Armv8.8-A and Armv9.3-A - moves

By: rwessel (rwessel.delete@this.yahoo.com), September 29, 2021 12:58 pm
Room: Moderated Discussions
dmcq (dmcq.delete@this.fano.co.uk) on September 29, 2021 1:44 pm wrote:
> rwessel (rwessel.delete@this.yahoo.com) on September 29, 2021 11:35 am wrote:
> > dmcq (dmcq.delete@this.fano.co.uk) on September 29, 2021 7:53 am wrote:
> > > rwessel (rwessel.delete@this.yahoo.com) on September 29, 2021 6:55 am wrote:
> > > > NoSpammer (no.delete@this.spam.com) on September 29, 2021 3:53 am wrote:
> > > > > dmcq (dmcq.delete@this.fano.co.uk) on September 28, 2021 2:21 pm wrote:
> > > > > > The bits could vary between implementations so letting designers optimise better. More conditions
> > > > > > could be saved. The only problem I can see is big-little systems and they could just zero the bits
> > > > > > if moving between different cores - with the current system how can we tell if the form optimised
> > > > > > by one is okay for the other? And yes it seems like an unnecessary waste of opcodes and code space.
> > > > >
> > > > > I think 3 instructions make very simple implementations possible for the low-end. Per example:
> > > > > Initial instruction is movsb until aligned or end.
> > > > > Middle instruction is movs[your core's biggest R/W chunk]
> > > > > End instruction is movsb until end.
> > > > >
> > > > > Why have more state when the state can already be in the registers and PC?
> > > >
> > > >
> > > > Remember that in the general case, you can't get both operands aligned, so you can't avoid
> > > > dealing with at least some of that in the "middle" instruction. But the point is, how
> > > > hard could it be to detect the case where the initial or final instruction apply?
> > >
> > > And thinking yet again about it why bother even saving any
> > > bits? AT most it can get by with some bits that are
> > > passed between the micro-ops. If an interrupt happs one can
> > > just dump the bits and start anew from where stopped.
> > > I'm basically saying just have one op and if they want three
> > > have the one op split into three. Then there's no
> > > need to start wondering about describng what the state is like when restarting the second operation.
> >
> >
> > So update registers with intermediate state like 8x86 movs or S/370 mvcl? ;-)
>
> Well that does seem an obvious way to handle interrupts. But it could execute as if it was a number of
> operations with some extra state being passed between the stages, except the extra information can be
> discarded if an interrupt happens. So the first operation would set up a couple of microoperations. Then
> more would be generated dependent on each other till the count went to zero. An interrupt would just stop
> it after one of the operations had finished and updated the registers showing how much had been done.
> You want it to work okay in a longer pipeline so operations after the move can be done in parallel.

Sure, so long as the CPU was executing the move, externally visible state doesn't need to be updated. But so long as it's architected (like x86 movs), there's no problem moving between cores that might maintain some sort state internally while running a multi-word move.
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TopicPosted ByDate
Armv8.8-A and Armv9.3-Aanonymou52021/09/16 02:25 PM
  Armv8.8-A and Armv9.3-ADoug S2021/09/16 09:57 PM
    Armv8.8-A and Armv9.3-ABrett2021/09/16 10:32 PM
      Armv8.8-A and Armv9.3-Aanon2021/09/16 10:55 PM
        Armv8.8-A and Armv9.3-Anone2021/09/16 11:51 PM
      Armv8.8-A and Armv9.3-AJörn Engel2021/09/17 04:42 AM
        Armv8.8-A and Armv9.3-AMichael S2021/09/17 06:48 AM
          Armv8.8-A and Armv9.3-AJörn Engel2021/09/18 01:01 PM
            Armv8.8-A and Armv9.3-AMichael S2021/09/18 02:58 PM
              microbenchmark resultsMichael S2021/09/19 03:46 PM
                microbenchmark source codeMichael S2021/09/19 03:58 PM
                  microbenchmark source code-.-2021/09/20 03:49 PM
                    microbenchmark source codeMichael S2021/09/21 09:17 AM
                      microbenchmark source code-.-2021/09/21 03:33 PM
                        microbenchmark source codeMichael S2021/09/21 05:05 PM
                microbenchmark resultsAnon2021/09/19 04:32 PM
                  microbenchmark resultsJörn Engel2021/09/19 07:46 PM
                    microbenchmark resultsdmcq2021/09/20 01:19 AM
                      microbenchmark resultsMichael S2021/09/20 04:12 AM
                      microbenchmark results-.-2021/09/20 03:44 PM
                        microbenchmark resultsMichael S2021/09/21 09:23 AM
                          microbenchmark results-.-2021/09/21 03:35 PM
                            microbenchmark resultsAndrey2021/09/21 04:25 PM
                              I agree (NT)Michael S2021/09/21 05:07 PM
                              microbenchmark results-.-2021/09/22 04:56 PM
                                microbenchmark resultsMichael S2021/09/23 05:11 AM
                                  microbenchmark resultsdmcq2021/09/23 06:53 AM
                                  microbenchmark resultsAndrey2021/09/23 09:20 AM
                                microbenchmark resultsAndrey2021/09/23 09:11 AM
                                  microbenchmark results-.-2021/09/23 07:01 PM
                                    microbenchmark resultsSimon Farnsworth2021/09/24 01:47 AM
                                      microbenchmark results-.-2021/09/24 05:00 PM
                                    microbenchmark resultsAndrey2021/09/24 07:29 AM
                                      microbenchmark resultsdmcq2021/09/24 12:05 PM
                                        microbenchmark resultsDoug S2021/09/24 01:12 PM
                                          microbenchmark results---2021/09/24 06:06 PM
                                            microbenchmark resultsDoug S2021/09/24 10:46 PM
                                              microbenchmark results---2021/09/25 08:56 AM
                                                microbenchmark resultsJukka Larja2021/09/26 01:01 AM
                                                microbenchmark resultsDoug S2021/09/26 08:41 AM
                                                  microbenchmark resultsdmcq2021/09/26 12:37 PM
                                                    microbenchmark resultsDoug S2021/09/27 09:32 AM
                                                      microbenchmark resultsdmcq2021/09/28 06:56 AM
                                              microbenchmark resultsDummond D. Slow2021/09/25 11:49 AM
                                                microbenchmark resultsBrett2021/09/25 02:31 PM
                                              microbenchmark resultsdmcq2021/09/25 11:51 AM
                                                microbenchmark resultsDoug S2021/09/26 08:45 AM
                                            microbenchmark resultsRichard S2021/09/25 12:51 AM
                                              microbenchmark resultsDummond D. Slow2021/09/25 11:52 AM
                                                microbenchmark results---2021/09/25 02:04 PM
                                      SVE alignment with non power-of-2 widths-.-2021/09/24 05:10 PM
                                        SVE alignment with non power-of-2 widthsAndrey2021/09/25 03:46 AM
                                          SVE alignment with non power-of-2 widths-.-2021/09/25 04:35 PM
                                          SVE alignment with non power-of-2 widthsKevin G2021/09/27 08:46 AM
                                            SVE alignment with non power-of-2 widths-.-2021/09/27 08:06 PM
