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_COMPILER_DEX_VERIFIED_METHOD_H_
18 #define ART_COMPILER_DEX_VERIFIED_METHOD_H_
19 
20 #include <vector>
21 
22 #include "base/mutex.h"
23 #include "method_reference.h"
24 #include "safe_map.h"
25 
26 namespace art {
27 
28 namespace verifier {
29 class MethodVerifier;
30 }  // namespace verifier
31 
32 class VerifiedMethod {
33  public:
34   // Cast elision set type.
35   // Since we're adding the dex PCs to the set in increasing order, a sorted vector
36   // is better for performance (not just memory usage), especially for large sets.
37   typedef std::vector<uint32_t> SafeCastSet;
38 
39   // Devirtualization map type maps dex offset to concrete method reference.
40   typedef SafeMap<uint32_t, MethodReference> DevirtualizationMap;
41 
42   static const VerifiedMethod* Create(verifier::MethodVerifier* method_verifier, bool compile)
43       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
44   ~VerifiedMethod() = default;
45 
GetDexGcMap()46   const std::vector<uint8_t>& GetDexGcMap() const {
47     return dex_gc_map_;
48   }
49 
GetDevirtMap()50   const DevirtualizationMap& GetDevirtMap() const {
51     return devirt_map_;
52   }
53 
GetSafeCastSet()54   const SafeCastSet& GetSafeCastSet() const {
55     return safe_cast_set_;
56   }
57 
58   // Returns the devirtualization target method, or nullptr if none.
59   const MethodReference* GetDevirtTarget(uint32_t dex_pc) const;
60 
61   // Returns true if the cast can statically be verified to be redundant
62   // by using the check-cast elision peephole optimization in the verifier.
63   bool IsSafeCast(uint32_t pc) const;
64 
65  private:
66   VerifiedMethod() = default;
67 
68   /*
69    * Generate the GC map for a method that has just been verified (i.e. we're doing this as part of
70    * verification). For type-precise determination we have all the data we need, so we just need to
71    * encode it in some clever fashion.
72    * Stores the data in dex_gc_map_, returns true on success and false on failure.
73    */
74   bool GenerateGcMap(verifier::MethodVerifier* method_verifier);
75 
76   // Verify that the GC map associated with method_ is well formed.
77   static void VerifyGcMap(verifier::MethodVerifier* method_verifier,
78                           const std::vector<uint8_t>& data);
79 
80   // Compute sizes for GC map data.
81   static void ComputeGcMapSizes(verifier::MethodVerifier* method_verifier,
82                                 size_t* gc_points, size_t* ref_bitmap_bits, size_t* log2_max_gc_pc);
83 
84   // Generate devirtualizaion map into devirt_map_.
85   void GenerateDevirtMap(verifier::MethodVerifier* method_verifier)
86       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
87 
88   // Generate safe case set into safe_cast_set_.
89   void GenerateSafeCastSet(verifier::MethodVerifier* method_verifier)
90       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
91 
92   std::vector<uint8_t> dex_gc_map_;
93   DevirtualizationMap devirt_map_;
94   SafeCastSet safe_cast_set_;
95 };
96 
97 }  // namespace art
98 
99 #endif  // ART_COMPILER_DEX_VERIFIED_METHOD_H_
100