"New ISA Prefix Fusion"

By: Maynard Handley (name99.delete@this.name99.org), August 18, 2020 3:42 pm
Room: Moderated Discussions
dmcq (dmcq.delete@this.fano.co.uk) on August 18, 2020 1:00 pm wrote:
> hobold (hobold.delete@this.vectorizer.org) on August 18, 2020 11:58 am wrote:
> > Michael S (already5chosen.delete@this.yahoo.com) on August 18, 2020 4:48 am wrote:
> > [...]
> > > BTW, Power ISA™ Version 3.1 manual is here https://ibm.ent.box.com/s/hhjfw0x0lrbtyzmiaffnbxh2fuo0fog0
> > >
> >
> > Thanks for the link!
> >
> > Looks like they are really serious about autovectorization. Quite a few SIMD
> > bits to round out functionality, and more interoperation between scalar and
> > SIMD. They even have "vector centrifuge" now ... that is ... interesting.
>
> Gah! You can't split a prefixed instruction over a 64 byte boundary.
> I wonder why they felt it necessary to impose that.

For precisely the reasons I discussed!
If you have that restriction, then (along with other things being easier) an instruction is never split across two cache lines.
Which means pre-decode can mark instructions as pairs.
Which means that, yes, it IS possible to track a branch into the middle of a pair of instructions and behave appropriately (which, IMHO, should be to fault).
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IBM introduces POWER10Crystal S. Diamond2020/08/16 10:20 PM
  "New ISA Prefix Fusion"QAnon2020/08/16 11:21 PM
    "New ISA Prefix Fusion"Anon32020/08/17 06:59 AM
      "New ISA Prefix Fusion"Kevin G2020/08/17 10:51 AM
        "New ISA Prefix Fusion"Maynard Handley2020/08/17 11:51 AM
          "New ISA Prefix Fusion"Anon32020/08/17 04:10 PM
            "New ISA Prefix Fusion"Maynard Handley2020/08/17 04:34 PM
              "New ISA Prefix Fusion"Anon32020/08/17 05:34 PM
                "New ISA Prefix Fusion"Adrian2020/08/17 06:39 PM
                "New ISA Prefix Fusion"anon22020/08/17 09:24 PM
                  "New ISA Prefix Fusion"Doug S2020/08/17 09:58 PM
                    "New ISA Prefix Fusion"hobold2020/08/18 01:47 AM
                    "New ISA Prefix Fusion"Michael S2020/08/18 04:48 AM
                      "New ISA Prefix Fusion"hobold2020/08/18 11:58 AM
                        "New ISA Prefix Fusion"dmcq2020/08/18 01:00 PM
                          "New ISA Prefix Fusion"Michael S2020/08/18 01:48 PM
                            "New ISA Prefix Fusion"hobold2020/08/18 02:29 PM
                            "New ISA Prefix Fusion"Maynard Handley2020/08/18 03:46 PM
                          "New ISA Prefix Fusion"Maynard Handley2020/08/18 03:42 PM
                            "New ISA Prefix Fusion"anon22020/08/18 07:04 PM
                              "New ISA Prefix Fusion"Maynard Handley2020/08/18 09:17 PM
                                "New ISA Prefix Fusion"dmcq2020/08/19 04:08 AM
                                  "New ISA Prefix Fusion"Maynard Handley2020/08/19 10:02 AM
                                    "New ISA Prefix Fusion"dmcq2020/08/19 11:08 AM
                                      "New ISA Prefix Fusion"Maynard Handley2020/08/19 12:05 PM
                                        "New ISA Prefix Fusion"dmcq2020/08/19 02:14 PM
                                          "New ISA Prefix Fusion"Maynard Handley2020/08/19 02:44 PM
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      IBM introduces POWER10Thu2020/08/17 03:27 AM
        IBM introduces POWER10TransientStudent2020/08/17 04:23 AM
          IBM introduces POWER10Rayla2020/08/17 04:29 AM
          IBM introduces POWER10Maynard Handley2020/08/17 10:44 AM
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