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88 lines
2.7 KiB
88 lines
2.7 KiB
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_DEX2OAT_LINKER_INDEX_BSS_MAPPING_ENCODER_H_
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#define ART_DEX2OAT_LINKER_INDEX_BSS_MAPPING_ENCODER_H_
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#include <android-base/logging.h>
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#include "base/bit_utils.h"
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#include "base/bit_vector-inl.h"
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#include "index_bss_mapping.h"
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namespace art {
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namespace linker {
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// Helper class for encoding compressed IndexBssMapping.
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class IndexBssMappingEncoder {
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public:
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IndexBssMappingEncoder(size_t number_of_indexes, size_t slot_size)
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: index_bits_(IndexBssMappingEntry::IndexBits(number_of_indexes)),
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slot_size_(slot_size) {
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entry_.index_and_mask = static_cast<uint32_t>(-1);
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entry_.bss_offset = static_cast<uint32_t>(-1);
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DCHECK_NE(number_of_indexes, 0u);
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}
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// Try to merge the next index -> bss_offset mapping into the current entry.
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// Return true on success, false on failure.
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bool TryMerge(uint32_t index, uint32_t bss_offset) {
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DCHECK_LE(MinimumBitsToStore(index), index_bits_);
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DCHECK_NE(index, entry_.GetIndex(index_bits_));
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if (entry_.bss_offset + slot_size_ != bss_offset) {
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return false;
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}
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uint32_t diff = index - entry_.GetIndex(index_bits_);
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if (diff > 32u - index_bits_) {
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return false;
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}
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uint32_t mask = entry_.GetMask(index_bits_);
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if ((mask & ~(static_cast<uint32_t>(-1) << diff)) != 0u) {
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return false;
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}
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// Insert the bit indicating the index we've just overwritten
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// and shift bits indicating indexes before that.
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mask = ((mask << index_bits_) >> diff) | (static_cast<uint32_t>(1u) << (32 - diff));
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entry_.index_and_mask = mask | index;
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entry_.bss_offset = bss_offset;
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return true;
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}
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void Reset(uint32_t method_index, uint32_t bss_offset) {
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DCHECK_LE(MinimumBitsToStore(method_index), index_bits_);
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entry_.index_and_mask = method_index; // Mask bits set to 0.
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entry_.bss_offset = bss_offset;
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}
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IndexBssMappingEntry GetEntry() {
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return entry_;
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}
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size_t GetIndexBits() const {
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return index_bits_;
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}
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private:
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const size_t index_bits_;
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const size_t slot_size_;
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IndexBssMappingEntry entry_;
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};
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} // namespace linker
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} // namespace art
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#endif // ART_DEX2OAT_LINKER_INDEX_BSS_MAPPING_ENCODER_H_
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