Basic Control Structures

[f0rki]

in mapping-control-structures-to-llvm-ir

• how if/then/else and loops map to basic blocks and branch instructions
• switch
• The role of SSA in LLVM IR. Explain the purpose of the phi instruction; show how it becomes obvious that you need it as soon as you encounter multiple blocks that contribute a value through different temporaries. In a way, phi ought to have been called "join" as it sort of joins up subexpressions from different basic blocks.
• calls, returns, callgraph
• add additional resources, link to LLVM documentation

I think we should keep this rather short, as this is probably general knowledge for people looking at this article and is covered very well by other LLVM documentation already. For completeness sake we shouldn't remove it entirely though.