Move the default optimisation steps from OptimiserSuite to OptimiserSettings

- Now it's a mandatory parameter in OptimiserSuite::run()

libsolidity/codegen/CompilerContext.cpp

@@ -502,6 +502,7 @@ void CompilerContext::optimizeYul(yul::Object& _object, yul::EVMDialect const& _
 		&meter,
 		_object,
 		_optimiserSettings.optimizeStackAllocation,
+		_optimiserSettings.yulOptimiserSteps,
 		_externalIdentifiers
 	);
 

libsolidity/interface/OptimiserSettings.h

@@ -23,12 +23,31 @@
 #pragma once
 
 #include <cstddef>
+#include <string>
 
 namespace solidity::frontend
 {
 
 struct OptimiserSettings
 {
+	static char constexpr DefaultYulOptimiserSteps[] =
+		"dhfoDgvulfnTUtnIf"            // None of these can make stack problems worse
+		"["
+			"xarrscLM"                 // Turn into SSA and simplify
+			"cCTUtTOntnfDIul"          // Perform structural simplification
+			"Lcul"                     // Simplify again
+			"Vcul jj"                  // Reverse SSA
+
+			// should have good "compilability" property here.
+
+			"eul"                      // Run functional expression inliner
+			"xarulrul"                 // Prune a bit more in SSA
+			"xarrcL"                   // Turn into SSA again and simplify
+			"gvif"                     // Run full inliner
+			"CTUcarrLsTOtfDncarrIulc"  // SSA plus simplify
+		"]"
+		"jmuljuljul VcTOcul jmul";     // Make source short and pretty
+
 	/// No optimisations at all - not recommended.
 	static OptimiserSettings none()
 	{
@@ -74,6 +93,7 @@ struct OptimiserSettings
 			runConstantOptimiser == _other.runConstantOptimiser &&
 			optimizeStackAllocation == _other.optimizeStackAllocation &&
 			runYulOptimiser == _other.runYulOptimiser &&
+			yulOptimiserSteps == _other.yulOptimiserSteps &&
 			expectedExecutionsPerDeployment == _other.expectedExecutionsPerDeployment;
 	}
 
@@ -95,6 +115,11 @@ struct OptimiserSettings
 	bool optimizeStackAllocation = false;
 	/// Yul optimiser with default settings. Will only run on certain parts of the code for now.
 	bool runYulOptimiser = false;
+	/// Sequence of optimisation steps to be performed by Yul optimiser.
+	/// Note that there are some hard-coded steps in the optimiser and you cannot disable
+	/// them just by setting this to an empty string. Set @a runYulOptimiser to false if you want
+	/// no optimisations.
+	std::string yulOptimiserSteps = DefaultYulOptimiserSteps;
 	/// This specifies an estimate on how often each opcode in this assembly will be executed,
 	/// i.e. use a small value to optimise for size and a large value to optimise for runtime gas usage.
 	size_t expectedExecutionsPerDeployment = 200;

libyul/AssemblyStack.cpp

@@ -183,7 +183,8 @@ void AssemblyStack::optimize(Object& _object, bool _isCreation)
 		dialect,
 		meter.get(),
 		_object,
-		m_optimiserSettings.optimizeStackAllocation
+		m_optimiserSettings.optimizeStackAllocation,
+		m_optimiserSettings.yulOptimiserSteps
 	);
 }
 

libyul/optimiser/Suite.cpp

@@ -79,6 +79,7 @@ void OptimiserSuite::run(
 	GasMeter const* _meter,
 	Object& _object,
 	bool _optimizeStackAllocation,
+	string const& _optimisationSequence,
 	set<YulString> const& _externallyUsedIdentifiers
 )
 {
@@ -94,25 +95,12 @@ void OptimiserSuite::run(
 
 	OptimiserSuite suite(_dialect, reservedIdentifiers, Debug::None, ast);
 
-	suite.runSequence(
-		"dhfoDgvulfnTUtnIf"            // None of these can make stack problems worse
-		"["
-			"xarrscLM"                 // Turn into SSA and simplify
-			"cCTUtTOntnfDIul"          // Perform structural simplification
-			"Lcul"                     // Simplify again
-			"Vcul jj"                  // Reverse SSA
+	// Some steps depend on properties ensured by FunctionHoister, FunctionGrouper and
+	// ForLoopInitRewriter. Run them first to be able to run arbitrary sequences safely.
+	suite.runSequence("fgo", ast);
 
-			// should have good "compilability" property here.
-
-			"eul"                      // Run functional expression inliner
-			"xarulrul"                 // Prune a bit more in SSA
-			"xarrcL"                   // Turn into SSA again and simplify
-			"gvif"                     // Run full inliner
-			"CTUcarrLsTOtfDncarrIulc"  // SSA plus simplify
-		"]"
-		"jmuljuljul VcTOcul jmul",     // Make source short and pretty
-		ast
-	);
+	// Now the user-supplied part
+	suite.runSequence(_optimisationSequence, ast);
 
 	// This is a tuning parameter, but actually just prevents infinite loops.
 	size_t stackCompressorMaxIterations = 16;

libyul/optimiser/Suite.h

@@ -62,6 +62,7 @@ public:
 		GasMeter const* _meter,
 		Object& _object,
 		bool _optimizeStackAllocation,
+		std::string const& _optimisationSequence,
 		std::set<YulString> const& _externallyUsedIdentifiers = {}
 	);
 

test/libyul/YulOptimizerTest.cpp

@@ -74,6 +74,8 @@
 
 #include <libsolutil/AnsiColorized.h>
 
+#include <libsolidity/interface/OptimiserSettings.h>
+
 #include <boost/test/unit_test.hpp>
 #include <boost/algorithm/string.hpp>
 
@@ -342,7 +344,7 @@ TestCase::TestResult YulOptimizerTest::run(ostream& _stream, string const& _line
 		yul::Object obj;
 		obj.code = m_ast;
 		obj.analysisInfo = m_analysisInfo;
-		OptimiserSuite::run(*m_dialect, &meter, obj, true);
+		OptimiserSuite::run(*m_dialect, &meter, obj, true, solidity::frontend::OptimiserSettings::DefaultYulOptimiserSteps);
 	}
 	else
 	{