Tests for knowledge base.

Author: chriseth

test/libyul/KnowledgeBaseTest.cpp

@@ -26,6 +26,8 @@
 #include <libyul/optimiser/KnowledgeBase.h>
 #include <libyul/optimiser/SSAValueTracker.h>
 #include <libyul/optimiser/DataFlowAnalyzer.h>
+#include <libyul/optimiser/NameDispenser.h>
+#include <libyul/optimiser/CommonSubexpressionEliminator.h>
 #include <libyul/backends/evm/EVMDialect.h>
 
 #include <liblangutil/ErrorReporter.h>
@@ -44,20 +46,25 @@ class KnowledgeBaseTest
 	KnowledgeBase constructKnowledgeBase(string const& _source)
 	{
 		ErrorList errorList;
-		shared_ptr<Object> object;
 		shared_ptr<AsmAnalysisInfo> analysisInfo;
-		std::tie(object, analysisInfo) = yul::test::parse(_source, m_dialect, errorList);
-		BOOST_REQUIRE(object && errorList.empty() && object->code);
+		std::tie(m_object, analysisInfo) = yul::test::parse(_source, m_dialect, errorList);
+		BOOST_REQUIRE(m_object && errorList.empty() && m_object->code);
 
-		SSAValueTracker ssaValues;
-		ssaValues(*object->code);
-		for (auto const& [name, expression]: ssaValues.values())
+		NameDispenser dispenser(m_dialect, *m_object->code);
+		std::set<YulString> reserved;
+		OptimiserStepContext context{m_dialect, dispenser, reserved, 0};
+		CommonSubexpressionEliminator::run(context, *m_object->code);
+
+		m_ssaValues(*m_object->code);
+		for (auto const& [name, expression]: m_ssaValues.values())
 			m_values[name].value = expression;
 
 		return KnowledgeBase(m_dialect, m_values);
 	}
 
 	EVMDialect m_dialect{EVMVersion{}, true};
+	shared_ptr<Object> m_object;
+	SSAValueTracker m_ssaValues;
 	map<YulString, AssignedValue> m_values;
 };
 
@@ -75,10 +82,51 @@ BOOST_AUTO_TEST_CASE(basic)
 	})");
 
 	BOOST_CHECK(!kb.knownToBeDifferent("a"_yulstring, "b"_yulstring));
+	// This only works if the variable names are the same.
+	// It assumes that SSA+CSE+Simplifier actually replaces the variables.
+	BOOST_CHECK(!kb.knownToBeEqual("a"_yulstring, "b"_yulstring));
+	BOOST_CHECK(!kb.valueIfKnownConstant("a"_yulstring));
 	BOOST_CHECK(kb.valueIfKnownConstant("zero"_yulstring) == u256(0));
+}
+
+BOOST_AUTO_TEST_CASE(difference)
+{
+	yul::KnowledgeBase kb = constructKnowledgeBase(R"({
+		let a := calldataload(0)
+		let b := add(a, 200)
+		let c := add(a, 220)
+		let d := add(c, 12)
+		let e := sub(c, 12)
+	})");
 
+	BOOST_CHECK(
+		kb.differenceIfKnownConstant("c"_yulstring, "b"_yulstring) ==
+		u256(20)
+	);
+	BOOST_CHECK(
+		kb.differenceIfKnownConstant("b"_yulstring, "c"_yulstring) ==
+		u256(-20)
+	);
+	BOOST_CHECK(!kb.knownToBeDifferentByAtLeast32("b"_yulstring, "c"_yulstring));
+	BOOST_CHECK(kb.knownToBeDifferentByAtLeast32("b"_yulstring, "d"_yulstring));
+	BOOST_CHECK(kb.knownToBeDifferentByAtLeast32("a"_yulstring, "b"_yulstring));
+	BOOST_CHECK(kb.knownToBeDifferentByAtLeast32("b"_yulstring, "a"_yulstring));
+
+	BOOST_CHECK(
+		kb.differenceIfKnownConstant("e"_yulstring, "a"_yulstring) == u256(208)
+	);
+	BOOST_CHECK(
+		kb.differenceIfKnownConstant("e"_yulstring, "b"_yulstring) == u256(8)
+	);
+	BOOST_CHECK(
+		kb.differenceIfKnownConstant("a"_yulstring, "e"_yulstring) == u256(-208)
+	);
+	BOOST_CHECK(
+		kb.differenceIfKnownConstant("b"_yulstring, "e"_yulstring) == u256(-8)
+	);
 }
 
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }