Side-effects of user-defined functions.

libyul/optimiser/CommonSubexpressionEliminator.cpp

@@ -23,6 +23,9 @@
 
 #include <libyul/optimiser/Metrics.h>
 #include <libyul/optimiser/SyntacticalEquality.h>
+#include <libyul/optimiser/CallGraphGenerator.h>
+#include <libyul/optimiser/Semantics.h>
+#include <libyul/SideEffects.h>
 #include <libyul/Exceptions.h>
 #include <libyul/AsmData.h>
 #include <libyul/Dialect.h>
@@ -31,6 +34,23 @@ using namespace std;
 using namespace dev;
 using namespace yul;
 
+void CommonSubexpressionEliminator::run(Dialect const& _dialect, Block& _ast)
+{
+	CommonSubexpressionEliminator cse{
+		_dialect,
+		SideEffectsPropagator::sideEffects(_dialect, CallGraphGenerator::callGraph(_ast))
+	};
+	cse(_ast);
+}
+
+CommonSubexpressionEliminator::CommonSubexpressionEliminator(
+	Dialect const& _dialect,
+	map<YulString, SideEffects> _functionSideEffects
+):
+	DataFlowAnalyzer(_dialect, std::move(_functionSideEffects))
+{
+}
+
 void CommonSubexpressionEliminator::visit(Expression& _e)
 {
 	bool descend = true;

libyul/optimiser/CommonSubexpressionEliminator.h

@@ -27,6 +27,7 @@ namespace yul
 {
 
 struct Dialect;
+struct SideEffects;
 
 /**
  * Optimisation stage that replaces expressions known to be the current value of a variable
@@ -37,7 +38,14 @@ struct Dialect;
 class CommonSubexpressionEliminator: public DataFlowAnalyzer
 {
 public:
-	CommonSubexpressionEliminator(Dialect const& _dialect): DataFlowAnalyzer(_dialect) {}
+	/// Runs the CSE pass. @a _ast needs to be the complete AST of the program!
+	static void run(Dialect const& _dialect, Block& _ast);
+
+private:
+	CommonSubexpressionEliminator(
+		Dialect const& _dialect,
+		std::map<YulString, SideEffects> _functionSideEffects
+	);
 
 protected:
 	using ASTModifier::visit;

libyul/optimiser/DataFlowAnalyzer.cpp

@@ -211,7 +211,7 @@ void DataFlowAnalyzer::handleAssignment(set<YulString> const& _variables, Expres
 {
 	clearValues(_variables);
 
-	MovableChecker movableChecker{m_dialect};
+	MovableChecker movableChecker{m_dialect, &m_functionSideEffects};
 	if (_value)
 		movableChecker.visit(*_value);
 	else

libyul/optimiser/DataFlowAnalyzer.h

@@ -26,6 +26,7 @@
 #include <libyul/optimiser/KnowledgeBase.h>
 #include <libyul/YulString.h>
 #include <libyul/AsmData.h>
+#include <libyul/SideEffects.h>
 
 // TODO avoid
 #include <libevmasm/Instruction.h>
@@ -38,6 +39,7 @@
 namespace yul
 {
 struct Dialect;
+struct SideEffects;
 
 /**
  * Base class to perform data flow analysis during AST walks.
@@ -67,8 +69,16 @@ struct Dialect;
 class DataFlowAnalyzer: public ASTModifier
 {
 public:
-	explicit DataFlowAnalyzer(Dialect const& _dialect):
+	/// @param _functionSideEffects
+	///            Side-effects of user-defined functions. Worst-case side-effects are assumed
+	///            if this is not provided or the function is not found.
+	///            The parameter is mostly used to determine movability of expressions.
+	explicit DataFlowAnalyzer(
+		Dialect const& _dialect,
+		std::map<YulString, SideEffects> _functionSideEffects = {}
+	):
 		m_dialect(_dialect),
+		m_functionSideEffects(std::move(_functionSideEffects)),
 		m_knowledgeBase(_dialect, m_value)
 	{}
 
