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by hooli42 642 days ago
Hah, neat.

The 'weird' instructions can often be 3-4 orders of magnitude slower than arithmetic instructions, though I doubt that matters here.

1 comments

CRC32 is the same speed as an integer multiply, going all the way back to Nehalem (2008). 3 cycles latency, and you can start a new one each cycle (or more than one, on Zen 5).
Sure, in the same way SIMD instructions get a linear speedup in theory.

If you Google the words "CRC32 is slow", you can see hundreds of people complaining about this.