Add variable declaration initializer.

libyul/optimiser/VarDeclInitializer.cpp

@@ -0,0 +1,56 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <libyul/optimiser/VarDeclInitializer.h>
+#include <libyul/AsmData.h>
+
+#include <libdevcore/CommonData.h>
+#include <libdevcore/Visitor.h>
+
+using namespace std;
+using namespace dev;
+using namespace yul;
+
+void VarDeclInitializer::operator()(Block& _block)
+{
+	ASTModifier::operator()(_block);
+
+	static Expression const zero{Literal{{}, LiteralKind::Number, YulString{"0"}, {}}};
+
+	using OptionalStatements = boost::optional<vector<Statement>>;
+	GenericFallbackReturnsVisitor<OptionalStatements, VariableDeclaration> visitor{
+		[](VariableDeclaration& _varDecl) -> OptionalStatements
+		{
+			if (_varDecl.value)
+				return {};
+			else if (_varDecl.variables.size() == 1)
+			{
+				_varDecl.value = make_shared<Expression>(zero);
+				return {};
+			}
+			else
+			{
+				OptionalStatements ret{vector<Statement>{}};
+				langutil::SourceLocation loc{std::move(_varDecl.location)};
+				for (auto& var: _varDecl.variables)
+					ret->push_back(VariableDeclaration{loc, {std::move(var)}, make_shared<Expression>(zero)});
+				return ret;
+			}
+		}
+	};
+	iterateReplacing(_block.statements, boost::apply_visitor(visitor));
+}