Valgrind - register allocator overhaul

Register allocator is a key component in Valgrind's VEX subsystem. Superficially it only translates virtual registers to the real ones. But is that really all? What actually happens under the covers, what algorithms are at play here and what are the constraints under which it operates? In 2017, a major overhaul of the Valgrind VEX register allocator has been done, resulting in a new version v3 which is now used by Valgrind. In addition to a new design, new register allocation algorithms have been also implemented, producing faster and smaller code.