Merge pull request #3297 from ethereum/separate_expression_and_statement

Separate expression and statement

21 files changed, 202 insertions, 86 deletions

diff --git a/libjulia/ASTDataForward.h b/libjulia/ASTDataForward.h
index 3806e321..143b9c46 100644
--- a/libjulia/ASTDataForward.h
+++ b/libjulia/ASTDataForward.h
@@ -42,11 +42,13 @@ using If = solidity::assembly::If;
 using Case = solidity::assembly::Case;
 using Switch = solidity::assembly::Switch;
 using ForLoop = solidity::assembly::ForLoop;
+using ExpressionStatement = solidity::assembly::ExpressionStatement;
 using Block = solidity::assembly::Block;
 
 using TypedName = solidity::assembly::TypedName;
 
-using Statement = boost::variant<Instruction, Literal, Label, StackAssignment, Identifier, Assignment, FunctionCall, FunctionalInstruction, VariableDeclaration, FunctionDefinition, If, Switch, ForLoop, Block>;
+using Expression = boost::variant<FunctionalInstruction, FunctionCall, Identifier, Literal>;
+using Statement = boost::variant<ExpressionStatement, Instruction, Label, StackAssignment, Assignment, VariableDeclaration, FunctionDefinition, If, Switch, ForLoop, Block>;
 
 }
 }
diff --git a/libjulia/backends/evm/EVMCodeTransform.cpp b/libjulia/backends/evm/EVMCodeTransform.cpp
index f92939be..0c7365fb 100644
--- a/libjulia/backends/evm/EVMCodeTransform.cpp
+++ b/libjulia/backends/evm/EVMCodeTransform.cpp
@@ -77,6 +77,13 @@ void CodeTransform::operator()(StackAssignment const& _assignment)
 	checkStackHeight(&_assignment);
 }
 
+void CodeTransform::operator()(ExpressionStatement const& _statement)
+{
+	m_assembly.setSourceLocation(_statement.location);
+	boost::apply_visitor(*this, _statement.expression);
+	checkStackHeight(&_statement);
+}
+
 void CodeTransform::operator()(Label const& _label)
 {
 	m_assembly.setSourceLocation(_label.location);
@@ -460,7 +467,7 @@ AbstractAssembly::LabelID CodeTransform::functionEntryID(string const& _name, Sc
 	return m_context->functionEntryIDs[&_function];
 }
 
-void CodeTransform::visitExpression(Statement const& _expression)
+void CodeTransform::visitExpression(Expression const& _expression)
 {
 	int height = m_assembly.stackHeight();
 	boost::apply_visitor(*this, _expression);
diff --git a/libjulia/backends/evm/EVMCodeTransform.h b/libjulia/backends/evm/EVMCodeTransform.h
index 577cc8ba..0f2aaf95 100644
--- a/libjulia/backends/evm/EVMCodeTransform.h
+++ b/libjulia/backends/evm/EVMCodeTransform.h
@@ -101,6 +101,7 @@ public:
 	void operator()(Identifier const& _identifier);
 	void operator()(FunctionalInstruction const& _instr);
 	void operator()(FunctionCall const&);
+	void operator()(ExpressionStatement const& _statement);
 	void operator()(Label const& _label);
 	void operator()(StackAssignment const& _assignment);
 	void operator()(Assignment const& _assignment);
@@ -118,7 +119,7 @@ private:
 	AbstractAssembly::LabelID labelID(solidity::assembly::Scope::Label const& _label);
 	AbstractAssembly::LabelID functionEntryID(std::string const& _name, solidity::assembly::Scope::Function const& _function);
 	/// Generates code for an expression that is supposed to return a single value.
-	void visitExpression(Statement const& _expression);
+	void visitExpression(Expression const& _expression);
 
 	void visitStatements(std::vector<Statement> const& _statements);
 
diff --git a/libjulia/optimiser/ASTCopier.cpp b/libjulia/optimiser/ASTCopier.cpp
index a461f434..5c47be64 100644
--- a/libjulia/optimiser/ASTCopier.cpp
+++ b/libjulia/optimiser/ASTCopier.cpp
@@ -37,6 +37,11 @@ Statement ASTCopier::operator()(Instruction const&)
 	return {};
 }
 
+Statement ASTCopier::operator()(ExpressionStatement const& _statement)
+{
+	return ExpressionStatement{ _statement.location, translate(_statement.expression) };
+}
+
 Statement ASTCopier::operator()(VariableDeclaration const& _varDecl)
 {
 	return VariableDeclaration{
@@ -67,7 +72,7 @@ Statement ASTCopier::operator()(Label const&)
 	return {};
 }
 
-Statement ASTCopier::operator()(FunctionCall const& _call)
+Expression ASTCopier::operator()(FunctionCall const& _call)
 {
 	return FunctionCall{
 		_call.location,
@@ -76,7 +81,7 @@ Statement ASTCopier::operator()(FunctionCall const& _call)
 	};
 }
 
