An example of Instructions being implemented in Microcode is AMD's implementation of PDEP and PEXT on the Zen and Zen2 chips, leading to shockingly bad performa

An example of Instructions being implemented in Microcode is AMD's implementation of PDEP and PEXT on the Zen and Zen2 chips, leading to shockingly bad performance of 289 cycles vs 1 on Intel: https://twitter.com/uops_info/status/1202950247900684290 https://twitter.com/uops_info/status/1202950247900684290 https://github.com/llvm-project/llvm/blob/master/lib/Target/X86/X86ScheduleZnver1.td#L747 https://github.com/llvm-project/llvm/blob/master/lib/Target/...