Merge pull request #3332 from ethereum/elimination_descirption

Rematerialisation step.

1 files changed, 54 insertions, 0 deletions

diff --git a/libjulia/optimiser/Rematerialiser.cpp b/libjulia/optimiser/Rematerialiser.cpp
new file mode 100644
index 00000000..eaa75e33
--- /dev/null
+++ b/libjulia/optimiser/Rematerialiser.cpp
@@ -0,0 +1,54 @@
+/*(
+	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 variables by their most recently assigned expressions.
+ */
+
+#include <libjulia/optimiser/Rematerialiser.h>
+
+#include <libjulia/optimiser/Metrics.h>
+#include <libjulia/optimiser/ASTCopier.h>
+
+#include <libsolidity/inlineasm/AsmData.h>
+
+using namespace std;
+using namespace dev;
+using namespace dev::julia;
+
+void Rematerialiser::visit(Expression& _e)
+{
+	if (_e.type() == typeid(Identifier))
+	{
+		Identifier& identifier = boost::get<Identifier>(_e);
+		if (m_value.count(identifier.name))
+		{
+			string name = identifier.name;
+			bool expressionValid = true;
+			for (auto const& ref: m_references[name])
+				if (!inScope(ref))
+				{
+					expressionValid = false;
+					break;
+				}
+			solAssert(m_value.at(name), "");
+			auto const& value = *m_value.at(name);
+			if (expressionValid && CodeSize::codeSize(value) <= 7)
+				_e = (ASTCopier{}).translate(value);
+		}
+	}
+	DataFlowAnalyzer::visit(_e);
+}