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Merge pull request #12796 from ethereum/refactorStackCompressor

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Refactor stack compressor
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chriseth 2022-03-16 16:36:41 +01:00 committed by GitHub
commit af86a80536
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6 changed files with 99 additions and 130 deletions
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20
libyul/optimiser/NameCollector.cpp
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@ -30,18 +30,22 @@ using namespace solidity::util;
void NameCollector::operator()(VariableDeclaration const& _varDecl)
{
for (auto const& var: _varDecl.variables)
m_names.emplace(var.name);
if (m_collectWhat != OnlyFunctions)
for (auto const& var: _varDecl.variables)
m_names.emplace(var.name);
}
void NameCollector::operator ()(FunctionDefinition const& _funDef)
void NameCollector::operator()(FunctionDefinition const& _funDef)
{
if (m_collectWhat == VariablesAndFunctions)
if (m_collectWhat != OnlyVariables)
m_names.emplace(_funDef.name);
for (auto const& arg: _funDef.parameters)
m_names.emplace(arg.name);
for (auto const& ret: _funDef.returnVariables)
m_names.emplace(ret.name);
if (m_collectWhat != OnlyFunctions)
{
for (auto const& arg: _funDef.parameters)
m_names.emplace(arg.name);
for (auto const& ret: _funDef.returnVariables)
m_names.emplace(ret.name);
}
ASTWalker::operator ()(_funDef);
}

2
libyul/optimiser/NameCollector.h
View File

@ -35,7 +35,7 @@ namespace solidity::yul
class NameCollector: public ASTWalker
{
public:
enum CollectWhat { VariablesAndFunctions, OnlyVariables };
enum CollectWhat { VariablesAndFunctions, OnlyVariables, OnlyFunctions };
explicit NameCollector(
Block const& _block,

23
libyul/optimiser/Rematerialiser.cpp
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@ -37,16 +37,6 @@ void Rematerialiser::run(Dialect const& _dialect, Block& _ast, set<YulString> _v
Rematerialiser{_dialect, _ast, std::move(_varsToAlwaysRematerialize), _onlySelectedVariables}(_ast);
}
void Rematerialiser::run(
Dialect const& _dialect,
FunctionDefinition& _function,
set<YulString> _varsToAlwaysRematerialize,
bool _onlySelectedVariables
)
{
Rematerialiser{_dialect, _function, std::move(_varsToAlwaysRematerialize), _onlySelectedVariables}(_function);
}
Rematerialiser::Rematerialiser(
Dialect const& _dialect,
Block& _ast,
@ -60,19 +50,6 @@ Rematerialiser::Rematerialiser(
{
}
Rematerialiser::Rematerialiser(
Dialect const& _dialect,
FunctionDefinition& _function,
set<YulString> _varsToAlwaysRematerialize,
bool _onlySelectedVariables
):
DataFlowAnalyzer(_dialect),
m_referenceCounts(ReferencesCounter::countReferences(_function)),
m_varsToAlwaysRematerialize(std::move(_varsToAlwaysRematerialize)),
m_onlySelectedVariables(_onlySelectedVariables)
{
}
void Rematerialiser::visit(Expression& _e)
{
if (holds_alternative<Identifier>(_e))

12
libyul/optimiser/Rematerialiser.h
View File

@ -53,12 +53,6 @@ public:
std::set<YulString> _varsToAlwaysRematerialize = {},
bool _onlySelectedVariables = false
);
static void run(
Dialect const& _dialect,
FunctionDefinition& _function,
std::set<YulString> _varsToAlwaysRematerialize = {},
bool _onlySelectedVariables = false
);
protected:
Rematerialiser(
@ -67,12 +61,6 @@ protected:
std::set<YulString> _varsToAlwaysRematerialize = {},
bool _onlySelectedVariables = false
);
Rematerialiser(
Dialect const& _dialect,
FunctionDefinition& _function,
std::set<YulString> _varsToAlwaysRematerialize = {},
bool _onlySelectedVariables = false
);
using DataFlowAnalyzer::operator();

