Compatibility with StackCompressor and StackLimitEvader.

libyul/optimiser/Rematerialiser.cpp

@@ -32,39 +32,44 @@ using namespace std;
 using namespace solidity;
 using namespace solidity::yul;
 
-void Rematerialiser::run(Dialect const& _dialect, Block& _ast, set<YulString> _varsToAlwaysRematerialize)
+void Rematerialiser::run(Dialect const& _dialect, Block& _ast, set<YulString> _varsToAlwaysRematerialize, bool _onlySelectedVariables)
 {
-	Rematerialiser{_dialect, _ast, std::move(_varsToAlwaysRematerialize)}(_ast);
+	Rematerialiser{_dialect, _ast, std::move(_varsToAlwaysRematerialize), _onlySelectedVariables}(_ast);
 }
 
 void Rematerialiser::run(
 	Dialect const& _dialect,
 	FunctionDefinition& _function,
-	set<YulString> _varsToAlwaysRematerialize
+	set<YulString> _varsToAlwaysRematerialize,
+	bool _onlySelectedVariables
 )
 {
-	Rematerialiser{_dialect, _function, std::move(_varsToAlwaysRematerialize)}(_function);
+	Rematerialiser{_dialect, _function, std::move(_varsToAlwaysRematerialize), _onlySelectedVariables}(_function);
 }
 
 Rematerialiser::Rematerialiser(
 	Dialect const& _dialect,
 	Block& _ast,
-	set<YulString> _varsToAlwaysRematerialize
+	set<YulString> _varsToAlwaysRematerialize,
+	bool _onlySelectedVariables
 ):
 	DataFlowAnalyzer(_dialect),
 	m_referenceCounts(ReferencesCounter::countReferences(_ast)),
-	m_varsToAlwaysRematerialize(std::move(_varsToAlwaysRematerialize))
+	m_varsToAlwaysRematerialize(std::move(_varsToAlwaysRematerialize)),
+	m_onlySelectedVariables(_onlySelectedVariables)
 {
 }
 
 Rematerialiser::Rematerialiser(
 	Dialect const& _dialect,
 	FunctionDefinition& _function,
-	set<YulString> _varsToAlwaysRematerialize
+	set<YulString> _varsToAlwaysRematerialize,
+	bool _onlySelectedVariables
 ):
 	DataFlowAnalyzer(_dialect),
 	m_referenceCounts(ReferencesCounter::countReferences(_function)),
-	m_varsToAlwaysRematerialize(std::move(_varsToAlwaysRematerialize))
+	m_varsToAlwaysRematerialize(std::move(_varsToAlwaysRematerialize)),
+	m_onlySelectedVariables(_onlySelectedVariables)
 {
 }
 
@@ -81,10 +86,13 @@ void Rematerialiser::visit(Expression& _e)
 			size_t refs = m_referenceCounts[name];
 			size_t cost = CodeCost::codeCost(m_dialect, *value.value);
 			if (
-				(refs <= 1 && value.loopDepth == m_loopDepth) ||
-				cost == 0 ||
-				(refs <= 5 && cost <= 1 && m_loopDepth == 0) ||
-				m_varsToAlwaysRematerialize.count(name)
+				(
+					!m_onlySelectedVariables && (
+						(refs <= 1 && value.loopDepth == m_loopDepth) ||
+						cost == 0 ||
+						(refs <= 5 && cost <= 1 && m_loopDepth == 0)
+					)
+				) || m_varsToAlwaysRematerialize.count(name)
 			)
 			{
 				assertThrow(m_referenceCounts[name] > 0, OptimizerException, "");

libyul/optimiser/Rematerialiser.h

@@ -50,24 +50,28 @@ public:
 	static void run(
 		Dialect const& _dialect,
 		Block& _ast,
-		std::set<YulString> _varsToAlwaysRematerialize = {}
+		std::set<YulString> _varsToAlwaysRematerialize = {},
+		bool _onlySelectedVariables = false
 	);
 	static void run(
 		Dialect const& _dialect,
 		FunctionDefinition& _function,
-		std::set<YulString> _varsToAlwaysRematerialize = {}
+		std::set<YulString> _varsToAlwaysRematerialize = {},
+		bool _onlySelectedVariables = false
 	);
 
 protected:
 	Rematerialiser(
 		Dialect const& _dialect,
 		Block& _ast,
-		std::set<YulString> _varsToAlwaysRematerialize = {}
+		std::set<YulString> _varsToAlwaysRematerialize = {},
+		bool _onlySelectedVariables = false
 	);
 	Rematerialiser(
 		Dialect const& _dialect,
 		FunctionDefinition& _function,
-		std::set<YulString> _varsToAlwaysRematerialize = {}
+		std::set<YulString> _varsToAlwaysRematerialize = {},
+		bool _onlySelectedVariables = false
 	);
 
 	using DataFlowAnalyzer::operator();
@@ -77,6 +81,7 @@ protected:
 
 	std::map<YulString, size_t> m_referenceCounts;
 	std::set<YulString> m_varsToAlwaysRematerialize;
+	bool m_onlySelectedVariables = false;
 };
 
