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Merge pull request #13708 from ethereum/refactor_join_knowledge

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Refactor join knowledge.
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chriseth 2022-11-14 17:40:06 +01:00 committed by GitHub
commit 4100a59cca
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2 changed files with 63 additions and 65 deletions
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95
libyul/optimiser/DataFlowAnalyzer.cpp
View File

@ -72,21 +72,21 @@ void DataFlowAnalyzer::operator()(ExpressionStatement& _statement)
if (auto vars = isSimpleStore(StoreLoadLocation::Storage, _statement))
{
ASTModifier::operator()(_statement);
cxx20::erase_if(m_state.storage, mapTuple([&](auto&& key, auto&& value) {
cxx20::erase_if(m_state.environment.storage, mapTuple([&](auto&& key, auto&& value) {
return
!m_knowledgeBase.knownToBeDifferent(vars->first, key) &&
!m_knowledgeBase.knownToBeEqual(vars->second, value);
}));
m_state.storage[vars->first] = vars->second;
m_state.environment.storage[vars->first] = vars->second;
return;
}
else if (auto vars = isSimpleStore(StoreLoadLocation::Memory, _statement))
{
ASTModifier::operator()(_statement);
cxx20::erase_if(m_state.memory, mapTuple([&](auto&& key, auto&& /* value */) {
cxx20::erase_if(m_state.environment.memory, mapTuple([&](auto&& key, auto&& /* value */) {
return !m_knowledgeBase.knownToBeDifferentByAtLeast32(vars->first, key);
}));
m_state.memory[vars->first] = vars->second;
m_state.environment.memory[vars->first] = vars->second;
return;
}
}
@ -124,12 +124,11 @@ void DataFlowAnalyzer::operator()(VariableDeclaration& _varDecl)
void DataFlowAnalyzer::operator()(If& _if)
{
clearKnowledgeIfInvalidated(*_if.condition);
unordered_map<YulString, YulString> storage = m_state.storage;
unordered_map<YulString, YulString> memory = m_state.memory;
Environment preEnvironment = m_state.environment;
ASTModifier::operator()(_if);
joinKnowledge(storage, memory);
joinKnowledge(preEnvironment);
clearValues(assignedVariableNames(_if.body));
}
@ -141,10 +140,9 @@ void DataFlowAnalyzer::operator()(Switch& _switch)
set<YulString> assignedVariables;
for (auto& _case: _switch.cases)
{
unordered_map<YulString, YulString> storage = m_state.storage;
unordered_map<YulString, YulString> memory = m_state.memory;
Environment preEnvironment = m_state.environment;
(*this)(_case.body);
joinKnowledge(storage, memory);
joinKnowledge(preEnvironment);
set<YulString> variables = assignedVariableNames(_case.body);
assignedVariables += variables;
@ -225,7 +223,7 @@ void DataFlowAnalyzer::operator()(Block& _block)
optional<YulString> DataFlowAnalyzer::storageValue(YulString _key) const
{
if (YulString const* value = util::valueOrNullptr(m_state.storage, _key))
if (YulString const* value = util::valueOrNullptr(m_state.environment.storage, _key))
return *value;
else
return nullopt;
@ -233,7 +231,7 @@ optional<YulString> DataFlowAnalyzer::storageValue(YulString _key) const
optional<YulString> DataFlowAnalyzer::memoryValue(YulString _key) const
{
if (YulString const* value = util::valueOrNullptr(m_state.memory, _key))
if (YulString const* value = util::valueOrNullptr(m_state.environment.memory, _key))
return *value;
else
return nullopt;
@ -267,13 +265,13 @@ void DataFlowAnalyzer::handleAssignment(set<YulString> const& _variables, Expres
if (!_isDeclaration)
{
// assignment to slot denoted by "name"
m_state.storage.erase(name);
m_state.environment.storage.erase(name);
// assignment to slot contents denoted by "name"
cxx20::erase_if(m_state.storage, mapTuple([&name](auto&& /* key */, auto&& value) { return value == name; }));
cxx20::erase_if(m_state.environment.storage, mapTuple([&name](auto&& /* key */, auto&& value) { return value == name; }));
// assignment to slot denoted by "name"
m_state.memory.erase(name);
m_state.environment.memory.erase(name);
// assignment to slot contents denoted by "name"
cxx20::erase_if(m_state.memory, mapTuple([&name](auto&& /* key */, auto&& value) { return value == name; }));
cxx20::erase_if(m_state.environment.memory, mapTuple([&name](auto&& /* key */, auto&& value) { return value == name; }));
}
}
@ -286,9 +284,9 @@ void DataFlowAnalyzer::handleAssignment(set<YulString> const& _variables, Expres
// On the other hand, if we knew the value in the slot
// already, then the sload() / mload() would have been replaced by a variable anyway.
if (auto key = isSimpleLoad(StoreLoadLocation::Memory, *_value))
m_state.memory[*key] = variable;
m_state.environment.memory[*key] = variable;
else if (auto key = isSimpleLoad(StoreLoadLocation::Storage, *_value))
m_state.storage[*key] = variable;
m_state.environment.storage[*key] = variable;
}
}
}
@ -329,8 +327,8 @@ void DataFlowAnalyzer::clearValues(set<YulString> _variables)
auto eraseCondition = mapTuple([&_variables](auto&& key, auto&& value) {
return _variables.count(key) || _variables.count(value);
});
cxx20::erase_if(m_state.storage, eraseCondition);
cxx20::erase_if(m_state.memory, eraseCondition);
cxx20::erase_if(m_state.environment.storage, eraseCondition);
cxx20::erase_if(m_state.environment.memory, eraseCondition);
// Also clear variables that reference variables to be cleared.
for (auto const& variableToClear: _variables)
@ -357,9 +355,9 @@ void DataFlowAnalyzer::clearKnowledgeIfInvalidated(Block const& _block)
return;
SideEffectsCollector sideEffects(m_dialect, _block, &m_functionSideEffects);
if (sideEffects.invalidatesStorage())
m_state.storage.clear();
m_state.environment.storage.clear();
if (sideEffects.invalidatesMemory())
m_state.memory.clear();
m_state.environment.memory.clear();
}
void DataFlowAnalyzer::clearKnowledgeIfInvalidated(Expression const& _expr)
@ -368,35 +366,9 @@ void DataFlowAnalyzer::clearKnowledgeIfInvalidated(Expression const& _expr)
return;
SideEffectsCollector sideEffects(m_dialect, _expr, &m_functionSideEffects);
if (sideEffects.invalidatesStorage())
m_state.storage.clear();
m_state.environment.storage.clear();
if (sideEffects.invalidatesMemory())
m_state.memory.clear();
}
void DataFlowAnalyzer::joinKnowledge(
unordered_map<YulString, YulString> const& _olderStorage,
unordered_map<YulString, YulString> const& _olderMemory
)
{
if (!m_analyzeStores)
return;
joinKnowledgeHelper(m_state.storage, _olderStorage);
joinKnowledgeHelper(m_state.memory, _olderMemory);
}
void DataFlowAnalyzer::joinKnowledgeHelper(
std::unordered_map<YulString, YulString>& _this,
std::unordered_map<YulString, YulString> const& _older
)
{
// We clear if the key does not exist in the older map or if the value is different.
// This also works for memory because _older is an "older version"
// of m_state.memory and thus any overlapping write would have cleared the keys
// that are not known to be different inside m_state.memory already.
cxx20::erase_if(_this, mapTuple([&_older](auto&& key, auto&& currentValue){
YulString const* oldValue = util::valueOrNullptr(_older, key);
return !oldValue || *oldValue != currentValue;
}));
m_state.environment.memory.clear();
}
bool DataFlowAnalyzer::inScope(YulString _variableName) const
@ -443,3 +415,26 @@ std::optional<YulString> DataFlowAnalyzer::isSimpleLoad(
return key->name;
return {};
}
void DataFlowAnalyzer::joinKnowledge(Environment const& _olderEnvironment)
{
if (!m_analyzeStores)
return;
joinKnowledgeHelper(m_state.environment.storage, _olderEnvironment.storage);
joinKnowledgeHelper(m_state.environment.memory, _olderEnvironment.memory);
}
void DataFlowAnalyzer::joinKnowledgeHelper(
std::unordered_map<YulString, YulString>& _this,
std::unordered_map<YulString, YulString> const& _older
)
{
// We clear if the key does not exist in the older map or if the value is different.
// This also works for memory because _older is an "older version"
// of m_state.environment.memory and thus any overlapping write would have cleared the keys
// that are not known to be different inside m_state.environment.memory already.
cxx20::erase_if(_this, mapTuple([&_older](auto&& key, auto&& currentValue){
YulString const* oldValue = util::valueOrNullptr(_older, key);
return !oldValue || *oldValue != currentValue;
}));
}

