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Aug 4, 2024 · Fundamentals

Why RISC‑V’s Integer ISA Omits a Multiply‑Accumulate Instruction – A Microarchitectural Guess

The article speculates why the RISC‑V integer ISA does not define a multiply‑accumulate (MAC) instruction, examining how such an instruction would affect integer‑unit micro‑architecture, decoder width, rename complexity, and OoO window size, and compares these trade‑offs with ARM and Apple M1 designs.