tmp

liblangutil/Token.h

@@ -268,8 +268,10 @@ namespace solidity::langutil
 	/* Yul-specific tokens, but not keywords. */                       \
 	T(Leave, "leave", 0)                                               \
 	\
+	T(NonExperimentalEnd, nullptr, 0) /* used as non-experimental enum end marker */ \
     /* Experimental Solidity specific keywords. */                     \
 	K(Word, "word", 0)                                                 \
+	K(Void, "void", 0)                                                 \
 	K(StaticAssert, "static_assert", 0)                                \
 	T(ExperimentalEnd, nullptr, 0) /* used as experimental enum end marker */ \
 	\
@@ -295,7 +297,10 @@ namespace TokenTraits
 	constexpr size_t count() { return static_cast<size_t>(Token::NUM_TOKENS); }
 
 	// Predicates
-	constexpr bool isElementaryTypeName(Token tok) { return (Token::Int <= tok && tok < Token::TypesEnd) || tok == Token::Word; }
+	constexpr bool isElementaryTypeName(Token tok)
+	{
+		return (Token::Int <= tok && tok < Token::TypesEnd) || tok == Token::Word || tok == Token::Void;
+	}
 	constexpr bool isAssignmentOp(Token tok) { return Token::Assign <= tok && tok <= Token::AssignMod; }
 	constexpr bool isBinaryOp(Token op) { return Token::Comma <= op && op <= Token::Exp; }
 	constexpr bool isCommutativeOp(Token op) { return op == Token::BitOr || op == Token::BitXor || op == Token::BitAnd ||
@@ -331,11 +336,11 @@ namespace TokenTraits
 	{
 		return tok == Token::Assembly || tok == Token::Contract || tok == Token::External || tok == Token::Fallback ||
 			tok == Token::Pragma || tok == Token::Import || tok == Token::As || tok == Token::Function || tok == Token::Let ||
-			(tok >= Token::Word && tok < Token::ExperimentalEnd);
+			(tok > Token::NonExperimentalEnd && tok < Token::ExperimentalEnd);
 	}
 	constexpr bool isExperimentalSolidityOnlyKeyword(Token tok)
 	{
-		return tok >= Token::Word && tok < Token::ExperimentalEnd;
+		return tok > Token::NonExperimentalEnd && tok < Token::ExperimentalEnd;
 	}
 
 	bool isYulKeyword(std::string const& _literal);

libsolidity/CMakeLists.txt

@@ -98,6 +98,7 @@ set(sources
 	codegen/ReturnInfo.cpp
 	codegen/YulUtilFunctions.h
 	codegen/YulUtilFunctions.cpp
+	codegen/experimental/IRGenerationContext.h
 	codegen/experimental/IRGenerator.cpp
 	codegen/experimental/IRGenerator.h
 	codegen/experimental/IRGeneratorForStatements.cpp

libsolidity/analysis/experimental/Analysis.cpp

@@ -36,7 +36,7 @@ bool Analysis::check(vector<shared_ptr<SourceUnit const>> const& _sourceUnits)
 	for (auto source: _sourceUnits)
 		if (!syntaxRestrictor.check(*source))
 			return false;
-	TypeInference typeInference{m_errorReporter};
+	TypeInference typeInference{*this};
 	for (auto source: _sourceUnits)
 		if (!typeInference.analyze(*source))
 			return false;

libsolidity/analysis/experimental/Analysis.h

@@ -38,7 +38,11 @@ class Analysis
 {
 public:
 	Analysis(langutil::ErrorReporter& _errorReporter, uint64_t _maxAstId);
+	Analysis(Analysis const&) = delete;
+	Analysis const& operator=(Analysis const&) = delete;
 	bool check(std::vector<std::shared_ptr<SourceUnit const>> const& _sourceUnits);
+	langutil::ErrorReporter& errorReporter() { return m_errorReporter; }
+	uint64_t maxAstId() const { return m_maxAstId; }
 private:
 	langutil::ErrorReporter& m_errorReporter;
 	uint64_t m_maxAstId = 0;

libsolidity/analysis/experimental/SyntaxRestrictor.h

@@ -43,6 +43,7 @@ private:
 	bool visit(ContractDefinition const& _contractDefinition) override;
 	bool visit(FunctionDefinition const& _functionDefinition) override;
 	bool visit(ExpressionStatement const&) override { return true; }
+	bool visit(FunctionCall const&) override { return true; }
 	bool visit(Assignment const&) override { return true; }
 	bool visit(Block const&) override { return true; }
 	bool visit(InlineAssembly const&) override { return true; }

libsolidity/analysis/experimental/TypeInference.cpp

@@ -18,17 +18,39 @@
 
 
 #include <libsolidity/analysis/experimental/TypeInference.h>
+#include <libsolidity/analysis/experimental/Analysis.h>
 #include <liblangutil/Exceptions.h>
 
 #include <libyul/AsmAnalysis.h>
 #include <libyul/AsmAnalysisInfo.h>
 #include <libyul/AST.h>
 
+#include <range/v3/view/transform.hpp>
+
 using namespace std;
 using namespace solidity::frontend;
 using namespace solidity::frontend::experimental;
 using namespace solidity::langutil;
 
+TypeInference::TypeInference(Analysis& _analysis):
+m_analysis(_analysis),
+m_errorReporter(_analysis.errorReporter())
+{
+	for (auto [type, name, arity]: std::initializer_list<std::tuple<BuiltinType, const char*, uint64_t>> {
+			 {BuiltinType::Void, "void", 0},
+			 {BuiltinType::Function, "fun", 2},
+			 {BuiltinType::Unit, "unit", 0},
+			 {BuiltinType::Pair, "pair", 2},
+			 {BuiltinType::Word, "word", 0}
+	})
+		m_typeSystem.declareBuiltinType(type, name, arity);
+	m_voidType = m_typeSystem.builtinType(BuiltinType::Void, {});
+	m_wordType = m_typeSystem.builtinType(BuiltinType::Word, {});
+	m_env = make_unique<TypeEnvironment>(m_typeSystem);
+
+	m_typeAnnotations.resize(_analysis.maxAstId());
+}
+
 bool TypeInference::analyze(SourceUnit const& _sourceUnit)
 {
 	_sourceUnit.accept(*this);
@@ -37,13 +59,37 @@ bool TypeInference::analyze(SourceUnit const& _sourceUnit)
 
 bool TypeInference::visit(FunctionDefinition const& _functionDefinition)
 {
-	ScopedSaveAndRestore env{m_env, {}};
+	auto& functionAnnotation = annotation(_functionDefinition);
+	if (functionAnnotation.type)
+		return false;
+
+	Type functionType;
+	{
 		_functionDefinition.parameterList().accept(*this);
 		if (_functionDefinition.returnParameterList())
 			_functionDefinition.returnParameterList()->accept(*this);
 
 		_functionDefinition.body().accept(*this);
 
+		auto typeFromParameterList = [&](ParameterList const* _list) {
+			if (!_list)
+				return m_typeSystem.builtinType(BuiltinType::Unit, {});
+			return TypeSystemHelpers{m_typeSystem}.tupleType(_list->parameters() | ranges::view::transform([&](auto _param) {
+				auto& argAnnotation = annotation(*_param);
+				solAssert(argAnnotation.type);
+				return *argAnnotation.type;
+			}) | ranges::to<std::vector<Type>>);
+		};
+
+		Type argType = typeFromParameterList(&_functionDefinition.parameterList());
+		Type resultType = typeFromParameterList(_functionDefinition.returnParameterList().get());
+
+		functionType = m_typeSystem.builtinType(BuiltinType::Function, {argType, resultType});
+	}
+	functionAnnotation.type = functionType;
+
+	m_errorReporter.warning(0000_error, _functionDefinition.location(), m_typeSystem.typeToString(m_typeSystem.resolve(functionType)));
+
 	return false;
 }
 
@@ -52,6 +98,20 @@ bool TypeInference::visit(ParameterList const&)
 	return true;
 }
 
+void TypeInference::endVisit(ParameterList const& _parameterList)
+{
+	auto& listAnnotation = annotation(_parameterList);
+	solAssert(!listAnnotation.type);
+	std::vector<Type> argTypes;
+	for(auto arg: _parameterList.parameters())
+	{
+		auto& argAnnotation = annotation(*arg);
+		solAssert(argAnnotation.type);
+		argTypes.emplace_back(*argAnnotation.type);
+	}
+	listAnnotation.type = TypeSystemHelpers{m_typeSystem}.tupleType(argTypes);
+}
+
 bool TypeInference::visitNode(ASTNode const& _node)
 {
 	m_errorReporter.typeError(0000_error, _node.location(), "Unsupported AST node during type inference.");
@@ -65,7 +125,9 @@ experimental::Type TypeInference::fromTypeName(TypeName const& _typeName)
 		switch(elementaryTypeName->typeName().token())
 		{
 		case Token::Word:
-			return WordType{};
+			return m_wordType;
+		case Token::Void:
+			return m_voidType;
 		default:
 			m_errorReporter.typeError(0000_error, _typeName.location(), "Only elementary types are supported.");
 			break;
@@ -73,7 +135,8 @@ experimental::Type TypeInference::fromTypeName(TypeName const& _typeName)
 	}
 	else
 		m_errorReporter.typeError(0000_error, _typeName.location(), "Only elementary types are supported.");
-	return m_env.freshFreeType();
+	// TODO: free type?
+	return m_typeSystem.freshTypeVariable();
 
 }
 
@@ -101,7 +164,9 @@ bool TypeInference::visit(InlineAssembly const& _inlineAssembly)
 		Declaration const* declaration = identifierInfo.declaration;
 		solAssert(!!declaration, "");
 
-		m_env.assignType(m_typeSystem, declaration, WordType{});
+		auto& declarationAnnotation = annotation(*declaration);
+		solAssert(declarationAnnotation.type);
+		m_typeSystem.unify(*declarationAnnotation.type, m_wordType);
 		identifierInfo.valueSize = 1;
 		return true;
 	};
@@ -120,19 +185,83 @@ bool TypeInference::visit(InlineAssembly const& _inlineAssembly)
 
 bool TypeInference::visit(VariableDeclaration const& _variableDeclaration)
 {
-	Type type = _variableDeclaration.hasTypeName() ? fromTypeName(_variableDeclaration.typeName()) : m_typeSystem.freshTypeVariable();
+	solAssert(!_variableDeclaration.value());
-	m_env.assignType(m_typeSystem, &_variableDeclaration, type);
+	auto& variableAnnotation = annotation(_variableDeclaration);
+	solAssert(!variableAnnotation.type);
+	variableAnnotation.type = [&] {
+		if (_variableDeclaration.hasTypeName())
+			return fromTypeName(_variableDeclaration.typeName());
+		else
+			return m_typeSystem.freshTypeVariable();
+	}();
 	return false;
 }
 
-bool TypeInference::visit(Assignment const& _assignment)
+bool TypeInference::visit(Assignment const&)
 {
-	(void)_assignment;
 	return true;
 }
 
+void TypeInference::endVisit(Assignment const& _assignment)
+{
+	auto& assignmentAnnotation = annotation(_assignment);
+	solAssert(!assignmentAnnotation.type);
+
+	auto& lhsAnnotation = annotation(_assignment.leftHandSide());
+	solAssert(lhsAnnotation.type);
+	auto& rhsAnnotation = annotation(_assignment.rightHandSide());
+	solAssert(rhsAnnotation.type);
+	m_typeSystem.unify(*lhsAnnotation.type, *rhsAnnotation.type);
+	assignmentAnnotation.type = m_typeSystem.resolve(*lhsAnnotation.type);
+}
+
+TypeInference::TypeAnnotation& TypeInference::annotation(ASTNode const& _node)
+{
+	auto& annotation = m_typeAnnotations.at(static_cast<size_t>(_node.id()));
+	if (!annotation)
+		annotation = make_unique<TypeAnnotation>();
+	return *annotation;
+}
+
 bool TypeInference::visit(Identifier const& _identifier)
 {
-	(void)_identifier;
+	auto& identifierAnnotation = annotation(_identifier);
+	solAssert(!identifierAnnotation.type);
+
+	auto const* referencedDeclaration = _identifier.annotation().referencedDeclaration;
+	solAssert(referencedDeclaration);
+
+	auto& declarationAnnotation = annotation(*referencedDeclaration);
+	if (!declarationAnnotation.type)
+		referencedDeclaration->accept(*this);
+
+	solAssert(declarationAnnotation.type);
+	identifierAnnotation.type = declarationAnnotation.type;
+
 	return true;
 }
+
+bool TypeInference::visit(FunctionCall const&) { return true; }
+void TypeInference::endVisit(FunctionCall const& _functionCall)
+{
+	auto& functionCallAnnotation = annotation(_functionCall);
+	solAssert(!functionCallAnnotation.type);
+
+	auto& expressionAnnotation = annotation(_functionCall.expression());
+	solAssert(expressionAnnotation.type);
+
+	Type functionType = m_typeSystem.fresh(*expressionAnnotation.type);
+
+	std::vector<Type> argTypes;
+	for(auto arg: _functionCall.arguments())
+	{
+		auto& argAnnotation = annotation(*arg);
+		solAssert(argAnnotation.type);
+		argTypes.emplace_back(*argAnnotation.type);
+	}
+	Type argTuple = TypeSystemHelpers{m_typeSystem}.tupleType(argTypes);
+	Type genericFunctionType = TypeSystemHelpers{m_typeSystem}.functionType(argTuple, m_typeSystem.freshTypeVariable());
+	m_typeSystem.unify(genericFunctionType, functionType);
+
+	functionCallAnnotation.type = m_typeSystem.resolve(std::get<1>(TypeSystemHelpers{m_typeSystem}.destFunctionType(m_typeSystem.resolve(genericFunctionType))));
+}

libsolidity/analysis/experimental/TypeInference.h

@@ -27,10 +27,12 @@
 namespace solidity::frontend::experimental
 {
 
+class Analysis;
+
 class TypeInference: public ASTConstVisitor
 {
 public:
-	TypeInference(langutil::ErrorReporter& _errorReporter): m_errorReporter(_errorReporter) {}
+	TypeInference(Analysis& _analysis);
 
 	bool analyze(SourceUnit const& _sourceUnit);
 private:
@@ -40,6 +42,7 @@ private:
 
 	bool visit(FunctionDefinition const& _functionDefinition) override;
 	bool visit(ParameterList const& _parameterList) override;
+	void endVisit(ParameterList const& _parameterList) override;
 	bool visit(SourceUnit const&) override { return true; }
 	bool visit(ContractDefinition const&) override { return true; }
 	bool visit(InlineAssembly const& _inlineAssembly) override;
@@ -47,14 +50,29 @@ private:
 
 	bool visit(ExpressionStatement const&) override { return true; }
 	bool visit(Assignment const&) override;
+	void endVisit(Assignment const&) override;
 	bool visit(Identifier const&) override;
+	bool visit(FunctionCall const& _functionCall) override;
+	void endVisit(FunctionCall const& _functionCall) override;
 
 	bool visitNode(ASTNode const& _node) override;
 
 	Type fromTypeName(TypeName const& _typeName);
-	TypeSystem m_typeSystem;
+	Analysis& m_analysis;
 	langutil::ErrorReporter& m_errorReporter;
-	TypeEnvironment m_env;
+	TypeSystem m_typeSystem;
+	std::unique_ptr<TypeEnvironment> m_env;
+	Type m_voidType;
+	Type m_wordType;
+
+	struct TypeAnnotation
+	{
+		std::optional<Type> type;
+	};
+
+	TypeAnnotation& annotation(ASTNode const& _node);
+
+	std::vector<std::unique_ptr<TypeAnnotation>> m_typeAnnotations;
 };
 
 }

libsolidity/ast/experimental/TypeSystem.cpp

@@ -18,47 +18,225 @@
 
 
 #include <libsolidity/ast/experimental/TypeSystem.h>
+#include <libsolidity/ast/AST.h>
 #include <liblangutil/Exceptions.h>
 
+#include <libsolutil/Visitor.h>
+
+#include <range/v3/to_container.hpp>
+#include <range/v3/view/drop_exactly.hpp>
+#include <range/v3/view/drop_last.hpp>
+#include <range/v3/view/reverse.hpp>
+#include <range/v3/view/zip.hpp>
+
+#include <fmt/format.h>
+
 using namespace std;
 using namespace solidity::frontend;
 using namespace solidity::frontend::experimental;
 
-void TypeEnvironment::assignType(TypeSystem& _typeSystem, Declaration const* _declaration, Type _typeAssignment)
+std::string TypeSystem::typeToString(Type const& _type) const
+{
+	return std::visit(util::GenericVisitor{
+		[&](AtomicType const& _type) {
+			std::stringstream stream;
+			if (!_type.arguments.empty())
+			{
+				stream << "(";
+				for (auto type: _type.arguments | ranges::views::drop_last(1))
+					stream << typeToString(type) << ", ";
+				stream << typeToString(_type.arguments.back());
+				stream << ") ";
+			}
+			stream << std::visit(util::GenericVisitor{
+				[&](Declaration const* _declaration) {
+					return _declaration->name();
+				},
+				[&](BuiltinType _builtinType) -> string {
+					return builtinTypeName(_builtinType);
+				}
+			}, _type.constructor);
+			return stream.str();
+		},
+		[](FreeTypeVariable const& _type) {
+			return fmt::format("free[{}]", _type.index());
+		},
+		[](GenericTypeVariable const& _type) {
+			return fmt::format("var[{}]", _type.index());
+		},
+	}, resolve(_type));
+}
+
+void TypeEnvironment::assignType(Declaration const* _declaration, Type _typeAssignment)
 {
 	auto&& [type, newlyInserted] = m_types.emplace(std::piecewise_construct, std::forward_as_tuple(_declaration), std::forward_as_tuple(std::move(_typeAssignment)));
 	if (!newlyInserted)
 	{
-		unify(_typeSystem, type->second, _typeAssignment);
+		m_parent.unify(type->second, _typeAssignment);
 	}
 }
-Type TypeEnvironment::lookup(TypeSystem& _typeSystem, Declaration const* _declaration)
+std::optional<experimental::Type> TypeEnvironment::lookup(Declaration const* _declaration)
 {
 	if (m_types.count(_declaration))
 		return m_types[_declaration];
-	Type result = _typeSystem.freshTypeVariable();
+	return std::nullopt;
-	m_types.emplace(std::piecewise_construct, std::forward_as_tuple(_declaration), std::forward_as_tuple(result));
+}
+
+
+void TypeSystem::unify(Type _a, Type _b)
+{
+	auto unificationFailure = [&]() {
+		solAssert(false, fmt::format("cannot unify {} and {}", typeToString(_a), typeToString(_b)));
+	};
+	_a = resolve(_a);
+	_b = resolve(_b);
+	std::visit(util::GenericVisitor{
+		[&](GenericTypeVariable _left, GenericTypeVariable _right) {
+			validate(_left);
+			validate(_right);
+			if (_left.index() != _right.index())
+				instantiate(_left, _right);
+		},
+		[&](GenericTypeVariable _var, auto) {
+			instantiate(_var, _b);
+		},
+		[&](auto, GenericTypeVariable _var) {
+			instantiate(_var, _a);
+		},
+		[&](AtomicType _atomicLeft, AtomicType _atomicRight) {
+		  if(_atomicLeft.constructor != _atomicRight.constructor)
+			  unificationFailure();
+		  if (_atomicLeft.arguments.size() != _atomicRight.arguments.size())
+			  unificationFailure();
+		   for (auto&& [left, right]: ranges::zip_view(_atomicLeft.arguments, _atomicRight.arguments))
+			  unify(left, right);
+		},
+		[&](auto, auto) {
+			unificationFailure();
+		}
+	}, _a, _b);
+}
+
+unique_ptr<TypeEnvironment> TypeEnvironment::fresh() const
+{
+	auto newEnv = make_unique<TypeEnvironment>(m_parent);
+	for(auto [decl,type]: m_types)
+		newEnv->m_types.emplace(decl, type);
+	return newEnv;
+
+}
+
+experimental::Type TypeSystem::freshTypeVariable()
+{
+	uint64_t index = m_typeVariables.size();
+	m_typeVariables.emplace_back(std::nullopt);
+	return GenericTypeVariable(*this, index);
+}
+
+experimental::Type TypeSystem::freshFreeType()
+{
+	uint64_t index = m_freeTypes.size();
+	m_freeTypes.emplace_back(std::nullopt);
+	return FreeTypeVariable(*this, index);
+}
+
+void TypeSystem::instantiate(GenericTypeVariable _variable, Type _type)
+{
+	validate(_variable);
+	solAssert(!m_typeVariables.at(_variable.index()).has_value());
+	solAssert(_variable.m_parent == this);
+	m_typeVariables[_variable.index()] = _type;
+}
+
+experimental::Type TypeSystem::resolve(Type _type) const
+{
+	Type result = _type;
+	while(auto const* var = std::get_if<GenericTypeVariable>(&result))
+		if (auto value = m_typeVariables.at(var->index()))
+			result = *value;
+		else
+			break;
 	return result;
 }
-Type TypeEnvironment::freshFreeType()
+
+void TypeSystem::declareBuiltinType(BuiltinType _builtinType, std::string _name, uint64_t _arity)
 {
-	return FreeType{m_numFreeTypes++};
+	solAssert(m_builtinTypes.count(_builtinType) == 0, "Builtin type already declared.");
+	m_builtinTypes[_builtinType] = TypeConstructorInfo{
+		_name,
+		_arity
+	};
+}
+
+experimental::Type TypeSystem::builtinType(BuiltinType _builtinType, std::vector<Type> _arguments) const
+{
+	auto const& info = m_builtinTypes.at(_builtinType);
+	solAssert(info.arity == _arguments.size(), "Invalid arity.");
+	return AtomicType{_builtinType, _arguments};
+}
+
+void TypeSystem::validate(GenericTypeVariable _variable) const
+{
+	solAssert(_variable.m_parent == this);
+	solAssert(_variable.index() < m_typeVariables.size());
+}
+
+experimental::Type TypeSystemHelpers::tupleType(vector<Type> _elements) const
+{
+	if (_elements.empty())
+		return typeSystem.builtinType(BuiltinType::Unit, {});
+	if (_elements.size() == 1)
+		return _elements.front();
+	Type result = _elements.back();
+	for (Type type: _elements | ranges::view::reverse | ranges::view::drop_exactly(1))
+		result = typeSystem.builtinType(BuiltinType::Pair, {type, result});
+	return result;
+}
+
+experimental::Type TypeSystemHelpers::functionType(experimental::Type _argType, experimental::Type _resultType) const
+{
+	return typeSystem.builtinType(BuiltinType::Function, {_argType, _resultType});
+}
+
+experimental::Type TypeSystem::fresh(Type _type)
+{
+	return std::visit(util::GenericVisitor{
+		[&](AtomicType const& _type) -> Type {
+			return AtomicType{
+				_type.constructor,
+				_type.arguments | ranges::view::transform([&](Type _argType) {
+					return fresh(_argType);
+				}) | ranges::to<vector<Type>>
+			};
+		},
+		[&](FreeTypeVariable const&) {
+			return _type;
+		},
+		[&](GenericTypeVariable const&) {
+			return freshTypeVariable();
+		},
+	}, resolve(_type));
+}
+
+tuple<AtomicType::Constructor, vector<experimental::Type>> TypeSystemHelpers::destAtomicType(Type _functionType) const
+{
+	using ResultType = tuple<AtomicType::Constructor, vector<Type>>;
+	return std::visit(util::GenericVisitor{
+		[&](AtomicType const& _type) -> ResultType {
+			return std::make_tuple(_type.constructor, _type.arguments);
+		},
+		[](auto) -> ResultType {
+			solAssert(false);
+		}
+	}, _functionType);
 }
 
 
-void TypeEnvironment::unify(TypeSystem& _context, Type _a, Type _b)
+tuple<experimental::Type, experimental::Type> TypeSystemHelpers::destFunctionType(Type _functionType) const
 {
-	_a = _context.resolve(_a);
+	auto [constructor, arguments] = destAtomicType(_functionType);
-	_b = _context.resolve(_b);
+	auto const* builtinType = get_if<BuiltinType>(&constructor);
-	if (auto* varA = get_if<TypeVariable>(&_a))
+	solAssert(builtinType && *builtinType == BuiltinType::Function);
-		_context.instantiate(*varA, _b);
+	solAssert(arguments.size() == 2);
-	else if (holds_alternative<WordType>(_a))
+	return make_tuple(arguments.front(), arguments.back());
-	{
-		if (holds_alternative<WordType>(_b))
-			return;
-		else
-			solAssert(false, "unification failed");
-	}
-
-	solAssert(false, fmt::format("cannot unify {} and {}", typeToString(_a), typeToString(_b)));
 }

libsolidity/ast/experimental/TypeSystem.h

@@ -19,8 +19,6 @@
 
 #include <liblangutil/Exceptions.h>
 
-#include <fmt/format.h>
-
 #include <optional>
 #include <string>
 #include <variant>
@@ -35,99 +33,64 @@ namespace solidity::frontend::experimental
 {
 
 class TypeSystem;
+class TypeEnvironment;
 
-struct SumType;
+struct AtomicType;
-struct TupleType;
+struct GenericTypeVariable;
-struct FunctionType;
+struct FreeTypeVariable;
-struct WordType;
-struct UserDefinedType;
-struct TypeVariable;
-struct FreeType;
 
-using Type = std::variant<SumType, TupleType, FunctionType, WordType, UserDefinedType, TypeVariable, FreeType>;
+using Type = std::variant<AtomicType, GenericTypeVariable, FreeTypeVariable>;
 
-struct SumType
+enum class BuiltinType
 {
-	std::vector<Type const*> alternatives;
+	Void,
-	std::string toString() const
+	Function,
-	{
+	Unit,
-		return "sum";
+	Pair,
-	}
+	Word
 };
 
-struct TupleType
+struct AtomicType
 {
-	std::vector<Type const*> components;
+	using Constructor = std::variant<BuiltinType, Declaration const*>;
-	std::string toString() const
+	Constructor constructor;
-	{
+	std::vector<Type> arguments;
-		return "tuple";
+
-	}
 };
 
