The libc CMake build system

At the cost of verbosity, we want to keep the build system of LLVM libc as simple as possible. We also want to be highly modular with our build targets. This makes picking and choosing desired pieces a straightforward task.

Targets for entrypoints

Every entrypoint in LLVM-libc has its own build target, listed using the add_entrypoint_object rule. This rule generates a single object file containing the implementation.

For more technical details on how to register entrypoints, see the Entrypoints in LLVM libc documentation.

Targets for entrypoint libraries

Standards like POSIX require that a libc provide certain library files like libc.a, libm.a, etc. The targets for such library files are listed in the lib directory as add_entrypoint_library targets.