Mathieu Chartier | 8892c6b | 2018-01-09 15:10:17 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2018 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 | #include "compact_dex_debug_info.h" |
| 18 | |
| 19 | #include "compact_dex_utils.h" |
| 20 | #include "leb128.h" |
| 21 | |
| 22 | namespace art { |
| 23 | |
| 24 | constexpr size_t CompactDexDebugInfoOffsetTable::kElementsPerIndex; |
| 25 | |
| 26 | CompactDexDebugInfoOffsetTable::Accessor::Accessor(const uint8_t* data_begin, |
| 27 | uint32_t debug_info_base, |
| 28 | uint32_t debug_info_table_offset) |
| 29 | : table_(reinterpret_cast<const uint32_t*>(data_begin + debug_info_table_offset)), |
| 30 | debug_info_base_(debug_info_base), |
| 31 | data_begin_(data_begin) {} |
| 32 | |
| 33 | uint32_t CompactDexDebugInfoOffsetTable::Accessor::GetDebugInfoOffset(uint32_t method_idx) const { |
| 34 | const uint32_t offset = table_[method_idx / kElementsPerIndex]; |
| 35 | const size_t bit_index = method_idx % kElementsPerIndex; |
| 36 | |
| 37 | const uint8_t* block = data_begin_ + offset; |
| 38 | uint16_t bit_mask = *block; |
| 39 | ++block; |
| 40 | bit_mask = (bit_mask << kBitsPerByte) | *block; |
| 41 | ++block; |
| 42 | if ((bit_mask & (1 << bit_index)) == 0) { |
| 43 | // Bit is not set means the offset is 0 for the debug info. |
| 44 | return 0u; |
| 45 | } |
| 46 | // Trim off the bits above the index we want and count how many bits are set. This is how many |
| 47 | // lebs we need to decode. |
| 48 | size_t count = POPCOUNT(static_cast<uintptr_t>(bit_mask) << (kBitsPerIntPtrT - 1 - bit_index)); |
| 49 | DCHECK_GT(count, 0u); |
| 50 | uint32_t current_offset = debug_info_base_; |
| 51 | do { |
| 52 | current_offset += DecodeUnsignedLeb128(&block); |
| 53 | --count; |
| 54 | } while (count > 0); |
| 55 | return current_offset; |
| 56 | } |
| 57 | |
| 58 | void CompactDexDebugInfoOffsetTable::Build(const std::vector<uint32_t>& debug_info_offsets, |
| 59 | std::vector<uint8_t>* out_data, |
| 60 | uint32_t* out_min_offset, |
| 61 | uint32_t* out_table_offset) { |
| 62 | DCHECK(out_data != nullptr); |
| 63 | DCHECK(out_data->empty()); |
| 64 | // Calculate the base offset and return it. |
| 65 | *out_min_offset = std::numeric_limits<uint32_t>::max(); |
| 66 | for (const uint32_t offset : debug_info_offsets) { |
| 67 | if (offset != 0u) { |
| 68 | *out_min_offset = std::min(*out_min_offset, offset); |
| 69 | } |
| 70 | } |
| 71 | // Write the leb blocks and store the important offsets (each kElementsPerIndex elements). |
| 72 | size_t block_start = 0; |
| 73 | |
| 74 | std::vector<uint32_t> offset_table; |
| 75 | |
| 76 | // Write data first then the table. |
| 77 | while (block_start < debug_info_offsets.size()) { |
| 78 | // Write the offset of the block for each block. |
| 79 | offset_table.push_back(out_data->size()); |
| 80 | |
| 81 | // Block size of up to kElementsPerIndex |
| 82 | const size_t block_size = std::min(debug_info_offsets.size() - block_start, kElementsPerIndex); |
| 83 | |
| 84 | // Calculate bit mask since need to write that first. |
| 85 | uint16_t bit_mask = 0u; |
| 86 | for (size_t i = 0; i < block_size; ++i) { |
| 87 | if (debug_info_offsets[block_start + i] != 0u) { |
| 88 | bit_mask |= 1 << i; |
| 89 | } |
| 90 | } |
| 91 | // Write bit mask. |
| 92 | out_data->push_back(static_cast<uint8_t>(bit_mask >> kBitsPerByte)); |
| 93 | out_data->push_back(static_cast<uint8_t>(bit_mask)); |
| 94 | |
| 95 | // Write debug info offsets relative to the current offset. |
| 96 | uint32_t current_offset = *out_min_offset; |
| 97 | for (size_t i = 0; i < block_size; ++i) { |
| 98 | const uint32_t debug_info_offset = debug_info_offsets[block_start + i]; |
| 99 | if (debug_info_offset != 0u) { |
| 100 | uint32_t delta = debug_info_offset - current_offset; |
| 101 | EncodeUnsignedLeb128(out_data, delta); |
| 102 | current_offset = debug_info_offset; |
| 103 | } |
| 104 | } |
| 105 | |
| 106 | block_start += block_size; |
| 107 | } |
| 108 | |
| 109 | // Write the offset table. |
| 110 | AlignmentPadVector(out_data, alignof(uint32_t)); |
| 111 | *out_table_offset = out_data->size(); |
| 112 | out_data->insert(out_data->end(), |
| 113 | reinterpret_cast<const uint8_t*>(&offset_table[0]), |
| 114 | reinterpret_cast<const uint8_t*>(&offset_table[0] + offset_table.size())); |
| 115 | } |
| 116 | |
| 117 | } // namespace art |