Show HN: Minimax – A Compressed-First, Microcoded RISC-V CPU https://ift.tt/DEYQ7v3

Show HN: Minimax – A Compressed-First, Microcoded RISC-V CPU RISC-V's compressed instruction (RVC) extension is intended as an add-on to the regular, 32-bit instruction set, not a replacement or competitor. Its designers intended RVC instructions to be expanded into regular 32-bit RV32I equivalents via a pre-decoder. What happens if we explicitly architect a RISC-V CPU to execute RVC instructions, and "mop up" any RV32I instructions that aren't convenient via a microcode layer? What architectural optimizations are unlocked as a result? "Minimax" is an experimental RISC-V implementation intended to establish if an RVC-optimized CPU is, in practice, any simpler than an ordinary RV32I core with pre-decoder. While it passes a modest test suite, you should not use it without caution. (There are a large number of excellent, open source, "little" RISC-V implementations you should probably use reach for first.) https://ift.tt/lSujKNs November 1, 2022 at 09:11PM