-Statement ASTCopier::operator()(FunctionalInstruction const& _instruction)
+Expression ASTCopier::operator()(FunctionalInstruction const& _instruction)
 {
 	return FunctionalInstruction{
 		_instruction.location,
@@ -85,12 +90,12 @@ Statement ASTCopier::operator()(FunctionalInstruction const& _instruction)
 	};
 }
 
-Statement ASTCopier::operator()(Identifier const& _identifier)
+Expression ASTCopier::operator()(Identifier const& _identifier)
 {
 	return Identifier{_identifier.location, translateIdentifier(_identifier.name)};
 }
 
-Statement ASTCopier::operator()(Literal const& _literal)
+Expression ASTCopier::operator()(Literal const& _literal)
 {
 	return translate(_literal);
 }
@@ -140,9 +145,14 @@ Statement ASTCopier::operator ()(Block const& _block)
 	return translate(_block);
 }
 
+Expression ASTCopier::translate(Expression const& _expression)
+{
+	return _expression.apply_visitor(static_cast<ExpressionCopier&>(*this));
+}
+
 Statement ASTCopier::translate(Statement const& _statement)
 {
-	return boost::apply_visitor(*this, _statement);
+	return _statement.apply_visitor(static_cast<StatementCopier&>(*this));
 }
 
 Block ASTCopier::translate(Block const& _block)
diff --git a/libjulia/optimiser/ASTCopier.h b/libjulia/optimiser/ASTCopier.h
index 5dde2ce9..36a1ced5 100644
--- a/libjulia/optimiser/ASTCopier.h
+++ b/libjulia/optimiser/ASTCopier.h
@@ -34,28 +34,55 @@ namespace dev
 namespace julia
 {
 
+class ExpressionCopier: public boost::static_visitor<Expression>
+{
+public:
+	virtual Expression operator()(Literal const& _literal) = 0;
+	virtual Expression operator()(Identifier const& _identifier) = 0;
+	virtual Expression operator()(FunctionalInstruction const& _instr) = 0;
+	virtual Expression operator()(FunctionCall const&) = 0;
+};
+
+class StatementCopier: public boost::static_visitor<Statement>
+{
+public:
+	virtual Statement operator()(ExpressionStatement const& _statement) = 0;
+	virtual Statement operator()(Instruction const& _instruction) = 0;
+	virtual Statement operator()(Label const& _label) = 0;
+	virtual Statement operator()(StackAssignment const& _assignment) = 0;
+	virtual Statement operator()(Assignment const& _assignment) = 0;
+	virtual Statement operator()(VariableDeclaration const& _varDecl) = 0;
+	virtual Statement operator()(If const& _if) = 0;
+	virtual Statement operator()(Switch const& _switch) = 0;
+	virtual Statement operator()(FunctionDefinition const&) = 0;
+	virtual Statement operator()(ForLoop const&) = 0;
+	virtual Statement operator()(Block const& _block) = 0;
+};
+
 /**
  * Creates a copy of a iulia AST potentially replacing identifier names.
  * Base class to be extended.
  */
-class ASTCopier: public boost::static_visitor<Statement>
+class ASTCopier: public ExpressionCopier, public StatementCopier
 {
 public:
-	Statement operator()(Literal const& _literal);
-	Statement operator()(Instruction const& _instruction);
-	Statement operator()(Identifier const& _identifier);
-	Statement operator()(FunctionalInstruction const& _instr);
-	Statement operator()(FunctionCall const&);
-	Statement operator()(Label const& _label);
-	Statement operator()(StackAssignment const& _assignment);
-	Statement operator()(Assignment const& _assignment);
-	Statement operator()(VariableDeclaration const& _varDecl);
-	Statement operator()(If const& _if);
-	Statement operator()(Switch const& _switch);
-	Statement operator()(FunctionDefinition const&);
-	Statement operator()(ForLoop const&);
-	Statement operator()(Block const& _block);
-
+	virtual Expression operator()(Literal const& _literal) override;
+	virtual Statement operator()(Instruction const& _instruction) override;
+	virtual Expression operator()(Identifier const& _identifier) override;
+	virtual Expression operator()(FunctionalInstruction const& _instr) override;
+	virtual Expression operator()(FunctionCall const&) override;
+	virtual Statement operator()(ExpressionStatement const& _statement) override;
+	virtual Statement operator()(Label const& _label) override;
+	virtual Statement operator()(StackAssignment const& _assignment) override;
+	virtual Statement operator()(Assignment const& _assignment) override;
+	virtual Statement operator()(VariableDeclaration const& _varDecl) override;
+	virtual Statement operator()(If const& _if) override;
+	virtual Statement operator()(Switch const& _switch) override;
+	virtual Statement operator()(FunctionDefinition const&) override;
+	virtual Statement operator()(ForLoop const&) override;
+	virtual Statement operator()(Block const& _block) override;
+
+	virtual Expression translate(Expression const& _expression);
 	virtual Statement translate(Statement const& _statement);
 
 protected:
diff --git a/libjulia/optimiser/ASTWalker.cpp b/libjulia/optimiser/ASTWalker.cpp
index 0caef04e..499b4bf2 100644
--- a/libjulia/optimiser/ASTWalker.cpp
+++ b/libjulia/optimiser/ASTWalker.cpp
@@ -42,6 +42,11 @@ void ASTWalker::operator()(FunctionCall const& _funCall)
 	walkVector(_funCall.arguments | boost::adaptors::reversed);
 }
 
