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      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
     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
     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 
     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 
     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 
     62   void SetMethodIndex(size_t index, MethodIndexType method_index) {
     63     region_.StoreBits(index * BitSizeOf<MethodIndexType>(),
     64                       method_index,
     65                       BitSizeOf<MethodIndexType>());
     66   }
     67 
     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