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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "dex_to_dex_decompiler.h"
#include <android-base/logging.h>
#include "base/macros.h"
#include "base/mutex.h"
#include "dex/bytecode_utils.h"
#include "dex/code_item_accessors-inl.h"
#include "dex/dex_file-inl.h"
#include "dex/dex_instruction-inl.h"
#include "quicken_info.h"
namespace art {
namespace optimizer {
class DexDecompiler {
public:
DexDecompiler(const DexFile& dex_file,
const dex::CodeItem& code_item,
const ArrayRef<const uint8_t>& quickened_info,
bool decompile_return_instruction)
: code_item_accessor_(dex_file, &code_item),
quicken_info_(quickened_info),
decompile_return_instruction_(decompile_return_instruction) {}
bool Decompile();
private:
void DecompileInstanceFieldAccess(Instruction* inst, Instruction::Code new_opcode) {
uint16_t index = NextIndex();
inst->SetOpcode(new_opcode);
inst->SetVRegC_22c(index);
}
void DecompileInvokeVirtual(Instruction* inst, Instruction::Code new_opcode, bool is_range) {
const uint16_t index = NextIndex();
inst->SetOpcode(new_opcode);
if (is_range) {
inst->SetVRegB_3rc(index);
} else {
inst->SetVRegB_35c(index);
}
}
void DecompileNop(Instruction* inst) {
const uint16_t reference_index = NextIndex();
if (reference_index == DexFile::kDexNoIndex16) {
// This means it was a normal nop and not a check-cast.
return;
}
const uint16_t type_index = NextIndex();
inst->SetOpcode(Instruction::CHECK_CAST);
inst->SetVRegA_21c(reference_index);
inst->SetVRegB_21c(type_index);
}
uint16_t NextIndex() {
DCHECK_LT(quicken_index_, quicken_info_.NumIndices());
const uint16_t ret = quicken_info_.GetData(quicken_index_);
quicken_index_++;
return ret;
}
const CodeItemInstructionAccessor code_item_accessor_;
const QuickenInfoTable quicken_info_;
const bool decompile_return_instruction_;
size_t quicken_index_ = 0u;
DISALLOW_COPY_AND_ASSIGN(DexDecompiler);
};
bool DexDecompiler::Decompile() {
// We need to iterate over the code item, and not over the quickening data,
// because the RETURN_VOID quickening is not encoded in the quickening data. Because
// unquickening is a rare need and not performance sensitive, it is not worth the
// added storage to also add the RETURN_VOID quickening in the quickened data.
for (const DexInstructionPcPair& pair : code_item_accessor_) {
Instruction* inst = const_cast<Instruction*>(&pair.Inst());
switch (inst->Opcode()) {
case Instruction::RETURN_VOID_NO_BARRIER:
if (decompile_return_instruction_) {
inst->SetOpcode(Instruction::RETURN_VOID);
}
break;
case Instruction::NOP:
if (quicken_info_.NumIndices() > 0) {
// Only try to decompile NOP if there are more than 0 indices. Not having
// any index happens when we unquicken a code item that only has
// RETURN_VOID_NO_BARRIER as quickened instruction.
DecompileNop(inst);
}
break;
case Instruction::IGET_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IGET);
break;
case Instruction::IGET_WIDE_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IGET_WIDE);
break;
case Instruction::IGET_OBJECT_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IGET_OBJECT);
break;
case Instruction::IGET_BOOLEAN_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IGET_BOOLEAN);
break;
case Instruction::IGET_BYTE_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IGET_BYTE);
break;
case Instruction::IGET_CHAR_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IGET_CHAR);
break;
case Instruction::IGET_SHORT_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IGET_SHORT);
break;
case Instruction::IPUT_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IPUT);
break;
case Instruction::IPUT_BOOLEAN_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IPUT_BOOLEAN);
break;
case Instruction::IPUT_BYTE_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IPUT_BYTE);
break;
case Instruction::IPUT_CHAR_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IPUT_CHAR);
break;
case Instruction::IPUT_SHORT_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IPUT_SHORT);
break;
case Instruction::IPUT_WIDE_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IPUT_WIDE);
break;
case Instruction::IPUT_OBJECT_QUICK:
DecompileInstanceFieldAccess(inst, Instruction::IPUT_OBJECT);
break;
case Instruction::INVOKE_VIRTUAL_QUICK:
DecompileInvokeVirtual(inst, Instruction::INVOKE_VIRTUAL, false);
break;
case Instruction::INVOKE_VIRTUAL_RANGE_QUICK:
DecompileInvokeVirtual(inst, Instruction::INVOKE_VIRTUAL_RANGE, true);
break;
default:
break;
}
}
if (quicken_index_ != quicken_info_.NumIndices()) {
if (quicken_index_ == 0) {
LOG(WARNING) << "Failed to use any value in quickening info,"
<< " potentially due to duplicate methods.";
} else {
LOG(FATAL) << "Failed to use all values in quickening info."
<< " Actual: " << std::hex << quicken_index_
<< " Expected: " << quicken_info_.NumIndices();
}
}
return true;
}
bool ArtDecompileDEX(const DexFile& dex_file,
const dex::CodeItem& code_item,
const ArrayRef<const uint8_t>& quickened_info,
bool decompile_return_instruction) {
if (quickened_info.size() == 0 && !decompile_return_instruction) {
return true;
}
DexDecompiler decompiler(dex_file, code_item, quickened_info, decompile_return_instruction);
return decompiler.Decompile();
}
} // namespace optimizer
} // namespace art
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