Stack height checks and fix.

Compiler.cpp

@@ -34,6 +34,20 @@ using namespace std;
 namespace dev {
 namespace solidity {
 
+/**
+ * Simple helper class to ensure that the stack height is the same at certain places in the code.
+ */
+class StackHeightChecker
+{
+public:
+	StackHeightChecker(CompilerContext const& _context):
+		m_context(_context), stackHeight(m_context.getStackHeight()) {}
+	void check() { solAssert(m_context.getStackHeight() == stackHeight, "I sense a disturbance in the stack."); }
+private:
+	CompilerContext const& m_context;
+	unsigned stackHeight;
+};
+
 void Compiler::compileContract(ContractDefinition const& _contract,
 							   map<ContractDefinition const*, bytes const*> const& _contracts)
 {
@@ -340,6 +354,8 @@ bool Compiler::visit(FunctionDefinition const& _function)
 
 bool Compiler::visit(IfStatement const& _ifStatement)
 {
+	StackHeightChecker checker(m_context);
+
 	compileExpression(_ifStatement.getCondition());
 	eth::AssemblyItem trueTag = m_context.appendConditionalJump();
 	if (_ifStatement.getFalseStatement())
@@ -348,11 +364,15 @@ bool Compiler::visit(IfStatement const& _ifStatement)
 	m_context << trueTag;
 	_ifStatement.getTrueStatement().accept(*this);
 	m_context << endTag;
+
+	checker.check();
 	return false;
 }
 
 bool Compiler::visit(WhileStatement const& _whileStatement)
 {
+	StackHeightChecker checker(m_context);
+
 	eth::AssemblyItem loopStart = m_context.newTag();
 	eth::AssemblyItem loopEnd = m_context.newTag();
 	m_continueTags.push_back(loopStart);
@@ -370,11 +390,15 @@ bool Compiler::visit(WhileStatement const& _whileStatement)
 
 	m_continueTags.pop_back();
 	m_breakTags.pop_back();
+
+	checker.check();
 	return false;
 }
 
 bool Compiler::visit(ForStatement const& _forStatement)
 {
+	StackHeightChecker checker(m_context);
+
 	eth::AssemblyItem loopStart = m_context.newTag();
 	eth::AssemblyItem loopEnd = m_context.newTag();
 	m_continueTags.push_back(loopStart);
@@ -404,6 +428,8 @@ bool Compiler::visit(ForStatement const& _forStatement)
 
 	m_continueTags.pop_back();
 	m_breakTags.pop_back();
+
+	checker.check();
 	return false;
 }
 
@@ -438,29 +464,35 @@ bool Compiler::visit(Return const& _return)
 	return false;
 }
 
-bool Compiler::visit(VariableDeclarationStatement const& _variableDefinition)
+bool Compiler::visit(VariableDeclarationStatement const& _variableDeclarationStatement)
 {
-	if (Expression const* expression = _variableDefinition.getExpression())
+	StackHeightChecker checker(m_context);
+	if (Expression const* expression = _variableDeclarationStatement.getExpression())
 	{
-		compileExpression(*expression, _variableDefinition.getDeclaration().getType());
+		compileExpression(*expression, _variableDeclarationStatement.getDeclaration().getType());
-		CompilerUtils(m_context).moveToStackVariable(_variableDefinition.getDeclaration());
+		CompilerUtils(m_context).moveToStackVariable(_variableDeclarationStatement.getDeclaration());
 	}
+	checker.check();
 	return false;
 }
 
 bool Compiler::visit(ExpressionStatement const& _expressionStatement)
 {
+	StackHeightChecker checker(m_context);
 	Expression const& expression = _expressionStatement.getExpression();
 	compileExpression(expression);
 	CompilerUtils(m_context).popStackElement(*expression.getType());
+	checker.check();
 	return false;
 }
 
 bool Compiler::visit(PlaceholderStatement const&)
 {
+	StackHeightChecker checker(m_context);
 	++m_modifierDepth;
 	appendModifierOrFunctionCode();
 	--m_modifierDepth;
+	checker.check();
 	return true;
 }
 

Compiler.h

@@ -69,7 +69,7 @@ private:
 	virtual bool visit(Continue const& _continue) override;
 	virtual bool visit(Break const& _break) override;
 	virtual bool visit(Return const& _return) override;
-	virtual bool visit(VariableDeclarationStatement const& _variableDefinition) override;
+	virtual bool visit(VariableDeclarationStatement const& _variableDeclarationStatement) override;
 	virtual bool visit(ExpressionStatement const& _expressionStatement) override;
 	virtual bool visit(PlaceholderStatement const&) override;
 

CompilerContext.h

@@ -48,7 +48,7 @@ public:
 	bytes const& getCompiledContract(ContractDefinition const& _contract) const;
 
 	void adjustStackOffset(int _adjustment) { m_asm.adjustDeposit(_adjustment); }
-	unsigned getStackHeight() { solAssert(m_asm.deposit() >= 0, ""); return unsigned(m_asm.deposit()); }
+	unsigned getStackHeight() const { solAssert(m_asm.deposit() >= 0, ""); return unsigned(m_asm.deposit()); }
 
 	bool isMagicGlobal(Declaration const* _declaration) const { return m_magicGlobals.count(_declaration) != 0; }
 	bool isLocalVariable(Declaration const* _declaration) const;

Types.cpp

@@ -833,10 +833,17 @@ string FunctionType::toString() const
 
 unsigned FunctionType::getSizeOnStack() const
 {
+	Location location = m_location;
+	if (m_location == Location::SetGas || m_location == Location::SetValue)
+	{
+		solAssert(m_returnParameterTypes.size() == 1, "");
+		location = dynamic_cast<FunctionType const&>(*m_returnParameterTypes.front()).m_location;
+	}
+
 	unsigned size = 0;
-	if (m_location == Location::External)
+	if (location == Location::External)
 		size = 2;
-	else if (m_location == Location::Internal || m_location == Location::Bare)
+	else if (location == Location::Internal || location == Location::Bare)
 		size = 1;
 	if (m_gasSet)
 		size++;