The LLVM Project is a collection of modular and reusable compiler and toolchain technologies. The llvm tag is mostly for writing C++ code (or another language via the C bindings) to interface with the LLVM library, not about any of the (growing amount of) tools that have LLVM under the hood. See the `llvm-codegen` tag for questions about machine code generated by LLVM.
Welcome to the LLVM Project.
The LLVM Core libraries provide a modern source- and target-independent optimizer, along with code generation support for many popular CPUs (as well as some less common ones!).
These libraries are built around a well specified code representation known as the LLVM intermediate representation ("LLVM IR").
The LLVM Core libraries are well documented, and it is particularly easy to invent your own language (or port an existing compiler) to use LLVM as an optimizer and code generator.
As much as everything else, LLVM has a broad and friendly community of people who are interested in building great low-level tools. If you are interested in getting involved, a good first place is to skim the LLVM Blog and to sign up for the LLVM Developer mailing list.
What not to ask: user-level questions about XCode are off-topic, please only use the xcode tag for those. The llvm tag is mostly for writing C++ code (or another language via the C bindings) to interface with the LLVM library, not about any of the (growing amount of) tools that have LLVM under the hood.