 /**

libyul/optimiser/StackCompressor.cpp

@@ -27,6 +27,13 @@
 #include <libyul/optimiser/Metrics.h>
 #include <libyul/optimiser/Semantics.h>
 
+#include <libyul/backends/evm/ControlFlowGraphBuilder.h>
+#include <libyul/backends/evm/StackHelpers.h>
+#include <libyul/backends/evm/StackLayoutGenerator.h>
+
+#include <libyul/AsmAnalysis.h>
+#include <libyul/AsmAnalysisInfo.h>
+
 #include <libyul/CompilabilityChecker.h>
 
 #include <libyul/AST.h>
@@ -150,6 +157,40 @@ void eliminateVariables(
 	UnusedPruner::runUntilStabilised(_dialect, _node, _allowMSizeOptimization);
 }
 
+void eliminateVariables(
+	Dialect const& _dialect,
+	Block& _block,
+	vector<StackLayoutGenerator::StackTooDeep> const& _unreachables,
+	bool _allowMSizeOptimization
+)
+{
+	RematCandidateSelector selector{_dialect};
+	selector(_block);
+	std::map<YulString, size_t> candidates;
+	for (auto [cost, name, dependencies]: selector.candidates())
+		candidates[name] = cost;
+
+	set<YulString> varsToEliminate;
+
+	for (auto const& unreachable: _unreachables)
+	{
+		set<tuple<size_t, 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))
+				suitableCandidates.insert(std::make_tuple(*cost, varName));
+		}
+
+		for (auto candidate: suitableCandidates | ranges::views::take(neededSlots))
+			varsToEliminate.emplace(get<1>(candidate));
+	}
+	Rematerialiser::run(_dialect, _block, std::move(varsToEliminate), true);
+	UnusedPruner::runUntilStabilised(_dialect, _block, _allowMSizeOptimization);
+}
+
 }
 
 bool StackCompressor::run(
@@ -164,39 +205,63 @@ bool StackCompressor::run(
 		_object.code->statements.size() > 0 && holds_alternative<Block>(_object.code->statements.at(0)),
 		"Need to run the function grouper before the stack compressor."
 	);
+	bool usesOptimizedCodeGenerator = false;
+	if (auto evmDialect = dynamic_cast<EVMDialect const*>(&_dialect))
+		usesOptimizedCodeGenerator = _optimizeStackAllocation && evmDialect->evmVersion() > langutil::EVMVersion::homestead();
 	bool allowMSizeOptimzation = !MSizeFinder::containsMSize(_dialect, *_object.code);
-	for (size_t iterations = 0; iterations < _maxIterations; iterations++)
+	if (usesOptimizedCodeGenerator)
 	{
-		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
-			);
-		}
-
+		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 (!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
-			);
+			if (
+				auto stackTooDeepErrors = StackLayoutGenerator::reportStackTooDeep(*cfg, fun.name);
+				!stackTooDeepErrors.empty()
+			)
+				eliminateVariables(_dialect, fun.body, stackTooDeepErrors, allowMSizeOptimzation);
 		}
 	}
+	else
+		for (size_t iterations = 0; iterations < _maxIterations; iterations++)
+		{
+			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
+				);
+			}
+		}
 	return false;
 }
 

libyul/optimiser/StackLimitEvader.cpp

@@ -21,14 +21,18 @@
 #include <libyul/optimiser/FunctionDefinitionCollector.h>
 #include <libyul/optimiser/NameDispenser.h>
 #include <libyul/optimiser/StackToMemoryMover.h>
+#include <libyul/backends/evm/ControlFlowGraphBuilder.h>
 #include <libyul/backends/evm/EVMDialect.h>
+#include <libyul/AsmAnalysis.h>
 #include <libyul/AST.h>
+#include <libyul/CompilabilityChecker.h>
 #include <libyul/Exceptions.h>
 #include <libyul/Object.h>
 #include <libyul/Utilities.h>
 #include <libsolutil/Algorithms.h>
 #include <libsolutil/CommonData.h>
 
+#include <range/v3/range/conversion.hpp>
 #include <range/v3/view/concat.hpp>
 #include <range/v3/view/take.hpp>
 
