/src/solidity/libevmasm/SemanticInformation.cpp

Source (jump to first uncovered line)
/*
  This file is part of solidity.

  solidity is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  solidity is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with solidity.  If not, see <http://www.gnu.org/licenses/>.
*/
// SPDX-License-Identifier: GPL-3.0
/**
 * @file SemanticInformation.cpp
 * @author Christian <c@ethdev.com>
 * @date 2015
 * Helper to provide semantic information about assembly items.
 */

#include <libevmasm/SemanticInformation.h>
#include <libevmasm/AssemblyItem.h>

using namespace std;
using namespace solidity;
using namespace solidity::evmasm;

vector<SemanticInformation::Operation> SemanticInformation::readWriteOperations(Instruction _instruction)
{
  switch (_instruction)
  {
  case Instruction::SSTORE:
  case Instruction::SLOAD:
  {
    assertThrow(memory(_instruction) == Effect::None, OptimizerException, "");
    assertThrow(storage(_instruction) != Effect::None, OptimizerException, "");
    Operation op;
    op.effect = storage(_instruction);
    op.location = Location::Storage;
    op.startParameter = 0;
    // We know that exactly one slot is affected.
    op.lengthConstant = 1;
    return {op};
  }
  case Instruction::MSTORE:
  case Instruction::MSTORE8:
  case Instruction::MLOAD:
  {
    assertThrow(memory(_instruction) != Effect::None, OptimizerException, "");
    assertThrow(storage(_instruction) == Effect::None, OptimizerException, "");
    Operation op;
    op.effect = memory(_instruction);
    op.location = Location::Memory;
    op.startParameter = 0;
    if (_instruction == Instruction::MSTORE || _instruction == Instruction::MLOAD)
      op.lengthConstant = 32;
    else if (_instruction == Instruction::MSTORE8)
      op.lengthConstant = 1;

    return {op};
  }
  case Instruction::REVERT:
  case Instruction::RETURN:
  case Instruction::KECCAK256:
  case Instruction::LOG0:
  case Instruction::LOG1:
  case Instruction::LOG2:
  case Instruction::LOG3:
  case Instruction::LOG4:
  {
    assertThrow(storage(_instruction) == Effect::None, OptimizerException, "");
    assertThrow(memory(_instruction) == Effect::Read, OptimizerException, "");
    Operation op;
    op.effect = memory(_instruction);
    op.location = Location::Memory;
    op.startParameter = 0;
    op.lengthParameter = 1;
    return {op};
  }
  case Instruction::EXTCODECOPY:
  {
    assertThrow(memory(_instruction) == Effect::Write, OptimizerException, "");
    assertThrow(storage(_instruction) == Effect::None, OptimizerException, "");
    Operation op;
    op.effect = memory(_instruction);
    op.location = Location::Memory;
    op.startParameter = 1;
    op.lengthParameter = 3;
    return {op};
  }
  case Instruction::CODECOPY:
  case Instruction::CALLDATACOPY:
  case Instruction::RETURNDATACOPY:
  {
    assertThrow(memory(_instruction) == Effect::Write, OptimizerException, "");
    assertThrow(storage(_instruction) == Effect::None, OptimizerException, "");
    Operation op;
    op.effect = memory(_instruction);
    op.location = Location::Memory;
    op.startParameter = 0;
    op.lengthParameter = 2;
    return {op};
  }
  case Instruction::STATICCALL:
  case Instruction::CALL:
  case Instruction::CALLCODE:
  case Instruction::DELEGATECALL:
  {
    size_t paramCount = static_cast<size_t>(instructionInfo(_instruction).args);
    vector<Operation> operations{
      Operation{Location::Memory, Effect::Read, paramCount - 4, paramCount - 3, {}},
      Operation{Location::Storage, Effect::Read, {}, {}, {}}
    };
    if (_instruction != Instruction::STATICCALL)
      operations.emplace_back(Operation{Location::Storage, Effect::Write, {}, {}, {}});
    operations.emplace_back(Operation{
      Location::Memory,
      Effect::Write,
      paramCount - 2,
      // Length is in paramCount - 1, but it is only a max length,
      // there is no guarantee that the full area is written to.
      {},
      {}
    });
    return operations;
  }
  case Instruction::CREATE:
  case Instruction::CREATE2:
    return vector<Operation>{
      Operation{
        Location::Memory,
        Effect::Read,
        1,
        2,
        {}
      },
      Operation{Location::Storage, Effect::Read, {}, {}, {}},
      Operation{Location::Storage, Effect::Write, {}, {}, {}}
    };
  case Instruction::MSIZE:
    // This is just to satisfy the assert below.
    return vector<Operation>{};
  default:
    assertThrow(storage(_instruction) == None && memory(_instruction) == None, AssemblyException, "");
  }
  return {};
}