                                              SVE alignment with non power-of-2 widthsJukka Larja2021/09/28 05:37 AM
                                                SVE alignment with non power-of-2 widthsAndrey2021/09/28 11:12 AM
                                                  SVE alignment with non power-of-2 widthsdmcq2021/09/28 01:29 PM
                                                SVE alignment with non power-of-2 widths-.-2021/09/28 05:37 PM
                                                  SVE alignment with non power-of-2 widthsJukka Larja2021/09/29 05:50 AM
                    microbenchmark results---2021/09/20 06:11 AM
                    microbenchmark resultsJörn Engel2021/09/23 04:10 AM
                      microbenchmark resultsMichael S2021/09/23 04:55 AM
                        microbenchmark resultsJörn Engel2021/09/23 08:24 AM
                          microbenchmark resultsRoyi2021/09/26 03:25 PM
                      microbenchmark resultsdmcq2021/09/23 09:42 AM
                        microbenchmark results---2021/09/23 10:53 AM
                      microbenchmark resultsanon22021/09/23 01:40 PM
                microbenchmark results: Zen 3Adrian2021/09/22 12:57 AM
                  microbenchmark results: Zen 3Adrian2021/09/22 01:08 AM
                    microbenchmark results: Zen 3Michael S2021/09/22 04:48 AM
                      microbenchmark results: Zen 3Adrian2021/09/22 05:05 AM
        Armv8.8-A and Armv9.3-AKonrad Schwarz2021/09/28 04:45 AM
    Armv8.8-A and Armv9.3-ALinus Torvalds2021/09/17 07:59 AM
      Armv8.8-A and Armv9.3-ADoug S2021/09/17 10:35 AM
        Armv8.8-A and Armv9.3-Anksingh2021/09/17 11:23 AM
          Armv8.8-A and Armv9.3-ADoug S2021/09/17 01:35 PM
            Armv8.8-A and Armv9.3-AKonrad Schwarz2021/10/15 05:23 AM
              Armv8.8-A and Armv9.3-Arwessel2021/10/15 05:49 AM
        Armv8.8-A and Armv9.3-AAdrian2021/09/17 10:07 PM
          Armv8.8-A and Armv9.3-ADoug S2021/09/18 06:34 AM
            Armv8.8-A and Armv9.3-AAdrian2021/09/18 06:38 AM
      Armv8.8-A and Armv9.3-Ablaine2021/09/18 09:37 AM
      Armv8.8-A and Armv9.3-ABrett2021/09/19 12:06 PM
        Armv8.8-A and Armv9.3-Admcq2021/09/19 12:36 PM
        Armv8.8-A and Armv9.3-ADoug S2021/09/19 05:07 PM
          Armv8.8-A and Armv9.3-A - movesdmcq2021/09/28 08:54 AM
            Armv8.8-A and Armv9.3-A - movesDoug S2021/09/28 12:57 PM
              Armv8.8-A and Armv9.3-A - movesdmcq2021/09/28 01:21 PM
                Armv8.8-A and Armv9.3-A - movesNoSpammer2021/09/29 02:53 AM
                  Armv8.8-A and Armv9.3-A - movesrwessel2021/09/29 05:55 AM
                    Armv8.8-A and Armv9.3-A - movesdmcq2021/09/29 06:53 AM
                      Armv8.8-A and Armv9.3-A - movesrwessel2021/09/29 10:35 AM
                        Armv8.8-A and Armv9.3-A - movesdmcq2021/09/29 12:44 PM
                          Armv8.8-A and Armv9.3-A - movesrwessel2021/09/29 12:58 PM
                            Armv8.8-A and Armv9.3-A - movesdmcq2021/09/29 02:52 PM
                              Armv8.8-A and Armv9.3-A - movesrwessel2021/09/29 05:36 PM
                              Armv8.8-A and Armv9.3-A - movesAndrey2021/09/29 06:58 PM
                    Armv8.8-A and Armv9.3-A - movesDoug S2021/09/29 09:10 AM
                      Armv8.8-A and Armv9.3-A - movesrwessel2021/09/29 10:30 AM
                        Armv8.8-A and Armv9.3-A - movesDoug S2021/09/29 09:02 PM
                          Armv8.8-A and Armv9.3-A - movesrwessel2021/09/29 10:22 PM
                            Armv8.8-A and Armv9.3-A - movesMark Roulo2021/09/30 06:37 AM
                              Armv8.8-A and Armv9.3-A - movesrwessel2021/09/30 07:02 AM
                                Did they publish a full description? (NT)Michael S2021/09/30 07:12 AM
                                  Did they publish a full description?rwessel2021/09/30 08:18 AM
                                    Did they publish a full description?Michael S2021/09/30 09:24 AM
                                      Did they publish a full description?rwessel2021/09/30 09:42 AM
                                    Did they publish a full description?Adrian2021/09/30 11:22 PM
                                  Do we even okiw it's three instructions per move?Carson2021/09/30 09:28 PM
                                    Do we even okiw it's three instructions per move?Adrian2021/09/30 11:27 PM
                                    Do we even okiw it's three instructions per move?rwessel2021/10/01 03:19 AM
                            Armv8.8-A and Armv9.3-A - movesDoug S2021/09/30 08:48 AM
