Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2016 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_CHA_H_ |
| 18 | #define ART_RUNTIME_CHA_H_ |
| 19 | |
Andreas Gampe | 8cf9cb3 | 2017-07-19 09:28:38 -0700 | [diff] [blame] | 20 | #include <unordered_map> |
| 21 | #include <unordered_set> |
| 22 | |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 23 | #include "base/enums.h" |
Andreas Gampe | 7fbc4a5 | 2018-11-28 08:26:47 -0800 | [diff] [blame] | 24 | #include "base/locks.h" |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 25 | #include "handle.h" |
| 26 | #include "mirror/class.h" |
| 27 | #include "oat_quick_method_header.h" |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 28 | |
| 29 | namespace art { |
| 30 | |
Andreas Gampe | d490129 | 2017-05-30 18:41:34 -0700 | [diff] [blame] | 31 | class ArtMethod; |
Mathieu Chartier | cf79cf5 | 2017-07-21 11:17:57 -0700 | [diff] [blame] | 32 | class LinearAlloc; |
Andreas Gampe | d490129 | 2017-05-30 18:41:34 -0700 | [diff] [blame] | 33 | |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 34 | /** |
| 35 | * Class Hierarchy Analysis (CHA) tries to devirtualize virtual calls into |
| 36 | * direct calls based on the info generated by analyzing class hierarchies. |
| 37 | * If a class is not subclassed, or even if it's subclassed but one of its |
| 38 | * virtual methods isn't overridden, a virtual call for that method can be |
| 39 | * changed into a direct call. |
| 40 | * |
| 41 | * Each virtual method carries a single-implementation status. The status is |
| 42 | * incrementally maintained at the end of class linking time when method |
| 43 | * overriding takes effect. |
| 44 | * |
| 45 | * Compiler takes advantage of the single-implementation info of a |
| 46 | * method. If a method A has the single-implementation flag set, the compiler |
| 47 | * devirtualizes the virtual call for method A into a direct call, and |
| 48 | * further try to inline the direct call as a result. The compiler will |
| 49 | * also register a dependency that the compiled code depends on the |
| 50 | * assumption that method A has single-implementation status. |
| 51 | * |
| 52 | * When single-implementation info is updated at the end of class linking, |
| 53 | * and if method A's single-implementation status is invalidated, all compiled |
| 54 | * code that depends on the assumption that method A has single-implementation |
| 55 | * status need to be invalidated. Method entrypoints that have this dependency |
| 56 | * will be updated as a result. Method A can later be recompiled with less |
| 57 | * aggressive assumptions. |
| 58 | * |
| 59 | * For live compiled code that's on stack, deoptmization will be initiated |
| 60 | * to force the invalidated compiled code into interpreter mode to guarantee |
| 61 | * correctness. The deoptimization mechanism used is a hybrid of |
| 62 | * synchronous and asynchronous deoptimization. The synchronous deoptimization |
| 63 | * part checks a hidden local variable flag for the method, and if true, |
| 64 | * initiates deoptimization. The asynchronous deoptimization part issues a |
| 65 | * checkpoint that walks the stack and for any compiled code on the stack |
| 66 | * that should be deoptimized, set the hidden local variable value to be true. |
| 67 | * |
| 68 | * A cha_lock_ needs to be held for updating single-implementation status, |
| 69 | * and registering/unregistering CHA dependencies. Registering CHA dependency |
| 70 | * and making compiled code visible also need to be atomic. Otherwise, we |
| 71 | * may miss invalidating CHA dependents or making compiled code visible even |
| 72 | * after it is invalidated. Care needs to be taken between cha_lock_ and |
| 73 | * JitCodeCache::lock_ to guarantee the atomicity. |
| 74 | * |
| 75 | * We base our CHA on dynamically linked class profiles instead of doing static |
| 76 | * analysis. Static analysis can be too aggressive due to dynamic class loading |
| 77 | * at runtime, and too conservative since some classes may not be really loaded |
| 78 | * at runtime. |
| 79 | */ |
| 80 | class ClassHierarchyAnalysis { |
| 81 | public: |
| 82 | // Types for recording CHA dependencies. |
| 83 | // For invalidating CHA dependency, we need to know both the ArtMethod and |
| 84 | // the method header. If the ArtMethod has compiled code with the method header |
| 85 | // as the entrypoint, we update the entrypoint to the interpreter bridge. |
| 86 | // We will also deoptimize frames that are currently executing the code of |
| 87 | // the method header. |
| 88 | typedef std::pair<ArtMethod*, OatQuickMethodHeader*> MethodAndMethodHeaderPair; |
| 89 | typedef std::vector<MethodAndMethodHeaderPair> ListOfDependentPairs; |
| 90 | |
| 91 | ClassHierarchyAnalysis() {} |
| 92 | |
| 93 | // Add a dependency that compiled code with `dependent_header` for `dependent_method` |
| 94 | // assumes that virtual `method` has single-implementation. |
| 95 | void AddDependency(ArtMethod* method, |
| 96 | ArtMethod* dependent_method, |
| 97 | OatQuickMethodHeader* dependent_header) REQUIRES(Locks::cha_lock_); |
| 98 | |
| 99 | // Return compiled code that assumes that `method` has single-implementation. |
Mingyao Yang | cc10450 | 2017-05-24 17:13:03 -0700 | [diff] [blame] | 100 | const ListOfDependentPairs& GetDependents(ArtMethod* method) REQUIRES(Locks::cha_lock_); |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 101 | |
| 102 | // Remove dependency tracking for compiled code that assumes that |
| 103 | // `method` has single-implementation. |
Mingyao Yang | cc10450 | 2017-05-24 17:13:03 -0700 | [diff] [blame] | 104 | void RemoveAllDependenciesFor(ArtMethod* method) REQUIRES(Locks::cha_lock_); |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 105 | |
| 106 | // Remove from cha_dependency_map_ all entries that contain OatQuickMethodHeader from |
| 107 | // the given `method_headers` set. |
| 108 | // This is used when some compiled code is freed. |
| 109 | void RemoveDependentsWithMethodHeaders( |
| 110 | const std::unordered_set<OatQuickMethodHeader*>& method_headers) |
| 111 | REQUIRES(Locks::cha_lock_); |
| 112 | |
Alexey Grebenkin | be4c2bd | 2018-02-01 19:09:59 +0300 | [diff] [blame] | 113 | // If a given class belongs to a linear allocation that is about to be deleted, in all its |
| 114 | // superclasses and superinterfaces reset SingleImplementation fields of their methods |
| 115 | // that might be affected by the deletion. |
| 116 | // The method is intended to be called during GC before ReclaimPhase, since it gets info from |
| 117 | // Java objects that are going to be collected. |
| 118 | // For the same reason it's important to access objects without read barrier to not revive them. |
| 119 | void ResetSingleImplementationInHierarchy(ObjPtr<mirror::Class> klass, |
| 120 | const LinearAlloc* alloc, |
| 121 | PointerSize pointer_size) |
| 122 | const REQUIRES_SHARED(Locks::mutator_lock_); |
| 123 | |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 124 | // Update CHA info for methods that `klass` overrides, after loading `klass`. |
| 125 | void UpdateAfterLoadingOf(Handle<mirror::Class> klass) REQUIRES_SHARED(Locks::mutator_lock_); |
| 126 | |
Mathieu Chartier | cf79cf5 | 2017-07-21 11:17:57 -0700 | [diff] [blame] | 127 | // Remove all of the dependencies for a linear allocator. This is called when dex cache unloading |
| 128 | // occurs. |
| 129 | void RemoveDependenciesForLinearAlloc(const LinearAlloc* linear_alloc) |
| 130 | REQUIRES(!Locks::cha_lock_); |
| 131 | |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 132 | private: |
Mingyao Yang | e8fcd01 | 2017-01-20 10:43:30 -0800 | [diff] [blame] | 133 | void InitSingleImplementationFlag(Handle<mirror::Class> klass, |
| 134 | ArtMethod* method, |
| 135 | PointerSize pointer_size) |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 136 | REQUIRES_SHARED(Locks::mutator_lock_); |
| 137 | |
Nicolas Geoffray | 18ea1c9 | 2017-03-27 08:00:18 +0000 | [diff] [blame] | 138 | // Check/update single-implementation info when one virtual method |
| 139 | // overrides another. |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 140 | // `virtual_method` in `klass` overrides `method_in_super`. |
Nicolas Geoffray | 18ea1c9 | 2017-03-27 08:00:18 +0000 | [diff] [blame] | 141 | // This may invalidate some assumptions on single-implementation. |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 142 | // Append methods that should have their single-implementation flag invalidated |
| 143 | // to `invalidated_single_impl_methods`. |
Nicolas Geoffray | 18ea1c9 | 2017-03-27 08:00:18 +0000 | [diff] [blame] | 144 | void CheckVirtualMethodSingleImplementationInfo( |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 145 | Handle<mirror::Class> klass, |
| 146 | ArtMethod* virtual_method, |
| 147 | ArtMethod* method_in_super, |
Mingyao Yang | e8fcd01 | 2017-01-20 10:43:30 -0800 | [diff] [blame] | 148 | std::unordered_set<ArtMethod*>& invalidated_single_impl_methods, |
| 149 | PointerSize pointer_size) |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 150 | REQUIRES_SHARED(Locks::mutator_lock_); |
| 151 | |
Nicolas Geoffray | 18ea1c9 | 2017-03-27 08:00:18 +0000 | [diff] [blame] | 152 | // Check/update single-implementation info when one method |
| 153 | // implements an interface method. |
| 154 | // `implementation_method` in `klass` implements `interface_method`. |
| 155 | // Append `interface_method` to `invalidated_single_impl_methods` |
| 156 | // if `interface_method` gets a new implementation. |
| 157 | void CheckInterfaceMethodSingleImplementationInfo( |
| 158 | Handle<mirror::Class> klass, |
| 159 | ArtMethod* interface_method, |
| 160 | ArtMethod* implementation_method, |
| 161 | std::unordered_set<ArtMethod*>& invalidated_single_impl_methods, |
| 162 | PointerSize pointer_size) |
| 163 | REQUIRES_SHARED(Locks::mutator_lock_); |
| 164 | |
| 165 | void InvalidateSingleImplementationMethods( |
| 166 | std::unordered_set<ArtMethod*>& invalidated_single_impl_methods) |
| 167 | REQUIRES_SHARED(Locks::mutator_lock_); |
| 168 | |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 169 | // A map that maps a method to a set of compiled code that assumes that method has a |
| 170 | // single implementation, which is used to do CHA-based devirtualization. |
Mingyao Yang | cc10450 | 2017-05-24 17:13:03 -0700 | [diff] [blame] | 171 | std::unordered_map<ArtMethod*, ListOfDependentPairs> cha_dependency_map_ |
Mingyao Yang | 063fc77 | 2016-08-02 11:02:54 -0700 | [diff] [blame] | 172 | GUARDED_BY(Locks::cha_lock_); |
| 173 | |
| 174 | DISALLOW_COPY_AND_ASSIGN(ClassHierarchyAnalysis); |
| 175 | }; |
| 176 | |
| 177 | } // namespace art |
| 178 | |
| 179 | #endif // ART_RUNTIME_CHA_H_ |