bool SemanticInformation::breaksCSEAnalysisBlock(AssemblyItem const& _item, bool _msizeImportant)
{
  switch (_item.type())
  {
  default:
  case UndefinedItem:
  case Tag:
  case PushDeployTimeAddress:
  case AssignImmutable:
  case VerbatimBytecode:
    return true;
  case Push:
  case PushTag:
  case PushSub:
  case PushSubSize:
  case PushProgramSize:
  case PushData:
  case PushLibraryAddress:
  case PushImmutable:
    return false;
  case evmasm::Operation:
  {
    if (isSwapInstruction(_item) || isDupInstruction(_item))
      return false;
    if (_item.instruction() == Instruction::GAS || _item.instruction() == Instruction::PC)
      return true; // GAS and PC assume a specific order of opcodes
    if (_item.instruction() == Instruction::MSIZE)
      return true; // msize is modified already by memory access, avoid that for now
    InstructionInfo info = instructionInfo(_item.instruction());
    if (_item.instruction() == Instruction::SSTORE)
      return false;
    if (_item.instruction() == Instruction::MSTORE)
      return false;
    if (!_msizeImportant && (
      _item.instruction() == Instruction::MLOAD ||
      _item.instruction() == Instruction::KECCAK256
    ))
      return false;
    //@todo: We do not handle the following memory instructions for now:
    // calldatacopy, codecopy, extcodecopy, mstore8,
    // msize (note that msize also depends on memory read access)

    // the second requirement will be lifted once it is implemented
    return info.sideEffects || info.args > 2;
  }
  }
}

bool SemanticInformation::isCommutativeOperation(AssemblyItem const& _item)
{
  if (_item.type() != evmasm::Operation)
    return false;
  switch (_item.instruction())
  {
  case Instruction::ADD:
  case Instruction::MUL:
  case Instruction::EQ:
  case Instruction::AND:
  case Instruction::OR:
  case Instruction::XOR:
    return true;
  default:
    return false;
  }
}

bool SemanticInformation::isDupInstruction(AssemblyItem const& _item)
{
  if (_item.type() != evmasm::Operation)
    return false;
  return evmasm::isDupInstruction(_item.instruction());
}

bool SemanticInformation::isSwapInstruction(AssemblyItem const& _item)
{
  if (_item.type() != evmasm::Operation)
    return false;
  return evmasm::isSwapInstruction(_item.instruction());
}

bool SemanticInformation::isJumpInstruction(AssemblyItem const& _item)
{
  return _item == Instruction::JUMP || _item == Instruction::JUMPI;
}

bool SemanticInformation::altersControlFlow(AssemblyItem const& _item)
{
  if (_item.type() != evmasm::Operation)
    return false;
  switch (_item.instruction())
  {
  // note that CALL, CALLCODE and CREATE do not really alter the control flow, because we
  // continue on the next instruction
  case Instruction::JUMP:
  case Instruction::JUMPI:
  case Instruction::RETURN:
  case Instruction::SELFDESTRUCT:
  case Instruction::STOP:
  case Instruction::INVALID:
  case Instruction::REVERT:
    return true;
  default:
    return false;
  }
}

bool SemanticInformation::terminatesControlFlow(Instruction _instruction)
{
  switch (_instruction)
  {
  case Instruction::RETURN:
  case Instruction::SELFDESTRUCT:
  case Instruction::STOP:
  case Instruction::INVALID:
  case Instruction::REVERT:
    return true;
  default:
    return false;
  }
}

bool SemanticInformation::reverts(Instruction _instruction)
{
  switch (_instruction)
  {
    case Instruction::INVALID:
    case Instruction::REVERT:
      return true;
    default:
      return false;
  }
}

bool SemanticInformation::isDeterministic(AssemblyItem const& _item)
{
  assertThrow(_item.type() != VerbatimBytecode, AssemblyException, "");

  if (_item.type() != evmasm::Operation)
    return true;