-struct FunctionType
+struct FreeTypeVariable
 {
-	Type const* codomain = nullptr;
+	TypeSystem const& parent() const { return *m_parent; }
-	Type const* domain = nullptr;
-	std::string toString() const
-	{
-		return "fun";
-	}
-};
-
-struct WordType
-{
-	std::string toString() const
-	{
-		return "word";
-	}
-};
-
-struct UserDefinedType
-{
-	Declaration const* declaration = nullptr;
-	std::vector<Type const*> arguments;
-	std::string toString() const
-	{
-		return "user_defined_type";
-	}
-};
-
-struct TypeVariable
-{
-	std::string toString() const
-	{
-		return fmt::format("var<{}>", m_index);
-	}
-private:
 	uint64_t index() const { return m_index; }
+private:
 	friend class TypeSystem;
+	TypeSystem const* m_parent = nullptr;
 	uint64_t m_index = 0;
-	TypeVariable(uint64_t _index): m_index(_index) {}
+	FreeTypeVariable(TypeSystem const& _parent, uint64_t _index): m_parent(&_parent), m_index(_index) {}
 };
 
-struct FreeType
+struct GenericTypeVariable
 {
-	uint64_t index = 0;
+	TypeSystem const& parent() const { return *m_parent; }
-	std::string toString() const
+	uint64_t index() const { return m_index; }
-	{
+private:
-		return fmt::format("free<{}>", index);
+	friend class TypeSystem;
-	}
+	TypeSystem const* m_parent = nullptr;
+	uint64_t m_index = 0;
+	GenericTypeVariable(TypeSystem const& _parent, uint64_t _index): m_parent(&_parent), m_index(_index) {}
 };
 
-inline std::string typeToString(Type const& _type)
-{
-	return std::visit([](auto _type) { return _type.toString(); }, _type);
-}
-
 class TypeEnvironment
 {
 public:
-	void assignType(TypeSystem& _typeSystem, Declaration const* _declaration, Type _typeAssignment);
+	TypeEnvironment(TypeSystem& _parent): m_parent(_parent) {}
-	Type lookup(TypeSystem& _typeSystem, Declaration const* _declaration);
+	TypeEnvironment(TypeEnvironment const& _env) = delete;
-	Type freshFreeType();
+	TypeEnvironment& operator=(TypeEnvironment const& _env) = delete;
-	void unify(TypeSystem& _typeSystem, Type _a, Type _b);
+	std::unique_ptr<TypeEnvironment> fresh() const;
+	void assignType(Declaration const* _declaration, Type _typeAssignment);
+	std::optional<Type> lookup(Declaration const* _declaration);
 private:
-	uint64_t m_numFreeTypes = 0;
+	TypeSystem& m_parent;
 	std::map<Declaration const*, Type> m_types;
 };
 
@@ -138,30 +101,38 @@ public:
 	TypeSystem() {}
 	TypeSystem(TypeSystem const&) = delete;
 	TypeSystem const& operator=(TypeSystem const&) = delete;
-	Type freshTypeVariable()
+	void declareBuiltinType(BuiltinType _builtinType, std::string _name, uint64_t _arity);
+	Type builtinType(BuiltinType _builtinType, std::vector<Type> _arguments) const;
+	std::string builtinTypeName(BuiltinType _builtinType) const
 	{
-		uint64_t index = m_typeVariables.size();
+		return m_builtinTypes.at(_builtinType).name;
-		m_typeVariables.emplace_back(std::nullopt);
-		return TypeVariable(index);
-	}
-	void instantiate(TypeVariable _variable, Type _type)
-	{
-		solAssert(_variable.index() < m_typeVariables.size());
-		solAssert(!m_typeVariables.at(_variable.index()).has_value());
-		m_typeVariables[_variable.index()] = _type;
-	}
-	Type resolve(Type _type)
-	{
-		Type result = _type;
-		while(auto const* var = std::get_if<TypeVariable>(&result))
-			if (auto value = m_typeVariables.at(var->index()))
-				result = *value;
-			else
-				break;
-		return result;
 	}
+	Type freshFreeType();
+	void instantiate(GenericTypeVariable _variable, Type _type);
+	void validate(GenericTypeVariable _variable) const;
+	Type resolve(Type _type) const;
+	std::string typeToString(Type const& _type) const;
+	Type freshTypeVariable();
+	Type fresh(Type _type);
+	void unify(Type _a, Type _b);
 private:
+	std::vector<std::optional<Type>> m_freeTypes;
+	struct TypeConstructorInfo
+	{
+		std::string name;
+		uint64_t arity = 0;
+	};
+	std::map<BuiltinType, TypeConstructorInfo> m_builtinTypes;
 	std::vector<std::optional<Type>> m_typeVariables;
 };
 
+struct TypeSystemHelpers
+{
+	TypeSystem& typeSystem;
+	Type tupleType(std::vector<Type> _elements) const;
+	Type functionType(Type _argType, Type _resultType) const;
+	std::tuple<AtomicType::Constructor, std::vector<Type>> destAtomicType(Type _functionType) const;
+	std::tuple<Type, Type> destFunctionType(Type _functionType) const;
+};
+
 }

libsolidity/codegen/experimental/IRGenerationContext.h

@@ -0,0 +1,43 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+// SPDX-License-Identifier: GPL-3.0
+
+#pragma once
+
+#include <libsolidity/ast/ASTForward.h>
+
+#include <list>
+#include <set>
+
+namespace solidity::frontend::experimental
+{
+
+class Analysis;
+
+struct IRGenerationContext
+{
+	Analysis const& analysis;
+	std::list<FunctionDefinition const*> functionQueue;
+	std::set<FunctionDefinition const*> generatedFunctions;
+	void enqueueFunctionDefinition(FunctionDefinition const* _functionDefinition)
+	{
+		if (!generatedFunctions.count(_functionDefinition))
+			functionQueue.emplace_back(_functionDefinition);
+	}
+};
+
+}

libsolidity/codegen/experimental/IRGenerator.cpp

@@ -18,6 +18,7 @@
 
 #include <libsolidity/codegen/experimental/IRGenerator.h>
 
+#include <libsolidity/codegen/experimental/IRGenerationContext.h>
 #include <libsolidity/codegen/experimental/IRGeneratorForStatements.h>
 
