Also optimize memory.

libyul/optimiser/LoadResolver.cpp

@@ -0,0 +1,66 @@
+/*
+	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/>.
+*/
+/**
+ * Optimisation stage that replaces expressions of type ``sload(x)`` by the value
+ * currently stored in storage, if known.
+ */
+
+#include <libyul/optimiser/LoadResolver.h>
+
+#include <libyul/backends/evm/EVMDialect.h>
+#include <libyul/optimiser/Semantics.h>
+#include <libyul/AsmData.h>
+
+using namespace std;
+using namespace dev;
+using namespace yul;
+
+void LoadResolver::run(Dialect const& _dialect, Block& _ast)
+{
+	bool containsMSize = SideEffectsCollector(_dialect, _ast).containsMSize();
+	LoadResolver{_dialect, !containsMSize}(_ast);
+}
+
+void LoadResolver::visit(Expression& _e)
+{
+	if (_e.type() == typeid(FunctionCall))
+	{
+		FunctionCall const& funCall = boost::get<FunctionCall>(_e);
+		if (auto const* builtin = dynamic_cast<EVMDialect const&>(m_dialect).builtin(funCall.functionName.name))
+			if (!builtin->parameters.empty() && funCall.arguments.at(0).type() == typeid(Identifier))
+			{
+				YulString key = boost::get<Identifier>(funCall.arguments.at(0)).name;
+				if (
+					builtin->instruction == dev::eth::Instruction::SLOAD &&
+					m_storage.values.count(key)
+				)
+				{
+					_e = Identifier{locationOf(_e), m_storage.values[key]};
+					return;
+				}
+				else if (
+					m_optimizeMLoad &&
+					builtin->instruction == dev::eth::Instruction::MLOAD &&
+					m_memory.values.count(key)
+				)
+				{
+					_e = Identifier{locationOf(_e), m_memory.values[key]};
+					return;
+				}
+			}
+	}
+}