4 ms·

The JSC JIT people seemed kind of surprised by this, which was weird. Maybe the V8 JIT people asked for it?

• monocasa 6y ago
  Is there a source for that? I was under the impression this initially shipped on iOS devices so it'd be weird for JSC to be surprised by it.
  • why_only_15 6y ago
    According to this bug it was shipped six months after the bug was created and they didn't seem super familiar with it.
    • monocasa 6y ago
      It was public knowledge that Apple had a shipped implementation using this instruction before that patch was merged. https://news.ycombinator.com/item?id=18163433 https://news.ycombinator.com/item?id=18163433 I also don't really see any indication that the project maintainers don't know about the instruction. Looks like an example of JSC not being developed in the open more than anything else.
      • why_only_15 6y ago
        are you referring to the tweet linked there? That tweet is wrong in a lot of ways, because that instruction gives you a 1-2% boost, not a 30% boost like they claimed.
        • monocasa 6y ago
          They're talking about a 30% boost overall on a new release which is an amalgamation of many pieces, including use of this new instruction. Can you give an example of something the maintainers said that made them seem "not super familiar with it"?