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Peephole optimizer for double push.

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This commit is contained in:
chriseth 2017-06-14 19:40:53 +02:00
parent f008ddf836
commit e5b0ad562e
4 changed files with 55 additions and 7 deletions
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8
libevmasm/AssemblyItem.h
View File

@ -148,6 +148,14 @@ private:
using AssemblyItems = std::vector<AssemblyItem>;
inline size_t bytesRequired(AssemblyItems const& _items, size_t _addressLength)
{
size_t size = 0;
for (AssemblyItem const& item: _items)
size += item.bytesRequired(_addressLength);
return size;
}
std::ostream& operator<<(std::ostream& _out, AssemblyItem const& _item);
inline std::ostream& operator<<(std::ostream& _out, AssemblyItems const& _items)
{

5
libevmasm/ConstantOptimiser.cpp
View File

@ -99,10 +99,7 @@ bigint ConstantOptimisationMethod::dataGas(bytes const& _data) const
size_t ConstantOptimisationMethod::bytesRequired(AssemblyItems const& _items)
{
size_t size = 0;
for (AssemblyItem const& item: _items)
size += item.bytesRequired(3); // assume 3 byte addresses
return size;
return eth::bytesRequired(_items, 3); // assume 3 byte addresses
}
void ConstantOptimisationMethod::replaceConstants(

23
libevmasm/PeepholeOptimiser.cpp
View File

@ -136,6 +136,21 @@ struct DoubleSwap: SimplePeepholeOptimizerMethod<DoubleSwap, 2>
}
};
struct DoublePush: SimplePeepholeOptimizerMethod<DoublePush, 2>
{
static bool applySimple(AssemblyItem const& _push1, AssemblyItem const& _push2, std::back_insert_iterator<AssemblyItems> _out)
{
if (_push1.type() == Push && _push2.type() == Push && _push1.data() == _push2.data())
{
*_out = _push1;
*_out = {Instruction::DUP1, _push2.location()};
return true;
}
else
return false;
}
};
struct JumpToNext: SimplePeepholeOptimizerMethod<JumpToNext, 3>
{
static size_t applySimple(
@ -235,13 +250,15 @@ bool PeepholeOptimiser::optimise()
{
OptimiserState state {m_items, 0, std::back_inserter(m_optimisedItems)};
while (state.i < m_items.size())
applyMethods(state, PushPop(), OpPop(), DoubleSwap(), JumpToNext(), UnreachableCode(), TagConjunctions(), Identity());
if (m_optimisedItems.size() < m_items.size())
applyMethods(state, PushPop(), OpPop(), DoublePush(), DoubleSwap(), JumpToNext(), UnreachableCode(), TagConjunctions(), Identity());
if (m_optimisedItems.size() < m_items.size() || (
m_optimisedItems.size() == m_items.size() &&
eth::bytesRequired(m_optimisedItems, 3) < eth::bytesRequired(m_items, 3)
))
{
m_items = std::move(m_optimisedItems);
return true;
}
else
return false;
}

26
test/libsolidity/SolidityOptimizer.cpp
View File

@ -1189,6 +1189,32 @@ BOOST_AUTO_TEST_CASE(clear_unreachable_code)
);
}
BOOST_AUTO_TEST_CASE(peephole_double_push)
{
AssemblyItems items{
u256(0),
u256(0),
u256(5),
u256(5),
u256(4),
u256(5)
};
AssemblyItems expectation{
u256(0),
Instruction::DUP1,
u256(5),
Instruction::DUP1,
u256(4),
u256(5)
};
PeepholeOptimiser peepOpt(items);
BOOST_REQUIRE(peepOpt.optimise());
BOOST_CHECK_EQUAL_COLLECTIONS(
items.begin(), items.end(),
expectation.begin(), expectation.end()
);
}
BOOST_AUTO_TEST_CASE(computing_constants)
{
char const* sourceCode = R"(