Compatibility with StackCompressor and StackLimitEvader.

libsolidity/codegen/ir/IRGenerator.cpp

@@ -1069,9 +1069,6 @@ string IRGenerator::dispatchRoutine(ContractDefinition const& _contract)
 
 string IRGenerator::memoryInit(bool _useMemoryGuard)
 {
-	// TODO: Remove once we have made sure it is safe, i.e. after "Yul memory objects lite".
-	//       Also restore the tests removed in the commit that adds this comment.
-	_useMemoryGuard = false;
 	// This function should be called at the beginning of the EVM call frame
 	// and thus can assume all memory to be zero, including the contents of
 	// the "zero memory area" (the position CompilerUtils::zeroPointer points to).

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>
@@ -162,6 +169,50 @@ 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, candidatesWithCost]: selector.candidates())
+		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)
+		{
+			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;
+		}
+	}
+	Rematerialiser::run(_dialect, _block, std::move(varsToEliminate), true);
+	UnusedPruner::runUntilStabilised(_dialect, _block, _allowMSizeOptimization);
+}
+
 }
 
 bool StackCompressor::run(
@@ -176,39 +227,66 @@ 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().canOverchargeGasForCall() &&
+			evmDialect->providesObjectAccess();
 	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().canOverchargeGasForCall())
+	{
+		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

@@ -95,6 +95,12 @@ void OptimiserSuite::run(
 	set<YulString> const& _externallyUsedIdentifiers
 )
 {
+	EVMDialect const* evmDialect = dynamic_cast<EVMDialect const*>(&_dialect);
+	bool usesOptimizedCodeGenerator =
+		_optimizeStackAllocation &&
+		evmDialect &&
+		evmDialect->evmVersion().canOverchargeGasForCall() &&
+		evmDialect->providesObjectAccess();
 	set<YulString> reservedIdentifiers = _externallyUsedIdentifiers;
 	reservedIdentifiers += _dialect.fixedFunctionNames();
 
@@ -121,24 +127,32 @@ 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))
 	{