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This commit is contained in:
chriseth 2022-03-17 17:27:17 +01:00
parent b835716fb4
commit 52b32374a1
1 changed files with 28 additions and 9 deletions
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37
libyul/optimiser/DataFlowAnalyzer.cpp
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@ -192,6 +192,7 @@ void DataFlowAnalyzer::operator()(Break&)
if (m_breakState) if (m_breakState)
joinKnowledge(*m_breakState); joinKnowledge(*m_breakState);
m_breakState = move(m_state); m_breakState = move(m_state);
m_state = {};
// we now have an empty state, which will clear everything. // we now have an empty state, which will clear everything.
// if this is in a conditional, it will be ignored. // if this is in a conditional, it will be ignored.
} }
@ -201,6 +202,7 @@ void DataFlowAnalyzer::operator()(Continue&)
if (m_continueState) if (m_continueState)
joinKnowledge(*m_continueState); joinKnowledge(*m_continueState);
m_continueState = move(m_state); m_continueState = move(m_state);
m_state = {};
// we now have an empty state, which will clear everything. // we now have an empty state, which will clear everything.
// if this is in a conditional, it will be ignored. // if this is in a conditional, it will be ignored.
} }
@ -224,16 +226,31 @@ void DataFlowAnalyzer::operator()(ForLoop& _for)
visit(*_for.condition); visit(*_for.condition);
State preState = m_state; State preLoopState = m_state;
(*this)(_for.body); (*this)(_for.body);
if (m_continueState) if (m_continueState)
joinKnowledge(*m_continueState); {
if (hasFlowOutControlFlow(_for.body))
joinKnowledge(*m_continueState);
else
m_state = move(*m_continueState);
}
(*this)(_for.post); (*this)(_for.post);
if (m_breakState)
joinKnowledge(*m_breakState);
joinKnowledge(preState); if (m_breakState)
{
if (hasFlowOutControlFlow(_for.post))
joinKnowledge(*m_breakState);
else
m_state = move(*m_breakState);
// TODO The state here is after post, but we actually
// execute the condition once more.
// On the other hand, we already clear knowledge before
// assigning preLoopState.
}
joinKnowledge(preLoopState);
--m_loopDepth; --m_loopDepth;
} }
@ -451,10 +468,6 @@ void DataFlowAnalyzer::joinKnowledge(State const& _olderState)
joinKnowledgeHelper(m_state.storage, _olderState.storage); joinKnowledgeHelper(m_state.storage, _olderState.storage);
joinKnowledgeHelper(m_state.memory, _olderState.memory); joinKnowledgeHelper(m_state.memory, _olderState.memory);
// TODO verify that this does not have to be symmetric,
// i.e. that variables that are only in _olderState
// do not have to be cleared here.
// We should not rely on _olderState really being an ancestor.
set<YulString> variablesToClear; set<YulString> variablesToClear;
for (auto it = m_state.latestAssignment.begin(); it != m_state.latestAssignment.end();) for (auto it = m_state.latestAssignment.begin(); it != m_state.latestAssignment.end();)
{ {
@ -470,6 +483,12 @@ void DataFlowAnalyzer::joinKnowledge(State const& _olderState)
it = m_state.latestAssignment.erase(it); it = m_state.latestAssignment.erase(it);
} }
} }
// TODO is there a way we don't have to iterate both?
// Can we iterate in parallel?
for (auto&& [var, counter]: _olderState.latestAssignment)
if (!m_state.latestAssignment.count(var))
variablesToClear.emplace(var);
clearValues(variablesToClear); clearValues(variablesToClear);
} }