1 /* 2 * Copyright (C) 2014 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 #ifndef ART_RUNTIME_READ_BARRIER_H_ 18 #define ART_RUNTIME_READ_BARRIER_H_ 19 20 #include "base/mutex.h" 21 #include "base/macros.h" 22 #include "gc_root.h" 23 #include "jni.h" 24 #include "mirror/object_reference.h" 25 #include "offsets.h" 26 #include "read_barrier_c.h" 27 28 // This is a C++ (not C) header file, separate from read_barrier_c.h 29 // which needs to be a C header file for asm_support.h. 30 31 namespace art { 32 namespace mirror { 33 class Object; 34 template<typename MirrorType> class HeapReference; 35 } // namespace mirror 36 class ArtMethod; 37 38 class ReadBarrier { 39 public: 40 // TODO: disable thse flags for production use. 41 // Enable the to-space invariant checks. 42 static constexpr bool kEnableToSpaceInvariantChecks = true; 43 // Enable the read barrier checks. 44 static constexpr bool kEnableReadBarrierInvariantChecks = true; 45 46 // It's up to the implementation whether the given field gets updated whereas the return value 47 // must be an updated reference unless kAlwaysUpdateField is true. 48 template <typename MirrorType, ReadBarrierOption kReadBarrierOption = kWithReadBarrier, 49 bool kAlwaysUpdateField = false> 50 ALWAYS_INLINE static MirrorType* Barrier( 51 mirror::Object* obj, MemberOffset offset, mirror::HeapReference<MirrorType>* ref_addr) 52 SHARED_REQUIRES(Locks::mutator_lock_); 53 54 // It's up to the implementation whether the given root gets updated 55 // whereas the return value must be an updated reference. 56 template <typename MirrorType, ReadBarrierOption kReadBarrierOption = kWithReadBarrier> 57 ALWAYS_INLINE static MirrorType* BarrierForRoot(MirrorType** root, 58 GcRootSource* gc_root_source = nullptr) 59 SHARED_REQUIRES(Locks::mutator_lock_); 60 61 // It's up to the implementation whether the given root gets updated 62 // whereas the return value must be an updated reference. 63 template <typename MirrorType, ReadBarrierOption kReadBarrierOption = kWithReadBarrier> 64 ALWAYS_INLINE static MirrorType* BarrierForRoot(mirror::CompressedReference<MirrorType>* root, 65 GcRootSource* gc_root_source = nullptr) 66 SHARED_REQUIRES(Locks::mutator_lock_); 67 68 static bool IsDuringStartup(); 69 70 // Without the holder object. AssertToSpaceInvariant(mirror::Object * ref)71 static void AssertToSpaceInvariant(mirror::Object* ref) 72 SHARED_REQUIRES(Locks::mutator_lock_) { 73 AssertToSpaceInvariant(nullptr, MemberOffset(0), ref); 74 } 75 // With the holder object. 76 static void AssertToSpaceInvariant(mirror::Object* obj, MemberOffset offset, 77 mirror::Object* ref) 78 SHARED_REQUIRES(Locks::mutator_lock_); 79 // With GcRootSource. 80 static void AssertToSpaceInvariant(GcRootSource* gc_root_source, mirror::Object* ref) 81 SHARED_REQUIRES(Locks::mutator_lock_); 82 83 // ALWAYS_INLINE on this caused a performance regression b/26744236. 84 static mirror::Object* Mark(mirror::Object* obj) SHARED_REQUIRES(Locks::mutator_lock_); 85 WhitePtr()86 static mirror::Object* WhitePtr() { 87 return reinterpret_cast<mirror::Object*>(white_ptr_); 88 } GrayPtr()89 static mirror::Object* GrayPtr() { 90 return reinterpret_cast<mirror::Object*>(gray_ptr_); 91 } BlackPtr()92 static mirror::Object* BlackPtr() { 93 return reinterpret_cast<mirror::Object*>(black_ptr_); 94 } 95 96 ALWAYS_INLINE static bool HasGrayReadBarrierPointer(mirror::Object* obj, 97 uintptr_t* out_rb_ptr_high_bits) 98 SHARED_REQUIRES(Locks::mutator_lock_); 99 100 // Note: These couldn't be constexpr pointers as reinterpret_cast isn't compatible with them. 101 static constexpr uintptr_t white_ptr_ = 0x0; // Not marked. 102 static constexpr uintptr_t gray_ptr_ = 0x1; // Marked, but not marked through. On mark stack. 103 static constexpr uintptr_t black_ptr_ = 0x2; // Marked through. Used for non-moving objects. 104 static constexpr uintptr_t rb_ptr_mask_ = 0x3; // The low 2 bits for white|gray|black. 105 }; 106 107 } // namespace art 108 109 #endif // ART_RUNTIME_READ_BARRIER_H_ 110