33
libyul/optimiser/DataFlowAnalyzer.h
View File

@ -131,19 +131,6 @@ protected:
/// Clears knowledge about storage or memory if they may be modified inside the expression.
void clearKnowledgeIfInvalidated(Expression const& _expression);
/// Joins knowledge about storage and memory with an older point in the control-flow.
/// This only works if the current state is a direct successor of the older point,
/// i.e. `_otherStorage` and `_otherMemory` cannot have additional changes.
void joinKnowledge(
std::unordered_map<YulString, YulString> const& _olderStorage,
std::unordered_map<YulString, YulString> const& _olderMemory
);
static void joinKnowledgeHelper(
std::unordered_map<YulString, YulString>& _thisData,
std::unordered_map<YulString, YulString> const& _olderData
);
/// Returns true iff the variable is in scope.
bool inScope(YulString _variableName) const;
@ -176,6 +163,11 @@ protected:
std::map<YulString, SideEffects> m_functionSideEffects;
private:
struct Environment
{
std::unordered_map<YulString, YulString> storage;
std::unordered_map<YulString, YulString> memory;
};
struct State
{
/// Current values of variables, always movable.
@ -183,9 +175,20 @@ private:
/// m_references[a].contains(b) <=> the current expression assigned to a references b
std::unordered_map<YulString, std::set<YulString>> references;
std::unordered_map<YulString, YulString> storage;
std::unordered_map<YulString, YulString> memory;
Environment environment;
};
/// Joins knowledge about storage and memory with an older point in the control-flow.
/// This only works if the current state is a direct successor of the older point,
/// i.e. `_olderState.storage` and `_olderState.memory` cannot have additional changes.
/// Does nothing if memory and storage analysis is disabled / ignored.
void joinKnowledge(Environment const& _olderEnvironment);
static void joinKnowledgeHelper(
std::unordered_map<YulString, YulString>& _thisData,
std::unordered_map<YulString, YulString> const& _olderData
);
State m_state;
protected: