15 files changed, 1002 insertions, 314 deletions

diff --git a/libsolidity/inlineasm/AsmAnalysis.cpp b/libsolidity/inlineasm/AsmAnalysis.cpp
index a3ddb61d..dad05a78 100644
--- a/libsolidity/inlineasm/AsmAnalysis.cpp
+++ b/libsolidity/inlineasm/AsmAnalysis.cpp
@@ -21,6 +21,9 @@
 #include <libsolidity/inlineasm/AsmAnalysis.h>
 
 #include <libsolidity/inlineasm/AsmData.h>
+#include <libsolidity/inlineasm/AsmScopeFiller.h>
+#include <libsolidity/inlineasm/AsmScope.h>
+#include <libsolidity/inlineasm/AsmAnalysisInfo.h>
 
 #include <libsolidity/interface/Exceptions.h>
 #include <libsolidity/interface/Utils.h>
@@ -35,146 +38,363 @@ using namespace dev;
 using namespace dev::solidity;
 using namespace dev::solidity::assembly;
 
-
-bool Scope::registerLabel(string const& _name)
+AsmAnalyzer::AsmAnalyzer(
+	AsmAnalysisInfo& _analysisInfo,
+	ErrorList& _errors,
+	ExternalIdentifierAccess::Resolver const& _resolver
+):
+	m_resolver(_resolver), m_info(_analysisInfo), m_errors(_errors)
 {
-	if (exists(_name))
-		return false;
-	identifiers[_name] = Label();
-	return true;
 }
 
-bool Scope::registerVariable(string const& _name)
+bool AsmAnalyzer::analyze(Block const& _block)
 {
-	if (exists(_name))
+	if (!(ScopeFiller(m_info.scopes, m_errors))(_block))
 		return false;
-	identifiers[_name] = Variable();
-	return true;
-}
 
-bool Scope::registerFunction(string const& _name, size_t _arguments, size_t _returns)
-{
-	if (exists(_name))
-		return false;
-	identifiers[_name] = Function(_arguments, _returns);
-	return true;
+	return (*this)(_block);
 }
 
-Scope::Identifier* Scope::lookup(string const& _name)
+bool AsmAnalyzer::operator()(Label const& _label)
 {
-	if (identifiers.count(_name))
-		return &identifiers[_name];
-	else if (superScope && !closedScope)
-		return superScope->lookup(_name);
-	else
-		return nullptr;
-}
-
-bool Scope::exists(string const& _name)
-{
-	if (identifiers.count(_name))
-		return true;
-	else if (superScope)
-		return superScope->exists(_name);
-	else
-		return false;
+	m_info.stackHeightInfo[&_label] = m_stackHeight;
+	return true;
 }
 
-AsmAnalyzer::AsmAnalyzer(AsmAnalyzer::Scopes& _scopes, ErrorList& _errors):
-	m_scopes(_scopes), m_errors(_errors)
+bool AsmAnalyzer::operator()(assembly::Instruction const& _instruction)
 {
-	// Make the Solidity ErrorTag available to inline assembly
-	m_scopes[nullptr] = make_shared<Scope>();
-	Scope::Label errorLabel;
-	errorLabel.id = Scope::Label::errorLabelId;
-	m_scopes[nullptr]->identifiers["invalidJumpLabel"] = errorLabel;
-	m_currentScope = m_scopes[nullptr].get();
+	auto const& info = instructionInfo(_instruction.instruction);
+	m_stackHeight += info.ret - info.args;
+	m_info.stackHeightInfo[&_instruction] = m_stackHeight;
+	return true;
 }
 
 bool AsmAnalyzer::operator()(assembly::Literal const& _literal)
 {
+	++m_stackHeight;
 	if (!_literal.isNumber && _literal.value.size() > 32)
 	{
 		m_errors.push_back(make_shared<Error>(
 			Error::Type::TypeError,
-			"String literal too long (" + boost::lexical_cast<std::string>(_literal.value.size()) + " > 32)"
+			"String literal too long (" + boost::lexical_cast<std::string>(_literal.value.size()) + " > 32)",
+			_literal.location
 		));
 		return false;
 	}
+	m_info.stackHeightInfo[&_literal] = m_stackHeight;
 	return true;
 }
 
+bool AsmAnalyzer::operator()(assembly::Identifier const& _identifier)
+{
+	size_t numErrorsBefore = m_errors.size();
+	bool success = true;
+	if (m_currentScope->lookup(_identifier.name, Scope::Visitor(
+		[&](Scope::Variable const& _var)
+		{
+			if (!_var.active)
+			{
+				m_errors.push_back(make_shared<Error>(
+					Error::Type::DeclarationError,
+					"Variable " + _identifier.name + " used before it was declared.",
+					_identifier.location
+				));
+				success = false;
+			}
+			++m_stackHeight;
+		},
+		[&](Scope::Label const&)
+		{
+			++m_stackHeight;
+		},
+		[&](Scope::Function const&)
+		{
+			m_errors.push_back(make_shared<Error>(
+				Error::Type::TypeError,
+				"Function " + _identifier.name + " used without being called.",
+				_identifier.location
+			));
+			success = false;
+		}
+	)))
+	{
+	}
+	else
+	{
+		size_t stackSize(-1);
+		if (m_resolver)
+			stackSize = m_resolver(_identifier, IdentifierContext::RValue);
+		if (stackSize == size_t(-1))
+		{
+			// Only add an error message if the callback did not do it.
+			if (numErrorsBefore == m_errors.size())
+				m_errors.push_back(make_shared<Error>(
+					Error::Type::DeclarationError,
+					"Identifier not found.",
+					_identifier.location
+				));
+			success = false;
+		}
+		m_stackHeight += stackSize == size_t(-1) ? 1 : stackSize;
+	}
+	m_info.stackHeightInfo[&_identifier] = m_stackHeight;
+	return success;
+}
+
 bool AsmAnalyzer::operator()(FunctionalInstruction const& _instr)
 {
 	bool success = true;
 	for (auto const& arg: _instr.arguments | boost::adaptors::reversed)
+	{
+		int const stackHeight = m_stackHeight;
 		if (!boost::apply_visitor(*this, arg))
 			success = false;
+		if (!expectDeposit(1, stackHeight, locationOf(arg)))
+			success = false;
+	}
+	// Parser already checks that the number of arguments is correct.
+	solAssert(instructionInfo(_instr.instruction.instruction).args == int(_instr.arguments.size()), "");
 	if (!(*this)(_instr.instruction))
 		success = false;
+	m_info.stackHeightInfo[&_instr] = m_stackHeight;
 	return success;
 }
 
-bool AsmAnalyzer::operator()(Label const& _item)
+bool AsmAnalyzer::operator()(assembly::Assignment const& _assignment)
 {
-	if (!m_currentScope->registerLabel(_item.name))
-	{
-		//@TODO secondary location
-		m_errors.push_back(make_shared<Error>(
-			Error::Type::DeclarationError,
-			"Label name " + _item.name + " already taken in this scope.",
-			_item.location
-		));
-		return false;
-	}
-	return true;
+	bool success = checkAssignment(_assignment.variableName, size_t(-1));
+	m_info.stackHeightInfo[&_assignment] = m_stackHeight;
+	return success;
 }
 
+
 bool AsmAnalyzer::operator()(FunctionalAssignment const& _assignment)
 {
-	return boost::apply_visitor(*this, *_assignment.value);
+	int const stackHeight = m_stackHeight;
+	bool success = boost::apply_visitor(*this, *_assignment.value);
+	solAssert(m_stackHeight >= stackHeight, "Negative value size.");
+	if (!checkAssignment(_assignment.variableName, m_stackHeight - stackHeight))
+		success = false;
+	m_info.stackHeightInfo[&_assignment] = m_stackHeight;
+	return success;
 }
 
 bool AsmAnalyzer::operator()(assembly::VariableDeclaration const& _varDecl)
 {
+	int const stackHeight = m_stackHeight;
 	bool success = boost::apply_visitor(*this, *_varDecl.value);
-	if (!m_currentScope->registerVariable(_varDecl.name))
-	{
-		//@TODO secondary location
-		m_errors.push_back(make_shared<Error>(
-			Error::Type::DeclarationError,
-			"Variable name " + _varDecl.name + " already taken in this scope.",
-			_varDecl.location
-		));
-		success = false;
-	}
+	solAssert(m_stackHeight - stackHeight == 1, "Invalid value size.");
+	boost::get<Scope::Variable>(m_currentScope->identifiers.at(_varDecl.name)).active = true;
+	m_info.stackHeightInfo[&_varDecl] = m_stackHeight;
 	return success;
 }
 
-bool AsmAnalyzer::operator()(assembly::FunctionDefinition const&)
+bool AsmAnalyzer::operator()(assembly::FunctionDefinition const& _funDef)
 {
-	// TODO - we cannot throw an exception here because of some tests.
-	return true;
+	Scope& bodyScope = scope(&_funDef.body);
+	for (auto const& var: _funDef.arguments + _funDef.returns)
+		boost::get<Scope::Variable>(bodyScope.identifiers.at(var)).active = true;
+
+	int const stackHeight = m_stackHeight;
+	m_stackHeight = _funDef.arguments.size() + _funDef.returns.size();
+	m_virtualVariablesInNextBlock = m_stackHeight;
+
+	bool success = (*this)(_funDef.body);
+
+	m_stackHeight = stackHeight;
+	m_info.stackHeightInfo[&_funDef] = m_stackHeight;
+	return success;
 }
 
-bool AsmAnalyzer::operator()(assembly::FunctionCall const&)
+bool AsmAnalyzer::operator()(assembly::FunctionCall const& _funCall)
 {
-	// TODO - we cannot throw an exception here because of some tests.
-	return true;
+	bool success = true;
+	size_t arguments = 0;
+	size_t returns = 0;
+	if (!m_currentScope->lookup(_funCall.functionName.name, Scope::Visitor(
+		[&](Scope::Variable const&)
+		{
+			m_errors.push_back(make_shared<Error>(
+				Error::Type::TypeError,
+				"Attempt to call variable instead of function.",
+				_funCall.functionName.location
+			));
+			success = false;
+		},
+		[&](Scope::Label const&)
+		{
+			m_errors.push_back(make_shared<Error>(
+				Error::Type::TypeError,
+				"Attempt to call label instead of function.",
+				_funCall.functionName.location
+				));
+			success = false;
+		},
+		[&](Scope::Function const& _fun)
+		{
+			arguments = _fun.arguments;
+			returns = _fun.returns;
+		}
+	)))
+	{
+		m_errors.push_back(make_shared<Error>(
+			Error::Type::DeclarationError,
+			"Function not found.",
+			_funCall.functionName.location
+		));
+		success = false;
+	}
+	if (success)
+	{
+		if (_funCall.arguments.size() != arguments)
+		{
+			m_errors.push_back(make_shared<Error>(
+				Error::Type::TypeError,
+				"Expected " +
+				boost::lexical_cast<string>(arguments) +
+				" arguments but got " +
+				boost::lexical_cast<string>(_funCall.arguments.size()) +
+				".",
+				_funCall.functionName.location
+				));
+			success = false;
+		}
+	}
+	for (auto const& arg: _funCall.arguments | boost::adaptors::reversed)
+	{
+		int const stackHeight = m_stackHeight;
+		if (!boost::apply_visitor(*this, arg))
+			success = false;
+		if (!expectDeposit(1, stackHeight, locationOf(arg)))
+			success = false;
+	}
+	m_stackHeight += int(returns) - int(arguments);
+	m_info.stackHeightInfo[&_funCall] = m_stackHeight;
+	return success;
 }
 
 bool AsmAnalyzer::operator()(Block const& _block)
 {
 	bool success = true;
-	auto scope = make_shared<Scope>();
-	scope->superScope = m_currentScope;
-	m_scopes[&_block] = scope;
-	m_currentScope = scope.get();
+	m_currentScope = &scope(&_block);
+
+	int const initialStackHeight = m_stackHeight - m_virtualVariablesInNextBlock;
+	m_virtualVariablesInNextBlock = 0;
 
 	for (auto const& s: _block.statements)
 		if (!boost::apply_visitor(*this, s))
 			success = false;
 
+	for (auto const& identifier: scope(&_block).identifiers)
+		if (identifier.second.type() == typeid(Scope::Variable))
+			--m_stackHeight;
+
+	int const stackDiff = m_stackHeight - initialStackHeight;
+	if (stackDiff != 0)
+	{
+		m_errors.push_back(make_shared<Error>(
+			Error::Type::DeclarationError,
+			"Unbalanced stack at the end of a block: " +
+			(
+				stackDiff > 0 ?
+				to_string(stackDiff) + string(" surplus item(s).") :
+				to_string(-stackDiff) + string(" missing item(s).")
+			),
+			_block.location
+		));
+		success = false;
+	}
+
 	m_currentScope = m_currentScope->superScope;
+	m_info.stackHeightInfo[&_block] = m_stackHeight;
+	return success;
+}
+
+bool AsmAnalyzer::checkAssignment(assembly::Identifier const& _variable, size_t _valueSize)
+{
+	bool success = true;
+	size_t numErrorsBefore = m_errors.size();
+	size_t variableSize(-1);
+	if (Scope::Identifier const* var = m_currentScope->lookup(_variable.name))
+	{
+		// Check that it is a variable
+		if (var->type() != typeid(Scope::Variable))
+		{
+			m_errors.push_back(make_shared<Error>(
+				Error::Type::TypeError,
+				"Assignment requires variable.",
+				_variable.location
+			));
+			success = false;
+		}
+		else if (!boost::get<Scope::Variable>(*var).active)
+		{
+			m_errors.push_back(make_shared<Error>(
+				Error::Type::DeclarationError,
+				"Variable " + _variable.name + " used before it was declared.",
+				_variable.location
+			));
+			success = false;
+		}
+		variableSize = 1;
+	}
+	else if (m_resolver)
+		variableSize = m_resolver(_variable, IdentifierContext::LValue);
+	if (variableSize == size_t(-1))
+	{
+		// Only add message if the callback did not.
+		if (numErrorsBefore == m_errors.size())
+			m_errors.push_back(make_shared<Error>(
+				Error::Type::DeclarationError,
+				"Variable not found or variable not lvalue.",
+				_variable.location
+			));
+		success = false;
+	}
+	if (_valueSize == size_t(-1))
+		_valueSize = variableSize == size_t(-1) ? 1 : variableSize;
+
+	m_stackHeight -= _valueSize;
+
+	if (_valueSize != variableSize && variableSize != size_t(-1))
+	{
+		m_errors.push_back(make_shared<Error>(
+			Error::Type::TypeError,
+			"Variable size (" +
+			to_string(variableSize) +
+			") and value size (" +
+			to_string(_valueSize) +
+			") do not match.",
+			_variable.location
+		));
+		success = false;
+	}
 	return success;
 }
+
+bool AsmAnalyzer::expectDeposit(int const _deposit, int const _oldHeight, SourceLocation const& _location)
+{
+	int stackDiff = m_stackHeight - _oldHeight;
+	if (stackDiff != _deposit)
+	{
+		m_errors.push_back(make_shared<Error>(
+			Error::Type::TypeError,
+			"Expected instruction(s) to deposit " +
+			boost::lexical_cast<string>(_deposit) +
+			" item(s) to the stack, but did deposit " +
+			boost::lexical_cast<string>(stackDiff) +
+			" item(s).",
+			_location
+		));
+		return false;
+	}
+	else
+		return true;
+}
+
+Scope& AsmAnalyzer::scope(Block const* _block)
+{
+	auto scopePtr = m_info.scopes.at(_block);
+	solAssert(scopePtr, "Scope requested but not present.");
+	return *scopePtr;
+}
diff --git a/libsolidity/inlineasm/AsmAnalysis.h b/libsolidity/inlineasm/AsmAnalysis.h
index 9726210d..426ee0d2 100644
--- a/libsolidity/inlineasm/AsmAnalysis.h
+++ b/libsolidity/inlineasm/AsmAnalysis.h
@@ -20,6 +20,8 @@
 
 #pragma once
 
+#include <libsolidity/inlineasm/AsmStack.h>
+
 #include <libsolidity/interface/Exceptions.h>
 
 #include <boost/variant.hpp>
@@ -46,101 +48,32 @@ struct Assignment;
 struct FunctionDefinition;
 struct FunctionCall;
 
-template <class...>
-struct GenericVisitor{};
-
-template <class Visitable, class... Others>
-struct GenericVisitor<Visitable, Others...>: public GenericVisitor<Others...>
-{
-	using GenericVisitor<Others...>::operator ();
-	explicit GenericVisitor(
-		std::function<void(Visitable&)> _visitor,
-		std::function<void(Others&)>... _otherVisitors
-	):
-		GenericVisitor<Others...>(_otherVisitors...),
-		m_visitor(_visitor)
-	{}
-
-	void operator()(Visitable& _v) const { m_visitor(_v); }
-
-	std::function<void(Visitable&)> m_visitor;
-};
-template <>
-struct GenericVisitor<>: public boost::static_visitor<> {
-	void operator()() const {}
-};
-
-
-struct Scope
-{
-	struct Variable
-	{
-		int stackHeight = 0;
-		bool active = false;
-	};
-
-	struct Label
-	{
-		size_t id = unassignedLabelId;
-		static const size_t errorLabelId = -1;
-		static const size_t unassignedLabelId = 0;
-	};
-
-	struct Function
-	{
-		Function(size_t _arguments, size_t _returns): arguments(_arguments), returns(_returns) {}
-		size_t arguments = 0;
-		size_t returns = 0;
-	};
-
-	using Identifier = boost::variant<Variable, Label, Function>;
-	using Visitor = GenericVisitor<Variable const, Label const, Function const>;
-	using NonconstVisitor = GenericVisitor<Variable, Label, Function>;
-
-	bool registerVariable(std::string const& _name);
-	bool registerLabel(std::string const& _name);
-	bool registerFunction(std::string const& _name, size_t _arguments, size_t _returns);
-
-	/// Looks up the identifier in this or super scopes (stops and function and assembly boundaries)
-	/// and returns a valid pointer if found or a nullptr if not found.
-	/// The pointer will be invalidated if the scope is modified.
-	Identifier* lookup(std::string const& _name);
-	/// Looks up the identifier in this and super scopes (stops and function and assembly boundaries)
-	/// and calls the visitor, returns false if not found.
-	template <class V>
-	bool lookup(std::string const& _name, V const& _visitor)
-	{
-		if (Identifier* id = lookup(_name))
-		{
-			boost::apply_visitor(_visitor, *id);
-			return true;
-		}
-		else
-			return false;
-	}
-	/// @returns true if the name exists in this scope or in super scopes (also searches
-	/// across function and assembly boundaries).
-	bool exists(std::string const& _name);
-	Scope* superScope = nullptr;
-	/// If true, identifiers from the super scope are not visible here, but they are still
-	/// taken into account to prevent shadowing.
-	bool closedScope = false;
-	std::map<std::string, Identifier> identifiers;
-};
+struct Scope;
 
+struct AsmAnalysisInfo;
 
+/**
+ * Performs the full analysis stage, calls the ScopeFiller internally, then resolves
+ * references and performs other checks.
+ * If all these checks pass, code generation should not throw errors.
+ */
 class AsmAnalyzer: public boost::static_visitor<bool>
 {
 public:
-	using Scopes = std::map<assembly::Block const*, std::shared_ptr<Scope>>;
-	AsmAnalyzer(Scopes& _scopes, ErrorList& _errors);
+	AsmAnalyzer(
+		AsmAnalysisInfo& _analysisInfo,
+		ErrorList& _errors,
+		ExternalIdentifierAccess::Resolver const& _resolver = ExternalIdentifierAccess::Resolver()
+	);
+
+	bool analyze(assembly::Block const& _block);
 
-	bool operator()(assembly::Instruction const&) { return true; }
+	bool operator()(assembly::Instruction const&);
 	bool operator()(assembly::Literal const& _literal);
-	bool operator()(assembly::Identifier const&) { return true; }
+	bool operator()(assembly::Identifier const&);
 	bool operator()(assembly::FunctionalInstruction const& _functionalInstruction);
 	bool operator()(assembly::Label const& _label);
-	bool operator()(assembly::Assignment const&) { return true; }
+	bool operator()(assembly::Assignment const&);
 	bool operator()(assembly::FunctionalAssignment const& _functionalAssignment);
 	bool operator()(assembly::VariableDeclaration const& _variableDeclaration);
 	bool operator()(assembly::FunctionDefinition const& _functionDefinition);
@@ -148,8 +81,20 @@ public:
 	bool operator()(assembly::Block const& _block);
 
 private:
+	/// Verifies that a variable to be assigned to exists and has the same size
+	/// as the value, @a _valueSize, unless that is equal to -1.
+	bool checkAssignment(assembly::Identifier const& _assignment, size_t _valueSize = size_t(-1));
+	bool expectDeposit(int _deposit, int _oldHeight, SourceLocation const& _location);
+	Scope& scope(assembly::Block const* _block);
+
+	/// This is used when we enter the body of a function definition. There, the parameters
+	/// and return parameters appear as variables which are already on the stack before
+	/// we enter the block.
+	int m_virtualVariablesInNextBlock = 0;
+	int m_stackHeight = 0;
+	ExternalIdentifierAccess::Resolver const& m_resolver;
 	Scope* m_currentScope = nullptr;
-	Scopes& m_scopes;
+	AsmAnalysisInfo& m_info;
 	ErrorList& m_errors;
 };
 
diff --git a/libsolidity/inlineasm/AsmAnalysisInfo.cpp b/libsolidity/inlineasm/AsmAnalysisInfo.cpp
new file mode 100644
index 00000000..22318b12
--- /dev/null
+++ b/libsolidity/inlineasm/AsmAnalysisInfo.cpp
@@ -0,0 +1,26 @@
+/*
+	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/>.
+*/
+/**
+ * Information generated during analyzer part of inline assembly.
+ */
+
+#include <libsolidity/inlineasm/AsmAnalysisInfo.h>
+
+#include <libsolidity/inlineasm/AsmScope.h>
+
+#include <ostream>
+
diff --git a/libsolidity/inlineasm/AsmAnalysisInfo.h b/libsolidity/inlineasm/AsmAnalysisInfo.h
new file mode 100644
index 00000000..e21eb2c5
--- /dev/null
+++ b/libsolidity/inlineasm/AsmAnalysisInfo.h
@@ -0,0 +1,61 @@
+/*
+	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/>.
+*/
+/**
+ * Information generated during analyzer part of inline assembly.
+ */
+
+#pragma once
+
+#include <boost/variant.hpp>
+
+#include <map>
+#include <memory>
+
+namespace dev
+{
+namespace solidity
+{
+namespace assembly
+{
+
+struct Literal;
+struct Block;
+struct Label;
+struct FunctionalInstruction;
+struct FunctionalAssignment;
+struct VariableDeclaration;
+struct Instruction;
+struct Identifier;
+struct Assignment;
+struct FunctionDefinition;
+struct FunctionCall;
+
+struct Scope;
+
+using Statement = boost::variant<Instruction, Literal, Label, Assignment, Identifier, FunctionalAssignment, FunctionCall, FunctionalInstruction, VariableDeclaration, FunctionDefinition, Block>;
+
+struct AsmAnalysisInfo
+{
+	using StackHeightInfo = std::map<void const*, int>;
+	using Scopes = std::map<assembly::Block const*, std::shared_ptr<Scope>>;
+	Scopes scopes;
+	StackHeightInfo stackHeightInfo;
+};
+
+}
+}
+}
diff --git a/libsolidity/inlineasm/AsmCodeGen.cpp b/libsolidity/inlineasm/AsmCodeGen.cpp
index 78a9ee27..9ef3e6e7 100644
--- a/libsolidity/inlineasm/AsmCodeGen.cpp
+++ b/libsolidity/inlineasm/AsmCodeGen.cpp
@@ -24,7 +24,9 @@
 
 #include <libsolidity/inlineasm/AsmParser.h>
 #include <libsolidity/inlineasm/AsmData.h>
+#include <libsolidity/inlineasm/AsmScope.h>
 #include <libsolidity/inlineasm/AsmAnalysis.h>
+#include <libsolidity/inlineasm/AsmAnalysisInfo.h>
 
 #include <libevmasm/Assembly.h>
 #include <libevmasm/SourceLocation.h>
@@ -46,13 +48,8 @@ using namespace dev::solidity::assembly;
 
 struct GeneratorState
 {
-	GeneratorState(ErrorList& _errors, eth::Assembly& _assembly):
-		errors(_errors), assembly(_assembly) {}
-
-	void addError(Error::Type _type, std::string const& _description, SourceLocation const& _location = SourceLocation())
-	{
-		errors.push_back(make_shared<Error>(_type, _description, _location));
-	}
+	GeneratorState(ErrorList& _errors, AsmAnalysisInfo& _analysisInfo, eth::Assembly& _assembly):
+		errors(_errors), info(_analysisInfo), assembly(_assembly) {}
 
 	size_t newLabelId()
 	{
@@ -66,8 +63,8 @@ struct GeneratorState
 		return size_t(id);
 	}
 
-	std::map<assembly::Block const*, shared_ptr<Scope>> scopes;
 	ErrorList& errors;
+	AsmAnalysisInfo info;
 	eth::Assembly& assembly;
 };
 
@@ -80,13 +77,24 @@ public:
 	explicit CodeTransform(
 		GeneratorState& _state,
 		assembly::Block const& _block,
-		assembly::CodeGenerator::IdentifierAccess const& _identifierAccess = assembly::CodeGenerator::IdentifierAccess()
+		assembly::ExternalIdentifierAccess const& _identifierAccess = assembly::ExternalIdentifierAccess()
+	): CodeTransform(_state, _block, _identifierAccess, _state.assembly.deposit())
+	{
+	}
+
+private:
+	CodeTransform(
+		GeneratorState& _state,
+		assembly::Block const& _block,
+		assembly::ExternalIdentifierAccess const& _identifierAccess,
+		int _initialDeposit
 	):
 		m_state(_state),
-		m_scope(*m_state.scopes.at(&_block)),
-		m_initialDeposit(m_state.assembly.deposit()),
-		m_identifierAccess(_identifierAccess)
+		m_scope(*m_state.info.scopes.at(&_block)),
+		m_identifierAccess(_identifierAccess),
+		m_initialDeposit(_initialDeposit)
 	{
+		int blockStartDeposit = m_state.assembly.deposit();
 		std::for_each(_block.statements.begin(), _block.statements.end(), boost::apply_visitor(*this));
 
 		m_state.assembly.setSourceLocation(_block.location);
@@ -96,31 +104,16 @@ public:
 			if (identifier.second.type() == typeid(Scope::Variable))
 				m_state.assembly.append(solidity::Instruction::POP);
 
-		int deposit = m_state.assembly.deposit() - m_initialDeposit;
-
-		// issue warnings for stack height discrepancies
-		if (deposit < 0)
-		{
-			m_state.addError(
-				Error::Type::Warning,
-				"Inline assembly block is not balanced. It takes " + toString(-deposit) + " item(s) from the stack.",
-				_block.location
-			);
-		}
-		else if (deposit > 0)
-		{
-			m_state.addError(
-				Error::Type::Warning,
-				"Inline assembly block is not balanced. It leaves " + toString(deposit) + " item(s) on the stack.",
-				_block.location
-			);
-		}
+		int deposit = m_state.assembly.deposit() - blockStartDeposit;
+		solAssert(deposit == 0, "Invalid stack height at end of block.");
 	}
 
+public:
 	void operator()(assembly::Instruction const& _instruction)
 	{
 		m_state.assembly.setSourceLocation(_instruction.location);
 		m_state.assembly.append(_instruction.instruction);
+		checkStackHeight(&_instruction);
 	}
 	void operator()(assembly::Literal const& _literal)
 	{
@@ -130,8 +123,9 @@ public:
 		else
 		{
 			solAssert(_literal.value.size() <= 32, "");
-			m_state.assembly.append(_literal.value);
+			m_state.assembly.append(u256(h256(_literal.value, h256::FromBinary, h256::AlignLeft)));
 		}
+		checkStackHeight(&_literal);
 	}
 	void operator()(assembly::Identifier const& _identifier)
 	{
@@ -153,20 +147,18 @@ public:
 			},
 			[=](Scope::Function&)
 			{
-				solAssert(false, "Not yet implemented");
+				solAssert(false, "Function not removed during desugaring.");
 			}
 		)))
 		{
+			return;
 		}
-		else if (!m_identifierAccess || !m_identifierAccess(_identifier, m_state.assembly, CodeGenerator::IdentifierContext::RValue))
-		{
-			m_state.addError(
-				Error::Type::DeclarationError,
-				"Identifier not found or not unique",
-				_identifier.location
-			);
-			m_state.assembly.append(u256(0));
-		}
+		solAssert(
+			m_identifierAccess.generateCode,
+			"Identifier not found and no external access available."
+		);
+		m_identifierAccess.generateCode(_identifier, IdentifierContext::RValue, m_state.assembly);
+		checkStackHeight(&_identifier);
 	}
 	void operator()(FunctionalInstruction const& _instr)
 	{
@@ -174,9 +166,10 @@ public:
 		{
 			int height = m_state.assembly.deposit();
 			boost::apply_visitor(*this, *it);
-			expectDeposit(1, height, locationOf(*it));
+			expectDeposit(1, height);
 		}
 		(*this)(_instr.instruction);
+		checkStackHeight(&_instr);
 	}
 	void operator()(assembly::FunctionCall const&)
 	{
@@ -186,36 +179,39 @@ public:
 	{
 		m_state.assembly.setSourceLocation(_label.location);
 		solAssert(m_scope.identifiers.count(_label.name), "");
-		Scope::Label& label = boost::get<Scope::Label>(m_scope.identifiers[_label.name]);
+		Scope::Label& label = boost::get<Scope::Label>(m_scope.identifiers.at(_label.name));
 		assignLabelIdIfUnset(label);
 		m_state.assembly.append(eth::AssemblyItem(eth::Tag, label.id));
+		checkStackHeight(&_label);
 	}
 	void operator()(assembly::Assignment const& _assignment)
 	{
 		m_state.assembly.setSourceLocation(_assignment.location);
 		generateAssignment(_assignment.variableName, _assignment.location);
+		checkStackHeight(&_assignment);
 	}
 	void operator()(FunctionalAssignment const& _assignment)
 	{
 		int height = m_state.assembly.deposit();
 		boost::apply_visitor(*this, *_assignment.value);
-		expectDeposit(1, height, locationOf(*_assignment.value));
+		expectDeposit(1, height);
 		m_state.assembly.setSourceLocation(_assignment.location);
 		generateAssignment(_assignment.variableName, _assignment.location);
+		checkStackHeight(&_assignment);
 	}
 	void operator()(assembly::VariableDeclaration const& _varDecl)
 	{
 		int height = m_state.assembly.deposit();
 		boost::apply_visitor(*this, *_varDecl.value);
-		expectDeposit(1, height, locationOf(*_varDecl.value));
-		solAssert(m_scope.identifiers.count(_varDecl.name), "");
-		auto& var = boost::get<Scope::Variable>(m_scope.identifiers[_varDecl.name]);
+		expectDeposit(1, height);
+		auto& var = boost::get<Scope::Variable>(m_scope.identifiers.at(_varDecl.name));
 		var.stackHeight = height;
 		var.active = true;
 	}
 	void operator()(assembly::Block const& _block)
 	{
-		CodeTransform(m_state, _block, m_identifierAccess);
+		CodeTransform(m_state, _block, m_identifierAccess, m_initialDeposit);
+		checkStackHeight(&_block);
 	}
 	void operator()(assembly::FunctionDefinition const&)
 	{
@@ -225,35 +221,22 @@ public:
 private:
 	void generateAssignment(assembly::Identifier const& _variableName, SourceLocation const& _location)
 	{
-		if (m_scope.lookup(_variableName.name, Scope::Visitor(
-			[=](Scope::Variable const& _var)
-			{
-				if (int heightDiff = variableHeightDiff(_var, _location, true))
-					m_state.assembly.append(solidity::swapInstruction(heightDiff - 1));
-				m_state.assembly.append(solidity::Instruction::POP);
-			},
-			[=](Scope::Label const&)
-			{
-				m_state.addError(
-					Error::Type::DeclarationError,
-					"Label \"" + string(_variableName.name) + "\" used as variable."
-				);
-			},
-			[=](Scope::Function const&)
-			{
-				m_state.addError(
-					Error::Type::DeclarationError,
-					"Function \"" + string(_variableName.name) + "\" used as variable."
-				);
-			}
-		)))
+		auto var = m_scope.lookup(_variableName.name);
+		if (var)
 		{
+			Scope::Variable const& _var = boost::get<Scope::Variable>(*var);
+			if (int heightDiff = variableHeightDiff(_var, _location, true))
+				m_state.assembly.append(solidity::swapInstruction(heightDiff - 1));
+			m_state.assembly.append(solidity::Instruction::POP);
 		}
-		else if (!m_identifierAccess || !m_identifierAccess(_variableName, m_state.assembly, CodeGenerator::IdentifierContext::LValue))
-			m_state.addError(
-				Error::Type::DeclarationError,
-				"Identifier \"" + string(_variableName.name) + "\" not found, not unique or not lvalue."
+		else
+		{
+			solAssert(
+				m_identifierAccess.generateCode,
+				"Identifier not found and no external access available."
 			);
+			m_identifierAccess.generateCode(_variableName, IdentifierContext::LValue, m_state.assembly);
+		}
 	}
 
