Merge pull request #2225 from ethereum/julia-for

Implement for statement in assembly parser / printer / code generator

2 files changed, 75 insertions, 40 deletions

diff --git a/libjulia/backends/evm/EVMCodeTransform.cpp b/libjulia/backends/evm/EVMCodeTransform.cpp
index 7c14eb8b..b231ecec 100644
--- a/libjulia/backends/evm/EVMCodeTransform.cpp
+++ b/libjulia/backends/evm/EVMCodeTransform.cpp
@@ -33,26 +33,6 @@ using namespace dev::julia;
 using namespace dev::solidity;
 using namespace dev::solidity::assembly;
 
-void CodeTransform::run(Block const& _block)
-{
-	m_scope = m_info.scopes.at(&_block).get();
-
-	int blockStartStackHeight = m_assembly.stackHeight();
-	std::for_each(_block.statements.begin(), _block.statements.end(), boost::apply_visitor(*this));
-
-	m_assembly.setSourceLocation(_block.location);
-
-	// pop variables
-	for (auto const& identifier: m_scope->identifiers)
-		if (identifier.second.type() == typeid(Scope::Variable))
-			m_assembly.appendInstruction(solidity::Instruction::POP);
-
-	int deposit = m_assembly.stackHeight() - blockStartStackHeight;
-	solAssert(deposit == 0, "Invalid stack height at end of block.");
-	checkStackHeight(&_block);
-}
-
-
 void CodeTransform::operator()(VariableDeclaration const& _varDecl)
 {
 	solAssert(m_scope, "");
@@ -315,7 +295,7 @@ void CodeTransform::operator()(FunctionDefinition const& _function)
 	}
 
 	CodeTransform(m_assembly, m_info, m_evm15, m_identifierAccess, localStackAdjustment, m_context)
-		.run(_function.body);
+		(_function.body);
 
 	{
 		// The stack layout here is:
@@ -358,9 +338,54 @@ void CodeTransform::operator()(FunctionDefinition const& _function)
 	checkStackHeight(&_function);
 }
 
+void CodeTransform::operator()(ForLoop const& _forLoop)
+{
+	Scope* originalScope = m_scope;
+	// We start with visiting the block, but not finalizing it.
+	m_scope = m_info.scopes.at(&_forLoop.pre).get();
+	int stackStartHeight = m_assembly.stackHeight();
+
+	visitStatements(_forLoop.pre.statements);
+
+	// TODO: When we implement break and continue, the labels and the stack heights at that point
+	// have to be stored in a stack.
+	AbstractAssembly::LabelID loopStart = m_assembly.newLabelId();
+	AbstractAssembly::LabelID loopEnd = m_assembly.newLabelId();
+	AbstractAssembly::LabelID postPart = m_assembly.newLabelId();
+
+	m_assembly.setSourceLocation(_forLoop.location);
+	m_assembly.appendLabel(loopStart);
+
+	visitExpression(*_forLoop.condition);
+	m_assembly.setSourceLocation(_forLoop.location);
+	m_assembly.appendInstruction(solidity::Instruction::ISZERO);
+	m_assembly.appendJumpToIf(loopEnd);
+
+	(*this)(_forLoop.body);
+
+	m_assembly.setSourceLocation(_forLoop.location);
+	m_assembly.appendLabel(postPart);
+
+	(*this)(_forLoop.post);
+
+	m_assembly.setSourceLocation(_forLoop.location);
+	m_assembly.appendJumpTo(loopStart);
+	m_assembly.appendLabel(loopEnd);
+
+	finalizeBlock(_forLoop.pre, stackStartHeight);
+	m_scope = originalScope;
+}
+
 void CodeTransform::operator()(Block const& _block)
 {
-	CodeTransform(m_assembly, m_info, m_evm15, m_identifierAccess, m_stackAdjustment, m_context).run(_block);
+	Scope* originalScope = m_scope;
+	m_scope = m_info.scopes.at(&_block).get();
+
+	int blockStartStackHeight = m_assembly.stackHeight();
+	visitStatements(_block.statements);
+
+	finalizeBlock(_block, blockStartStackHeight);
+	m_scope = originalScope;
 }
 
