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diff --git a/libyul/optimiser/SSATransform.h b/libyul/optimiser/SSATransform.h
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+/*
+	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/>.
+*/
+/**
+ * Optimiser component that turns subsequent assignments to variable declarations
+ * and assignments.
+ */
+#pragma once
+
+#include <libyul/ASTDataForward.h>
+
+#include <libyul/optimiser/ASTWalker.h>
+
+#include <vector>
+
+namespace dev
+{
+namespace yul
+{
+
+class NameDispenser;
+
+/**
+ * Optimizer stage that tries to replace repeated assignments to
+ * existing variables by declarations of new variables as much as
+ * possible.
+ * The reassignments are still there, but all references to the
+ * reassigned variables are replaced by the newly declared variables.
+ *
+ * Example:
+ * {
+ *   let a := 1
+ *   mstore(a, 2)
+ *   a := 3
+ * }
+ * is transformed to
+ * {
+ *   let a_1 := 1
+ *   let a := a_1
+ *   mstore(a_1, 2)
+ *   let a_3 := 3
+ *   a := a_3
+ * }
+ *
+ * Exact semantics:
+ *
+ * For any variable a that is assigned to somewhere in the code (assignment with
+ * declaration does not count) perform the following transforms:
+ *  - replace "let a := v" by "let a_1 := v   let a := a_1"
+ *  - replace "a := v" by "let a_1 := v   a := a_1"
+ * Furthermore, always note the current variable/value assigned to a and replace each
+ * reference to a by this variable.
+ * The current value mapping is cleared for a variable a at the end of each block
+ * in which it was assigned and just after the for loop init block if it is assigned
+ * inside the for loop.
+ *
+ * After this stage, redundantAssignmentRemover is recommended to remove the unnecessary
+ * intermediate assignments.
+ *
+ * This stage provides best results if CSE is run right before it, because
+ * then it does not generate excessive amounts of variables.
+ *
+ * TODO Which transforms are required to keep this idempotent?
+ */
+class SSATransform: public ASTModifier
+{
+public:
+	void operator()(Identifier&) override;
+	void operator()(ForLoop&) override;
+	void operator()(Block& _block) override;
+
+	static void run(Block& _ast, NameDispenser& _nameDispenser);
+
+private:
+	explicit SSATransform(NameDispenser& _nameDispenser, std::set<std::string> const& _variablesToReplace):
+		m_nameDispenser(_nameDispenser), m_variablesToReplace(_variablesToReplace)
+	{ }
+
+	NameDispenser& m_nameDispenser;
+	std::set<std::string> const& m_variablesToReplace;
+	std::map<std::string, std::string> m_currentVariableValues;
+};
+
+}
+}