1 It is often convenient to be able to build compiler-rt libraries for a certain 2 platform without having a full SDK or development environment installed. 3 4 This makes it easy for users to build a compiler which can target a number of 5 different platforms, without having to actively maintain full development 6 environments for those platforms. 7 8 Since compiler-rt's libraries typically have minimal interaction with the 9 system, we achieve this by stubbing out the SDKs of certain platforms. 10