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_QUICKEN_INFO_H_
18 #define ART_RUNTIME_QUICKEN_INFO_H_
19 
20 #include "base/array_ref.h"
21 #include "base/leb128.h"
22 #include "dex/compact_offset_table.h"
23 #include "dex/dex_instruction.h"
24 
25 namespace art {
26 
27 // QuickenInfoTable is a table of 16 bit dex indices. There is one slot for every instruction that
28 // is possibly dequickenable.
29 class QuickenInfoTable {
30  public:
31   class Builder {
32    public:
Builder(std::vector<uint8_t> * out_data,size_t num_elements)33     Builder(std::vector<uint8_t>* out_data, size_t num_elements) : out_data_(out_data) {
34       EncodeUnsignedLeb128(out_data_, num_elements);
35     }
36 
AddIndex(uint16_t index)37     void AddIndex(uint16_t index) {
38       out_data_->push_back(static_cast<uint8_t>(index));
39       out_data_->push_back(static_cast<uint8_t>(index >> 8));
40     }
41 
42    private:
43     std::vector<uint8_t>* const out_data_;
44   };
45 
QuickenInfoTable(ArrayRef<const uint8_t> data)46   explicit QuickenInfoTable(ArrayRef<const uint8_t> data)
47       : data_(data.data()),
48         num_elements_(!data.empty() ? DecodeUnsignedLeb128(&data_) : 0u) {}
49 
IsNull()50   bool IsNull() const {
51     return data_ == nullptr;
52   }
53 
GetData(size_t index)54   uint16_t GetData(size_t index) const {
55     return data_[index * 2] | (static_cast<uint16_t>(data_[index * 2 + 1]) << 8);
56   }
57 
58   // Returns true if the dex instruction has an index in the table. (maybe dequickenable).
NeedsIndexForInstruction(const Instruction * inst)59   static bool NeedsIndexForInstruction(const Instruction* inst) {
60     return inst->IsQuickened() || inst->Opcode() == Instruction::NOP;
61   }
62 
NumberOfIndices(size_t bytes)63   static size_t NumberOfIndices(size_t bytes) {
64     return bytes / sizeof(uint16_t);
65   }
66 
SizeInBytes(ArrayRef<const uint8_t> data)67   static size_t SizeInBytes(ArrayRef<const uint8_t> data) {
68     QuickenInfoTable table(data);
69     return table.data_ + table.NumIndices() * 2 - data.data();
70   }
71 
NumIndices()72   uint32_t NumIndices() const {
73     return num_elements_;
74   }
75 
76  private:
77   const uint8_t* data_;
78   const uint32_t num_elements_;
79 
80   DISALLOW_COPY_AND_ASSIGN(QuickenInfoTable);
81 };
82 
83 }  // namespace art
84 
85 #endif  // ART_RUNTIME_QUICKEN_INFO_H_
86