The main source of documentation about how to use LLVM IR was the Clang C++ front-end:

clang -S -emit-llvm -o example.llr example.cpp
cat example.llr

C++ example translations with Clang unravel how to map specific constructs into LLVM IR.

• LLVM Language Reference Manual
• LLVM GetElementPtr

• Mapping High Level Constructs to LLVM IR Documentation
• Mapping High Level Constructs to LLVM IR

• Performance Tips

• LLVMdev: The nsw story

• Rockspec-format