@@ -114,6 +118,45 @@ u256 literalArgumentValue(FunctionCall const& _call)
 }
 }
 
+void StackLimitEvader::run(
+	OptimiserStepContext& _context,
+	Object& _object
+)
+{
+	auto const* evmDialect = dynamic_cast<EVMDialect const*>(&_context.dialect);
+	yulAssert(
+		evmDialect && evmDialect->providesObjectAccess(),
+		"StackLimitEvader can only be run on objects using the EVMDialect with object access."
+	);
+	if (evmDialect && evmDialect->evmVersion() > langutil::EVMVersion::homestead())
+	{
+		yul::AsmAnalysisInfo analysisInfo = yul::AsmAnalyzer::analyzeStrictAssertCorrect(*evmDialect, _object);
+		unique_ptr<CFG> cfg = ControlFlowGraphBuilder::build(analysisInfo, *evmDialect, *_object.code);
+		run(_context, _object, StackLayoutGenerator::reportStackTooDeep(*cfg));
+	}
+	else
+		run(_context, _object, CompilabilityChecker{
+			_context.dialect,
+			_object,
+			true
+		}.unreachableVariables);
+
+}
+
+void StackLimitEvader::run(
+	OptimiserStepContext& _context,
+	Object& _object,
+	map<YulString, vector<StackLayoutGenerator::StackTooDeep>> const& _stackTooDeepErrors
+)
+{
+	map<YulString, set<YulString>> unreachableVariables;
+	for (auto&& [function, stackTooDeepErrors]: _stackTooDeepErrors)
+		// TODO: choose wisely.
+		for (auto const& stackTooDeepError: stackTooDeepErrors)
+			unreachableVariables[function] += stackTooDeepError.variableChoices | ranges::views::take(stackTooDeepError.deficit) | ranges::to<set<YulString>>;
+	run(_context, _object, unreachableVariables);
+}
+
 void StackLimitEvader::run(
 	OptimiserStepContext& _context,
 	Object& _object,

libyul/optimiser/StackLimitEvader.h

@@ -22,6 +22,7 @@
 #pragma once
 
 #include <libyul/optimiser/OptimiserStep.h>
+#include <libyul/backends/evm/StackLayoutGenerator.h>
 
 namespace solidity::yul
 {
@@ -61,6 +62,25 @@ public:
 		Object& _object,
 		std::map<YulString, std::set<YulString>> const& _unreachableVariables
 	);
+	/// @a _stackTooDeepErrors can be determined by the StackLayoutGenerator.
+	/// Can only be run on the EVM dialect with objects.
+	/// Abort and do nothing, if no ``memoryguard`` call or several ``memoryguard`` calls
+	/// with non-matching arguments are found, or if any of the @a _stackTooDeepErrors
+	/// are contained in a recursive function.
+	static void run(
+		OptimiserStepContext& _context,
+		Object& _object,
+		std::map<YulString, std::vector<StackLayoutGenerator::StackTooDeep>> const& _stackTooDeepErrors
+	);
+	/// Determines stack too deep errors using the appropriate code generation backend.
+	/// Can only be run on the EVM dialect with objects.
+	/// Abort and do nothing, if no ``memoryguard`` call or several ``memoryguard`` calls
+	/// with non-matching arguments are found, or if any of the unreachable variables
+	/// are contained in a recursive function.
+	static void run(
+		OptimiserStepContext& _context,
+		Object& _object
+	);
 };
 
 }

libyul/optimiser/Suite.cpp

@@ -92,6 +92,11 @@ void OptimiserSuite::run(
 	set<YulString> const& _externallyUsedIdentifiers
 )
 {
+	EVMDialect const* evmDialect = dynamic_cast<EVMDialect const*>(&_dialect);
+	bool usesOptimizedCodeGenerator =
+		_optimizeStackAllocation &&
+		evmDialect &&
+		evmDialect->evmVersion() > langutil::EVMVersion::homestead();
 	set<YulString> reservedIdentifiers = _externallyUsedIdentifiers;
 	reservedIdentifiers += _dialect.fixedFunctionNames();
 
@@ -118,24 +123,32 @@ void OptimiserSuite::run(
 
 	// We ignore the return value because we will get a much better error
 	// message once we perform code generation.
-	StackCompressor::run(
-		_dialect,
-		_object,
-		_optimizeStackAllocation,
-		stackCompressorMaxIterations
-	);
+	if (!usesOptimizedCodeGenerator)
+		StackCompressor::run(
+			_dialect,
+			_object,
+			_optimizeStackAllocation,
+			stackCompressorMaxIterations
+		);
 	suite.runSequence("fDnTOc g", ast);
 
-	if (EVMDialect const* dialect = dynamic_cast<EVMDialect const*>(&_dialect))
+	if (evmDialect)
 	{
 		yulAssert(_meter, "");
-		ConstantOptimiser{*dialect, *_meter}(ast);
-		if (dialect->providesObjectAccess() && _optimizeStackAllocation)
-			StackLimitEvader::run(suite.m_context, _object, CompilabilityChecker{
+		ConstantOptimiser{*evmDialect, *_meter}(ast);
+		if (usesOptimizedCodeGenerator)
+		{
+			StackCompressor::run(
 				_dialect,
 				_object,
-				_optimizeStackAllocation
-			}.unreachableVariables);
+				_optimizeStackAllocation,
+				stackCompressorMaxIterations
+			);
+			if (evmDialect->providesObjectAccess())
+				StackLimitEvader::run(suite.m_context, _object);
+		}
+		else if (evmDialect->providesObjectAccess() && _optimizeStackAllocation)
+			StackLimitEvader::run(suite.m_context, _object);
 	}
 	else if (dynamic_cast<WasmDialect const*>(&_dialect))
 	{