Vladimir Marko | f3c52b4 | 2017-11-17 17:32:12 +0000 | [diff] [blame] | 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_DEX2OAT_LINKER_INDEX_BSS_MAPPING_ENCODER_H_ |
| 18 | #define ART_DEX2OAT_LINKER_INDEX_BSS_MAPPING_ENCODER_H_ |
| 19 | |
Andreas Gampe | 5794381 | 2017-12-06 21:39:13 -0800 | [diff] [blame] | 20 | #include <android-base/logging.h> |
| 21 | |
Vladimir Marko | f3c52b4 | 2017-11-17 17:32:12 +0000 | [diff] [blame] | 22 | #include "base/bit_utils.h" |
| 23 | #include "base/bit_vector-inl.h" |
Vladimir Marko | f3c52b4 | 2017-11-17 17:32:12 +0000 | [diff] [blame] | 24 | #include "index_bss_mapping.h" |
| 25 | |
| 26 | namespace art { |
| 27 | namespace linker { |
| 28 | |
| 29 | // Helper class for encoding compressed IndexBssMapping. |
| 30 | class IndexBssMappingEncoder { |
| 31 | public: |
| 32 | IndexBssMappingEncoder(size_t number_of_indexes, size_t slot_size) |
| 33 | : index_bits_(IndexBssMappingEntry::IndexBits(number_of_indexes)), |
| 34 | slot_size_(slot_size) { |
| 35 | entry_.index_and_mask = static_cast<uint32_t>(-1); |
| 36 | entry_.bss_offset = static_cast<uint32_t>(-1); |
| 37 | DCHECK_NE(number_of_indexes, 0u); |
| 38 | } |
| 39 | |
| 40 | // Try to merge the next index -> bss_offset mapping into the current entry. |
| 41 | // Return true on success, false on failure. |
| 42 | bool TryMerge(uint32_t index, uint32_t bss_offset) { |
| 43 | DCHECK_LE(MinimumBitsToStore(index), index_bits_); |
| 44 | DCHECK_NE(index, entry_.GetIndex(index_bits_)); |
| 45 | if (entry_.bss_offset + slot_size_ != bss_offset) { |
| 46 | return false; |
| 47 | } |
| 48 | uint32_t diff = index - entry_.GetIndex(index_bits_); |
| 49 | if (diff > 32u - index_bits_) { |
| 50 | return false; |
| 51 | } |
| 52 | uint32_t mask = entry_.GetMask(index_bits_); |
| 53 | if ((mask & ~(static_cast<uint32_t>(-1) << diff)) != 0u) { |
| 54 | return false; |
| 55 | } |
| 56 | // Insert the bit indicating the index we've just overwritten |
| 57 | // and shift bits indicating indexes before that. |
| 58 | mask = ((mask << index_bits_) >> diff) | (static_cast<uint32_t>(1u) << (32 - diff)); |
| 59 | entry_.index_and_mask = mask | index; |
| 60 | entry_.bss_offset = bss_offset; |
| 61 | return true; |
| 62 | } |
| 63 | |
| 64 | void Reset(uint32_t method_index, uint32_t bss_offset) { |
| 65 | DCHECK_LE(MinimumBitsToStore(method_index), index_bits_); |
| 66 | entry_.index_and_mask = method_index; // Mask bits set to 0. |
| 67 | entry_.bss_offset = bss_offset; |
| 68 | } |
| 69 | |
| 70 | IndexBssMappingEntry GetEntry() { |
| 71 | return entry_; |
| 72 | } |
| 73 | |
| 74 | size_t GetIndexBits() const { |
| 75 | return index_bits_; |
| 76 | } |
| 77 | |
| 78 | private: |
| 79 | const size_t index_bits_; |
| 80 | const size_t slot_size_; |
| 81 | IndexBssMappingEntry entry_; |
| 82 | }; |
| 83 | |
| 84 | } // namespace linker |
| 85 | } // namespace art |
| 86 | |
| 87 | #endif // ART_DEX2OAT_LINKER_INDEX_BSS_MAPPING_ENCODER_H_ |