171
libyul/optimiser/StackCompressor.cpp
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@ -50,31 +50,41 @@ namespace
/**
* Class that discovers all variables that can be fully eliminated by rematerialization,
* and the corresponding approximate costs.
*
* Prerequisite: Disambiguator, Function Grouper
*/
class RematCandidateSelector: public DataFlowAnalyzer
{
public:
explicit RematCandidateSelector(Dialect const& _dialect): DataFlowAnalyzer(_dialect) {}
/// @returns a map from rematerialisation costs to a vector of variables to rematerialise
/// @returns a map from function name to rematerialisation costs to a vector of variables to rematerialise
/// and variables that occur in their expression.
/// While the map is sorted by cost, the contained vectors are sorted by the order of occurrence.
map<size_t, vector<tuple<YulString, set<YulString>>>> candidates()
map<YulString, map<size_t, vector<tuple<YulString, set<YulString>>>>> candidates()
{
map<size_t, vector<tuple<YulString, set<YulString>>>> cand;
for (auto const& candidate: m_candidates)
map<YulString, map<size_t, vector<tuple<YulString, set<YulString>>>>> cand;
for (auto const& [functionName, candidate]: m_candidates)
{
if (size_t const* cost = util::valueOrNullptr(m_expressionCodeCost, candidate))
{
size_t numRef = m_numReferences[candidate];
set<YulString> const* ref = references(candidate);
cand[*cost * numRef].emplace_back(candidate, ref ? move(*ref) : set<YulString>{});
cand[functionName][*cost * numRef].emplace_back(candidate, ref ? move(*ref) : set<YulString>{});
}
}
return cand;
}
using DataFlowAnalyzer::operator();
void operator()(FunctionDefinition& _function) override
{
yulAssert(m_currentFunctionName.empty());
m_currentFunctionName = _function.name;
DataFlowAnalyzer::operator()(_function);
m_currentFunctionName = {};
}
void operator()(VariableDeclaration& _varDecl) override
{
DataFlowAnalyzer::operator()(_varDecl);
@ -84,7 +94,7 @@ public:
if (AssignedValue const* value = variableValue(varName))
{
yulAssert(!m_expressionCodeCost.count(varName), "");
m_candidates.emplace_back(varName);
m_candidates.emplace_back(m_currentFunctionName, varName);
m_expressionCodeCost[varName] = CodeCost::codeCost(m_dialect, *value->value);
}
}
@ -122,8 +132,10 @@ public:
m_expressionCodeCost.erase(_variable);
}
/// All candidate variables in order of occurrence.
vector<YulString> m_candidates;
YulString m_currentFunctionName = {};
/// All candidate variables by function name, in order of occurrence.
vector<pair<YulString, YulString>> m_candidates;
/// Candidate variables and the code cost of their value.
map<YulString, size_t> m_expressionCodeCost;
/// Number of references to each candidate variable.
@ -156,62 +168,80 @@ set<YulString> chooseVarsToEliminate(
return varsToEliminate;
}
template <typename ASTNode>
void eliminateVariables(
Dialect const& _dialect,
ASTNode& _node,
size_t _numVariables,
Block& _ast,
map<YulString, int> const& _numVariables,
bool _allowMSizeOptimization
)
{
RematCandidateSelector selector{_dialect};
selector(_node);
Rematerialiser::run(_dialect, _node, chooseVarsToEliminate(selector.candidates(), _numVariables));
UnusedPruner::runUntilStabilised(_dialect, _node, _allowMSizeOptimization);
selector(_ast);
map<YulString, map<size_t, vector<tuple<YulString, set<YulString>>>>> candidates = selector.candidates();
set<YulString> varsToEliminate;
for (auto const& [functionName, numVariables]: _numVariables)
{
yulAssert(numVariables > 0);
varsToEliminate += chooseVarsToEliminate(candidates[functionName], static_cast<size_t>(numVariables));
}
Rematerialiser::run(_dialect, _ast, move(varsToEliminate));
// Do not remove functions.
set<YulString> allFunctions = NameCollector{_ast, NameCollector::OnlyFunctions}.names();
UnusedPruner::runUntilStabilised(_dialect, _ast, _allowMSizeOptimization, nullptr, allFunctions);
}
void eliminateVariables(
void eliminateVariablesOptimizedCodegen(
Dialect const& _dialect,
Block& _block,
vector<StackLayoutGenerator::StackTooDeep> const& _unreachables,
Block& _ast,
map<YulString, vector<StackLayoutGenerator::StackTooDeep>> const& _unreachables,
bool _allowMSizeOptimization
)
{
if (std::all_of(_unreachables.begin(), _unreachables.end(), [](auto const& _item) { return _item.second.empty(); }))
return;
RematCandidateSelector selector{_dialect};
selector(_block);
std::map<YulString, size_t> candidates;
for (auto [cost, candidatesWithCost]: selector.candidates())
for (auto candidate: candidatesWithCost)