@@ -124,6 +134,9 @@ protected:
 	) const;
 
 	Dialect const& m_dialect;
+	/// Side-effects of user-defined functions. Worst-case side-effects are assumed
+	/// if this is not provided or the function is not found.
+	std::map<YulString, SideEffects> m_functionSideEffects;
 
 	/// Current values of variables, always movable.
 	std::map<YulString, Expression const*> m_value;

libyul/optimiser/Semantics.cpp

@@ -64,8 +64,11 @@ void SideEffectsCollector::operator()(FunctionCall const& _functionCall)
 {
 	ASTWalker::operator()(_functionCall);
 
-	if (BuiltinFunction const* f = m_dialect.builtin(_functionCall.functionName.name))
+	YulString functionName = _functionCall.functionName.name;
+	if (BuiltinFunction const* f = m_dialect.builtin(functionName))
 		m_sideEffects += f->sideEffects;
+	else if (m_functionSideEffects && m_functionSideEffects->count(functionName))
+		m_sideEffects += m_functionSideEffects->at(functionName);
 	else
 		m_sideEffects += SideEffects::worst();
 }

libyul/optimiser/Semantics.h

@@ -22,6 +22,7 @@
 
 #include <libyul/optimiser/ASTWalker.h>
 #include <libyul/SideEffects.h>
+#include <libyul/AsmData.h>
 
 #include <set>
 
@@ -36,7 +37,10 @@ struct Dialect;
 class SideEffectsCollector: public ASTWalker
 {
 public:
-	explicit SideEffectsCollector(Dialect const& _dialect): m_dialect(_dialect) {}
+	explicit SideEffectsCollector(
+		Dialect const& _dialect,
+		std::map<YulString, SideEffects> const* _functionSideEffects = nullptr
+	): m_dialect(_dialect), m_functionSideEffects(_functionSideEffects) {}
 	SideEffectsCollector(Dialect const& _dialect, Expression const& _expression);
 	SideEffectsCollector(Dialect const& _dialect, Statement const& _statement);
 	SideEffectsCollector(Dialect const& _dialect, Block const& _ast);
@@ -59,6 +63,7 @@ public:
 
 private:
 	Dialect const& m_dialect;
+	std::map<YulString, SideEffects> const* m_functionSideEffects = nullptr;
 	SideEffects m_sideEffects;
 };
 
@@ -108,7 +113,10 @@ private:
 class MovableChecker: public SideEffectsCollector
 {
 public:
-	explicit MovableChecker(Dialect const& _dialect): SideEffectsCollector(_dialect) {}
+	explicit MovableChecker(
+		Dialect const& _dialect,
+		std::map<YulString, SideEffects> const* _functionSideEffects = nullptr
+	): SideEffectsCollector(_dialect, _functionSideEffects) {}
 	MovableChecker(Dialect const& _dialect, Expression const& _expression);
 
 	void operator()(Identifier const& _identifier) override;

libyul/optimiser/Suite.cpp

@@ -23,6 +23,7 @@
 #include <libyul/optimiser/Disambiguator.h>
 #include <libyul/optimiser/VarDeclInitializer.h>
 #include <libyul/optimiser/BlockFlattener.h>
+#include <libyul/optimiser/CallGraphGenerator.h>
 #include <libyul/optimiser/ControlFlowSimplifier.h>
 #include <libyul/optimiser/DeadCodeEliminator.h>
 #include <libyul/optimiser/FunctionGrouper.h>
@@ -37,6 +38,7 @@
 #include <libyul/optimiser/UnusedPruner.h>
 #include <libyul/optimiser/ExpressionSimplifier.h>
 #include <libyul/optimiser/CommonSubexpressionEliminator.h>
+#include <libyul/optimiser/Semantics.h>
 #include <libyul/optimiser/SSAReverser.h>
 #include <libyul/optimiser/SSATransform.h>
 #include <libyul/optimiser/StackCompressor.h>
@@ -114,7 +116,8 @@ void OptimiserSuite::run(
 			RedundantAssignEliminator::run(_dialect, ast);
 