                              Armv8.8-A and Armv9.3-A - movesrwessel2021/09/30 09:39 AM
                                Armv8.8-A and Armv9.3-A - movesDoug S2021/09/30 01:56 PM
                                  Armv8.8-A and Armv9.3-A - movesrwessel2021/09/30 04:20 PM
                                    Armv8.8-A and Armv9.3-A - movesdmcq2021/10/01 03:38 AM
                                      Armv8.8-A and Armv9.3-A - movesMichael S2021/10/01 04:04 AM
                                        Armv8.8-A and Armv9.3-A - movesLinus Torvalds2021/10/01 10:01 AM
                                          memcpy - instruction cracking vs DMArpg2021/10/02 01:51 AM
                                            memcpy - instruction cracking vs DMAAdrian2021/10/02 02:45 AM
                                              memcpy - instruction cracking vs DMADoug S2021/10/02 08:47 AM
                                                memcpy - instruction cracking vs DMAAdrian2021/10/02 09:15 AM
                                                memcpy - instruction cracking vs DMArwessel2021/10/02 10:37 AM
                                                  memcpy - instruction cracking vs DMADoug S2021/10/02 05:49 PM
                                            memcpy - instruction cracking vs DMALinus Torvalds2021/10/02 09:43 AM
                                              memcpy - instruction cracking vs DMAdmcq2021/10/02 10:32 AM
                                              memcpy - instruction cracking vs DMABrett2021/10/02 10:45 AM
                                              memcpy - instruction cracking vs DMA---2021/10/02 02:03 PM
                                                memcpy - instruction cracking vs DMA---2021/10/02 02:12 PM
                                                  Moving copy to DRAM doesn't help for small copiesMark Roulo2021/10/02 02:59 PM
                                                    Moving copy to DRAM doesn't help for small copies---2021/10/02 06:32 PM
                                                      Moving copy to DRAM doesn't help for small copiesMichael S2021/10/03 12:40 AM
                                                        Moving copy to DRAM doesn't help for small copiesDoug S2021/10/03 09:09 AM
                                                          Moving copy to DRAM doesn't help for small copiesrwessel2021/10/03 09:51 AM
                                                          Moving copy to DRAM doesn't help for small copiesLinus Torvalds2021/10/03 10:09 AM
                                                            How about environments such as Java?Mark Roulo2021/10/03 11:41 AM
                                                              How about environments such as Java?rwessel2021/10/03 11:49 AM
                                                                How about environments such as Java?Mark Roulo2021/10/03 12:22 PM
                                                              How about environments such as Java?anon22021/10/03 06:58 PM
                                                                How about environments such as Java?Etienne Lorrain2021/10/04 04:08 AM
                                                                  Apart from "It depends" there is no short answer. (NT)Michael S2021/10/04 04:30 AM
                                                                  How about environments such as Java?Andrey2021/10/04 05:04 AM
                                                                  How about environments such as Java?anon22021/10/04 05:32 AM
                                                                How about environments such as Java?Mark Roulo2021/10/04 06:31 AM
                                                                How about environments such as Java?---2021/10/04 08:41 AM
                                                                  How about environments such as Java?Doug S2021/10/04 09:23 AM
                                                                    How about environments such as Java?Andrey2021/10/04 11:14 AM
                                                                      How about environments such as Java?Doug S2021/10/04 12:20 PM
                                                                  How about environments such as Java?anon22021/10/04 01:23 PM
                                                                  How about environments such as Java?rwessel2021/10/04 03:54 PM
                                                            Moving copy to DRAM doesn't help for small copiesJörn Engel2021/10/04 04:52 AM
