1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
|
/*
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/>.
*/
/** @file GasMeter.cpp
* @author Christian <c@ethdev.com>
* @date 2015
*/
#include "GasMeter.h"
#include <libevmasm/KnownState.h>
using namespace std;
using namespace dev;
using namespace dev::eth;
GasMeter::GasConsumption& GasMeter::GasConsumption::operator+=(GasConsumption const& _other)
{
if (_other.isInfinite && !isInfinite)
*this = infinite();
if (isInfinite)
return *this;
bigint v = bigint(value) + _other.value;
if (v > numeric_limits<u256>::max())
*this = infinite();
else
value = u256(v);
return *this;
}
GasMeter::GasConsumption GasMeter::estimateMax(AssemblyItem const& _item, bool _includeExternalCosts)
{
GasConsumption gas;
switch (_item.type())
{
case Push:
case PushTag:
case PushData:
case PushString:
case PushSub:
case PushSubSize:
case PushProgramSize:
case PushLibraryAddress:
gas = runGas(Instruction::PUSH1);
break;
case Tag:
gas = runGas(Instruction::JUMPDEST);
break;
case Operation:
{
ExpressionClasses& classes = m_state->expressionClasses();
gas = runGas(_item.instruction());
switch (_item.instruction())
{
case Instruction::SSTORE:
{
ExpressionClasses::Id slot = m_state->relativeStackElement(0);
ExpressionClasses::Id value = m_state->relativeStackElement(-1);
if (classes.knownZero(value) || (
m_state->storageContent().count(slot) &&
classes.knownNonZero(m_state->storageContent().at(slot))
))
gas += GasCosts::sstoreResetGas; //@todo take refunds into account
else
gas += GasCosts::sstoreSetGas;
break;
}
case Instruction::SLOAD:
gas += GasCosts::sloadGas;
break;
case Instruction::RETURN:
case Instruction::REVERT:
gas += memoryGas(0, -1);
break;
case Instruction::MLOAD:
case Instruction::MSTORE:
gas += memoryGas(classes.find(Instruction::ADD, {
m_state->relativeStackElement(0),
classes.find(AssemblyItem(32))
}));
break;
case Instruction::MSTORE8:
gas += memoryGas(classes.find(Instruction::ADD, {
m_state->relativeStackElement(0),
classes.find(AssemblyItem(1))
}));
break;
case Instruction::KECCAK256:
gas = GasCosts::keccak256Gas;
gas += wordGas(GasCosts::keccak256WordGas, m_state->relativeStackElement(-1));
gas += memoryGas(0, -1);
break;
case Instruction::CALLDATACOPY:
case Instruction::CODECOPY:
gas += memoryGas(0, -2);
gas += wordGas(GasCosts::copyGas, m_state->relativeStackElement(-2));
break;
case Instruction::EXTCODECOPY:
gas += memoryGas(-1, -3);
gas += wordGas(GasCosts::copyGas, m_state->relativeStackElement(-3));
break;
case Instruction::LOG0:
case Instruction::LOG1:
case Instruction::LOG2:
case Instruction::LOG3:
case Instruction::LOG4:
{
unsigned n = unsigned(_item.instruction()) - unsigned(Instruction::LOG0);
gas = GasCosts::logGas + GasCosts::logTopicGas * n;
gas += memoryGas(0, -1);
if (u256 const* value = classes.knownConstant(m_state->relativeStackElement(-1)))
gas += GasCosts::logDataGas * (*value);
else
gas = GasConsumption::infinite();
break;
}
case Instruction::CALL:
case Instruction::CALLCODE:
case Instruction::DELEGATECALL:
{
if (_includeExternalCosts)
// We assume that we do not know the target contract and thus, the consumption is infinite.
gas = GasConsumption::infinite();
else
{
gas = GasCosts::callGas;
if (u256 const* value = classes.knownConstant(m_state->relativeStackElement(0)))
gas += (*value);
else
gas = GasConsumption::infinite();
if (_item.instruction() == Instruction::CALL)
gas += GasCosts::callNewAccountGas; // We very rarely know whether the address exists.
int valueSize = _item.instruction() == Instruction::DELEGATECALL ? 0 : 1;
if (!classes.knownZero(m_state->relativeStackElement(-1 - valueSize)))
gas += GasCosts::callValueTransferGas;
gas += memoryGas(-2 - valueSize, -3 - valueSize);
gas += memoryGas(-4 - valueSize, -5 - valueSize);
}
break;
}
case Instruction::SELFDESTRUCT:
gas = GasCosts::selfdestructGas;
gas += GasCosts::callNewAccountGas; // We very rarely know whether the address exists.
break;
case Instruction::CREATE:
if (_includeExternalCosts)
// We assume that we do not know the target contract and thus, the consumption is infinite.
gas = GasConsumption::infinite();
else
{
gas = GasCosts::createGas;
gas += memoryGas(-1, -2);
}
break;
case Instruction::EXP:
gas = GasCosts::expGas;
if (u256 const* value = classes.knownConstant(m_state->relativeStackElement(-1)))
gas += GasCosts::expByteGas * (32 - (h256(*value).firstBitSet() / 8));
else
gas += GasCosts::expByteGas * 32;
break;
default:
break;
}
break;
}
default:
gas = GasConsumption::infinite();
break;
}
m_state->feedItem(_item);
return gas;
}
GasMeter::GasConsumption GasMeter::wordGas(u256 const& _multiplier, ExpressionClasses::Id _position)
{
u256 const* value = m_state->expressionClasses().knownConstant(_position);
if (!value)
return GasConsumption::infinite();
return GasConsumption(_multiplier * ((*value + 31) / 32));
}
GasMeter::GasConsumption GasMeter::memoryGas(ExpressionClasses::Id _position)
{
u256 const* value = m_state->expressionClasses().knownConstant(_position);
if (!value)
return GasConsumption::infinite();
if (*value < m_largestMemoryAccess)
return GasConsumption(u256(0));
u256 previous = m_largestMemoryAccess;
m_largestMemoryAccess = *value;
auto memGas = [=](u256 const& pos) -> u256
{
u256 size = (pos + 31) / 32;
return GasCosts::memoryGas * size + size * size / GasCosts::quadCoeffDiv;
};
return memGas(*value) - memGas(previous);
}
GasMeter::GasConsumption GasMeter::memoryGas(int _stackPosOffset, int _stackPosSize)
{
ExpressionClasses& classes = m_state->expressionClasses();
if (classes.knownZero(m_state->relativeStackElement(_stackPosSize)))
return GasConsumption(0);
else
return memoryGas(classes.find(Instruction::ADD, {
m_state->relativeStackElement(_stackPosOffset),
m_state->relativeStackElement(_stackPosSize)
}));
}
unsigned GasMeter::runGas(Instruction _instruction)
{
if (_instruction == Instruction::JUMPDEST)
return 1;
switch (instructionInfo(_instruction).gasPriceTier)
{
case Tier::Zero: return GasCosts::tier0Gas;
case Tier::Base: return GasCosts::tier1Gas;
case Tier::VeryLow: return GasCosts::tier2Gas;
case Tier::Low: return GasCosts::tier3Gas;
case Tier::Mid: return GasCosts::tier4Gas;
case Tier::High: return GasCosts::tier5Gas;
case Tier::Ext: return GasCosts::tier6Gas;
case Tier::Special: return GasCosts::tier7Gas;
case Tier::ExtCode: return GasCosts::extCodeGas;
case Tier::Balance: return GasCosts::balanceGas;
default: break;
}
assertThrow(false, OptimizerException, "Invalid gas tier.");
return 0;
}
|
