[$] QBE 1.3: metaprogramming, performance, and cross-platform support

QBE, a compact compiler backend developed by Quentin Carbonneaux, is alightweight alternative to larger compiler backends such as LLVM and GCC.Designed to be small enough for a single developer to understand, QBE uses astatic single-assignment (SSA) intermediate representation (IR), supports the C ABI,and serves as the backend for projects such as Hare andthe cproc C11 compiler. Frontendsemit the textual form of QBE's IR directly; QBE then takes care of register allocation,optimization, and native-code generation, producing assembly for the targetarchitecture.