  switch (_item.instruction())
  {
  case Instruction::CALL:
  case Instruction::CALLCODE:
  case Instruction::DELEGATECALL:
  case Instruction::STATICCALL:
  case Instruction::CREATE:
  case Instruction::CREATE2:
  case Instruction::GAS:
  case Instruction::PC:
  case Instruction::MSIZE: // depends on previous writes and reads, not only on content
  case Instruction::BALANCE: // depends on previous calls
  case Instruction::SELFBALANCE: // depends on previous calls
  case Instruction::EXTCODESIZE:
  case Instruction::EXTCODEHASH:
  case Instruction::RETURNDATACOPY: // depends on previous calls
  case Instruction::RETURNDATASIZE:
    return false;
  default:
    return true;
  }
}

bool SemanticInformation::movable(Instruction _instruction)
{
  // These are not really functional.
  if (isDupInstruction(_instruction) || isSwapInstruction(_instruction))
    return false;
  InstructionInfo info = instructionInfo(_instruction);
  if (info.sideEffects)
    return false;
  switch (_instruction)
  {
  case Instruction::KECCAK256:
  case Instruction::BALANCE:
  case Instruction::SELFBALANCE:
  case Instruction::EXTCODESIZE:
  case Instruction::EXTCODEHASH:
  case Instruction::RETURNDATASIZE:
  case Instruction::SLOAD:
  case Instruction::PC:
  case Instruction::MSIZE:
  case Instruction::GAS:
    return false;
  default:
    return true;
  }
  return true;
}

bool SemanticInformation::canBeRemoved(Instruction _instruction)
{
  // These are not really functional.
  assertThrow(!isDupInstruction(_instruction) && !isSwapInstruction(_instruction), AssemblyException, "");

  return !instructionInfo(_instruction).sideEffects;
}

bool SemanticInformation::canBeRemovedIfNoMSize(Instruction _instruction)
{
  if (_instruction == Instruction::KECCAK256 || _instruction == Instruction::MLOAD)
    return true;
  else
    return canBeRemoved(_instruction);
}

SemanticInformation::Effect SemanticInformation::memory(Instruction _instruction)
{
  switch (_instruction)
  {
  case Instruction::CALLDATACOPY:
  case Instruction::CODECOPY:
  case Instruction::EXTCODECOPY:
  case Instruction::RETURNDATACOPY:
  case Instruction::MSTORE:
  case Instruction::MSTORE8:
  case Instruction::CALL:
  case Instruction::CALLCODE:
  case Instruction::DELEGATECALL:
  case Instruction::STATICCALL:
    return SemanticInformation::Write;

  case Instruction::CREATE:
  case Instruction::CREATE2:
  case Instruction::KECCAK256:
  case Instruction::MLOAD:
  case Instruction::MSIZE:
  case Instruction::RETURN:
  case Instruction::REVERT:
  case Instruction::LOG0:
  case Instruction::LOG1:
  case Instruction::LOG2:
  case Instruction::LOG3:
  case Instruction::LOG4:
    return SemanticInformation::Read;

  default:
    return SemanticInformation::None;
  }
}

bool SemanticInformation::movableApartFromEffects(Instruction _instruction)
{
  switch (_instruction)
  {
  case Instruction::EXTCODEHASH:
  case Instruction::EXTCODESIZE:
  case Instruction::RETURNDATASIZE:
  case Instruction::BALANCE:
  case Instruction::SELFBALANCE:
  case Instruction::SLOAD:
  case Instruction::KECCAK256:
  case Instruction::MLOAD:
    return true;

  default:
    return movable(_instruction);
  }
}

SemanticInformation::Effect SemanticInformation::storage(Instruction _instruction)
{
  switch (_instruction)
  {
  case Instruction::CALL:
  case Instruction::CALLCODE:
  case Instruction::DELEGATECALL:
  case Instruction::CREATE:
  case Instruction::CREATE2:
  case Instruction::SSTORE:
    return SemanticInformation::Write;

  case Instruction::SLOAD:
  case Instruction::STATICCALL:
    return SemanticInformation::Read;

  default:
    return SemanticInformation::None;
  }
}

SemanticInformation::Effect SemanticInformation::otherState(Instruction _instruction)
{
  switch (_instruction)
  {
  case Instruction::CALL:
  case Instruction::CALLCODE:
  case Instruction::DELEGATECALL:
  case Instruction::CREATE:
  case Instruction::CREATE2:
  case Instruction::SELFDESTRUCT:
  case Instruction::STATICCALL: // because it can affect returndatasize
    // Strictly speaking, log0, .., log4 writes to the state, but the EVM cannot read it, so they
    // are just marked as having 'other side effects.'
    return SemanticInformation::Write;

