Merge pull request #8701 from ethereum/solc-yul-chromosome

solc option for selecting yul optimisations

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/CompilerStack.cpp

@@ -1265,6 +1265,7 @@ string CompilerStack::createMetadata(Contract const& _contract) const
 		{
 			details["yulDetails"] = Json::objectValue;
 			details["yulDetails"]["stackAllocation"] = m_optimiserSettings.optimizeStackAllocation;
+			details["yulDetails"]["optimizerSteps"] = m_optimiserSettings.yulOptimiserSteps;
 		}
 
 		meta["settings"]["optimizer"]["details"] = std::move(details);

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;

libsolidity/interface/StandardCompiler.cpp

@@ -25,6 +25,7 @@
 #include <libsolidity/ast/ASTJsonConverter.h>
 #include <libyul/AssemblyStack.h>
 #include <libyul/Exceptions.h>
+#include <libyul/optimiser/Suite.h>
 #include <liblangutil/SourceReferenceFormatter.h>
 #include <libevmasm/Instruction.h>
 #include <libsolutil/JSON.h>
@@ -402,6 +403,33 @@ std::optional<Json::Value> checkOptimizerDetail(Json::Value const& _details, std
 	return {};
 }
 
+std::optional<Json::Value> checkOptimizerDetailSteps(Json::Value const& _details, std::string const& _name, string& _setting)
+{
+	if (_details.isMember(_name))
+	{
+		if (_details[_name].isString())
+		{
+			try
+			{
+				yul::OptimiserSuite::validateSequence(_details[_name].asString());
+			}
+			catch (yul::OptimizerException const& _exception)
+			{
+				return formatFatalError(
+					"JSONError",
+					"Invalid optimizer step sequence in \"settings.optimizer.details." + _name + "\": " + _exception.what()
+				);
+			}
+
+			_setting = _details[_name].asString();
+		}
+		else
+			return formatFatalError("JSONError", "\"settings.optimizer.details." + _name + "\" must be a string");
+
+	}
+	return {};
+}
+
 std::optional<Json::Value> checkMetadataKeys(Json::Value const& _input)
 {
 	if (_input.isObject())
@@ -511,10 +539,12 @@ boost::variant<OptimiserSettings, Json::Value> parseOptimizerSettings(Json::Valu
 			if (!settings.runYulOptimiser)
 				return formatFatalError("JSONError", "\"Providing yulDetails requires Yul optimizer to be enabled.");
 
-			if (auto result = checkKeys(details["yulDetails"], {"stackAllocation"}, "settings.optimizer.details.yulDetails"))
+			if (auto result = checkKeys(details["yulDetails"], {"stackAllocation", "optimizerSteps"}, "settings.optimizer.details.yulDetails"))
 				return *result;
 			if (auto error = checkOptimizerDetail(details["yulDetails"], "stackAllocation", settings.optimizeStackAllocation))
 				return *error;
+			if (auto error = checkOptimizerDetailSteps(details["yulDetails"], "optimizerSteps", settings.yulOptimiserSteps))
+				return *error;
 		}
 	}
 	return { std::move(settings) };