 #include <libsolidity/codegen/ir/Common.h>
@@ -31,6 +32,8 @@
 
 #include <libsolutil/Whiskers.h>
 
+#include <range/v3/view/drop_last.hpp>
+
 #include <variant>
 
 using namespace std;
@@ -43,7 +46,7 @@ string IRGenerator::run(
 	ContractDefinition const& _contract,
 	bytes const& /*_cborMetadata*/,
 	map<ContractDefinition const*, string_view const> const& /*_otherYulSources*/
-) const
+)
 {
 
 	Whiskers t(R"(
@@ -66,30 +69,52 @@ string IRGenerator::run(
 	return t.render();
 }
 
-string IRGenerator::generate(ContractDefinition const& _contract) const
+string IRGenerator::generate(ContractDefinition const& _contract)
 {
 	std::stringstream code;
 	code << "{\n";
 	if (_contract.fallbackFunction())
 	{
 		code << IRNames::function(*_contract.fallbackFunction()) << "()\n";
+		m_context.functionQueue.emplace_front(_contract.fallbackFunction());
 	}
 	code << "revert(0,0)\n";
 	code << "}\n";
 
-	for (FunctionDefinition const* f: _contract.definedFunctions())
+	while (!m_context.functionQueue.empty())
-		code << generate(*f);
+	{
+		FunctionDefinition const* function = m_context.functionQueue.front();
+		m_context.functionQueue.pop_front();
+		m_context.generatedFunctions.insert(function);
+		code << generate(*function);
+	}
 
 	return code.str();
 }
 
-string IRGenerator::generate(FunctionDefinition const& _function) const
+string IRGenerator::generate(FunctionDefinition const& _function)
 {
 	std::stringstream code;
-	code << "function " << IRNames::function(_function) << "() {\n";
+	code << "function " << IRNames::function(_function) << "(";
+	if (_function.parameters().size() > 1)
+		for (auto const& arg: _function.parameters() | ranges::view::drop_last(1))
+			code << IRNames::localVariable(*arg) << ", ";
+	if (!_function.parameters().empty())
+		code << IRNames::localVariable(*_function.parameters().back());
+	code << ")";
+	if (_function.returnParameterList() && !_function.returnParameters().empty())
+	{
+		code << " -> ";
+		if (_function.returnParameters().size() > 1)
+			for (auto const& arg: _function.returnParameters() | ranges::view::drop_last(1))
+				code << IRNames::localVariable(*arg) << ", ";
+		if (!_function.returnParameters().empty())
+			code << IRNames::localVariable(*_function.returnParameters().back());
+	}
+	code << "{\n";
 	for (auto _statement: _function.body().statements())
 	{
-		IRGeneratorForStatements statementGenerator{m_analysis};
+		IRGeneratorForStatements statementGenerator{m_context};
 		code << statementGenerator.generate(*_statement);
 	}
 	code << "}\n";

libsolidity/codegen/experimental/IRGenerator.h

@@ -18,6 +18,7 @@
 
 #pragma once
 
+#include <libsolidity/codegen/experimental/IRGenerationContext.h>
 #include <libsolidity/interface/DebugSettings.h>
 #include <libsolidity/interface/OptimiserSettings.h>
 #include <libsolidity/ast/ASTForward.h>
@@ -53,24 +54,24 @@ public:
 		m_eofVersion(_eofVersion),
 		m_debugInfoSelection(_debugInfoSelection),
 		m_soliditySourceProvider(_soliditySourceProvider),
-		m_analysis(_analysis)
+		m_context{_analysis, {}, {}}
 	{}
 
 	std::string run(
 		ContractDefinition const& _contract,
 		bytes const& _cborMetadata,
 		std::map<ContractDefinition const*, std::string_view const> const& _otherYulSources
-	) const;
+	);
 
-	std::string generate(ContractDefinition const& _contract) const;
+	std::string generate(ContractDefinition const& _contract);
-	std::string generate(FunctionDefinition const& _function) const;
+	std::string generate(FunctionDefinition const& _function);
 private:
 	langutil::EVMVersion const m_evmVersion;
 	std::optional<uint8_t> const m_eofVersion;
 	OptimiserSettings const m_optimiserSettings;
 	langutil::DebugInfoSelection m_debugInfoSelection = {};
 	langutil::CharStreamProvider const* m_soliditySourceProvider = nullptr;
-	Analysis const& m_analysis;
+	IRGenerationContext m_context;
 };
 
