79 lines
2.5 KiB
C++
79 lines
2.5 KiB
C++
/*
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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_COMPILER_LINKER_METHOD_BSS_MAPPING_ENCODER_H_
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#define ART_COMPILER_LINKER_METHOD_BSS_MAPPING_ENCODER_H_
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#include "base/enums.h"
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#include "base/logging.h"
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#include "dex_file.h"
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#include "method_bss_mapping.h"
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namespace art {
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namespace linker {
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// Helper class for encoding compressed MethodBssMapping.
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class MethodBssMappingEncoder {
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public:
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explicit MethodBssMappingEncoder(PointerSize pointer_size)
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: pointer_size_(static_cast<size_t>(pointer_size)) {
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entry_.method_index = DexFile::kDexNoIndex16;
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entry_.index_mask = 0u;
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entry_.bss_offset = static_cast<uint32_t>(-1);
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}
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// Try to merge the next method_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 method_index, uint32_t bss_offset) {
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DCHECK_NE(method_index, entry_.method_index);
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if (entry_.bss_offset + pointer_size_ != bss_offset) {
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return false;
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}
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uint32_t diff = method_index - entry_.method_index;
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if (diff > 16u) {
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return false;
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}
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if ((entry_.index_mask & ~(static_cast<uint32_t>(-1) << diff)) != 0u) {
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return false;
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}
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entry_.method_index = method_index;
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// Insert the bit indicating the method index we've just overwritten
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// and shift bits indicating method indexes before that.
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entry_.index_mask = dchecked_integral_cast<uint16_t>(
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(static_cast<uint32_t>(entry_.index_mask) | 0x10000u) >> diff);
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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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entry_.method_index = method_index;
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entry_.index_mask = 0u;
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entry_.bss_offset = bss_offset;
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}
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MethodBssMappingEntry GetEntry() {
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return entry_;
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}
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private:
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size_t pointer_size_;
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MethodBssMappingEntry entry_;
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};
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} // namespace linker
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} // namespace art
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#endif // ART_COMPILER_LINKER_METHOD_BSS_MAPPING_ENCODER_H_
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