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The atomic trick was very satisfying, especially extrapolating the swizzle instruction from the PowerVR heritage. I don't know but wouldn't be surprised if the
by djmips 3y ago
The atomic trick was very satisfying, especially extrapolating the swizzle instruction from the PowerVR heritage. I don't know but wouldn't be surprised if the Apple engineers are learning from this or at least they would appreciate the sheer cleverness. It reminds me when back in the day, the Sega Genesis video hardware was reverse engineered at Accolade and our engineers used the public Texas Instruments TMS9918 VDP documentation as a starting point to extrapolate the evolved 9918 derived VDP in the Genesis (Mega Drive).
- saagarjha 3y agoI’m sure they appreciate the work but Apple has internal documentation on their chips. It’s not like they make a black box and forget how they designed them when it comes to writing software for them.
- ironlenny 3y agoSome times an outsider's attempt to reverse engineer your product brings new insights.
- saagarjha 3y agoThat is true, but one does not simply implement a fully conformant bit shuffle instruction by accident.
- dev_tty01 3y agoOr sometimes an instruction isn't in the compiler because the hardware has some strange corner case failures so they aren't using it. I would be nervous about depending upon an unused instruction.
- devit 3y agoThe article claims that Apple's compiler doesn't use the instruction, so it seems like the compiler author did indeed forget or never learn about it.
- kaba0 3y agoOr maybe it has some limitations they realized and blacklisted the instruction?