4 ms·

You're basically asking for the end of backwards compatibility and every processor having a obscure unknown custom ISA that nobody can ever replicate, since you

You're basically asking for the end of backwards compatibility and every processor having a obscure unknown custom ISA that nobody can ever replicate, since you want the instruction set to be designed so that no future processor can ever be created that adds even a single new instruction to an existing instruction set. The only way that is feasible is if there is a new instruction set every time a new processor comes out. Yikes, what a dumb idea.

colejohnson66 2y ago
That's how things were before the IBM PC era: every computer either had an incompatible system architecture, or a wholly different CPU.
- nickorlow 2y ago
  This would fragment compiler optimization because now instead of compiler developers (collectively) focusing on 1-3 ISAs they're split across way more.
  - 15155 2y ago
    Compiler developers lately seem focused on emitting LLVM IR.
    - nickorlow 2y ago
      Yeah, but there's still those that need to do IR -> ASM.
mike_hearn 2y ago
Hardly dumb. That's exactly how GPUs work. It's how mobile phones worked for a long time (J2ME). It's how Azul's old Java server worked too. Having software ship in a high level abstract form and then the hardware comes with an integrated OS/compiler combo is pretty nice from an architectural perspective. It definitely frees up the CPU designers to do things they otherwise couldn't do easily due to backwards compatibility constraints, as well as allowing new hardware features to be used immediately as long as the compiler can recognize patterns that benefit.
- 15155 2y ago
  > That's exactly how GPUs work. (NVIDIA) GPUs don't have one common instruction set - they are just shipped with one blessed suite of tooling that hides the differences between a very limited set of architecture families. Many different PTX instructions have radically different performance characteristics between families (because they aren't actually hardened in some.)

colejohnson66 2y ago

That's how things were before the IBM PC era: every computer either had an incompatible system architecture, or a wholly different CPU.

nickorlow 2y ago
This would fragment compiler optimization because now instead of compiler developers (collectively) focusing on 1-3 ISAs they're split across way more.
- 15155 2y ago
  Compiler developers lately seem focused on emitting LLVM IR.
  - nickorlow 2y ago
    Yeah, but there's still those that need to do IR -> ASM.

mike_hearn 2y ago

Hardly dumb. That's exactly how GPUs work. It's how mobile phones worked for a long time (J2ME). It's how Azul's old Java server worked too. Having software ship in a high level abstract form and then the hardware comes with an integrated OS/compiler combo is pretty nice from an architectural perspective. It definitely frees up the CPU designers to do things they otherwise couldn't do easily due to backwards compatibility constraints, as well as allowing new hardware features to be used immediately as long as the compiler can recognize patterns that benefit.

15155 2y ago
> That's exactly how GPUs work. (NVIDIA) GPUs don't have one common instruction set - they are just shipped with one blessed suite of tooling that hides the differences between a very limited set of architecture families. Many different PTX instructions have radically different performance characteristics between families (because they aren't actually hardened in some.)