  case Instruction::EXTCODESIZE:
  case Instruction::EXTCODEHASH:
  case Instruction::RETURNDATASIZE:
  case Instruction::BALANCE:
  case Instruction::SELFBALANCE:
  case Instruction::RETURNDATACOPY:
  case Instruction::EXTCODECOPY:
    // PC and GAS are specifically excluded here. Instructions such as CALLER, CALLVALUE,
    // ADDRESS are excluded because they cannot change during execution.
    return SemanticInformation::Read;

  default:
    return SemanticInformation::None;
  }
}

bool SemanticInformation::invalidInPureFunctions(Instruction _instruction)
{
  switch (_instruction)
  {
  case Instruction::ADDRESS:
  case Instruction::SELFBALANCE:
  case Instruction::BALANCE:
  case Instruction::ORIGIN:
  case Instruction::CALLER:
  case Instruction::CALLVALUE:
  case Instruction::CHAINID:
  case Instruction::BASEFEE:
  case Instruction::GAS:
  case Instruction::GASPRICE:
  case Instruction::EXTCODESIZE:
  case Instruction::EXTCODECOPY:
  case Instruction::EXTCODEHASH:
  case Instruction::BLOCKHASH:
  case Instruction::COINBASE:
  case Instruction::TIMESTAMP:
  case Instruction::NUMBER:
  case Instruction::DIFFICULTY:
  case Instruction::GASLIMIT:
  case Instruction::STATICCALL:
  case Instruction::SLOAD:
    return true;
  default:
    break;
  }
  return invalidInViewFunctions(_instruction);
}

bool SemanticInformation::invalidInViewFunctions(Instruction _instruction)
{
  switch (_instruction)
  {
  case Instruction::SSTORE:
  case Instruction::JUMP:
  case Instruction::JUMPI:
  case Instruction::LOG0:
  case Instruction::LOG1:
  case Instruction::LOG2:
  case Instruction::LOG3:
  case Instruction::LOG4:
  case Instruction::CREATE:
  case Instruction::CALL:
  case Instruction::CALLCODE:
  case Instruction::DELEGATECALL:
  case Instruction::CREATE2:
  case Instruction::SELFDESTRUCT:
    return true;
  default:
    break;
  }
  return false;
}