 	/// Determines the stack height difference to the given variables. Automatically generates
@@ -261,36 +244,33 @@ private:
 	/// errors and the (positive) stack height difference otherwise.
 	int variableHeightDiff(Scope::Variable const& _var, SourceLocation const& _location, bool _forSwap)
 	{
-		if (!_var.active)
-		{
-			m_state.addError( Error::Type::TypeError, "Variable used before it was declared", _location);
-			return 0;
-		}
 		int heightDiff = m_state.assembly.deposit() - _var.stackHeight;
 		if (heightDiff <= (_forSwap ? 1 : 0) || heightDiff > (_forSwap ? 17 : 16))
 		{
-			m_state.addError(
+			//@TODO move this to analysis phase.
+			m_state.errors.push_back(make_shared<Error>(
 				Error::Type::TypeError,
 				"Variable inaccessible, too deep inside stack (" + boost::lexical_cast<string>(heightDiff) + ")",
 				_location
-			);
+			));
 			return 0;
 		}
 		else
 			return heightDiff;
 	}
 
-	void expectDeposit(int _deposit, int _oldHeight, SourceLocation const& _location)
+	void expectDeposit(int _deposit, int _oldHeight)
 	{
-		if (m_state.assembly.deposit() != _oldHeight + 1)
-			m_state.addError(Error::Type::TypeError,
-				"Expected instruction(s) to deposit " +
-				boost::lexical_cast<string>(_deposit) +
-				" item(s) to the stack, but did deposit " +
-				boost::lexical_cast<string>(m_state.assembly.deposit() - _oldHeight) +
-				" item(s).",
-				_location
-			);
+		solAssert(m_state.assembly.deposit() == _oldHeight + _deposit, "Invalid stack deposit.");
+	}
+
+	void checkStackHeight(void const* _astElement)
+	{
+		solAssert(m_state.info.stackHeightInfo.count(_astElement), "Stack height for AST element not found.");
+		solAssert(
+			m_state.info.stackHeightInfo.at(_astElement) == m_state.assembly.deposit() - m_initialDeposit,
+			"Stack height mismatch between analysis and code generation phase."
+		);
 	}
 
 	/// Assigns the label's id to a value taken from eth::Assembly if it has not yet been set.
@@ -305,35 +285,29 @@ private:
 
 	GeneratorState& m_state;
 	Scope& m_scope;
+	ExternalIdentifierAccess m_identifierAccess;
 	int const m_initialDeposit;
-	assembly::CodeGenerator::IdentifierAccess m_identifierAccess;
 };
 
-bool assembly::CodeGenerator::typeCheck(assembly::CodeGenerator::IdentifierAccess const& _identifierAccess)
-{
-	size_t initialErrorLen = m_errors.size();
-	eth::Assembly assembly;
-	GeneratorState state(m_errors, assembly);
-	if (!(AsmAnalyzer(state.scopes, m_errors))(m_parsedData))
-		return false;
-	CodeTransform(state, m_parsedData, _identifierAccess);
-	return m_errors.size() == initialErrorLen;
-}
-
-eth::Assembly assembly::CodeGenerator::assemble(assembly::CodeGenerator::IdentifierAccess const& _identifierAccess)
+eth::Assembly assembly::CodeGenerator::assemble(
+	Block const& _parsedData,
+	AsmAnalysisInfo& _analysisInfo,
+	ExternalIdentifierAccess const& _identifierAccess
+)
 {
 	eth::Assembly assembly;
-	GeneratorState state(m_errors, assembly);
-	if (!(AsmAnalyzer(state.scopes, m_errors))(m_parsedData))
-		solAssert(false, "Assembly error");
-	CodeTransform(state, m_parsedData, _identifierAccess);
+	GeneratorState state(m_errors, _analysisInfo, assembly);
+	CodeTransform(state, _parsedData, _identifierAccess);
 	return assembly;
 }
 
-void assembly::CodeGenerator::assemble(eth::Assembly& _assembly, assembly::CodeGenerator::IdentifierAccess const& _identifierAccess)
+void assembly::CodeGenerator::assemble(
+	Block const& _parsedData,
+	AsmAnalysisInfo& _analysisInfo,
+	eth::Assembly& _assembly,
+	ExternalIdentifierAccess const& _identifierAccess
+)
 {
-	GeneratorState state(m_errors, _assembly);
-	if (!(AsmAnalyzer(state.scopes, m_errors))(m_parsedData))
-		solAssert(false, "Assembly error");
-	CodeTransform(state, m_parsedData, _identifierAccess);
+	GeneratorState state(m_errors, _analysisInfo, _assembly);
+	CodeTransform(state, _parsedData, _identifierAccess);
 }
diff --git a/libsolidity/inlineasm/AsmCodeGen.h b/libsolidity/inlineasm/AsmCodeGen.h
index bd71812e..e830e047 100644
--- a/libsolidity/inlineasm/AsmCodeGen.h
+++ b/libsolidity/inlineasm/AsmCodeGen.h
@@ -22,9 +22,11 @@
 
 #pragma once
 
-#include <functional>
+#include <libsolidity/inlineasm/AsmAnalysis.h>
 #include <libsolidity/interface/Exceptions.h>
 
+#include <functional>
+
 namespace dev
 {
 namespace eth
@@ -36,30 +38,27 @@ namespace solidity
 namespace assembly
 {
 struct Block;
-struct Identifier;
 
 class CodeGenerator
 {
 public:
-	enum class IdentifierContext { LValue, RValue };
-	/// Function type that is called for external identifiers. Such a function should search for
-	/// the identifier and append appropriate assembly items to the assembly. If in lvalue context,
-	/// the value to assign is assumed to be on the stack and an assignment is to be performed.
-	/// If in rvalue context, the function is assumed to append instructions to
-	/// push the value of the identifier onto the stack. On error, the function should return false.
-	using IdentifierAccess = std::function<bool(assembly::Identifier const&, eth::Assembly&, IdentifierContext)>;
-	CodeGenerator(Block const& _parsedData, ErrorList& _errors):
-		m_parsedData(_parsedData), m_errors(_errors) {}
-	/// Performs type checks and @returns false on error.
-	/// Actually runs the full code generation but discards the result.
-	bool typeCheck(IdentifierAccess const& _identifierAccess = IdentifierAccess());
+	CodeGenerator(ErrorList& _errors):
+		m_errors(_errors) {}
 	/// Performs code generation and @returns the result.
-	eth::Assembly assemble(IdentifierAccess const& _identifierAccess = IdentifierAccess());
+	eth::Assembly assemble(
+		Block const& _parsedData,
+		AsmAnalysisInfo& _analysisInfo,
+		ExternalIdentifierAccess const& _identifierAccess = ExternalIdentifierAccess()
+	);
 	/// Performs code generation and appends generated to to _assembly.
-	void assemble(eth::Assembly& _assembly, IdentifierAccess const& _identifierAccess = IdentifierAccess());
+	void assemble(
+		Block const& _parsedData,
+		AsmAnalysisInfo& _analysisInfo,
+		eth::Assembly& _assembly,
+		ExternalIdentifierAccess const& _identifierAccess = ExternalIdentifierAccess()
+	);
 
