/*
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* Copyright (C) 2016 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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#include "dex_to_dex_decompiler.h"
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#include <android-base/logging.h>
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#include "base/macros.h"
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#include "base/mutex.h"
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#include "dex/bytecode_utils.h"
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#include "dex/code_item_accessors-inl.h"
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#include "dex/dex_file-inl.h"
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#include "dex/dex_instruction-inl.h"
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#include "quicken_info.h"
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namespace art {
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namespace optimizer {
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class DexDecompiler {
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public:
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DexDecompiler(const DexFile& dex_file,
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const dex::CodeItem& code_item,
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const ArrayRef<const uint8_t>& quickened_info,
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bool decompile_return_instruction)
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: code_item_accessor_(dex_file, &code_item),
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quicken_info_(quickened_info),
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decompile_return_instruction_(decompile_return_instruction) {}
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bool Decompile();
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private:
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void DecompileInstanceFieldAccess(Instruction* inst, Instruction::Code new_opcode) {
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uint16_t index = NextIndex();
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inst->SetOpcode(new_opcode);
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inst->SetVRegC_22c(index);
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}
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void DecompileInvokeVirtual(Instruction* inst, Instruction::Code new_opcode, bool is_range) {
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const uint16_t index = NextIndex();
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inst->SetOpcode(new_opcode);
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if (is_range) {
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inst->SetVRegB_3rc(index);
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} else {
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inst->SetVRegB_35c(index);
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}
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}
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void DecompileNop(Instruction* inst) {
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const uint16_t reference_index = NextIndex();
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if (reference_index == DexFile::kDexNoIndex16) {
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// This means it was a normal nop and not a check-cast.
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return;
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}
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const uint16_t type_index = NextIndex();
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inst->SetOpcode(Instruction::CHECK_CAST);
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inst->SetVRegA_21c(reference_index);
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inst->SetVRegB_21c(type_index);
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}
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uint16_t NextIndex() {
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DCHECK_LT(quicken_index_, quicken_info_.NumIndices());
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const uint16_t ret = quicken_info_.GetData(quicken_index_);
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quicken_index_++;
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return ret;
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}
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const CodeItemInstructionAccessor code_item_accessor_;
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const QuickenInfoTable quicken_info_;
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const bool decompile_return_instruction_;
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size_t quicken_index_ = 0u;
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DISALLOW_COPY_AND_ASSIGN(DexDecompiler);
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};
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bool DexDecompiler::Decompile() {
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// We need to iterate over the code item, and not over the quickening data,
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// because the RETURN_VOID quickening is not encoded in the quickening data. Because
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// unquickening is a rare need and not performance sensitive, it is not worth the
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// added storage to also add the RETURN_VOID quickening in the quickened data.
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for (const DexInstructionPcPair& pair : code_item_accessor_) {
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Instruction* inst = const_cast<Instruction*>(&pair.Inst());
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switch (inst->Opcode()) {
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case Instruction::RETURN_VOID_NO_BARRIER:
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if (decompile_return_instruction_) {
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inst->SetOpcode(Instruction::RETURN_VOID);
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}
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break;
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case Instruction::NOP:
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if (quicken_info_.NumIndices() > 0) {
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// Only try to decompile NOP if there are more than 0 indices. Not having
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// any index happens when we unquicken a code item that only has
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// RETURN_VOID_NO_BARRIER as quickened instruction.
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DecompileNop(inst);
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}
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break;
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case Instruction::IGET_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IGET);
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break;
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case Instruction::IGET_WIDE_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IGET_WIDE);
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break;
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case Instruction::IGET_OBJECT_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IGET_OBJECT);
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break;
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case Instruction::IGET_BOOLEAN_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IGET_BOOLEAN);
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break;
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case Instruction::IGET_BYTE_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IGET_BYTE);
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break;
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case Instruction::IGET_CHAR_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IGET_CHAR);
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break;
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case Instruction::IGET_SHORT_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IGET_SHORT);
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break;
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case Instruction::IPUT_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IPUT);
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break;
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case Instruction::IPUT_BOOLEAN_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IPUT_BOOLEAN);
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break;
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case Instruction::IPUT_BYTE_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IPUT_BYTE);
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break;
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case Instruction::IPUT_CHAR_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IPUT_CHAR);
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break;
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case Instruction::IPUT_SHORT_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IPUT_SHORT);
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break;
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case Instruction::IPUT_WIDE_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IPUT_WIDE);
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break;
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case Instruction::IPUT_OBJECT_QUICK:
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DecompileInstanceFieldAccess(inst, Instruction::IPUT_OBJECT);
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break;
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case Instruction::INVOKE_VIRTUAL_QUICK:
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DecompileInvokeVirtual(inst, Instruction::INVOKE_VIRTUAL, false);
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break;
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case Instruction::INVOKE_VIRTUAL_RANGE_QUICK:
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DecompileInvokeVirtual(inst, Instruction::INVOKE_VIRTUAL_RANGE, true);
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break;
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default:
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break;
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}
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}
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if (quicken_index_ != quicken_info_.NumIndices()) {
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if (quicken_index_ == 0) {
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LOG(WARNING) << "Failed to use any value in quickening info,"
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<< " potentially due to duplicate methods.";
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} else {
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LOG(FATAL) << "Failed to use all values in quickening info."
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<< " Actual: " << std::hex << quicken_index_
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<< " Expected: " << quicken_info_.NumIndices();
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}
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}
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return true;
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}
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bool ArtDecompileDEX(const DexFile& dex_file,
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const dex::CodeItem& code_item,
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const ArrayRef<const uint8_t>& quickened_info,
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bool decompile_return_instruction) {
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if (quickened_info.size() == 0 && !decompile_return_instruction) {
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return true;
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}
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DexDecompiler decompiler(dex_file, code_item, quickened_info, decompile_return_instruction);
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return decompiler.Decompile();
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}
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} // namespace optimizer
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} // namespace art
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