+void ASTWalker::operator()(ExpressionStatement const& _statement)
+{
+	boost::apply_visitor(*this, _statement.expression);
+}
+
 void ASTWalker::operator()(Assignment const& _assignment)
 {
 	for (auto const& name: _assignment.variableNames)
@@ -100,6 +105,11 @@ void ASTModifier::operator()(FunctionCall& _funCall)
 	walkVector(_funCall.arguments | boost::adaptors::reversed);
 }
 
+void ASTModifier::operator()(ExpressionStatement& _statement)
+{
+	boost::apply_visitor(*this, _statement.expression);
+}
+
 void ASTModifier::operator()(Assignment& _assignment)
 {
 	for (auto& name: _assignment.variableNames)
diff --git a/libjulia/optimiser/ASTWalker.h b/libjulia/optimiser/ASTWalker.h
index 8bd867d5..4652a353 100644
--- a/libjulia/optimiser/ASTWalker.h
+++ b/libjulia/optimiser/ASTWalker.h
@@ -47,6 +47,7 @@ public:
 	virtual void operator()(Identifier const&) {}
 	virtual void operator()(FunctionalInstruction const& _instr);
 	virtual void operator()(FunctionCall const& _funCall);
+	virtual void operator()(ExpressionStatement const& _statement);
 	virtual void operator()(Label const&) { solAssert(false, ""); }
 	virtual void operator()(StackAssignment const&) { solAssert(false, ""); }
 	virtual void operator()(Assignment const& _assignment);
@@ -77,6 +78,7 @@ public:
 	virtual void operator()(Identifier&) {}
 	virtual void operator()(FunctionalInstruction& _instr);
 	virtual void operator()(FunctionCall& _funCall);
+	virtual void operator()(ExpressionStatement& _statement);
 	virtual void operator()(Label&) { solAssert(false, ""); }
 	virtual void operator()(StackAssignment&) { solAssert(false, ""); }
 	virtual void operator()(Assignment& _assignment);
@@ -98,6 +100,10 @@ protected:
 	{
 		boost::apply_visitor(*this, _st);
 	}
+	virtual void visit(Expression& _e)
+	{
+		boost::apply_visitor(*this, _e);
+	}
 };
 
 }
diff --git a/libjulia/optimiser/Substitution.cpp b/libjulia/optimiser/Substitution.cpp
index a49f1f7a..668b6cb6 100644
--- a/libjulia/optimiser/Substitution.cpp
+++ b/libjulia/optimiser/Substitution.cpp
@@ -26,14 +26,14 @@ using namespace std;
 using namespace dev;
 using namespace dev::julia;
 
-Statement Substitution::translate(Statement const& _statement)
+Expression Substitution::translate(Expression const& _expression)
 {
-	if (_statement.type() == typeid(Identifier))
+	if (_expression.type() == typeid(Identifier))
 	{
-		string const& name = boost::get<Identifier>(_statement).name;
+		string const& name = boost::get<Identifier>(_expression).name;
 		if (m_substitutions.count(name))
 			// No recursive substitution
 			return ASTCopier().translate(*m_substitutions.at(name));
 	}
-	return ASTCopier::translate(_statement);
+	return ASTCopier::translate(_expression);
 }
diff --git a/libjulia/optimiser/Substitution.h b/libjulia/optimiser/Substitution.h
index 10bdf32e..313a08d7 100644
--- a/libjulia/optimiser/Substitution.h
+++ b/libjulia/optimiser/Substitution.h
@@ -33,18 +33,17 @@ namespace julia
 
 /**
  * Specific AST copier that replaces certain identifiers with expressions.
- * Only works on ASTs that are expressions.
  */
 class Substitution: public ASTCopier
 {
 public:
-	Substitution(std::map<std::string, Statement const*> const& _substitutions):
+	Substitution(std::map<std::string, Expression const*> const& _substitutions):
 		m_substitutions(_substitutions)
 	{}
-	virtual Statement translate(Statement const& _statement) override;
+	virtual Expression translate(Expression const& _expression) override;
 
 private:
-	std::map<std::string, Statement const*> const& m_substitutions;
+	std::map<std::string, Expression const*> const& m_substitutions;
 };
 
 }
diff --git a/libsolidity/analysis/ViewPureChecker.cpp b/libsolidity/analysis/ViewPureChecker.cpp
index 6788cb05..6257ac6d 100644
--- a/libsolidity/analysis/ViewPureChecker.cpp
+++ b/libsolidity/analysis/ViewPureChecker.cpp
@@ -50,6 +50,10 @@ public:
 		for (auto const& arg: _instr.arguments)
 			boost::apply_visitor(*this, arg);
 	}
+	void operator()(assembly::ExpressionStatement const& _expr)
+	{
+		boost::apply_visitor(*this, _expr.expression);
+	}
 	void operator()(assembly::StackAssignment const&) {}
 	void operator()(assembly::Assignment const& _assignment)
 	{
diff --git a/libsolidity/inlineasm/AsmAnalysis.cpp b/libsolidity/inlineasm/AsmAnalysis.cpp
index 049af65f..17b7cce0 100644
--- a/libsolidity/inlineasm/AsmAnalysis.cpp
+++ b/libsolidity/inlineasm/AsmAnalysis.cpp
@@ -155,6 +155,16 @@ bool AsmAnalyzer::operator()(FunctionalInstruction const& _instr)
 	return success;
 }
 