 private:
-	Block const& m_parsedData;
 	ErrorList& m_errors;
 };
 
diff --git a/libsolidity/inlineasm/AsmParser.cpp b/libsolidity/inlineasm/AsmParser.cpp
index 0fc0a34f..d7f78958 100644
--- a/libsolidity/inlineasm/AsmParser.cpp
+++ b/libsolidity/inlineasm/AsmParser.cpp
@@ -24,6 +24,7 @@
 #include <ctype.h>
 #include <algorithm>
 #include <libsolidity/parsing/Scanner.h>
+#include <libsolidity/interface/Exceptions.h>
 
 using namespace std;
 using namespace dev;
@@ -68,12 +69,14 @@ assembly::Statement Parser::parseStatement()
 		return parseBlock();
 	case Token::Assign:
 	{
+		if (m_julia)
+			break;
 		assembly::Assignment assignment = createWithLocation<assembly::Assignment>();
 		m_scanner->next();
 		expectToken(Token::Colon);
 		assignment.variableName.location = location();
 		assignment.variableName.name = m_scanner->currentLiteral();
-		if (instructions().count(assignment.variableName.name))
+		if (!m_julia && instructions().count(assignment.variableName.name))
 			fatalParserError("Identifier expected, got instruction name.");
 		assignment.location.end = endPosition();
 		expectToken(Token::Identifier);
@@ -105,7 +108,7 @@ assembly::Statement Parser::parseStatement()
 		{
 			// functional assignment
 			FunctionalAssignment funAss = createWithLocation<FunctionalAssignment>(identifier.location);
-			if (instructions().count(identifier.name))
+			if (!m_julia && instructions().count(identifier.name))
 				fatalParserError("Cannot use instruction names for identifier names.");
 			m_scanner->next();
 			funAss.variableName = identifier;
@@ -180,7 +183,7 @@ assembly::Statement Parser::parseElementaryOperation(bool _onlySinglePusher)
 		else
 			literal = m_scanner->currentLiteral();
 		// first search the set of instructions.
-		if (instructions().count(literal))
+		if (!m_julia && instructions().count(literal))
 		{
 			dev::solidity::Instruction const& instr = instructions().at(literal);
 			if (_onlySinglePusher)
@@ -242,15 +245,13 @@ assembly::FunctionDefinition Parser::parseFunctionDefinition()
 	{
 		expectToken(Token::Sub);
 		expectToken(Token::GreaterThan);
-		expectToken(Token::LParen);
 		while (true)
 		{
 			funDef.returns.push_back(expectAsmIdentifier());
-			if (m_scanner->currentToken() == Token::RParen)
+			if (m_scanner->currentToken() == Token::LBrace)
 				break;
 			expectToken(Token::Comma);
 		}
-		expectToken(Token::RParen);
 	}
 	funDef.body = parseBlock();
 	funDef.location.end = funDef.body.location.end;
@@ -261,6 +262,7 @@ assembly::Statement Parser::parseFunctionalInstruction(assembly::Statement&& _in
 {
 	if (_instruction.type() == typeid(Instruction))
 	{
+		solAssert(!m_julia, "Instructions are invalid in JULIA");
 		FunctionalInstruction ret;
 		ret.instruction = std::move(boost::get<Instruction>(_instruction));
 		ret.location = ret.instruction.location;
@@ -323,7 +325,7 @@ assembly::Statement Parser::parseFunctionalInstruction(assembly::Statement&& _in
 string Parser::expectAsmIdentifier()
 {
 	string name = m_scanner->currentLiteral();
-	if (instructions().count(name))
+	if (!m_julia && instructions().count(name))
 		fatalParserError("Cannot use instruction names for identifier names.");
 	expectToken(Token::Identifier);
 	return name;
diff --git a/libsolidity/inlineasm/AsmParser.h b/libsolidity/inlineasm/AsmParser.h
index 4b4a24ae..c55fd2ac 100644
--- a/libsolidity/inlineasm/AsmParser.h
+++ b/libsolidity/inlineasm/AsmParser.h
@@ -37,7 +37,7 @@ namespace assembly
 class Parser: public ParserBase
 {
 public:
-	Parser(ErrorList& _errors): ParserBase(_errors) {}
+	explicit Parser(ErrorList& _errors, bool _julia = false): ParserBase(_errors), m_julia(_julia) {}
 
 	/// Parses an inline assembly block starting with `{` and ending with `}`.
 	/// @returns an empty shared pointer on error.
@@ -70,6 +70,9 @@ protected:
 	FunctionDefinition parseFunctionDefinition();
 	Statement parseFunctionalInstruction(Statement&& _instruction);
 	std::string expectAsmIdentifier();
+
+private:
+	bool m_julia = false;
 };
 
 }
diff --git a/libsolidity/inlineasm/AsmPrinter.cpp b/libsolidity/inlineasm/AsmPrinter.cpp
index a70b0b78..252e91f9 100644
--- a/libsolidity/inlineasm/AsmPrinter.cpp
+++ b/libsolidity/inlineasm/AsmPrinter.cpp
@@ -116,7 +116,7 @@ string AsmPrinter::operator()(assembly::FunctionDefinition const& _functionDefin
 {
 	string out = "function " + _functionDefinition.name + "(" + boost::algorithm::join(_functionDefinition.arguments, ", ") + ")";
 	if (!_functionDefinition.returns.empty())
-		out += " -> (" + boost::algorithm::join(_functionDefinition.returns, ", ") + ")";
+		out += " -> " + boost::algorithm::join(_functionDefinition.returns, ", ");
 	return out + "\n" + (*this)(_functionDefinition.body);
 }
 
diff --git a/libsolidity/inlineasm/AsmScope.cpp b/libsolidity/inlineasm/AsmScope.cpp
new file mode 100644
index 00000000..609dca16
--- /dev/null
+++ b/libsolidity/inlineasm/AsmScope.cpp
@@ -0,0 +1,79 @@
+/*
+	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/>.
+*/
+/**
+ * Scopes for identifiers.
+ */
+
+#include <libsolidity/inlineasm/AsmScope.h>
+
+using namespace std;
+using namespace dev::solidity::assembly;
+
+
+bool Scope::registerLabel(string const& _name)
+{
+	if (exists(_name))
+		return false;
+	identifiers[_name] = Label();
+	return true;
+}
+
+bool Scope::registerVariable(string const& _name)
+{
+	if (exists(_name))
+		return false;
+	identifiers[_name] = Variable();
+	return true;
+}
+
+bool Scope::registerFunction(string const& _name, size_t _arguments, size_t _returns)
+{
+	if (exists(_name))
+		return false;
+	identifiers[_name] = Function(_arguments, _returns);
+	return true;
+}
+
+Scope::Identifier* Scope::lookup(string const& _name)
+{
+	bool crossedFunctionBoundary = false;
+	for (Scope* s = this; s; s = s->superScope)
+	{
+		auto id = s->identifiers.find(_name);
+		if (id != s->identifiers.end())
+		{
+			if (crossedFunctionBoundary && id->second.type() == typeid(Scope::Variable))
+				return nullptr;
+			else
+				return &id->second;
+		}
+
+		if (s->functionScope)
+			crossedFunctionBoundary = true;
+	}
+	return nullptr;
+}
+
+bool Scope::exists(string const& _name)
+{
+	if (identifiers.count(_name))
+		return true;
+	else if (superScope)
+		return superScope->exists(_name);
+	else
+		return false;
+}
diff --git a/libsolidity/inlineasm/AsmScope.h b/libsolidity/inlineasm/AsmScope.h
new file mode 100644
index 00000000..37e0f0b8
--- /dev/null
+++ b/libsolidity/inlineasm/AsmScope.h
@@ -0,0 +1,128 @@
+/*
+	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/>.
+*/
+/**
+ * Scopes for identifiers.
+ */
+
+#pragma once
+
+#include <libsolidity/interface/Exceptions.h>
+
+#include <boost/variant.hpp>
+
+#include <functional>
+#include <memory>
+
+namespace dev
+{
+namespace solidity
+{
+namespace assembly
+{
+
+template <class...>
+struct GenericVisitor{};
+
+template <class Visitable, class... Others>
+struct GenericVisitor<Visitable, Others...>: public GenericVisitor<Others...>
+{
+	using GenericVisitor<Others...>::operator ();
+	explicit GenericVisitor(
+		std::function<void(Visitable&)> _visitor,
+		std::function<void(Others&)>... _otherVisitors
+	):
+		GenericVisitor<Others...>(_otherVisitors...),
+		m_visitor(_visitor)
+	{}
+
+	void operator()(Visitable& _v) const { m_visitor(_v); }
+
+	std::function<void(Visitable&)> m_visitor;
+};
+template <>
+struct GenericVisitor<>: public boost::static_visitor<> {
+	void operator()() const {}
+};
+
+
+struct Scope
+{
+	struct Variable
+	{
+		/// Used during code generation to store the stack height. @todo move there.
+		int stackHeight = 0;
+		/// Used during analysis to check whether we already passed the declaration inside the block.
+		/// @todo move there.
+		bool active = false;
+	};
+
+	struct Label
+	{
+		size_t id = unassignedLabelId;
+		static const size_t errorLabelId = -1;
+		static const size_t unassignedLabelId = 0;
+	};
+
+	struct Function
+	{
+		Function(size_t _arguments, size_t _returns): arguments(_arguments), returns(_returns) {}
+		size_t arguments = 0;
+		size_t returns = 0;
+	};
+
+	using Identifier = boost::variant<Variable, Label, Function>;
+	using Visitor = GenericVisitor<Variable const, Label const, Function const>;
+	using NonconstVisitor = GenericVisitor<Variable, Label, Function>;
+
+	bool registerVariable(std::string const& _name);
+	bool registerLabel(std::string const& _name);
+	bool registerFunction(std::string const& _name, size_t _arguments, size_t _returns);
+
+	/// Looks up the identifier in this or super scopes and returns a valid pointer if found
+	/// or a nullptr if not found. Variable lookups up across function boundaries will fail, as
+	/// will any lookups across assembly boundaries.
+	/// The pointer will be invalidated if the scope is modified.
+	/// @param _crossedFunction if true, we already crossed a function boundary during recursive lookup
+	Identifier* lookup(std::string const& _name);
+	/// Looks up the identifier in this and super scopes (will not find variables across function
+	/// boundaries and generally stops at assembly boundaries) and calls the visitor, returns
+	/// false if not found.
+	template <class V>
+	bool lookup(std::string const& _name, V const& _visitor)
+	{
+		if (Identifier* id = lookup(_name))
+		{
+			boost::apply_visitor(_visitor, *id);
+			return true;
+		}
+		else
+			return false;
+	}
+	/// @returns true if the name exists in this scope or in super scopes (also searches
+	/// across function and assembly boundaries).
+	bool exists(std::string const& _name);
+
+	Scope* superScope = nullptr;
+	/// If true, variables from the super scope are not visible here (other identifiers are),
+	/// but they are still taken into account to prevent shadowing.
+	bool functionScope = false;
+	std::map<std::string, Identifier> identifiers;
+};
+
+}
+}
+}
diff --git a/libsolidity/inlineasm/AsmScopeFiller.cpp b/libsolidity/inlineasm/AsmScopeFiller.cpp
new file mode 100644
index 00000000..de6fbdaa
--- /dev/null
+++ b/libsolidity/inlineasm/AsmScopeFiller.cpp
@@ -0,0 +1,130 @@
+/*
+	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/>.
+*/
+/**
+ * Module responsible for registering identifiers inside their scopes.
+ */
+
+#include <libsolidity/inlineasm/AsmScopeFiller.h>
+
+#include <libsolidity/inlineasm/AsmData.h>
+#include <libsolidity/inlineasm/AsmScope.h>
+
+#include <libsolidity/interface/Exceptions.h>
+#include <libsolidity/interface/Utils.h>
+
+#include <boost/range/adaptor/reversed.hpp>
+
+#include <memory>
+#include <functional>
+
+using namespace std;
+using namespace dev;
+using namespace dev::solidity;
+using namespace dev::solidity::assembly;
+
+ScopeFiller::ScopeFiller(ScopeFiller::Scopes& _scopes, ErrorList& _errors):
+	m_scopes(_scopes), m_errors(_errors)
+{
+	// Make the Solidity ErrorTag available to inline assembly
+	Scope::Label errorLabel;
+	errorLabel.id = Scope::Label::errorLabelId;
+	scope(nullptr).identifiers["invalidJumpLabel"] = errorLabel;
+	m_currentScope = &scope(nullptr);
+}
+
+bool ScopeFiller::operator()(Label const& _item)
+{
+	if (!m_currentScope->registerLabel(_item.name))
+	{
+		//@TODO secondary location
+		m_errors.push_back(make_shared<Error>(
+			Error::Type::DeclarationError,
+			"Label name " + _item.name + " already taken in this scope.",
+			_item.location
+		));
+		return false;
+	}
+	return true;
+}
+
+bool ScopeFiller::operator()(assembly::VariableDeclaration const& _varDecl)
+{
+	return registerVariable(_varDecl.name, _varDecl.location, *m_currentScope);
+}
+
+bool ScopeFiller::operator()(assembly::FunctionDefinition const& _funDef)
+{
+	bool success = true;
+	if (!m_currentScope->registerFunction(_funDef.name, _funDef.arguments.size(), _funDef.returns.size()))
+	{
+		//@TODO secondary location
+		m_errors.push_back(make_shared<Error>(
+			Error::Type::DeclarationError,
+			"Function name " + _funDef.name + " already taken in this scope.",
+			_funDef.location
+		));
+		success = false;
+	}
+	Scope& body = scope(&_funDef.body);
+	body.superScope = m_currentScope;
+	body.functionScope = true;
+	for (auto const& var: _funDef.arguments + _funDef.returns)
+		if (!registerVariable(var, _funDef.location, body))
+			success = false;
+
+	if (!(*this)(_funDef.body))
+		success = false;
+
+	return success;
+}
+
+bool ScopeFiller::operator()(Block const& _block)
+{
+	bool success = true;
+	scope(&_block).superScope = m_currentScope;
+	m_currentScope = &scope(&_block);
+
+	for (auto const& s: _block.statements)
+		if (!boost::apply_visitor(*this, s))
+			success = false;
+
+	m_currentScope = m_currentScope->superScope;
+	return success;
+}
+
+bool ScopeFiller::registerVariable(string const& _name, SourceLocation const& _location, Scope& _scope)
+{
+	if (!_scope.registerVariable(_name))
+	{
+		//@TODO secondary location
+		m_errors.push_back(make_shared<Error>(
+			Error::Type::DeclarationError,
+			"Variable name " + _name + " already taken in this scope.",
+			_location
+		));
+		return false;
+	}
+	return true;
+}
+
+Scope& ScopeFiller::scope(Block const* _block)
+{
+	auto& scope = m_scopes[_block];
+	if (!scope)
+		scope = make_shared<Scope>();
+	return *scope;
+}
diff --git a/libsolidity/inlineasm/AsmScopeFiller.h b/libsolidity/inlineasm/AsmScopeFiller.h
new file mode 100644
index 00000000..bb62948b
--- /dev/null
+++ b/libsolidity/inlineasm/AsmScopeFiller.h
@@ -0,0 +1,89 @@
+/*
+	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/>.
+*/
+/**
+ * Module responsible for registering identifiers inside their scopes.
+ */
+
+#pragma once
+
+#include <libsolidity/interface/Exceptions.h>
+
+#include <boost/variant.hpp>
+
+#include <functional>
+#include <memory>
+
+namespace dev
+{
+namespace solidity
+{
+namespace assembly
+{
+
+struct Literal;
+struct Block;
+struct Label;
+struct FunctionalInstruction;
+struct FunctionalAssignment;
+struct VariableDeclaration;
+struct Instruction;
+struct Identifier;
+struct Assignment;
+struct FunctionDefinition;
+struct FunctionCall;
+
+struct Scope;
+
+/**
+ * Fills scopes with identifiers and checks for name clashes.
+ * Does not resolve references.
+ */
+class ScopeFiller: public boost::static_visitor<bool>
+{
+public:
+	using Scopes = std::map<assembly::Block const*, std::shared_ptr<Scope>>;
+	ScopeFiller(Scopes& _scopes, ErrorList& _errors);
+
+	bool operator()(assembly::Instruction const&) { return true; }
+	bool operator()(assembly::Literal const&) { return true; }
+	bool operator()(assembly::Identifier const&) { return true; }
+	bool operator()(assembly::FunctionalInstruction const&) { return true; }
+	bool operator()(assembly::Label const& _label);
+	bool operator()(assembly::Assignment const&) { return true; }
+	bool operator()(assembly::FunctionalAssignment const&) { return true; }
+	bool operator()(assembly::VariableDeclaration const& _variableDeclaration);
+	bool operator()(assembly::FunctionDefinition const& _functionDefinition);
+	bool operator()(assembly::FunctionCall const&) { return true; }
+	bool operator()(assembly::Block const& _block);
+
+private:
+	bool registerVariable(
+		std::string const& _name,
+		SourceLocation const& _location,
+		Scope& _scope
+	);
+
+	Scope& scope(assembly::Block const* _block);
+
+	Scope* m_currentScope = nullptr;
+	Scopes& m_scopes;
+	ErrorList& m_errors;
+};
+
+}
+}
+}
diff --git a/libsolidity/inlineasm/AsmStack.cpp b/libsolidity/inlineasm/AsmStack.cpp
index 266136a1..c2a7d8ea 100644
--- a/libsolidity/inlineasm/AsmStack.cpp
+++ b/libsolidity/inlineasm/AsmStack.cpp
@@ -26,6 +26,7 @@
 #include <libsolidity/inlineasm/AsmCodeGen.h>
 #include <libsolidity/inlineasm/AsmPrinter.h>
 #include <libsolidity/inlineasm/AsmAnalysis.h>
+#include <libsolidity/inlineasm/AsmAnalysisInfo.h>
 