 			ExpressionSimplifier::run(_dialect, ast);
-			CommonSubexpressionEliminator{_dialect}(ast);
+
+			CommonSubexpressionEliminator::run(_dialect, ast);
 		}
 
 		{
@@ -126,16 +129,17 @@ void OptimiserSuite::run(
 			DeadCodeEliminator{_dialect}(ast);
 			UnusedPruner::runUntilStabilised(_dialect, ast, reservedIdentifiers);
 		}
+
 		{
 			// simplify again
-			CommonSubexpressionEliminator{_dialect}(ast);
+			CommonSubexpressionEliminator::run(_dialect, ast);
 			UnusedPruner::runUntilStabilised(_dialect, ast, reservedIdentifiers);
 		}
 
 		{
 			// reverse SSA
 			SSAReverser::run(ast);
-			CommonSubexpressionEliminator{_dialect}(ast);
+			CommonSubexpressionEliminator::run(_dialect, ast);
 			UnusedPruner::runUntilStabilised(_dialect, ast, reservedIdentifiers);
 
 			ExpressionJoiner::run(ast);
@@ -156,7 +160,7 @@ void OptimiserSuite::run(
 			SSATransform::run(ast, dispenser);
 			RedundantAssignEliminator::run(_dialect, ast);
 			RedundantAssignEliminator::run(_dialect, ast);
-			CommonSubexpressionEliminator{_dialect}(ast);
+			CommonSubexpressionEliminator::run(_dialect, ast);
 		}
 
 		{
@@ -177,12 +181,12 @@ void OptimiserSuite::run(
 			BlockFlattener{}(ast);
 			DeadCodeEliminator{_dialect}(ast);
 			ControlFlowSimplifier{_dialect}(ast);
-			CommonSubexpressionEliminator{_dialect}(ast);
+			CommonSubexpressionEliminator::run(_dialect, ast);
 			SSATransform::run(ast, dispenser);
 			RedundantAssignEliminator::run(_dialect, ast);
 			RedundantAssignEliminator::run(_dialect, ast);
 			UnusedPruner::runUntilStabilised(_dialect, ast, reservedIdentifiers);
-			CommonSubexpressionEliminator{_dialect}(ast);
+			CommonSubexpressionEliminator::run(_dialect, ast);
 		}
 	}
 
@@ -197,7 +201,7 @@ void OptimiserSuite::run(
 	UnusedPruner::runUntilStabilised(_dialect, ast, reservedIdentifiers);
 
 	SSAReverser::run(ast);
-	CommonSubexpressionEliminator{_dialect}(ast);
+	CommonSubexpressionEliminator::run(_dialect, ast);
 	UnusedPruner::runUntilStabilised(_dialect, ast, reservedIdentifiers);
 
 	ExpressionJoiner::run(ast);