 }

libsolidity/codegen/experimental/IRGeneratorForStatements.cpp

@@ -25,6 +25,8 @@
 
 #include <libsolidity/codegen/ir/Common.h>
 
+#include <range/v3/view/drop_last.hpp>
+
 using namespace std;
 using namespace solidity;
 using namespace solidity::util;
@@ -104,7 +106,7 @@ bool IRGeneratorForStatements::visit(InlineAssembly const& _assembly)
 	CopyTranslate bodyCopier{_assembly.dialect(), _assembly.annotation().externalReferences};
 	yul::Statement modified = bodyCopier(_assembly.operations());
 	solAssert(holds_alternative<yul::Block>(modified));
-	m_code << yul::AsmPrinter()(std::get<yul::Block>(modified));
+	m_code << yul::AsmPrinter()(std::get<yul::Block>(modified)) << "\n";
 	return false;
 }
 
@@ -119,6 +121,55 @@ bool IRGeneratorForStatements::visit(VariableDeclarationStatement const& _variab
 	return false;
 }
 
+bool IRGeneratorForStatements::visit(ExpressionStatement const&)
+{
+	return true;
+}
+
+bool IRGeneratorForStatements::visit(Identifier const& _identifier)
+{
+	auto const* rhsVar = dynamic_cast<VariableDeclaration const*>(_identifier.annotation().referencedDeclaration);
+	solAssert(rhsVar, "Can only reference identifiers referring to variables.");
+	m_code << "let " << IRNames::localVariable(_identifier) << " := " << IRNames::localVariable(*rhsVar) << "\n";
+	return false;
+}
+
+bool IRGeneratorForStatements::visit(FunctionCall const& _functionCall)
+{
+	for(auto arg: _functionCall.arguments())
+		arg->accept(*this);
+
+	auto const* identifier = dynamic_cast<Identifier const*>(&_functionCall.expression());
+	solAssert(identifier, "Complex function call expressions not supported.");
+	auto const* functionDefinition = dynamic_cast<FunctionDefinition const*>(identifier->annotation().referencedDeclaration);
+	solAssert(functionDefinition, "Function call expression must refer to a function definition.");
+	m_context.enqueueFunctionDefinition(functionDefinition);
+
+	m_code << "let " << IRNames::localVariable(_functionCall) << " := " << IRNames::function(*functionDefinition) << "(";
+	auto const& arguments = _functionCall.arguments();
+	if (arguments.size() > 1)
+		for (auto arg: arguments | ranges::view::drop_last(1))
+			m_code << IRNames::localVariable(*arg) << ", ";
+	if (!arguments.empty())
+		m_code << IRNames::localVariable(*arguments.back());
+	m_code << ")\n";
+	return false;
+}
+
+bool IRGeneratorForStatements::visit(Assignment const& _assignment)
+{
+	_assignment.rightHandSide().accept(*this);
+	auto const* lhs = dynamic_cast<Identifier const*>(&_assignment.leftHandSide());
+	solAssert(lhs, "Can only assign to identifiers.");
+	auto const* lhsVar = dynamic_cast<VariableDeclaration const*>(lhs->annotation().referencedDeclaration);
+	solAssert(lhsVar, "Can only assign to identifiers referring to variables.");
+	m_code << IRNames::localVariable(*lhsVar) << " := " << IRNames::localVariable(_assignment.rightHandSide()) << "\n";
+
+	m_code << "let " << IRNames::localVariable(_assignment) << " := " << IRNames::localVariable(*lhsVar) << "\n";
+	return false;
+}
+
+
 bool IRGeneratorForStatements::visitNode(ASTNode const&)
 {
 	solAssert(false, "Unsupported AST node during statement code generation.");

libsolidity/codegen/experimental/IRGeneratorForStatements.h

@@ -18,6 +18,7 @@
 
 #pragma once
 
+#include <libsolidity/codegen/experimental/IRGenerationContext.h>
 #include <libsolidity/ast/ASTVisitor.h>
 
 #include <functional>
@@ -30,15 +31,19 @@ class Analysis;
 class IRGeneratorForStatements: public ASTConstVisitor
 {
 public:
-	IRGeneratorForStatements(Analysis const& _analysis): m_analysis(_analysis) {}
+	IRGeneratorForStatements(IRGenerationContext& _context): m_context(_context) {}
 
 	std::string generate(ASTNode const& _node);
 private:
+	bool visit(ExpressionStatement const& _expressionStatement) override;
+	bool visit(Assignment const& _assignment) override;
+	bool visit(Identifier const& _identifier) override;
+	bool visit(FunctionCall const&) override;
 	bool visit(InlineAssembly const& _inlineAssembly) override;
 	bool visit(VariableDeclarationStatement const& _variableDeclarationStatement) override;
 	/// Default visit will reject all AST nodes that are not explicitly supported.
 	bool visitNode(ASTNode const& _node) override;
-	Analysis const& m_analysis;
+	IRGenerationContext& m_context;
 	std::stringstream m_code;
 };
 

test/libsolidity/semanticTests/experimental/stub.sol

@@ -1,9 +1,7 @@
 pragma experimental solidity;
 
-function f(a:word) -> (b:word) {
+function f(a) -> (b) {
-    assembly {
+    b = a;
-        b := a
-    }
 }
 
 contract C {
@@ -13,7 +11,7 @@ contract C {
 		assembly {
 			x := 0x42
 		}
-		y = x;
+		y = f(x);
 		assembly {
 			mstore(0, y)
 			return(0, 32)
@@ -23,4 +21,4 @@ contract C {
 // ====
 // compileViaYul: true
 // ----
-// () -> 0x42
+// () -> 21