Firstly, as this answer touches on complex and sensitive topics I want to make few disclaimers: I assume your question is about middle-end IRs of LLVM and GCC (as the term “LLVM IR” applies only to middle-end). Discussion of differences of back-end IRs (LLVM MachineIR and GCC RTL) and related codegen tools (LLVM Tablegen and … Read more
Do they re-typecheck, in the example above K(M) and K(N)? Yes, they do. It’s not that bad, though. The typechecker knows that K(M) is an application of K to M. It knows what the type of K is, and that should be a function type. It knows what the type of M is, and it … Read more
A phi node is an instruction used to select a value depending on the predecessor of the current block (Look here to see the full hierarchy – it’s also used as a value, which is one of the classes which it inherits from). Phi nodes are necessary due to the structure of the SSA (static … Read more