Merge pull request #5416 from ethereum/develop

Merge develop into release for 0.5.0

1 files changed, 60 insertions, 0 deletions

diff --git a/libyul/optimiser/ExpressionSimplifier.cpp b/libyul/optimiser/ExpressionSimplifier.cpp
new file mode 100644
index 00000000..64e9d7e7
--- /dev/null
+++ b/libyul/optimiser/ExpressionSimplifier.cpp
@@ -0,0 +1,60 @@
+/*
+	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 uses the simplification rules to simplify expressions.
+ */
+
+#include <libyul/optimiser/ExpressionSimplifier.h>
+
+#include <libyul/optimiser/SimplificationRules.h>
+#include <libyul/optimiser/Semantics.h>
+#include <libyul/optimiser/SSAValueTracker.h>
+
+#include <libsolidity/inlineasm/AsmData.h>
+
+#include <libdevcore/CommonData.h>
+
+using namespace std;
+using namespace dev;
+using namespace dev::yul;
+using namespace dev::solidity;
+
+
+void ExpressionSimplifier::visit(Expression& _expression)
+{
+	ASTModifier::visit(_expression);
+	while (auto match = SimplificationRules::findFirstMatch(_expression, m_ssaValues))
+	{
+		// Do not apply the rule if it removes non-constant parts of the expression.
+		// TODO: The check could actually be less strict than "movable".
+		// We only require "Does not cause side-effects".
+		// Note: References to variables that are only assigned once are always movable,
+		// so if the value of the variable is not movable, the expression that references
+		// the variable still is.
+
+		if (match->removesNonConstants && !MovableChecker(_expression).movable())
+			return;
+		_expression = match->action().toExpression(locationOf(_expression));
+	}
+}
+
+void ExpressionSimplifier::run(Block& _ast)
+{
+	SSAValueTracker ssaValues;
+	ssaValues(_ast);
+	ExpressionSimplifier{ssaValues.values()}(_ast);
+}