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My biggest wish for rust regex was support for ARM SIMD. Currently the literal optimization is only vectorized on x86. It seems that the author doesn’t own an A

My biggest wish for rust regex was support for ARM SIMD. Currently the literal optimization is only vectorized on x86. It seems that the author doesn’t own an ARM machine, and therefore can’t test implementation and so doesn’t want to support it.

burntsushi 3y ago
I actually have an M2 mac mini in the mail from Apple for exactly this purpose. My time horizon is very long. It takes me a long time to do things these days. It has never been true that I don't want to support it. Merely that it is difficult to verify and test if I can't do it myself. There is also the problem that the port from x86 to arm is not straight-forward, due to both my own ignorance and what I believe are important missing vector operations such as movemask. This is discussed a bit more here (including the bit about movemask): https://github.com/BurntSushi/memchr/issues/76 https://github.com/BurntSushi/memchr/issues/76
- celeritascelery 3y ago
  The current PR for ARM SIMD[1] uses a different instruction mix to achieve the same goals as movemask. I tested the PR and it has a significant speedup over the non-vectorized version. [1]https://github.com/BurntSushi/memchr/pull/114 https://github.com/BurntSushi/memchr/pull/114
  - burntsushi 3y ago
    Yup, thanks for the reminder. That's my starting point once my M2 arrives.
- deleted 3y ago
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AceJohnny2 3y ago
> It seems that the author doesn’t own an ARM machine, and therefore can’t test implementation and so doesn’t want to support it. Tangential (since he answered already), but in this era of cheap cloud instances, I'd be surprised if "not owning a <blank>" is any hindrance to support.
- cesarb 3y ago
  > but in this era of cheap cloud instances, I'd be surprised if "not owning a <blank>" is any hindrance to support. When you own a device, it doesn't cost you more (other than electricity) if you take longer while playing with it, and there's no extra cost (other than space) to having it ready to be used when necessary. When you rent a cloud instance, there's a direct monetary cost for every extra minute you take while investigating an issue, and it's less guaranteed that it'll be available when you need it. Or, to put it more simply: unless he has his own personal device to play with, he'll have to spend extra money for every issue he investigates and every change he makes to the ARM support.
  - burntsushi 3y ago
    Yes, exactly. There is a ton of friction.

burntsushi 3y ago

I actually have an M2 mac mini in the mail from Apple for exactly this purpose. My time horizon is very long. It takes me a long time to do things these days. It has never been true that I don't want to support it. Merely that it is difficult to verify and test if I can't do it myself. There is also the problem that the port from x86 to arm is not straight-forward, due to both my own ignorance and what I believe are important missing vector operations such as movemask. This is discussed a bit more here (including the bit about movemask): https://github.com/BurntSushi/memchr/issues/76 https://github.com/BurntSushi/memchr/issues/76

celeritascelery 3y ago
The current PR for ARM SIMD[1] uses a different instruction mix to achieve the same goals as movemask. I tested the PR and it has a significant speedup over the non-vectorized version. [1]https://github.com/BurntSushi/memchr/pull/114 https://github.com/BurntSushi/memchr/pull/114
- burntsushi 3y ago
  Yup, thanks for the reminder. That's my starting point once my M2 arrives.
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AceJohnny2 3y ago

> It seems that the author doesn’t own an ARM machine, and therefore can’t test implementation and so doesn’t want to support it. Tangential (since he answered already), but in this era of cheap cloud instances, I'd be surprised if "not owning a <blank>" is any hindrance to support.

cesarb 3y ago
> but in this era of cheap cloud instances, I'd be surprised if "not owning a <blank>" is any hindrance to support. When you own a device, it doesn't cost you more (other than electricity) if you take longer while playing with it, and there's no extra cost (other than space) to having it ready to be used when necessary. When you rent a cloud instance, there's a direct monetary cost for every extra minute you take while investigating an issue, and it's less guaranteed that it'll be available when you need it. Or, to put it more simply: unless he has his own personal device to play with, he'll have to spend extra money for every issue he investigates and every change he makes to the ARM support.
- burntsushi 3y ago
  Yes, exactly. There is a ton of friction.