From cd5f4958613ab131980c4b15563ad9d0017d8d5c Mon Sep 17 00:00:00 2001
From: Christian <c@ethdev.com>
Date: Mon, 8 Dec 2014 16:56:41 +0100
Subject: [PATCH] Register variably-sized variables on stack.

---
 Compiler.cpp        |  7 ++++---
 CompilerContext.cpp | 25 +++++++++++++++----------
 CompilerContext.h   | 10 ++++++----
 3 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/Compiler.cpp b/Compiler.cpp
index 17ad4fd16..66d938d17 100644
--- a/Compiler.cpp
+++ b/Compiler.cpp
@@ -199,11 +199,12 @@ bool Compiler::visit(FunctionDefinition& _function)
 	unsigned const numReturnValues = _function.getReturnParameters().size();
 	unsigned const numLocalVariables = _function.getLocalVariables().size();
 
-	for (ASTPointer<VariableDeclaration> const& variable: _function.getParameters() + _function.getReturnParameters())
+	for (ASTPointer<VariableDeclaration> const& variable: _function.getParameters())
 		m_context.addVariable(*variable);
+	for (ASTPointer<VariableDeclaration> const& variable: _function.getReturnParameters())
+		m_context.addAndInitializeVariable(*variable);
 	for (VariableDeclaration const* localVariable: _function.getLocalVariables())
-		m_context.addVariable(*localVariable);
-	m_context.initializeLocalVariables(numReturnValues + numLocalVariables);
+		m_context.addAndInitializeVariable(*localVariable);
 
 	_function.getBody().accept(*this);
 
diff --git a/CompilerContext.cpp b/CompilerContext.cpp
index b89a8e5b5..fa18520d0 100644
--- a/CompilerContext.cpp
+++ b/CompilerContext.cpp
@@ -41,20 +41,25 @@ void CompilerContext::addStateVariable(VariableDeclaration const& _declaration)
 	m_stateVariablesSize += _declaration.getType()->getStorageSize();
 }
 
-void CompilerContext::initializeLocalVariables(unsigned _numVariables)
+void CompilerContext::addVariable(VariableDeclaration const& _declaration)
 {
-	if (_numVariables > 0)
-	{
+	m_localVariables[&_declaration] = m_localVariablesSize;
+	m_localVariablesSize += _declaration.getType()->getSizeOnStack();
+}
+
+void CompilerContext::addAndInitializeVariable(VariableDeclaration const& _declaration)
+{
+	addVariable(_declaration);
+
+	unsigned const size = _declaration.getType()->getSizeOnStack();
+	for (unsigned i = 0; i < size; ++i)
 		*this << u256(0);
-		for (unsigned i = 1; i < _numVariables; ++i)
-			*this << eth::Instruction::DUP1;
-		m_asm.adjustDeposit(-_numVariables);
-	}
+	m_asm.adjustDeposit(-size);
 }
 
 bool CompilerContext::isLocalVariable(Declaration const* _declaration) const
 {
-	return std::find(m_localVariables.begin(), m_localVariables.end(), _declaration) != m_localVariables.end();
+	return m_localVariables.count(_declaration) > 0;
 }
 
 eth::AssemblyItem CompilerContext::getFunctionEntryLabel(FunctionDefinition const& _function) const
@@ -67,10 +72,10 @@ eth::AssemblyItem CompilerContext::getFunctionEntryLabel(FunctionDefinition cons
 
 unsigned CompilerContext::getBaseStackOffsetOfVariable(Declaration const& _declaration) const
 {
-	auto res = find(begin(m_localVariables), end(m_localVariables), &_declaration);
+	auto res = m_localVariables.find(&_declaration);
 	if (asserts(res != m_localVariables.end()))
 		BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Variable not found on stack."));
-	return unsigned(end(m_localVariables) - res - 1);
+	return m_localVariablesSize - res->second - 1;
 }
 
 unsigned CompilerContext::baseToCurrentStackOffset(unsigned _baseOffset) const
diff --git a/CompilerContext.h b/CompilerContext.h
index 6a48e1485..7272a368b 100644
--- a/CompilerContext.h
+++ b/CompilerContext.h
@@ -43,8 +43,8 @@ public:
 	void addMagicGlobal(MagicVariableDeclaration const& _declaration);
 	void addStateVariable(VariableDeclaration const& _declaration);
 	void startNewFunction() { m_localVariables.clear(); m_asm.setDeposit(0); }
-	void initializeLocalVariables(unsigned _numVariables);
-	void addVariable(VariableDeclaration const& _declaration) { m_localVariables.push_back(&_declaration); }
+	void addVariable(VariableDeclaration const& _declaration);
+	void addAndInitializeVariable(VariableDeclaration const& _declaration);
 	void addFunction(FunctionDefinition const& _function) { m_functionEntryLabels.insert(std::make_pair(&_function, m_asm.newTag())); }
 
 	void adjustStackOffset(int _adjustment) { m_asm.adjustDeposit(_adjustment); }
@@ -98,8 +98,10 @@ private:
 	u256 m_stateVariablesSize;
 	/// Storage offsets of state variables
 	std::map<Declaration const*, u256> m_stateVariables;
-	/// Offsets of local variables on the stack.
-	std::vector<Declaration const*> m_localVariables;
+	/// Offsets of local variables on the stack (relative to stack base).
+	std::map<Declaration const*, unsigned> m_localVariables;
+	/// Sum of stack sizes of local variables
+	unsigned m_localVariablesSize;
 	/// Labels pointing to the entry points of funcitons.
 	std::map<Declaration const*, eth::AssemblyItem> m_functionEntryLabels;
 };