 AbstractAssembly::LabelID CodeTransform::labelFromIdentifier(Identifier const& _identifier)
@@ -401,6 +426,26 @@ void CodeTransform::visitExpression(Statement const& _expression)
 	expectDeposit(1, height);
 }
 
+void CodeTransform::visitStatements(vector<Statement> const& _statements)
+{
+	for (auto const& statement: _statements)
+		boost::apply_visitor(*this, statement);
+}
+
+void CodeTransform::finalizeBlock(Block const& _block, int blockStartStackHeight)
+{
+	m_assembly.setSourceLocation(_block.location);
+
+	// pop variables
+	solAssert(m_info.scopes.at(&_block).get() == m_scope, "");
+	for (size_t i = 0; i < m_scope->numberOfVariables(); ++i)
+		m_assembly.appendInstruction(solidity::Instruction::POP);
+
+	int deposit = m_assembly.stackHeight() - blockStartStackHeight;
+	solAssert(deposit == 0, "Invalid stack height at end of block.");
+	checkStackHeight(&_block);
+}
+
 void CodeTransform::generateAssignment(Identifier const& _variableName)
 {
 	solAssert(m_scope, "");
diff --git a/libjulia/backends/evm/EVMCodeTransform.h b/libjulia/backends/evm/EVMCodeTransform.h
index 202f5051..d09ee87b 100644
--- a/libjulia/backends/evm/EVMCodeTransform.h
+++ b/libjulia/backends/evm/EVMCodeTransform.h
@@ -21,6 +21,7 @@
 #include <libjulia/backends/evm/EVMAssembly.h>
 
 #include <libsolidity/inlineasm/AsmScope.h>
+#include <libsolidity/inlineasm/AsmDataForward.h>
 
 #include <boost/variant.hpp>
 #include <boost/optional.hpp>
@@ -32,21 +33,6 @@ namespace solidity
 class ErrorReporter;
 namespace assembly
 {
-struct Literal;
-struct Block;
-struct Switch;
-struct Label;
-struct FunctionalInstruction;
-struct Assignment;
-struct VariableDeclaration;
-struct Instruction;
-struct Identifier;
-struct StackAssignment;
-struct FunctionDefinition;
-struct FunctionCall;
-
-using Statement = boost::variant<Instruction, Literal, Label, StackAssignment, Identifier, Assignment, FunctionCall, FunctionalInstruction, VariableDeclaration, FunctionDefinition, Switch, Block>;
-
 struct AsmAnalysisInfo;
 }
 }
@@ -75,9 +61,6 @@ public:
 	{
 	}
 
-	/// Processes the block and appends the resulting code to the assembly.
-	void run(solidity::assembly::Block const& _block);
-
 protected:
 	struct Context
 	{
@@ -115,6 +98,7 @@ public:
 	void operator()(solidity::assembly::VariableDeclaration const& _varDecl);
 	void operator()(solidity::assembly::Switch const& _switch);
 	void operator()(solidity::assembly::FunctionDefinition const&);
+	void operator()(solidity::assembly::ForLoop const&);
 	void operator()(solidity::assembly::Block const& _block);
 
 private:
@@ -126,6 +110,12 @@ private:
 	/// Generates code for an expression that is supposed to return a single value.
 	void visitExpression(solidity::assembly::Statement const& _expression);
 
+	void visitStatements(std::vector<solidity::assembly::Statement> const& _statements);
+
+	/// Pops all variables declared in the block and checks that the stack height is equal
+	/// to @a _blackStartStackHeight.
+	void finalizeBlock(solidity::assembly::Block const& _block, int _blockStartStackHeight);
+
 	void generateAssignment(solidity::assembly::Identifier const& _variableName);
 
 	/// Determines the stack height difference to the given variables. Throws