<mirror::Object, kVerifyNone, kWithoutReadBarrier>(result)));
118   return result;
119 }
120 
121 }  // namespace art
122