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Assume peephole optimizer was successful if number of pops increased.

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This commit is contained in:
chriseth 2017-10-13 18:59:04 +02:00
parent d9bb4b44a4
commit 7c94e5462a
4 changed files with 25 additions and 3 deletions
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1
Changelog.md
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@ -13,6 +13,7 @@ Features:
* Type Checker: Require ``storage`` or ``memory`` keyword for local variables as experimental 0.5.0 feature.
Bugfixes:
* Optimizer: Remove unused stack computation results.
* Parser: Fix source location of VariableDeclarationStatement.
* Type Checker: Properly check array length and don't rely on an assertion in code generation.
* Type Checker: Properly support overwriting members inherited from ``address`` in a contract

2
libevmasm/Assembly.cpp
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@ -407,7 +407,7 @@ map<u256, u256> Assembly::optimiseInternal(
if (_settings.runPeephole)
{
PeepholeOptimiser peepOpt(m_items);
while (peepOpt.optimise())
while (peepOpt.optimise() && count < 0xffffff)
count++;
}

11
libevmasm/PeepholeOptimiser.cpp
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@ -249,6 +249,11 @@ void applyMethods(OptimiserState& _state, Method, OtherMethods... _other)
applyMethods(_state, _other...);
}
size_t numberOfPops(AssemblyItems const& _items)
{
return std::count(_items.begin(), _items.end(), Instruction::POP);
}
}
bool PeepholeOptimiser::optimise()
@ -257,8 +262,10 @@ bool PeepholeOptimiser::optimise()
while (state.i < 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_optimisedItems.size() == m_items.size() && (
eth::bytesRequired(m_optimisedItems, 3) < eth::bytesRequired(m_items, 3) ||
numberOfPops(m_optimisedItems) > numberOfPops(m_items)
)
))
{
m_items = std::move(m_optimisedItems);

14
test/libevmasm/Optimiser.cpp
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@ -841,6 +841,20 @@ BOOST_AUTO_TEST_CASE(peephole_double_push)
);
}
BOOST_AUTO_TEST_CASE(peephole_pop_calldatasize)
{
AssemblyItems items{
u256(4),
Instruction::CALLDATASIZE,
Instruction::LT,
Instruction::POP
};
PeepholeOptimiser peepOpt(items);
for (size_t i = 0; i < 3; i++)
BOOST_CHECK(peepOpt.optimise());
BOOST_CHECK(items.empty());
}
BOOST_AUTO_TEST_CASE(jumpdest_removal)
{
AssemblyItems items{