+bool AsmAnalyzer::operator()(assembly::ExpressionStatement const& _statement)
+{
+//	size_t initialStackHeight = m_stackHeight;
+	bool success = boost::apply_visitor(*this, _statement.expression);
+//	if (!expectDeposit(0, initialStackHeight, _statement.location))
+//		success = false;
+	m_info.stackHeightInfo[&_statement] = m_stackHeight;
+	return success;
+}
+
 bool AsmAnalyzer::operator()(assembly::StackAssignment const& _assignment)
 {
 	solAssert(!m_julia, "");
@@ -407,13 +417,13 @@ bool AsmAnalyzer::operator()(Block const& _block)
 	return success;
 }
 
-bool AsmAnalyzer::expectExpression(Statement const& _statement)
+bool AsmAnalyzer::expectExpression(Expression const& _expr)
 {
 	bool success = true;
 	int const initialHeight = m_stackHeight;
-	if (!boost::apply_visitor(*this, _statement))
+	if (!boost::apply_visitor(*this, _expr))
 		success = false;
-	if (!expectDeposit(1, initialHeight, locationOf(_statement)))
+	if (!expectDeposit(1, initialHeight, locationOf(_expr)))
 		success = false;
 	return success;
 }
diff --git a/libsolidity/inlineasm/AsmAnalysis.h b/libsolidity/inlineasm/AsmAnalysis.h
index e484b876..00a33db3 100644
--- a/libsolidity/inlineasm/AsmAnalysis.h
+++ b/libsolidity/inlineasm/AsmAnalysis.h
@@ -65,6 +65,7 @@ public:
 	bool operator()(assembly::Identifier const&);
 	bool operator()(assembly::FunctionalInstruction const& _functionalInstruction);
 	bool operator()(assembly::Label const& _label);
+	bool operator()(assembly::ExpressionStatement const&);
 	bool operator()(assembly::StackAssignment const&);
 	bool operator()(assembly::Assignment const& _assignment);
 	bool operator()(assembly::VariableDeclaration const& _variableDeclaration);
@@ -77,7 +78,7 @@ public:
 
 private:
 	/// Visits the statement and expects it to deposit one item onto the stack.
-	bool expectExpression(Statement const& _statement);
+	bool expectExpression(Expression const& _expr);
 	bool expectDeposit(int _deposit, int _oldHeight, SourceLocation const& _location);
 
 	/// Verifies that a variable to be assigned to exists and has the same size
diff --git a/libsolidity/inlineasm/AsmData.h b/libsolidity/inlineasm/AsmData.h
index 11e56fae..2982d5e0 100644
--- a/libsolidity/inlineasm/AsmData.h
+++ b/libsolidity/inlineasm/AsmData.h
@@ -58,23 +58,25 @@ struct StackAssignment { SourceLocation location; Identifier variableName; };
 /// Multiple assignment ("x, y := f()"), where the left hand side variables each occupy
 /// a single stack slot and expects a single expression on the right hand returning
 /// the same amount of items as the number of variables.
-struct Assignment { SourceLocation location; std::vector<Identifier> variableNames; std::shared_ptr<Statement> value; };
+struct Assignment { SourceLocation location; std::vector<Identifier> variableNames; std::shared_ptr<Expression> value; };
 /// Functional instruction, e.g. "mul(mload(20:u256), add(2:u256, x))"
-struct FunctionalInstruction { SourceLocation location; solidity::Instruction instruction; std::vector<Statement> arguments; };
-struct FunctionCall { SourceLocation location; Identifier functionName; std::vector<Statement> arguments; };
+struct FunctionalInstruction { SourceLocation location; solidity::Instruction instruction; std::vector<Expression> arguments; };
+struct FunctionCall { SourceLocation location; Identifier functionName; std::vector<Expression> arguments; };
+/// Statement that contains only a single expression
+struct ExpressionStatement { SourceLocation location; Expression expression; };
 /// Block-scope variable declaration ("let x:u256 := mload(20:u256)"), non-hoisted
-struct VariableDeclaration { SourceLocation location; TypedNameList variables; std::shared_ptr<Statement> value; };
+struct VariableDeclaration { SourceLocation location; TypedNameList variables; std::shared_ptr<Expression> value; };
 /// Block that creates a scope (frees declared stack variables)
 struct Block { SourceLocation location; std::vector<Statement> statements; };
 /// Function definition ("function f(a, b) -> (d, e) { ... }")
 struct FunctionDefinition { SourceLocation location; std::string name; TypedNameList parameters; TypedNameList returnVariables; Block body; };
 /// Conditional execution without "else" part.
-struct If { SourceLocation location; std::shared_ptr<Statement> condition; Block body; };
+struct If { SourceLocation location; std::shared_ptr<Expression> condition; Block body; };
 /// Switch case or default case
 struct Case { SourceLocation location; std::shared_ptr<Literal> value; Block body; };
 /// Switch statement
-struct Switch { SourceLocation location; std::shared_ptr<Statement> expression; std::vector<Case> cases; };
-struct ForLoop { SourceLocation location; Block pre; std::shared_ptr<Statement> condition; Block post; Block body; };
+struct Switch { SourceLocation location; std::shared_ptr<Expression> expression; std::vector<Case> cases; };
+struct ForLoop { SourceLocation location; Block pre; std::shared_ptr<Expression> condition; Block post; Block body; };
 
