Binary transform for br and br_if.

libyul/backends/wasm/BinaryTransform.cpp

@@ -358,13 +358,13 @@ bytes BinaryTransform::operator()(If const& _if)
 		toBytes(Opcode::If) +
 		toBytes(ValueType::Void);
 
-	m_labels.push({});
+	m_labels.emplace_back();
 
 	result += visit(_if.statements);
 	if (_if.elseStatements)
 		result += toBytes(Opcode::Else) + visit(*_if.elseStatements);
 
-	m_labels.pop();
+	m_labels.pop_back();
 
 	result += toBytes(Opcode::End);
 	return result;
@@ -374,26 +374,24 @@ bytes BinaryTransform::operator()(Loop const& _loop)
 {
 	bytes result = toBytes(Opcode::Loop) + toBytes(ValueType::Void);
 
-	m_labels.push(_loop.labelName);
+	m_labels.emplace_back(_loop.labelName);
 	result += visit(_loop.statements);
-	m_labels.pop();
+	m_labels.pop_back();
 
 	result += toBytes(Opcode::End);
 	return result;
 }
 
-bytes BinaryTransform::operator()(Break const&)
+bytes BinaryTransform::operator()(Break const& _break)
 {
-	yulAssert(false, "br not yet implemented.");
-	// TODO the index is just the nesting depth.
-	return {};
+	return toBytes(Opcode::Br) + encodeLabelIdx(_break.label.name);
 }
 
-bytes BinaryTransform::operator()(BreakIf const&)
+bytes BinaryTransform::operator()(BreakIf const& _breakIf)
 {
-	yulAssert(false, "br_if not yet implemented.");
-	// TODO the index is just the nesting depth.
-	return {};
+	bytes result = std::visit(*this, *_breakIf.condition);
+	result += toBytes(Opcode::BrIf) + encodeLabelIdx(_breakIf.label.name);
+	return result;
 }
 
 bytes BinaryTransform::operator()(Return const&)
@@ -403,11 +401,14 @@ bytes BinaryTransform::operator()(Return const&)
 
 bytes BinaryTransform::operator()(Block const& _block)
 {
-	return
+	m_labels.emplace_back(_block.labelName);
+	bytes result =
 		toBytes(Opcode::Block) +
 		toBytes(ValueType::Void) +
 		visit(_block.statements) +
 		toBytes(Opcode::End);
+	m_labels.pop_back();
+	return result;
 }
 
 bytes BinaryTransform::operator()(FunctionDefinition const& _function)
@@ -427,9 +428,13 @@ bytes BinaryTransform::operator()(FunctionDefinition const& _function)
 	for (size_t i = 0; i < _function.locals.size(); ++i)
 		m_locals[_function.locals[i].variableName] = varIdx++;
 
+	yulAssert(m_labels.empty(), "Stray labels.");
+
 	ret += visit(_function.body);
 	ret += toBytes(Opcode::End);
 
+	yulAssert(m_labels.empty(), "Stray labels.");
+
 	return prefixSize(std::move(ret));
 }
 
@@ -581,6 +586,18 @@ bytes BinaryTransform::visitReversed(vector<Expression> const& _expressions)
 	return result;
 }
 
+bytes BinaryTransform::encodeLabelIdx(string const& _label) const
+{
+	yulAssert(!_label.empty(), "Empty label.");
+	size_t depth = 0;
+	for (string const& label: m_labels | boost::adaptors::reversed)
+		if (label == _label)
+			return lebEncode(depth);
+		else
+			++depth;
+	yulAssert(false, "Label not found.");
+}
+
 bytes BinaryTransform::encodeName(std::string const& _name)
 {
 	// UTF-8 is allowed here by the Wasm spec, but since all names here should stem from

libyul/backends/wasm/BinaryTransform.h

@@ -77,13 +77,15 @@ private:
 	bytes visit(std::vector<wasm::Expression> const& _expressions);
 	bytes visitReversed(std::vector<wasm::Expression> const& _expressions);
 
+	bytes encodeLabelIdx(std::string const& _label) const;
+
 	static bytes encodeName(std::string const& _name);
 
 	std::map<std::string, size_t> m_locals;
 	std::map<std::string, size_t> m_globals;
 	std::map<std::string, size_t> m_functions;
 	std::map<std::string, size_t> m_functionTypes;
-	std::stack<std::string> m_labels;
+	std::vector<std::string> m_labels;
 	std::map<std::string, std::pair<size_t, size_t>> m_subModulePosAndSize;
 };
 

libyul/backends/wasm/TextTransform.cpp

@@ -123,7 +123,7 @@ string TextTransform::operator()(wasm::Loop const& _loop)
 
 string TextTransform::operator()(wasm::Break const& _break)
 {
-	return "(break $" + _break.label.name + ")\n";
+	return "(br $" + _break.label.name + ")\n";
 }
 
 string TextTransform::operator()(wasm::BreakIf const& _break)