Coverage Report

Created: 2022-08-24 06:31

Line	Count	Source (jump to first uncovered line)
1		/*
2		This file is part of solidity.
3
4		solidity is free software: you can redistribute it and/or modify
5		it under the terms of the GNU General Public License as published by
6		the Free Software Foundation, either version 3 of the License, or
7		(at your option) any later version.
8
9		solidity is distributed in the hope that it will be useful,
10		but WITHOUT ANY WARRANTY; without even the implied warranty of
11		MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12		GNU General Public License for more details.
13
14		You should have received a copy of the GNU General Public License
15		along with solidity. If not, see <http://www.gnu.org/licenses/>.
16		*/
17		// SPDX-License-Identifier: GPL-3.0
18		/**
19		* @file SemanticInformation.cpp
20		* @author Christian <c@ethdev.com>
21		* @date 2015
22		* Helper to provide semantic information about assembly items.
23		*/
24
25		#include <libevmasm/SemanticInformation.h>
26		#include <libevmasm/AssemblyItem.h>
27
28		using namespace std;
29		using namespace solidity;
30		using namespace solidity::evmasm;
31
32		vector<SemanticInformation::Operation> SemanticInformation::readWriteOperations(Instruction _instruction)
33	0	{
34	0	switch (_instruction)
35	0	{
36	0	case Instruction::SSTORE:
37	0	case Instruction::SLOAD:
38	0	{
39	0	assertThrow(memory(_instruction) == Effect::None, OptimizerException, "");
40	0	assertThrow(storage(_instruction) != Effect::None, OptimizerException, "");
41	0	Operation op;
42	0	op.effect = storage(_instruction);
43	0	op.location = Location::Storage;
44	0	op.startParameter = 0;
45		// We know that exactly one slot is affected.
46	0	op.lengthConstant = 1;
47	0	return {op};
48	0	}
49	0	case Instruction::MSTORE:
50	0	case Instruction::MSTORE8:
51	0	case Instruction::MLOAD:
52	0	{
53	0	assertThrow(memory(_instruction) != Effect::None, OptimizerException, "");
54	0	assertThrow(storage(_instruction) == Effect::None, OptimizerException, "");
55	0	Operation op;
56	0	op.effect = memory(_instruction);
57	0	op.location = Location::Memory;
58	0	op.startParameter = 0;
59	0	if (_instruction == Instruction::MSTORE \|\| _instruction == Instruction::MLOAD)
60	0	op.lengthConstant = 32;
61	0	else if (_instruction == Instruction::MSTORE8)
62	0	op.lengthConstant = 1;
63
64	0	return {op};
65	0	}
66	0	case Instruction::REVERT:
67	0	case Instruction::RETURN:
68	0	case Instruction::KECCAK256:
69	0	case Instruction::LOG0:
70	0	case Instruction::LOG1:
71	0	case Instruction::LOG2:
72	0	case Instruction::LOG3:
73	0	case Instruction::LOG4:
74	0	{
75	0	assertThrow(storage(_instruction) == Effect::None, OptimizerException, "");
76	0	assertThrow(memory(_instruction) == Effect::Read, OptimizerException, "");
77	0	Operation op;
78	0	op.effect = memory(_instruction);
79	0	op.location = Location::Memory;
80	0	op.startParameter = 0;
81	0	op.lengthParameter = 1;
82	0	return {op};
83	0	}
84	0	case Instruction::EXTCODECOPY:
85	0	{
86	0	assertThrow(memory(_instruction) == Effect::Write, OptimizerException, "");
87	0	assertThrow(storage(_instruction) == Effect::None, OptimizerException, "");
88	0	Operation op;
89	0	op.effect = memory(_instruction);
90	0	op.location = Location::Memory;
91	0	op.startParameter = 1;
92	0	op.lengthParameter = 3;
93	0	return {op};
94	0	}
95	0	case Instruction::CODECOPY:
96	0	case Instruction::CALLDATACOPY:
97	0	case Instruction::RETURNDATACOPY:
98	0	{
99	0	assertThrow(memory(_instruction) == Effect::Write, OptimizerException, "");
100	0	assertThrow(storage(_instruction) == Effect::None, OptimizerException, "");
101	0	Operation op;
102	0	op.effect = memory(_instruction);
103	0	op.location = Location::Memory;
104	0	op.startParameter = 0;
105	0	op.lengthParameter = 2;
106	0	return {op};
107	0	}
108	0	case Instruction::STATICCALL:
109	0	case Instruction::CALL:
110	0	case Instruction::CALLCODE:
111	0	case Instruction::DELEGATECALL:
112	0	{
113	0	size_t paramCount = static_cast<size_t>(instructionInfo(_instruction).args);
114	0	vector<Operation> operations{