 struct LocationExtractor: boost::static_visitor<SourceLocation>
 {
diff --git a/libsolidity/inlineasm/AsmDataForward.h b/libsolidity/inlineasm/AsmDataForward.h
index 1ab62cc0..317e257c 100644
--- a/libsolidity/inlineasm/AsmDataForward.h
+++ b/libsolidity/inlineasm/AsmDataForward.h
@@ -45,11 +45,13 @@ struct If;
 struct Switch;
 struct Case;
 struct ForLoop;
+struct ExpressionStatement;
 struct Block;
 
 struct TypedName;
 
-using Statement = boost::variant<Instruction, Literal, Label, StackAssignment, Identifier, Assignment, FunctionCall, FunctionalInstruction, VariableDeclaration, FunctionDefinition, If, Switch, ForLoop, Block>;
+using Expression = boost::variant<FunctionalInstruction, FunctionCall, Identifier, Literal>;
+using Statement = boost::variant<ExpressionStatement, Instruction, Label, StackAssignment, Assignment, VariableDeclaration, FunctionDefinition, If, Switch, ForLoop, Block>;
 
 }
 }
diff --git a/libsolidity/inlineasm/AsmParser.cpp b/libsolidity/inlineasm/AsmParser.cpp
index 4f8802a0..273e1d5c 100644
--- a/libsolidity/inlineasm/AsmParser.cpp
+++ b/libsolidity/inlineasm/AsmParser.cpp
@@ -77,9 +77,7 @@ assembly::Statement Parser::parseStatement()
 	{
 		assembly::If _if = createWithLocation<assembly::If>();
 		m_scanner->next();
-		_if.condition = make_shared<Statement>(parseExpression());
-		if (_if.condition->type() == typeid(assembly::Instruction))
-			fatalParserError("Instructions are not supported as conditions for if - try to append \"()\".");
+		_if.condition = make_shared<Expression>(parseExpression());
 		_if.body = parseBlock();
 		return _if;
 	}
@@ -87,9 +85,7 @@ assembly::Statement Parser::parseStatement()
 	{
 		assembly::Switch _switch = createWithLocation<assembly::Switch>();
 		m_scanner->next();
-		_switch.expression = make_shared<Statement>(parseExpression());
-		if (_switch.expression->type() == typeid(assembly::Instruction))
-			fatalParserError("Instructions are not supported as expressions for switch - try to append \"()\".");
+		_switch.expression = make_shared<Expression>(parseExpression());
 		while (m_scanner->currentToken() == Token::Case)
 			_switch.cases.emplace_back(parseCase());
 		if (m_scanner->currentToken() == Token::Default)
@@ -127,18 +123,21 @@ assembly::Statement Parser::parseStatement()
 	// Simple instruction (might turn into functional),
 	// literal,
 	// identifier (might turn into label or functional assignment)
-	Statement statement(parseElementaryOperation(false));
+	ElementaryOperation elementary(parseElementaryOperation(false));
 	switch (currentToken())
 	{
 	case Token::LParen:
-		return parseCall(std::move(statement));
+	{
+		Expression expr = parseCall(std::move(elementary));
+		return ExpressionStatement{locationOf(expr), expr};
+	}
 	case Token::Comma:
 	{
 		// if a comma follows, a multiple assignment is assumed
 
-		if (statement.type() != typeid(assembly::Identifier))
+		if (elementary.type() != typeid(assembly::Identifier))
 			fatalParserError("Label name / variable name must precede \",\" (multiple assignment).");
-		assembly::Identifier const& identifier = boost::get<assembly::Identifier>(statement);
+		assembly::Identifier const& identifier = boost::get<assembly::Identifier>(elementary);
 
 		Assignment assignment = createWithLocation<Assignment>(identifier.location);
 		assignment.variableNames.emplace_back(identifier);
@@ -146,25 +145,25 @@ assembly::Statement Parser::parseStatement()
 		do
 		{
 			expectToken(Token::Comma);
-			statement = parseElementaryOperation(false);
-			if (statement.type() != typeid(assembly::Identifier))
+			elementary = parseElementaryOperation(false);
+			if (elementary.type() != typeid(assembly::Identifier))
 				fatalParserError("Variable name expected in multiple assignemnt.");
-			assignment.variableNames.emplace_back(boost::get<assembly::Identifier>(statement));
+			assignment.variableNames.emplace_back(boost::get<assembly::Identifier>(elementary));
 		}
 		while (currentToken() == Token::Comma);
 
 		expectToken(Token::Colon);
 		expectToken(Token::Assign);
 
