Add linkersymbol() builtin to Yul EVM dialect

libyul/AsmAnalysis.cpp

@@ -544,7 +544,7 @@ void AsmAnalyzer::expectType(YulString _expectedType, YulString _givenType, Sour
 bool AsmAnalyzer::warnOnInstructions(std::string const& _instructionIdentifier, langutil::SourceLocation const& _location)
 {
 	auto const builtin = EVMDialect::strictAssemblyForEVM(EVMVersion{}).builtin(YulString(_instructionIdentifier));
-	if (builtin)
+	if (builtin && builtin->instruction.has_value())
 		return warnOnInstructions(builtin->instruction.value(), _location);
 	else
 		return false;

libyul/backends/evm/EVMDialect.cpp

@@ -124,6 +124,17 @@ map<YulString, BuiltinFunctionForEVM> createBuiltins(langutil::EVMVersion _evmVe
 		)
 			builtins.emplace(createEVMFunction(instr.first, instr.second));
 
+	builtins.emplace(createFunction("linkersymbol", 1, 1, SideEffects{}, {true}, [](
+		FunctionCall const& _call,
+		AbstractAssembly& _assembly,
+		BuiltinContext&,
+		function<void(Expression const&)>
+	) {
+		yulAssert(_call.arguments.size() == 1, "");
+		Expression const& arg = _call.arguments.front();
+		_assembly.appendLinkerSymbol(std::get<Literal>(arg).value.str());
+	}));
+
 	if (_objectAccess)
 	{
 		builtins.emplace(createFunction("datasize", 1, 1, SideEffects{}, {true}, [](