[stephencanon]

The basic problem with almost every "SIMD is flawed, we should have vector ISAs" article or post (including the granddaddy, "SIMD Instructions Considered Harmful"), is that they invariably use SAXPY or something else trivial where everything stays neatly in lane as their demonstration case. Of course vector ISAs look good when you show them off using a pure vector task. This is fundamentally unserious.

There is an enormous quantity of SIMD code in the world that isn't SAXPY, and doesn't stay neatly in lane. Instead it's things like "base64 encode this data" or "unpack and deinterleave this 4:2:2 pixel data, apply a colorspace conversion as a 3x3 sparse matrix and gamma adjustment in 16Q12 fixed-point format, resize and rotate by 15˚ with three shear operations represented as a linear convolution with a sinc kernel per row," or "extract these fields from this JSON data". All of which _can totally be done_ with a well-designed vector ISA, but the comparison doesn't paint nearly as rosy of a picture. The reality is that you really want a mixture of ideas that come from fixed-width SIMD and ideas that come from the vector world (which is roughly what people actually shipping hardware have been steadily building over the last two decades, implementing more support for unaligned access, predication, etc, while the vector ISA crowd writes purist think pieces)