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This is what happens when a huge proportion of your die isn't doing instruction decoding. That's a misconception. Yes, decoding x86 is somewhat more complicate

This is what happens when a huge proportion of your die isn't doing instruction decoding. That's a misconception. Yes, decoding x86 is somewhat more complicated, as far as I'm aware that's mostly because instruction length differs at a byte granularity. Still, the area dedicated to it simply isn't that large on those huge out of order designs. I'm sure the instruction encoding plays some role, but I suspect what we're seeing is rather down to consistently good micro-architecture execution over the years and Apple being ahead of everybody else on manufacturing process. Compared to the x86 processors that exist today, M1 also benefits from having the memory in-package. Intel tried to be brave with Itanium, but failed because compilers weren't up to the job at the time. Compilers "failed" because VLIW is fundamentally not a particularly useful idea. The main problem for general purpose single-thread performance is memory latency, and VLIW just doesn't help there.

danmaz74 6y ago
Doesn't Apple use TSMC manufacturing?
- ylyn 6y ago
  Yes, and they are the only ones on TSMC 5nm currently.
  - anfilt 6y ago
    That's because apple bought the entire 5nm production capacity/runs for basically for the entire last quarter of 2020. I can tell you some companies were not too pleased about that.
    - chris_j 6y ago
      Which companies?
      - fmajid 6y ago
        AMD.
    - joachimma 6y ago
      Is there anything preventing those companies from "ganging" up on Apple and buying capacity jointly? Are they too many and too small? Is it possible to share wafer-space with other companies or does having multiple designs add too much complexity/cost?
      - nicoburns 6y ago
        I think Apple essentially outbid them, which it was able to do because it is has both large volume and large profit margins.
    - raverbashing 6y ago
      Ah yeah, Apple has f-you money and it knows how to use it.
      - normaljoe 6y ago
        They did this with FedEx planes out of China years back, forget which iPhone version, but they basically did the same thing they booked everything. All FedEx planes only had iPhones and everybody complained. I don't think they have tried that stunt again.
klelatti 6y ago
Not disputing what you're saying on instruction decoding but there is a lot of other stuff on an x86 processor that Apple hasn't needed or chosen to implement: 32bit, AVX, legacy SIMD, legacy modes, Intel Management Engine plus probably a more complex instruction set. Individually these may not make a difference but add them all up ....
- runeks 6y ago
  > Individually these may not make a difference but add them all up .... ... and it still may not make a difference.
  - klelatti 6y ago
    I have AVX512 on my laptop. Is it used by any software I use? No. Does it take up a lot of die area? Definitely.
djcapelis 6y ago
> Compilers "failed" because VLIW is fundamentally not a particularly useful idea. I think the problem isn’t just that it’s not particularly useful, but that it’s an actively bad idea. It statically encodes ILP that we get dynamically in chip designs today, which means that ILP can no longer react to changing conditions, like literally any core architecture changes as the underlying hardware evolves (or even on the same die, say finding itself running on an efficiency core rather than a performance core or vice versa) or running in an SMT environment in which it is not the only instruction stream going through the pipeline.
- foerbert 6y ago
  Adapting to advancing hardware isn't impossible. It's been awhile since I've looked so details are a little hazy, but I know the Mill architecture had an answer to this. I believe they were using effectively two-pass compilation. The first compiled against an abstract version of the architecture, and this is what was distributed. Then this could be further specialized on the user's machine as at that point the limits of the hardware would be known. I don't recall if they had an idea for SMT as well or not. It's possible they wrote it off entirely, particularly after Spectre and all that.
  - djcapelis 6y ago
    You are correct that with a lot of effort you can get a compiler to emit VLIW instructions that can claw back some of these problems and have some, but not all, of the information you have available to the processor core at runtime which can make things slightly smarter. And with all of that effort which involves changing software distribution models, jettisoning energy efficient flexible heterogenous architectures, and abandoning SMT, you might be able to get something close to performing as well as… what we already have today without VLIW. Not sure why anyone thinks that’s an argument for doing it.
    - Dylan16807 6y ago
      > Not sure why anyone thinks that’s an argument for doing it. Because it didn't take very much effort and it doesn't require changing distribution models or abandoning those things.
pjmlp 6y ago
Intel failed because AMD exists and has a cross license agreement that allowed them to be clever. Without AMD in the picture, Itanium issues would have eventually been sorted out.
- gpderetta 6y ago
  Well, yes, if Intel had no competition at all they might have been able to force whatever garbage on the market.
  - pjmlp 6y ago
    I actually liked Itanium and don't see it as garbage, and see as an unfortunate turn of events that I am not running one on this laptop. Also don't get the point of the cheering for AMD, because apparently many don't get that without Intel licenses, which depend on Intel existence, AMD won't have much to play with anyway.
    - beagle3 6y ago
      20 or so years later, it is my impression that there are no compilers that can do enough ILP (on software not specifically written for the Itanium) to justify the Itanium’s VLIW. Intel licensed some stuff to Cyrix, VIA, AMD, Harris and possibly others at the time. But if AMD didn’t license AMD64 back (by way of cross licensing) things might have been grim for Intel back in 2003-2008 when AMD was killing it previously. Intel did nothing out of the goodness of their heart, and neither did AMD - so I’m not sure why it is bothering you that people are cheering for AMD for providing (at this point) a technically and economically better product, and hating on Intel for being a fat cat. The pendulum may swing back sooner or later, both technically/economically and public opinion wise.
    - ralfd 6y ago
      I don't know much about Itaniumm, but that was a server architecture, right? That target platform would made it difficult to achieve the same performance per watt as the mobile focused ARM chips.
- 6y ago

danmaz74 6y ago

Doesn't Apple use TSMC manufacturing?