test/libyul/YulOptimizerTest.cpp

@@ -26,6 +26,7 @@
 #include <libyul/optimiser/ControlFlowSimplifier.h>
 #include <libyul/optimiser/DeadCodeEliminator.h>
 #include <libyul/optimiser/Disambiguator.h>
+#include <libyul/optimiser/CallGraphGenerator.h>
 #include <libyul/optimiser/CommonSubexpressionEliminator.h>
 #include <libyul/optimiser/NameCollector.h>
 #include <libyul/optimiser/EquivalentFunctionCombiner.h>
@@ -45,6 +46,7 @@
 #include <libyul/optimiser/ExpressionJoiner.h>
 #include <libyul/optimiser/SSAReverser.h>
 #include <libyul/optimiser/SSATransform.h>
+#include <libyul/optimiser/Semantics.h>
 #include <libyul/optimiser/RedundantAssignEliminator.h>
 #include <libyul/optimiser/StructuralSimplifier.h>
 #include <libyul/optimiser/StackCompressor.h>
@@ -149,7 +151,7 @@ TestCase::TestResult YulOptimizerTest::run(ostream& _stream, string const& _line
 	else if (m_optimizerStep == "commonSubexpressionEliminator")
 	{
 		disambiguate();
-		(CommonSubexpressionEliminator{*m_dialect})(*m_ast);
+		CommonSubexpressionEliminator::run(*m_dialect, *m_ast);
 	}
 	else if (m_optimizerStep == "expressionSplitter")
 	{
@@ -218,7 +220,7 @@ TestCase::TestResult YulOptimizerTest::run(ostream& _stream, string const& _line
 		NameDispenser nameDispenser{*m_dialect, *m_ast};
 		ExpressionSplitter{*m_dialect, nameDispenser}(*m_ast);
 		ForLoopInitRewriter{}(*m_ast);
-		CommonSubexpressionEliminator{*m_dialect}(*m_ast);
+		CommonSubexpressionEliminator::run(*m_dialect, *m_ast);
 		ExpressionSimplifier::run(*m_dialect, *m_ast);
 		UnusedPruner::runUntilStabilised(*m_dialect, *m_ast);
 		DeadCodeEliminator{*m_dialect}(*m_ast);
@@ -260,7 +262,7 @@ TestCase::TestResult YulOptimizerTest::run(ostream& _stream, string const& _line
 		ForLoopInitRewriter{}(*m_ast);
 		NameDispenser nameDispenser{*m_dialect, *m_ast};
 		ExpressionSplitter{*m_dialect, nameDispenser}(*m_ast);
-		CommonSubexpressionEliminator{*m_dialect}(*m_ast);
+		CommonSubexpressionEliminator::run(*m_dialect, *m_ast);
 		ExpressionSimplifier::run(*m_dialect, *m_ast);
 
 		LoadResolver::run(*m_dialect, *m_ast);
@@ -298,7 +300,7 @@ TestCase::TestResult YulOptimizerTest::run(ostream& _stream, string const& _line
 		RedundantAssignEliminator::run(*m_dialect, *m_ast);
 		// reverse SSA
 		SSAReverser::run(*m_ast);
-		CommonSubexpressionEliminator{*m_dialect}(*m_ast);
+		CommonSubexpressionEliminator::run(*m_dialect, *m_ast);
 		UnusedPruner::runUntilStabilised(*m_dialect, *m_ast);
 	}
 	else if (m_optimizerStep == "stackCompressor")

test/libyul/yulOptimizerTests/commonSubexpressionEliminator/movable_functions.yul

@@ -0,0 +1,26 @@
+{
+    function double(x) -> y { y := add(x, x) }
+    function double_with_se(x) -> y { y := add(x, x) mstore(40, 4) }
+    let i := mload(3)
+    let a := double(i)
+    let b := double(i)
+    let c := double_with_se(i)
+    let d := double_with_se(i)
+}
+// ====
+// step: commonSubexpressionEliminator
+// ----
+// {
+//     function double(x) -> y
+//     { y := add(x, x) }
+//     function double_with_se(x_1) -> y_2
+//     {
+//         y_2 := add(x_1, x_1)
+//         mstore(40, 4)
+//     }
+//     let i := mload(3)
+//     let a := double(i)
+//     let b := a
+//     let c := double_with_se(i)
+//     let d := double_with_se(i)
+// }

test/tools/yulopti.cpp

@@ -151,7 +151,7 @@ public:
 				ForLoopConditionIntoBody{}(*m_ast);
 				break;
 			case 'c':
-				(CommonSubexpressionEliminator{m_dialect})(*m_ast);
+				CommonSubexpressionEliminator::run(m_dialect, *m_ast);
 				break;
 			case 'd':
 				(VarDeclInitializer{})(*m_ast);