mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
125 lines
3.5 KiB
C++
125 lines
3.5 KiB
C++
/*
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This file is part of cpp-ethereum.
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cpp-ethereum is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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cpp-ethereum is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with cpp-ethereum. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file SemanticInformation.cpp
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* @author Christian <c@ethdev.com>
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* @date 2015
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* Helper to provide semantic information about assembly items.
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*/
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#include <libevmasm/SemanticInformation.h>
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#include <libevmasm/AssemblyItem.h>
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using namespace std;
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using namespace dev;
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using namespace dev::eth;
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bool SemanticInformation::breaksCSEAnalysisBlock(AssemblyItem const& _item)
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{
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switch (_item.type())
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{
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default:
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case UndefinedItem:
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case Tag:
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return true;
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case Push:
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case PushString:
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case PushTag:
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case PushSub:
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case PushSubSize:
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case PushProgramSize:
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case PushData:
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return false;
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case Operation:
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{
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if (isSwapInstruction(_item) || isDupInstruction(_item))
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return false;
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if (_item.instruction() == Instruction::GAS || _item.instruction() == Instruction::PC)
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return true; // GAS and PC assume a specific order of opcodes
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if (_item.instruction() == Instruction::MSIZE)
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return true; // msize is modified already by memory access, avoid that for now
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InstructionInfo info = instructionInfo(_item.instruction());
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if (_item.instruction() == Instruction::SSTORE)
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return false;
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if (_item.instruction() == Instruction::MSTORE)
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return false;
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//@todo: We do not handle the following memory instructions for now:
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// calldatacopy, codecopy, extcodecopy, mstore8,
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// msize (note that msize also depends on memory read access)
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// the second requirement will be lifted once it is implemented
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return info.sideEffects || info.args > 2;
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}
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}
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}
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bool SemanticInformation::isCommutativeOperation(AssemblyItem const& _item)
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{
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if (_item.type() != Operation)
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return false;
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switch (_item.instruction())
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{
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case Instruction::ADD:
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case Instruction::MUL:
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case Instruction::EQ:
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case Instruction::AND:
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case Instruction::OR:
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case Instruction::XOR:
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return true;
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default:
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return false;
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}
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}
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bool SemanticInformation::isDupInstruction(AssemblyItem const& _item)
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{
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if (_item.type() != Operation)
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return false;
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return Instruction::DUP1 <= _item.instruction() && _item.instruction() <= Instruction::DUP16;
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}
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bool SemanticInformation::isSwapInstruction(AssemblyItem const& _item)
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{
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if (_item.type() != Operation)
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return false;
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return Instruction::SWAP1 <= _item.instruction() && _item.instruction() <= Instruction::SWAP16;
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}
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bool SemanticInformation::isJumpInstruction(AssemblyItem const& _item)
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{
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return _item == AssemblyItem(Instruction::JUMP) || _item == AssemblyItem(Instruction::JUMPI);
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}
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bool SemanticInformation::altersControlFlow(AssemblyItem const& _item)
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{
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if (_item.type() != Operation)
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return false;
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switch (_item.instruction())
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{
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// note that CALL, CALLCODE and CREATE do not really alter the control flow, because we
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// continue on the next instruction (unless an exception happens which can always happen)
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case Instruction::JUMP:
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case Instruction::JUMPI:
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case Instruction::RETURN:
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case Instruction::SUICIDE:
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case Instruction::STOP:
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return true;
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default:
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return false;
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}
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}
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