candidates[get<0>(candidate)] = cost;
selector(_ast);
map<YulString, size_t> candidates;
for (auto const& [functionName, candidatesInFunction]: selector.candidates())
for (auto [cost, candidatesWithCost]: candidatesInFunction)
for (auto candidate: candidatesWithCost)
candidates[get<0>(candidate)] = cost;
set<YulString> varsToEliminate;
// TODO: this currently ignores the fact that variables may reference other variables we want to eliminate.
for (auto const& unreachable: _unreachables)
{
map<size_t, vector<YulString>> suitableCandidates;
size_t neededSlots = unreachable.deficit;
for (auto varName: unreachable.variableChoices)
for (auto const& [functionName, unreachables]: _unreachables)
for (auto const& unreachable: unreachables)
{
if (varsToEliminate.count(varName))
--neededSlots;
else if (size_t* cost = util::valueOrNullptr(candidates, varName))
if (!util::contains(suitableCandidates[*cost], varName))
suitableCandidates[*cost].emplace_back(varName);
}
for (auto candidatesByCost: suitableCandidates)
{
for (auto candidate: candidatesByCost.second)
if (neededSlots--)
varsToEliminate.emplace(candidate);
else
map<size_t, vector<YulString>> suitableCandidates;
size_t neededSlots = unreachable.deficit;
for (auto varName: unreachable.variableChoices)
{
if (varsToEliminate.count(varName))
--neededSlots;
else if (size_t* cost = util::valueOrNullptr(candidates, varName))
if (!util::contains(suitableCandidates[*cost], varName))
suitableCandidates[*cost].emplace_back(varName);
}
for (auto candidatesByCost: suitableCandidates)
{
for (auto candidate: candidatesByCost.second)
if (neededSlots--)
varsToEliminate.emplace(candidate);
else
break;
if (!neededSlots)
break;
if (!neededSlots)
break;
}
}
}
Rematerialiser::run(_dialect, _block, std::move(varsToEliminate), true);
UnusedPruner::runUntilStabilised(_dialect, _block, _allowMSizeOptimization);
Rematerialiser::run(_dialect, _ast, std::move(varsToEliminate), true);
// Do not remove functions.
set<YulString> allFunctions = NameCollector{_ast, NameCollector::OnlyFunctions}.names();
UnusedPruner::runUntilStabilised(_dialect, _ast, _allowMSizeOptimization, nullptr, allFunctions);
}
}
@ -239,21 +269,12 @@ bool StackCompressor::run(
{
yul::AsmAnalysisInfo analysisInfo = yul::AsmAnalyzer::analyzeStrictAssertCorrect(_dialect, _object);
unique_ptr<CFG> cfg = ControlFlowGraphBuilder::build(analysisInfo, _dialect, *_object.code);
Block& mainBlock = std::get<Block>(_object.code->statements.at(0));
if (
auto stackTooDeepErrors = StackLayoutGenerator::reportStackTooDeep(*cfg, YulString{});
!stackTooDeepErrors.empty()
)
eliminateVariables(_dialect, mainBlock, stackTooDeepErrors, allowMSizeOptimzation);
for (size_t i = 1; i < _object.code->statements.size(); ++i)
{
auto& fun = std::get<FunctionDefinition>(_object.code->statements[i]);
if (
auto stackTooDeepErrors = StackLayoutGenerator::reportStackTooDeep(*cfg, fun.name);
!stackTooDeepErrors.empty()
)
eliminateVariables(_dialect, fun.body, stackTooDeepErrors, allowMSizeOptimzation);
}
eliminateVariablesOptimizedCodegen(
_dialect,
*_object.code,
StackLayoutGenerator::reportStackTooDeep(*cfg),
allowMSizeOptimzation
);
}
else
for (size_t iterations = 0; iterations < _maxIterations; iterations++)
@ -261,32 +282,12 @@ bool StackCompressor::run(
map<YulString, int> stackSurplus = CompilabilityChecker(_dialect, _object, _optimizeStackAllocation).stackDeficit;
if (stackSurplus.empty())
return true;
if (stackSurplus.count(YulString{}))
{
yulAssert(stackSurplus.at({}) > 0, "Invalid surplus value.");
eliminateVariables(
_dialect,
std::get<Block>(_object.code->statements.at(0)),
static_cast<size_t>(stackSurplus.at({})),
allowMSizeOptimzation
);
}
for (size_t i = 1; i < _object.code->statements.size(); ++i)
{
auto& fun = std::get<FunctionDefinition>(_object.code->statements[i]);
if (!stackSurplus.count(fun.name))
continue;
yulAssert(stackSurplus.at(fun.name) > 0, "Invalid surplus value.");
eliminateVariables(
_dialect,
fun,
static_cast<size_t>(stackSurplus.at(fun.name)),
allowMSizeOptimzation
);
}
eliminateVariables(
_dialect,
*_object.code,
stackSurplus,
allowMSizeOptimzation
);
}
return false;
}

1
test/libyul/yulOptimizerTests/stackCompressor/inlineInFunction.yul
View File

@ -11,7 +11,6 @@
// step: stackCompressor
//
// {
// { let x := 8 }
// function f()
// {
// mstore(calldataload(calldataload(9)), add(add(add(add(add(add(add(add(add(add(add(add(add(add(add(add(add(add(calldataload(calldataload(9)), 1), 1), 1), 1), 1), 1), 1), 1), 1), 1), 1), 1), 1), 1), 1), 1), 1), 1))