                                                            Early software zeroing !=== early hardware zeroingPaul A. Clayton2021/10/05 10:19 AM
                                                              Early software zeroing !=== early hardware zeroingDoug S2021/10/05 11:21 AM
                                                memcpy - instruction cracking vs DMABrendan2021/10/02 03:53 PM
                                                  memcpy - instruction cracking vs DMALinus Torvalds2021/10/03 09:48 AM
                                                    memcpy - instruction cracking vs DMAdmcq2021/10/03 12:54 PM
                                              memcpy - instruction cracking vs DMAYuhong Bao2021/10/03 12:30 AM
                                                memcpy - instruction cracking vs DMADavid Hess2021/10/05 04:19 PM
                                                  memcpy - instruction cracking vs DMAAdrian2021/10/05 10:28 PM
                                                    memcpy - instruction cracking vs DMAEtienne Lorrain2021/10/06 01:24 AM
                                                    memcpy - instruction cracking vs DMArwessel2021/10/06 02:38 AM
                                                      memcpy - instruction cracking vs DMAAdrian2021/10/06 03:04 AM
                                                        memcpy - instruction cracking vs DMArwessel2021/10/06 04:59 AM
                                                    memcpy - instruction cracking vs DMA---2021/10/06 08:07 AM
                                                      memcpy - instruction cracking vs DMAAndrey2021/10/06 01:59 PM
                                                    memcpy - instruction cracking vs DMAgallier22021/10/06 10:06 PM
                                                      memcpy - instruction cracking vs DMAAdrian2021/10/06 10:59 PM
                                              memcpy - instruction cracking vs DMAMichael S2021/10/03 12:51 AM
                                                memcpy - instruction cracking vs DMArwessel2021/10/03 04:06 AM
                                                  memcpy - instruction cracking vs DMAMichael S2021/10/03 04:24 AM
                                                    memcpy - instruction cracking vs DMAMatt Sayler2021/10/03 07:02 AM
                                                    memcpy - instruction cracking vs DMADoug S2021/10/03 09:14 AM
                                      Armv8.8-A and Armv9.3-A - movesrwessel2021/10/01 04:10 AM
                                        Armv8.8-A and Armv9.3-A - movesEtienne Lorrain2021/10/01 06:55 AM
                                          Armv8.8-A and Armv9.3-A - movesrwessel2021/10/01 07:14 AM
                                            Armv8.8-A and Armv9.3-A - movesDoug S2021/10/01 10:17 AM
                                              Armv8.8-A and Armv9.3-A - movesrwessel2021/10/02 03:57 AM
  Armv8.8-A and Armv9.3-Anone2021/10/13 05:06 AM
    Armv8.8-A and Armv9.3-AAdrian2021/10/13 05:22 AM
      Armv8.8-A and Armv9.3-ADoug S2021/10/13 08:01 AM
        Armv8.8-A and Armv9.3-Admcq2021/10/13 09:17 AM
          Armv8.8-A and Armv9.3-Anone2021/10/13 09:26 PM
            Armv8.8-A and Armv9.3-Admcq2021/10/14 07:22 AM
    Armv8.8-A and Armv9.3-Arwessel2021/10/14 08:01 AM
      Armv8.8-A and Armv9.3-AAnon2021/10/14 10:08 AM
        Armv8.8-A and Armv9.3-AMichael S2021/10/14 12:25 PM
      Armv8.8-A and Armv9.3-ADoug S2021/10/14 10:18 AM
        Armv8.8-A and Armv9.3-Arwessel2021/10/14 06:07 PM
          Armv8.8-A and Armv9.3-ADoug S2021/10/14 09:23 PM
            Armv8.8-A and Armv9.3-Admcq2021/10/15 12:41 AM
              Armv8.8-A and Armv9.3-AGabriele Svelto2021/10/15 04:07 AM
            Armv8.8-A and Armv9.3-Arwessel2021/10/15 03:49 AM
              Armv8.8-A and Armv9.3-ADoug S2021/10/15 09:44 AM
                Armv8.8-A and Armv9.3-Ame2021/10/15 05:34 PM
                  Armv8.8-A and Armv9.3-ADoug S2021/10/16 08:47 AM
                    Armv8.8-A and Armv9.3-Ame2021/10/17 04:19 AM
                      Armv8.8-A and Armv9.3-ADoug S2021/10/17 09:17 AM
                        Armv8.8-A and Armv9.3-Ame2021/10/17 11:31 AM
                          Armv8.8-A and Armv9.3-ADoug S2021/10/17 12:33 PM
                            Armv8.8-A and Armv9.3-AzArchJon2021/10/18 09:35 AM
                              Armv8.8-A and Armv9.3-ADoug S2021/10/18 01:35 PM
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