-		assignment.value.reset(new Statement(parseExpression()));
+		assignment.value.reset(new Expression(parseExpression()));
 		assignment.location.end = locationOf(*assignment.value).end;
 		return assignment;
 	}
 	case Token::Colon:
 	{
-		if (statement.type() != typeid(assembly::Identifier))
+		if (elementary.type() != typeid(assembly::Identifier))
 			fatalParserError("Label name / variable name must precede \":\".");
-		assembly::Identifier const& identifier = boost::get<assembly::Identifier>(statement);
+		assembly::Identifier const& identifier = boost::get<assembly::Identifier>(elementary);
 		advance();
 		// identifier:=: should be parsed as identifier: =: (i.e. a label),
 		// while identifier:= (being followed by a non-colon) as identifier := (assignment).
@@ -175,7 +174,7 @@ assembly::Statement Parser::parseStatement()
 				fatalParserError("Cannot use instruction names for identifier names.");
 			advance();
 			assignment.variableNames.emplace_back(identifier);
-			assignment.value.reset(new Statement(parseExpression()));
+			assignment.value.reset(new Expression(parseExpression()));
 			assignment.location.end = locationOf(*assignment.value).end;
 			return assignment;
 		}
@@ -194,7 +193,21 @@ assembly::Statement Parser::parseStatement()
 			fatalParserError("Call or assignment expected.");
 		break;
 	}
-	return statement;
+	if (elementary.type() == typeid(assembly::Identifier))
+	{
+		Expression expr = boost::get<assembly::Identifier>(elementary);
+		return ExpressionStatement{locationOf(expr), expr};
+	}
+	else if (elementary.type() == typeid(assembly::Literal))
+	{
+		Expression expr = boost::get<assembly::Literal>(elementary);
+		return ExpressionStatement{locationOf(expr), expr};
+	}
+	else
+	{
+		solAssert(elementary.type() == typeid(assembly::Instruction), "Invalid elementary operation.");
+		return boost::get<assembly::Instruction>(elementary);
+	}
 }
 
 assembly::Case Parser::parseCase()
@@ -206,10 +219,10 @@ assembly::Case Parser::parseCase()
 	else if (m_scanner->currentToken() == Token::Case)
 	{
 		m_scanner->next();
-		assembly::Statement statement = parseElementaryOperation();
-		if (statement.type() != typeid(assembly::Literal))
+		ElementaryOperation literal = parseElementaryOperation();
+		if (literal.type() != typeid(assembly::Literal))
 			fatalParserError("Literal expected.");
-		_case.value = make_shared<Literal>(std::move(boost::get<assembly::Literal>(statement)));
+		_case.value = make_shared<Literal>(boost::get<assembly::Literal>(std::move(literal)));
 	}
 	else
 		fatalParserError("Case or default case expected.");
@@ -224,19 +237,17 @@ assembly::ForLoop Parser::parseForLoop()
 	ForLoop forLoop = createWithLocation<ForLoop>();
 	expectToken(Token::For);
 	forLoop.pre = parseBlock();
-	forLoop.condition = make_shared<Statement>(parseExpression());
-	if (forLoop.condition->type() == typeid(assembly::Instruction))
-		fatalParserError("Instructions are not supported as conditions for the for statement.");
+	forLoop.condition = make_shared<Expression>(parseExpression());
 	forLoop.post = parseBlock();
 	forLoop.body = parseBlock();
 	forLoop.location.end = forLoop.body.location.end;
 	return forLoop;
 }
 
-assembly::Statement Parser::parseExpression()
+assembly::Expression Parser::parseExpression()
 {
 	RecursionGuard recursionGuard(*this);
-	Statement operation = parseElementaryOperation(true);
+	ElementaryOperation operation = parseElementaryOperation(true);
 	if (operation.type() == typeid(Instruction))
 	{
 		Instruction const& instr = boost::get<Instruction>(operation);
@@ -252,8 +263,18 @@ assembly::Statement Parser::parseExpression()
 	}
 	if (currentToken() == Token::LParen)
 		return parseCall(std::move(operation));
+	else if (operation.type() == typeid(Instruction))
+	{
+		Instruction& instr = boost::get<Instruction>(operation);
+		return FunctionalInstruction{std::move(instr.location), instr.instruction, {}};
+	}
+	else if (operation.type() == typeid(assembly::Identifier))
+		return boost::get<assembly::Identifier>(operation);
 	else
-		return operation;
+	{
+		solAssert(operation.type() == typeid(assembly::Literal), "");
+		return boost::get<assembly::Literal>(operation);
+	}
 }
 
 std::map<string, dev::solidity::Instruction> const& Parser::instructions()
@@ -296,10 +317,10 @@ std::map<dev::solidity::Instruction, string> const& Parser::instructionNames()
 	return s_instructionNames;
 }
 