115	0	Operation{Location::Memory, Effect::Read, paramCount - 4, paramCount - 3, {}},
116	0	Operation{Location::Storage, Effect::Read, {}, {}, {}}
117	0	};
118	0	if (_instruction != Instruction::STATICCALL)
119	0	operations.emplace_back(Operation{Location::Storage, Effect::Write, {}, {}, {}});
120	0	operations.emplace_back(Operation{
121	0	Location::Memory,
122	0	Effect::Write,
123	0	paramCount - 2,
124		// Length is in paramCount - 1, but it is only a max length,
125		// there is no guarantee that the full area is written to.
126	0	{},
127	0	{}
128	0	});
129	0	return operations;
130	0	}
131	0	case Instruction::CREATE:
132	0	case Instruction::CREATE2:
133	0	return vector<Operation>{
134	0	Operation{
135	0	Location::Memory,
136	0	Effect::Read,
137	0	1,
138	0	2,
139	0	{}
140	0	},
141	0	Operation{Location::Storage, Effect::Read, {}, {}, {}},
142	0	Operation{Location::Storage, Effect::Write, {}, {}, {}}
143	0	};
144	0	case Instruction::MSIZE:
145		// This is just to satisfy the assert below.
146	0	return vector<Operation>{};
147	0	default:
148	0	assertThrow(storage(_instruction) == None && memory(_instruction) == None, AssemblyException, "");
149	0	}
150	0	return {};
151	0	}
152
153		bool SemanticInformation::breaksCSEAnalysisBlock(AssemblyItem const& _item, bool _msizeImportant)
154	0	{
155	0	switch (_item.type())
156	0	{
157	0	default:
158	0	case UndefinedItem:
159	0	case Tag:
160	0	case PushDeployTimeAddress:
161	0	case AssignImmutable:
162	0	case VerbatimBytecode:
163	0	return true;
164	0	case Push:
165	0	case PushTag:
166	0	case PushSub:
167	0	case PushSubSize:
168	0	case PushProgramSize:
169	0	case PushData:
170	0	case PushLibraryAddress:
171	0	case PushImmutable:
172	0	return false;
173	0	case evmasm::Operation:
174	0	{
175	0	if (isSwapInstruction(_item) \|\| isDupInstruction(_item))
176	0	return false;
177	0	if (_item.instruction() == Instruction::GAS \|\| _item.instruction() == Instruction::PC)
178	0	return true; // GAS and PC assume a specific order of opcodes
179	0	if (_item.instruction() == Instruction::MSIZE)
180	0	return true; // msize is modified already by memory access, avoid that for now
181	0	InstructionInfo info = instructionInfo(_item.instruction());
182	0	if (_item.instruction() == Instruction::SSTORE)
183	0	return false;
184	0	if (_item.instruction() == Instruction::MSTORE)
185	0	return false;
186	0	if (!_msizeImportant && (
187	0	_item.instruction() == Instruction::MLOAD \|\|
188	0	_item.instruction() == Instruction::KECCAK256
189	0	))
190	0	return false;
191		//@todo: We do not handle the following memory instructions for now:
192		// calldatacopy, codecopy, extcodecopy, mstore8,
193		// msize (note that msize also depends on memory read access)
194
195		// the second requirement will be lifted once it is implemented
196	0	return info.sideEffects \|\| info.args > 2;
197	0	}
198	0	}
199	0	}
200
201		bool SemanticInformation::isCommutativeOperation(AssemblyItem const& _item)
202	0	{
203	0	if (_item.type() != evmasm::Operation)
204	0	return false;
205	0	switch (_item.instruction())
206	0	{
207	0	case Instruction::ADD:
208	0	case Instruction::MUL:
209	0	case Instruction::EQ:
210	0	case Instruction::AND:
211	0	case Instruction::OR:
212	0	case Instruction::XOR:
213	0	return true;
214	0	default:
215	0	return false;
216	0	}
217	0	}
218
219		bool SemanticInformation::isDupInstruction(AssemblyItem const& _item)
220	0	{
221	0	if (_item.type() != evmasm::Operation)
222	0	return false;
223	0	return evmasm::isDupInstruction(_item.instruction());
224	0	}
225
226		bool SemanticInformation::isSwapInstruction(AssemblyItem const& _item)
227	0	{
228	0	if (_item.type() != evmasm::Operation)
229	0	return false;
230	0	return evmasm::isSwapInstruction(_item.instruction());
231	0	}
232
233		bool SemanticInformation::isJumpInstruction(AssemblyItem const& _item)
234	0	{
235	0	return _item == Instruction::JUMP \|\| _item == Instruction::JUMPI;
236	0	}
237
238		bool SemanticInformation::altersControlFlow(AssemblyItem const& _item)
239	0	{
240	0	if (_item.type() != evmasm::Operation)
241	0	return false;
242	0	switch (_item.instruction())
243	0	{
