1 /*
2  * Copyright (C) 2017 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_METHOD_INFO_H_
18 #define ART_RUNTIME_METHOD_INFO_H_
19 
20 #include <android-base/logging.h>
21 
22 #include "base/leb128.h"
23 #include "base/macros.h"
24 #include "memory_region.h"
25 
26 namespace art {
27 
28 // Method info is for not dedupe friendly data of a method. Currently it only holds methods indices.
29 // Putting this data in MethodInfo instead of code infos saves ~5% oat size.
30 class MethodInfo {
31   using MethodIndexType = uint16_t;
32 
33  public:
34   // Reading mode
MethodInfo(const uint8_t * ptr)35   explicit MethodInfo(const uint8_t* ptr) {
36     if (ptr != nullptr) {
37       num_method_indices_ = DecodeUnsignedLeb128(&ptr);
38       region_ = MemoryRegion(const_cast<uint8_t*>(ptr),
39                              num_method_indices_ * sizeof(MethodIndexType));
40     }
41   }
42 
43   // Writing mode
MethodInfo(uint8_t * ptr,size_t num_method_indices)44   MethodInfo(uint8_t* ptr, size_t num_method_indices) : num_method_indices_(num_method_indices) {
45     DCHECK(ptr != nullptr);
46     ptr = EncodeUnsignedLeb128(ptr, num_method_indices_);
47     region_ = MemoryRegion(ptr, num_method_indices_ * sizeof(MethodIndexType));
48   }
49 
ComputeSize(size_t num_method_indices)50   static size_t ComputeSize(size_t num_method_indices) {
51     uint8_t temp[8];
52     uint8_t* ptr = temp;
53     ptr = EncodeUnsignedLeb128(ptr, num_method_indices);
54     return (ptr - temp) + num_method_indices * sizeof(MethodIndexType);
55   }
56 
GetMethodIndex(size_t index)57   ALWAYS_INLINE MethodIndexType GetMethodIndex(size_t index) const {
58     // Use bit functions to avoid pesky alignment requirements.
59     return region_.LoadBits(index * BitSizeOf<MethodIndexType>(), BitSizeOf<MethodIndexType>());
60   }
61 
SetMethodIndex(size_t index,MethodIndexType method_index)62   void SetMethodIndex(size_t index, MethodIndexType method_index) {
63     region_.StoreBits(index * BitSizeOf<MethodIndexType>(),
64                       method_index,
65                       BitSizeOf<MethodIndexType>());
66   }
67 
NumMethodIndices()68   size_t NumMethodIndices() const {
69     return num_method_indices_;
70   }
71 
72  private:
73   size_t num_method_indices_ = 0u;
74   MemoryRegion region_;
75 };
76 
77 }  // namespace art
78 
79 #endif  // ART_RUNTIME_METHOD_INFO_H_
80