 #include <libsolidity/parsing/Scanner.h>
 
@@ -39,7 +40,10 @@ using namespace dev;
 using namespace dev::solidity;
 using namespace dev::solidity::assembly;
 
-bool InlineAssemblyStack::parse(shared_ptr<Scanner> const& _scanner)
+bool InlineAssemblyStack::parse(
+	shared_ptr<Scanner> const& _scanner,
+	ExternalIdentifierAccess::Resolver const& _resolver
+)
 {
 	m_parserResult = make_shared<Block>();
 	Parser parser(m_errors);
@@ -48,8 +52,8 @@ bool InlineAssemblyStack::parse(shared_ptr<Scanner> const& _scanner)
 		return false;
 
 	*m_parserResult = std::move(*result);
-	AsmAnalyzer::Scopes scopes;
-	return (AsmAnalyzer(scopes, m_errors))(*m_parserResult);
+	AsmAnalysisInfo analysisInfo;
+	return (AsmAnalyzer(analysisInfo, m_errors, _resolver)).analyze(*m_parserResult);
 }
 
 string InlineAssemblyStack::toString()
@@ -59,14 +63,17 @@ string InlineAssemblyStack::toString()
 
 eth::Assembly InlineAssemblyStack::assemble()
 {
-	CodeGenerator codeGen(*m_parserResult, m_errors);
-	return codeGen.assemble();
+	AsmAnalysisInfo analysisInfo;
+	AsmAnalyzer analyzer(analysisInfo, m_errors);
+	solAssert(analyzer.analyze(*m_parserResult), "");
+	CodeGenerator codeGen(m_errors);
+	return codeGen.assemble(*m_parserResult, analysisInfo);
 }
 
 bool InlineAssemblyStack::parseAndAssemble(
 	string const& _input,
 	eth::Assembly& _assembly,
-	CodeGenerator::IdentifierAccess const& _identifierAccess
+	ExternalIdentifierAccess const& _identifierAccess
 )
 {
 	ErrorList errors;
@@ -74,8 +81,12 @@ bool InlineAssemblyStack::parseAndAssemble(
 	auto parserResult = Parser(errors).parse(scanner);
 	if (!errors.empty())
 		return false;
+	solAssert(parserResult, "");
 
-	CodeGenerator(*parserResult, errors).assemble(_assembly, _identifierAccess);
+	AsmAnalysisInfo analysisInfo;
+	AsmAnalyzer analyzer(analysisInfo, errors, _identifierAccess.resolve);
+	solAssert(analyzer.analyze(*parserResult), "");
+	CodeGenerator(errors).assemble(*parserResult, analysisInfo, _assembly, _identifierAccess);
 
 	// At this point, the assembly might be messed up, but we should throw an
 	// internal compiler error anyway.
diff --git a/libsolidity/inlineasm/AsmStack.h b/libsolidity/inlineasm/AsmStack.h
index 4d5a99a4..77a7e02a 100644
--- a/libsolidity/inlineasm/AsmStack.h
+++ b/libsolidity/inlineasm/AsmStack.h
@@ -22,10 +22,10 @@
 
 #pragma once
 
+#include <libsolidity/interface/Exceptions.h>
+
 #include <string>
 #include <functional>
-#include <libsolidity/interface/Exceptions.h>
-#include <libsolidity/inlineasm/AsmCodeGen.h>
 
 namespace dev
 {
@@ -39,13 +39,34 @@ class Scanner;
 namespace assembly
 {
 struct Block;
+struct Identifier;
+
+enum class IdentifierContext { LValue, RValue };
+
+/// Object that is used to resolve references and generate code for access to identifiers external
+/// to inline assembly (not used in standalone assembly mode).
+struct ExternalIdentifierAccess
+{
+	using Resolver = std::function<size_t(assembly::Identifier const&, IdentifierContext)>;
+	/// Resolve a an external reference given by the identifier in the given context.
+	/// @returns the size of the value (number of stack slots) or size_t(-1) if not found.
+	Resolver resolve;
+	using CodeGenerator = std::function<void(assembly::Identifier const&, IdentifierContext, eth::Assembly&)>;
+	/// Generate code for retrieving the value (rvalue context) or storing the value (lvalue context)
+	/// of an identifier. The code should be appended to the assembly. In rvalue context, the value is supposed
+	/// to be put onto the stack, in lvalue context, the value is assumed to be at the top of the stack.
+	CodeGenerator generateCode;
+};
 
 class InlineAssemblyStack
 {
 public:
 	/// Parse the given inline assembly chunk starting with `{` and ending with the corresponding `}`.
 	/// @return false or error.
-	bool parse(std::shared_ptr<Scanner> const& _scanner);
+	bool parse(
+		std::shared_ptr<Scanner> const& _scanner,
+		ExternalIdentifierAccess::Resolver const& _externalIdentifierResolver = ExternalIdentifierAccess::Resolver()
+	);
 	/// Converts the parser result back into a string form (not necessarily the same form
 	/// as the source form, but it should parse into the same parsed form again).
 	std::string toString();
@@ -56,7 +77,7 @@ public:
 	bool parseAndAssemble(
 		std::string const& _input,
 		eth::Assembly& _assembly,
-		CodeGenerator::IdentifierAccess const& _identifierAccess = CodeGenerator::IdentifierAccess()
+		ExternalIdentifierAccess const& _identifierAccess = ExternalIdentifierAccess()
 	);
 
 	ErrorList const& errors() const { return m_errors; }