void Compiler::appendFunctionSelector(ContractDefinition const& _contract) { map<FixedHash<4>, FunctionTypePointer> interfaceFunctions = _contract.getInterfaceFunctions(); map<FixedHash<4>, const eth::AssemblyItem> callDataUnpackerEntryPoints; FunctionDefinition const* fallback = _contract.getFallbackFunction(); eth::AssemblyItem notFound = m_context.newTag(); // shortcut messages without data if we have many functions in order to be able to receive // ether with constant gas if (interfaceFunctions.size() > 5 || fallback) { m_context << eth::Instruction::CALLDATASIZE << eth::Instruction::ISZERO; m_context.appendConditionalJumpTo(notFound); } // retrieve the function signature hash from the calldata if (!interfaceFunctions.empty()) CompilerUtils(m_context).loadFromMemory(0, IntegerType(CompilerUtils::dataStartOffset * 8), true); // stack now is: 1 0 <funhash> for (auto const& it: interfaceFunctions) { callDataUnpackerEntryPoints.insert(std::make_pair(it.first, m_context.newTag())); m_context << eth::dupInstruction(1) << u256(FixedHash<4>::Arith(it.first)) << eth::Instruction::EQ; m_context.appendConditionalJumpTo(callDataUnpackerEntryPoints.at(it.first)); } m_context.appendJumpTo(notFound); m_context << notFound; if (fallback) { eth::AssemblyItem returnTag = m_context.pushNewTag(); fallback->accept(*this); m_context << returnTag; appendReturnValuePacker(FunctionType(*fallback).getReturnParameterTypes()); } else m_context << eth::Instruction::STOP; // function not found for (auto const& it: interfaceFunctions) { FunctionTypePointer const& functionType = it.second; solAssert(functionType->hasDeclaration(), ""); CompilerContext::LocationSetter locationSetter(m_context, functionType->getDeclaration()); m_context << callDataUnpackerEntryPoints.at(it.first); eth::AssemblyItem returnTag = m_context.pushNewTag(); appendCalldataUnpacker(functionType->getParameterTypes()); m_context.appendJumpTo(m_context.getFunctionEntryLabel(functionType->getDeclaration())); m_context << returnTag; appendReturnValuePacker(functionType->getReturnParameterTypes()); } }