1 /*
2  * Copyright (C) 2015 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_COMPILER_OPTIMIZING_REFERENCE_TYPE_PROPAGATION_H_
18 #define ART_COMPILER_OPTIMIZING_REFERENCE_TYPE_PROPAGATION_H_
19 
20 #include "base/arena_containers.h"
21 #include "driver/dex_compilation_unit.h"
22 #include "handle_scope-inl.h"
23 #include "nodes.h"
24 #include "obj_ptr.h"
25 #include "optimization.h"
26 #include "optimizing_compiler_stats.h"
27 
28 namespace art {
29 
30 /**
31  * Propagates reference types to instructions.
32  */
33 class ReferenceTypePropagation : public HOptimization {
34  public:
35   ReferenceTypePropagation(HGraph* graph,
36                            Handle<mirror::ClassLoader> class_loader,
37                            Handle<mirror::DexCache> hint_dex_cache,
38                            VariableSizedHandleScope* handles,
39                            bool is_first_run,
40                            const char* name = kReferenceTypePropagationPassName);
41 
42   // Visit a single instruction.
43   void Visit(HInstruction* instruction);
44 
45   void Run() OVERRIDE;
46 
47   // Returns true if klass is admissible to the propagation: non-null and resolved.
48   // For an array type, we also check if the component type is admissible.
IsAdmissible(mirror::Class * klass)49   static bool IsAdmissible(mirror::Class* klass) REQUIRES_SHARED(Locks::mutator_lock_) {
50     return klass != nullptr &&
51            klass->IsResolved() &&
52            (!klass->IsArrayClass() || IsAdmissible(klass->GetComponentType()));
53   }
54 
55   static constexpr const char* kReferenceTypePropagationPassName = "reference_type_propagation";
56 
57  private:
58   class HandleCache {
59    public:
HandleCache(VariableSizedHandleScope * handles)60     explicit HandleCache(VariableSizedHandleScope* handles) : handles_(handles) { }
61 
62     template <typename T>
NewHandle(T * object)63     MutableHandle<T> NewHandle(T* object) REQUIRES_SHARED(Locks::mutator_lock_) {
64       return handles_->NewHandle(object);
65     }
66 
67     template <typename T>
NewHandle(ObjPtr<T> object)68     MutableHandle<T> NewHandle(ObjPtr<T> object) REQUIRES_SHARED(Locks::mutator_lock_) {
69       return handles_->NewHandle(object);
70     }
71 
72     ReferenceTypeInfo::TypeHandle GetObjectClassHandle();
73     ReferenceTypeInfo::TypeHandle GetClassClassHandle();
74     ReferenceTypeInfo::TypeHandle GetStringClassHandle();
75     ReferenceTypeInfo::TypeHandle GetThrowableClassHandle();
76 
77    private:
78     VariableSizedHandleScope* handles_;
79 
80     ReferenceTypeInfo::TypeHandle object_class_handle_;
81     ReferenceTypeInfo::TypeHandle class_class_handle_;
82     ReferenceTypeInfo::TypeHandle string_class_handle_;
83     ReferenceTypeInfo::TypeHandle throwable_class_handle_;
84   };
85 
86   class RTPVisitor;
87 
88   void VisitPhi(HPhi* phi);
89   void VisitBasicBlock(HBasicBlock* block);
90   void UpdateBoundType(HBoundType* bound_type) REQUIRES_SHARED(Locks::mutator_lock_);
91   void UpdatePhi(HPhi* phi) REQUIRES_SHARED(Locks::mutator_lock_);
92   void BoundTypeForIfNotNull(HBasicBlock* block);
93   void BoundTypeForIfInstanceOf(HBasicBlock* block);
94   void ProcessWorklist();
95   void AddToWorklist(HInstruction* instr);
96   void AddDependentInstructionsToWorklist(HInstruction* instr);
97 
98   bool UpdateNullability(HInstruction* instr);
99   bool UpdateReferenceTypeInfo(HInstruction* instr);
100 
101   static void UpdateArrayGet(HArrayGet* instr, HandleCache* handle_cache)
102       REQUIRES_SHARED(Locks::mutator_lock_);
103 
104   ReferenceTypeInfo MergeTypes(const ReferenceTypeInfo& a, const ReferenceTypeInfo& b)
105       REQUIRES_SHARED(Locks::mutator_lock_);
106 
107   void ValidateTypes();
108 
109   Handle<mirror::ClassLoader> class_loader_;
110 
111   // Note: hint_dex_cache_ is usually, but not necessarily, the dex cache associated with
112   // graph_->GetDexFile(). Since we may look up also in other dex files, it's used only
113   // as a hint, to reduce the number of calls to the costly ClassLinker::FindDexCache().
114   Handle<mirror::DexCache> hint_dex_cache_;
115   HandleCache handle_cache_;
116 
117   ArenaVector<HInstruction*> worklist_;
118 
119   // Whether this reference type propagation is the first run we are doing.
120   const bool is_first_run_;
121 
122   static constexpr size_t kDefaultWorklistSize = 8;
123 
124   friend class ReferenceTypePropagationTest;
125 
126   DISALLOW_COPY_AND_ASSIGN(ReferenceTypePropagation);
127 };
128 
129 }  // namespace art
130 
131 #endif  // ART_COMPILER_OPTIMIZING_REFERENCE_TYPE_PROPAGATION_H_
132