ylyn 6y ago
Yes, and they are the only ones on TSMC 5nm currently.
- anfilt 6y ago
  That's because apple bought the entire 5nm production capacity/runs for basically for the entire last quarter of 2020. I can tell you some companies were not too pleased about that.
  - chris_j 6y ago
    Which companies?
    - fmajid 6y ago
      AMD.
  - joachimma 6y ago
    Is there anything preventing those companies from "ganging" up on Apple and buying capacity jointly? Are they too many and too small? Is it possible to share wafer-space with other companies or does having multiple designs add too much complexity/cost?
    - nicoburns 6y ago
      I think Apple essentially outbid them, which it was able to do because it is has both large volume and large profit margins.
  - raverbashing 6y ago
    Ah yeah, Apple has f-you money and it knows how to use it.
    - normaljoe 6y ago
      They did this with FedEx planes out of China years back, forget which iPhone version, but they basically did the same thing they booked everything. All FedEx planes only had iPhones and everybody complained. I don't think they have tried that stunt again.

klelatti 6y ago

Not disputing what you're saying on instruction decoding but there is a lot of other stuff on an x86 processor that Apple hasn't needed or chosen to implement: 32bit, AVX, legacy SIMD, legacy modes, Intel Management Engine plus probably a more complex instruction set. Individually these may not make a difference but add them all up ....

runeks 6y ago
> Individually these may not make a difference but add them all up .... ... and it still may not make a difference.
- klelatti 6y ago
  I have AVX512 on my laptop. Is it used by any software I use? No. Does it take up a lot of die area? Definitely.

djcapelis 6y ago

> Compilers "failed" because VLIW is fundamentally not a particularly useful idea. I think the problem isn’t just that it’s not particularly useful, but that it’s an actively bad idea. It statically encodes ILP that we get dynamically in chip designs today, which means that ILP can no longer react to changing conditions, like literally any core architecture changes as the underlying hardware evolves (or even on the same die, say finding itself running on an efficiency core rather than a performance core or vice versa) or running in an SMT environment in which it is not the only instruction stream going through the pipeline.

foerbert 6y ago
Adapting to advancing hardware isn't impossible. It's been awhile since I've looked so details are a little hazy, but I know the Mill architecture had an answer to this. I believe they were using effectively two-pass compilation. The first compiled against an abstract version of the architecture, and this is what was distributed. Then this could be further specialized on the user's machine as at that point the limits of the hardware would be known. I don't recall if they had an idea for SMT as well or not. It's possible they wrote it off entirely, particularly after Spectre and all that.
- djcapelis 6y ago
  You are correct that with a lot of effort you can get a compiler to emit VLIW instructions that can claw back some of these problems and have some, but not all, of the information you have available to the processor core at runtime which can make things slightly smarter. And with all of that effort which involves changing software distribution models, jettisoning energy efficient flexible heterogenous architectures, and abandoning SMT, you might be able to get something close to performing as well as… what we already have today without VLIW. Not sure why anyone thinks that’s an argument for doing it.
  - Dylan16807 6y ago
    > Not sure why anyone thinks that’s an argument for doing it. Because it didn't take very much effort and it doesn't require changing distribution models or abandoning those things.

pjmlp 6y ago

Intel failed because AMD exists and has a cross license agreement that allowed them to be clever. Without AMD in the picture, Itanium issues would have eventually been sorted out.

gpderetta 6y ago
Well, yes, if Intel had no competition at all they might have been able to force whatever garbage on the market.
- pjmlp 6y ago
  I actually liked Itanium and don't see it as garbage, and see as an unfortunate turn of events that I am not running one on this laptop. Also don't get the point of the cheering for AMD, because apparently many don't get that without Intel licenses, which depend on Intel existence, AMD won't have much to play with anyway.
  - beagle3 6y ago
    20 or so years later, it is my impression that there are no compilers that can do enough ILP (on software not specifically written for the Itanium) to justify the Itanium’s VLIW. Intel licensed some stuff to Cyrix, VIA, AMD, Harris and possibly others at the time. But if AMD didn’t license AMD64 back (by way of cross licensing) things might have been grim for Intel back in 2003-2008 when AMD was killing it previously. Intel did nothing out of the goodness of their heart, and neither did AMD - so I’m not sure why it is bothering you that people are cheering for AMD for providing (at this point) a technically and economically better product, and hating on Intel for being a fat cat. The pendulum may swing back sooner or later, both technically/economically and public opinion wise.
  - ralfd 6y ago
    I don't know much about Itaniumm, but that was a server architecture, right? That target platform would made it difficult to achieve the same performance per watt as the mobile focused ARM chips.
6y ago