-assembly::Statement Parser::parseElementaryOperation(bool _onlySinglePusher)
+Parser::ElementaryOperation Parser::parseElementaryOperation(bool _onlySinglePusher)
 {
 	RecursionGuard recursionGuard(*this);
-	Statement ret;
+	ElementaryOperation ret;
 	switch (currentToken())
 	{
 	case Token::Identifier:
@@ -402,7 +423,7 @@ assembly::VariableDeclaration Parser::parseVariableDeclaration()
 	{
 		expectToken(Token::Colon);
 		expectToken(Token::Assign);
-		varDecl.value.reset(new Statement(parseExpression()));
+		varDecl.value.reset(new Expression(parseExpression()));
 		varDecl.location.end = locationOf(*varDecl.value).end;
 	}
 	else
@@ -442,13 +463,13 @@ assembly::FunctionDefinition Parser::parseFunctionDefinition()
 	return funDef;
 }
 
-assembly::Statement Parser::parseCall(assembly::Statement&& _instruction)
+assembly::Expression Parser::parseCall(Parser::ElementaryOperation&& _initialOp)
 {
 	RecursionGuard recursionGuard(*this);
-	if (_instruction.type() == typeid(Instruction))
+	if (_initialOp.type() == typeid(Instruction))
 	{
 		solAssert(!m_julia, "Instructions are invalid in JULIA");
-		Instruction const& instruction = std::move(boost::get<Instruction>(_instruction));
+		Instruction& instruction = boost::get<Instruction>(_initialOp);
 		FunctionalInstruction ret;
 		ret.instruction = instruction.instruction;
 		ret.location = std::move(instruction.location);
@@ -499,10 +520,10 @@ assembly::Statement Parser::parseCall(assembly::Statement&& _instruction)
 		expectToken(Token::RParen);
 		return ret;
 	}
-	else if (_instruction.type() == typeid(Identifier))
+	else if (_initialOp.type() == typeid(Identifier))
 	{
 		FunctionCall ret;
-		ret.functionName = std::move(boost::get<Identifier>(_instruction));
+		ret.functionName = std::move(boost::get<Identifier>(_initialOp));
 		ret.location = ret.functionName.location;
 		expectToken(Token::LParen);
 		while (currentToken() != Token::RParen)
diff --git a/libsolidity/inlineasm/AsmParser.h b/libsolidity/inlineasm/AsmParser.h
index e46d1732..44889a13 100644
--- a/libsolidity/inlineasm/AsmParser.h
+++ b/libsolidity/inlineasm/AsmParser.h
@@ -44,6 +44,8 @@ public:
 	std::shared_ptr<Block> parse(std::shared_ptr<Scanner> const& _scanner);
 
 protected:
+	using ElementaryOperation = boost::variant<assembly::Instruction, assembly::Literal, assembly::Identifier>;
+
 	/// Creates an inline assembly node with the given source location.
 	template <class T> T createWithLocation(SourceLocation const& _loc = SourceLocation()) const
 	{
@@ -65,13 +67,13 @@ protected:
 	Case parseCase();
 	ForLoop parseForLoop();
 	/// Parses a functional expression that has to push exactly one stack element
-	Statement parseExpression();
+	assembly::Expression parseExpression();
 	static std::map<std::string, dev::solidity::Instruction> const& instructions();
 	static std::map<dev::solidity::Instruction, std::string> const& instructionNames();
-	Statement parseElementaryOperation(bool _onlySinglePusher = false);
+	ElementaryOperation parseElementaryOperation(bool _onlySinglePusher = false);
 	VariableDeclaration parseVariableDeclaration();
 	FunctionDefinition parseFunctionDefinition();
-	Statement parseCall(Statement&& _instruction);
+	assembly::Expression parseCall(ElementaryOperation&& _initialOp);
 	TypedName parseTypedName();
 	std::string expectAsmIdentifier();
 
diff --git a/libsolidity/inlineasm/AsmPrinter.cpp b/libsolidity/inlineasm/AsmPrinter.cpp
index c72586cb..bacd7a94 100644
--- a/libsolidity/inlineasm/AsmPrinter.cpp
+++ b/libsolidity/inlineasm/AsmPrinter.cpp
@@ -102,6 +102,11 @@ string AsmPrinter::operator()(assembly::FunctionalInstruction const& _functional
 		")";
 }
 
