Developments efforts to get rid of prebuilt binaries in the Replicant source are tracked on this page. Prebuilts usually belong to the toolchain, but they can also be found in other parts of the source code. Most of them reside in the
These binaries are committed to AOSP git repos and in most cases, it is poorly documented, how they can be rebuilt. Compiler rebuild scripts rely on the prebuilt compilers to build the compilers. It is possible that non-free software was used to build the prebuilts (e.g. Google-internal Java compiler). To keep the build trustworthy, we need to make sure, that as little prebuilts as possible are used.
Building as much from source as possible is one strategy to achieve this. Using packaged versions of the prebuilts that are provided by GNU/Linux distributions is an alternative way to ensure that the binaries can be trusted. If the prebuilts are available as packages, then these should be preferred before a clean build from source is investigated. A clean build means that no prebuilts from the source code are required.