That's the opinion of one ARM engineer I've never heard of.

Here's the opinion of probably THE most important ARM engineer of the 1990s and 2000s, Dave Jaggar who developed the ARM7TDMI, Thumb, Thumb2.

https://www.youtube.com/watch?v=_6sh097Dk5k

Check at 51:30 where he says "Are there any ARM snipers? No ... I would Google RISC-V and find out all about it. They've done a fine instruction set, a fine job [...] it's the state of the art now for 32-bit general purpose instruction sets. And it's got the 16-bit compressed stuff. So, yeah, learning about that, you're learning from the best."

Did he also design AArch64? Because I've noticed it can be used to design very fast processors, yet abandons most decisions in ARM7 and Thumb.

I was just curious about how SIMD worked in RISC-V so I looked it up… and apparently RISC-V doesn't have SIMD, instead it brings back microcoded large vector operations from the 70s, and the RISC-V designers called SIMD bad and compared it to the opioid crisis because it means there are too many instruction opcodes?

https://www.sigarch.org/simd-instructions-considered-harmful...

So I'm now even less impressed and also slightly offended. This is not realistic, short vectors are important and easy to do in hardware.

Many codes can be expressed much better with Vectors and there is also much ability to further extend it in the future. You can do short vectors with the RISC-V Vector extension and you can implement them in a simply way as well.

Have you worked with both or did you just form your opinion based on what you are used to?

Again, RISC-V is not one thing, its modular. The 'V' extension is considered to be the right thing for most serious processors.

However there is also the 'P' extension, for embedded that does Packed SIMD.

Performance is not one thing, we have processors from so small they can almost not be seen to gigantic AI chips. RISC-V made some design choices and some people like some of them and some people don't like others, just like with anything else in the world.

Christopher Celio as part of his PhD did ISA comparison and found no way that RISC-V is systematically worse, in fact in many situations its better.

David A Patterson, Dave Ditzel and many other long time engineers in this space seem to really like it.

And btw, you could make a much longer The Good, The Bad, The Ugly list about ARM as well. By that definition no ISA is well designed.