+string AsmPrinter::operator()(ExpressionStatement const& _statement)
+{
+	return boost::apply_visitor(*this, _statement.expression);
+}
+
 string AsmPrinter::operator()(assembly::Label const& _label)
 {
 	solAssert(!m_julia, "");
diff --git a/libsolidity/inlineasm/AsmPrinter.h b/libsolidity/inlineasm/AsmPrinter.h
index eadf81d9..5bd87aba 100644
--- a/libsolidity/inlineasm/AsmPrinter.h
+++ b/libsolidity/inlineasm/AsmPrinter.h
@@ -42,6 +42,7 @@ public:
 	std::string operator()(assembly::Literal const& _literal);
 	std::string operator()(assembly::Identifier const& _identifier);
 	std::string operator()(assembly::FunctionalInstruction const& _functionalInstruction);
+	std::string operator()(assembly::ExpressionStatement const& _expr);
 	std::string operator()(assembly::Label const& _label);
 	std::string operator()(assembly::StackAssignment const& _assignment);
 	std::string operator()(assembly::Assignment const& _assignment);
diff --git a/libsolidity/inlineasm/AsmScopeFiller.cpp b/libsolidity/inlineasm/AsmScopeFiller.cpp
index 0984e7d2..86f3809c 100644
--- a/libsolidity/inlineasm/AsmScopeFiller.cpp
+++ b/libsolidity/inlineasm/AsmScopeFiller.cpp
@@ -45,6 +45,11 @@ ScopeFiller::ScopeFiller(AsmAnalysisInfo& _info, ErrorReporter& _errorReporter):
 	m_currentScope = &scope(nullptr);
 }
 
+bool ScopeFiller::operator()(ExpressionStatement const& _expr)
+{
+	return boost::apply_visitor(*this, _expr.expression);
+}
+
 bool ScopeFiller::operator()(Label const& _item)
 {
 	if (!m_currentScope->registerLabel(_item.name))
diff --git a/libsolidity/inlineasm/AsmScopeFiller.h b/libsolidity/inlineasm/AsmScopeFiller.h
index ed28abbf..bb023f61 100644
--- a/libsolidity/inlineasm/AsmScopeFiller.h
+++ b/libsolidity/inlineasm/AsmScopeFiller.h
@@ -53,6 +53,7 @@ public:
 	bool operator()(assembly::Literal const&) { return true; }
 	bool operator()(assembly::Identifier const&) { return true; }
 	bool operator()(assembly::FunctionalInstruction const&) { return true; }
+	bool operator()(assembly::ExpressionStatement const& _expr);
 	bool operator()(assembly::Label const& _label);
 	bool operator()(assembly::StackAssignment const&) { return true; }
 	bool operator()(assembly::Assignment const&) { return true; }
diff --git a/test/libsolidity/InlineAssembly.cpp b/test/libsolidity/InlineAssembly.cpp
index 82bafd49..94e02b8f 100644
--- a/test/libsolidity/InlineAssembly.cpp
+++ b/test/libsolidity/InlineAssembly.cpp
@@ -266,7 +266,7 @@ BOOST_AUTO_TEST_CASE(if_statement_scope)
 
 BOOST_AUTO_TEST_CASE(if_statement_invalid)
 {
-	CHECK_PARSE_ERROR("{ if calldatasize {}", ParserError, "Instructions are not supported as conditions for if");
+	CHECK_PARSE_ERROR("{ if mload {} }", ParserError, "Expected token \"(\"");
 	BOOST_CHECK("{ if calldatasize() {}");
 	CHECK_PARSE_ERROR("{ if mstore(1, 1) {} }", ParserError, "Instruction \"mstore\" not allowed in this context");
 	CHECK_PARSE_ERROR("{ if 32 let x := 3 }", ParserError, "Expected token LBrace");
@@ -296,7 +296,7 @@ BOOST_AUTO_TEST_CASE(switch_duplicate_case)
 BOOST_AUTO_TEST_CASE(switch_invalid_expression)
 {
 	CHECK_PARSE_ERROR("{ switch {} default {} }", ParserError, "Literal, identifier or instruction expected.");
-	CHECK_PARSE_ERROR("{ switch calldatasize default {} }", ParserError, "Instructions are not supported as expressions for switch");
+	CHECK_PARSE_ERROR("{ switch mload default {} }", ParserError, "Expected token \"(\"");
 	CHECK_PARSE_ERROR("{ switch mstore(1, 1) default {} }", ParserError, "Instruction \"mstore\" not allowed in this context");
 }
 
@@ -332,7 +332,7 @@ BOOST_AUTO_TEST_CASE(for_invalid_expression)
 	CHECK_PARSE_ERROR("{ for 1 1 {} {} }", ParserError, "Expected token LBrace got 'Number'");
 	CHECK_PARSE_ERROR("{ for {} 1 1 {} }", ParserError, "Expected token LBrace got 'Number'");
 	CHECK_PARSE_ERROR("{ for {} 1 {} 1 }", ParserError, "Expected token LBrace got 'Number'");
-	CHECK_PARSE_ERROR("{ for {} calldatasize {} {} }", ParserError, "Instructions are not supported as conditions for the for statement.");
+	CHECK_PARSE_ERROR("{ for {} mload {} {} }", ParserError, "Expected token \"(\"");
 	CHECK_PARSE_ERROR("{ for {} mstore(1, 1) {} {} }", ParserError, "Instruction \"mstore\" not allowed in this context");
 }
 
@@ -540,7 +540,7 @@ BOOST_AUTO_TEST_CASE(function_calls)
 	function g(a, b, c)
 	{
 	}
-	g(1, mul(2, address), f(mul(2, caller)))
+	g(1, mul(2, address()), f(mul(2, caller())))
 	y()
 })";
 	boost::replace_all(source, "\t", "    ");