244		// note that CALL, CALLCODE and CREATE do not really alter the control flow, because we
245		// continue on the next instruction
246	0	case Instruction::JUMP:
247	0	case Instruction::JUMPI:
248	0	case Instruction::RETURN:
249	0	case Instruction::SELFDESTRUCT:
250	0	case Instruction::STOP:
251	0	case Instruction::INVALID:
252	0	case Instruction::REVERT:
253	0	return true;
254	0	default:
255	0	return false;
256	0	}
257	0	}
258
259		bool SemanticInformation::terminatesControlFlow(Instruction _instruction)
260	0	{
261	0	switch (_instruction)
262	0	{
263	0	case Instruction::RETURN:
264	0	case Instruction::SELFDESTRUCT:
265	0	case Instruction::STOP:
266	0	case Instruction::INVALID:
267	0	case Instruction::REVERT:
268	0	return true;
269	0	default:
270	0	return false;
271	0	}
272	0	}
273
274		bool SemanticInformation::reverts(Instruction _instruction)
275	0	{
276	0	switch (_instruction)
277	0	{
278	0	case Instruction::INVALID:
279	0	case Instruction::REVERT:
280	0	return true;
281	0	default:
282	0	return false;
283	0	}
284	0	}
285
286		bool SemanticInformation::isDeterministic(AssemblyItem const& _item)
287	0	{
288	0	assertThrow(_item.type() != VerbatimBytecode, AssemblyException, "");
289
290	0	if (_item.type() != evmasm::Operation)
291	0	return true;
292
293	0	switch (_item.instruction())
294	0	{
295	0	case Instruction::CALL:
296	0	case Instruction::CALLCODE:
297	0	case Instruction::DELEGATECALL:
298	0	case Instruction::STATICCALL:
299	0	case Instruction::CREATE:
300	0	case Instruction::CREATE2:
301	0	case Instruction::GAS:
302	0	case Instruction::PC:
303	0	case Instruction::MSIZE: // depends on previous writes and reads, not only on content
304	0	case Instruction::BALANCE: // depends on previous calls
305	0	case Instruction::SELFBALANCE: // depends on previous calls
306	0	case Instruction::EXTCODESIZE:
307	0	case Instruction::EXTCODEHASH:
308	0	case Instruction::RETURNDATACOPY: // depends on previous calls
309	0	case Instruction::RETURNDATASIZE:
310	0	return false;
311	0	default:
312	0	return true;
313	0	}
314	0	}
315
316		bool SemanticInformation::movable(Instruction _instruction)
317	0	{
318		// These are not really functional.
319	0	if (isDupInstruction(_instruction) \|\| isSwapInstruction(_instruction))
320	0	return false;
321	0	InstructionInfo info = instructionInfo(_instruction);
322	0	if (info.sideEffects)
323	0	return false;
324	0	switch (_instruction)
325	0	{
326	0	case Instruction::KECCAK256:
327	0	case Instruction::BALANCE:
328	0	case Instruction::SELFBALANCE:
329	0	case Instruction::EXTCODESIZE:
330	0	case Instruction::EXTCODEHASH:
331	0	case Instruction::RETURNDATASIZE:
332	0	case Instruction::SLOAD:
333	0	case Instruction::PC:
334	0	case Instruction::MSIZE:
335	0	case Instruction::GAS:
336	0	return false;
337	0	default:
338	0	return true;
339	0	}
340	0	return true;
341	0	}
342
343		bool SemanticInformation::canBeRemoved(Instruction _instruction)
344	0	{
345		// These are not really functional.
346	0	assertThrow(!isDupInstruction(_instruction) && !isSwapInstruction(_instruction), AssemblyException, "");
347
348	0	return !instructionInfo(_instruction).sideEffects;
349	0	}
350
351		bool SemanticInformation::canBeRemovedIfNoMSize(Instruction _instruction)
352	0	{
353	0	if (_instruction == Instruction::KECCAK256 \|\| _instruction == Instruction::MLOAD)
354	0	return true;
355	0	else
356	0	return canBeRemoved(_instruction);
357	0	}
358
359		SemanticInformation::Effect SemanticInformation::memory(Instruction _instruction)
360	0	{
361	0	switch (_instruction)
362	0	{
363	0	case Instruction::CALLDATACOPY:
364	0	case Instruction::CODECOPY:
365	0	case Instruction::EXTCODECOPY:
366	0	case Instruction::RETURNDATACOPY:
367	0	case Instruction::MSTORE:
368	0	case Instruction::MSTORE8:
369	0	case Instruction::CALL:
370	0	case Instruction::CALLCODE:
371	0	case Instruction::DELEGATECALL:
372	0	case Instruction::STATICCALL:
373	0	return SemanticInformation::Write;
374
375	0	case Instruction::CREATE:
376	0	case Instruction::CREATE2:
377	0	case Instruction::KECCAK256:
378	0	case Instruction::MLOAD:
379	0	case Instruction::MSIZE:
380	0	case Instruction::RETURN:
381	0	case Instruction::REVERT:
382	0	case Instruction::LOG0:
383	0	case Instruction::LOG1:
384	0	case Instruction::LOG2:
385	0	case Instruction::LOG3:
386	0	case Instruction::LOG4:
387	0	return SemanticInformation::Read;
388
389	0	default:
390	0	return SemanticInformation::None;
391	0	}
392	0	}
393
394		bool SemanticInformation::movableApartFromEffects(Instruction _instruction)
395	0	{
396	0	switch (_instruction)
397	0	{
398	0	case Instruction::EXTCODEHASH:
399	0	case Instruction::EXTCODESIZE:
400	0	case Instruction::RETURNDATASIZE:
401	0	case Instruction::BALANCE:
402	0	case Instruction::SELFBALANCE:
403	0	case Instruction::SLOAD:
404	0	case Instruction::KECCAK256:
405	0	case Instruction::MLOAD:
406	0	return true;
407
408	0	default:
409	0	return movable(_instruction);
410	0	}
411	0	}
412
413		SemanticInformation::Effect SemanticInformation::storage(Instruction _instruction)
414	0	{
415	0	switch (_instruction)
416	0	{
417	0	case Instruction::CALL:
418	0	case Instruction::CALLCODE:
419	0	case Instruction::DELEGATECALL:
420	0	case Instruction::CREATE:
421	0	case Instruction::CREATE2:
422	0	case Instruction::SSTORE:
423	0	return SemanticInformation::Write;
424
425	0	case Instruction::SLOAD:
426	0	case Instruction::STATICCALL:
427	0	return SemanticInformation::Read;
428
429	0	default:
430	0	return SemanticInformation::None;
431	0	}
432	0	}
433
434		SemanticInformation::Effect SemanticInformation::otherState(Instruction _instruction)
435	0	{
436	0	switch (_instruction)
437	0	{
438	0	case Instruction::CALL:
439	0	case Instruction::CALLCODE:
440	0	case Instruction::DELEGATECALL:
441	0	case Instruction::CREATE:
442	0	case Instruction::CREATE2:
443	0	case Instruction::SELFDESTRUCT:
444	0	case Instruction::STATICCALL: // because it can affect returndatasize
445		// Strictly speaking, log0, .., log4 writes to the state, but the EVM cannot read it, so they
446		// are just marked as having 'other side effects.'
447	0	return SemanticInformation::Write;
448
449	0	case Instruction::EXTCODESIZE:
450	0	case Instruction::EXTCODEHASH:
451	0	case Instruction::RETURNDATASIZE:
452	0	case Instruction::BALANCE:
453	0	case Instruction::SELFBALANCE:
454	0	case Instruction::RETURNDATACOPY:
455	0	case Instruction::EXTCODECOPY:
456		// PC and GAS are specifically excluded here. Instructions such as CALLER, CALLVALUE,
457		// ADDRESS are excluded because they cannot change during execution.
458	0	return SemanticInformation::Read;
459
460	0	default:
461	0	return SemanticInformation::None;
462	0	}
463	0	}
464
465		bool SemanticInformation::invalidInPureFunctions(Instruction _instruction)
466	0	{
467	0	switch (_instruction)
468	0	{
469	0	case Instruction::ADDRESS:
470	0	case Instruction::SELFBALANCE:
471	0	case Instruction::BALANCE:
472	0	case Instruction::ORIGIN:
473	0	case Instruction::CALLER:
474	0	case Instruction::CALLVALUE:
475	0	case Instruction::CHAINID:
476	0	case Instruction::BASEFEE:
477	0	case Instruction::GAS:
478	0	case Instruction::GASPRICE:
479	0	case Instruction::EXTCODESIZE:
480	0	case Instruction::EXTCODECOPY:
481	0	case Instruction::EXTCODEHASH:
482	0	case Instruction::BLOCKHASH:
483	0	case Instruction::COINBASE:
484	0	case Instruction::TIMESTAMP:
485	0	case Instruction::NUMBER:
486	0	case Instruction::DIFFICULTY:
487	0	case Instruction::GASLIMIT:
488	0	case Instruction::STATICCALL:
489	0	case Instruction::SLOAD:
490	0	return true;
491	0	default:
492	0	break;
493	0	}
494	0	return invalidInViewFunctions(_instruction);
495	0	}
496
497		bool SemanticInformation::invalidInViewFunctions(Instruction _instruction)
498	0	{
499	0	switch (_instruction)
500	0	{
501	0	case Instruction::SSTORE:
502	0	case Instruction::JUMP:
503	0	case Instruction::JUMPI:
504	0	case Instruction::LOG0:
505	0	case Instruction::LOG1:
506	0	case Instruction::LOG2:
507	0	case Instruction::LOG3:
508	0	case Instruction::LOG4:
509	0	case Instruction::CREATE:
510	0	case Instruction::CALL:
511	0	case Instruction::CALLCODE:
512	0	case Instruction::DELEGATECALL:
513	0	case Instruction::CREATE2:
514	0	case Instruction::SELFDESTRUCT:
515	0	return true;
516	0	default:
517	0	break;
518	0	}
519	0	return false;
520	0	}