New Article: ARM Goes 64-bit

Article: ARM Goes 64-bit
By: name99 (name99.delete@this.redheron.com), November 17, 2012 3:40 pm
Room: Moderated Discussions
bakaneko (nyan.dont.delete@this.hyan.wan) on August 14, 2012 4:21 am wrote:
> anon (anon.delete@this.anon.com) on August 14, 2012 2:37 am wrote:
> > Do you know if
> > implementations are going to execute 32 bit ARMv7 code at full speed? In that
> > case, won't predication shifting and addressing etc still complicate execution?
> > What's the plan there?
>
> Good question, it begs for microcode in 32bit mode. That way
> 32bit code would be as fast as the 64bit code which uses
> multiple instructions + overhead for microcode (if any).
>

I think the point about allowing implementations flexibility is VERY important, and thus means ARM want to make as little compulsory in the ISA as possible.

Take Apple as an obvious example. Given their track record, a very obvious strategy for them would be to ship the Swift-64-A (or whatever they call it) with 32-bit support and ALSO to tell their iOS developers "you have ONE, hear that, ONE year to convert your code to 64-bit". Then, Swift-64-B simply tosses 32-bit support overboard, to the relief of the designers, and allowing them rather more freedom in future designs.

Apple has, remember, astonishingly high rates of uptake of new OSs and new app versions, they control XCode, and they can easily do things like refuse to allow new code in the App store that doesn't come with both a 32-bit and 64-bit binary. They can even do things like, at app install/update time, strip out the unnecessary binary so as not to waste flash.

MS apparently could do the same thing with Win RT, but historically they have not had their act together enough to do so. Android..., yeah, good luck with that.

Meaning is: you have one partner that REALLY wants to ditch 32-bit ASAP, and other partners that want to keep it for a long time. It makes no sense for ARM to privilege one of these over the other. (And they will undoubtedly benefit from the halo if Apple CAN use ditching 32-bit to make a chip that's substantially faster, and makes ARM as a whole look good.)
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TopicPosted ByDate
New Article: ARM Goes 64-bitDavid Kanter08/14/12 12:04 AM
  New Article: ARM Goes 64-bitnone08/14/12 12:44 AM
    New Article: ARM Goes 64-bitDavid Kanter08/14/12 01:04 AM
    MIPS MT-ASEPaul A. Clayton08/14/12 09:01 AM
      MONITOR/MWAITEduardoS08/14/12 10:08 AM
        MWAIT not specifically MTPaul A. Clayton08/14/12 10:36 AM
          MWAIT not specifically MTEduardoS08/15/12 03:16 PM
        MONITOR/MWAITanonymou508/14/12 11:07 AM
          MONITOR/MWAITEduardoS08/15/12 03:20 PM
      MIPS MT-ASErwessel08/14/12 10:14 AM
  New Article: ARM Goes 64-bitSHK08/14/12 02:01 AM
  New Article: ARM Goes 64-bitanon08/14/12 02:37 AM
    New Article: ARM Goes 64-bitRichard Cownie08/14/12 03:57 AM
      New Article: ARM Goes 64-bitanon08/14/12 04:29 AM
      New Article: ARM Goes 64-bitnone08/14/12 04:44 AM
        New Article: ARM Goes 64-bitanon08/14/12 05:28 AM
          New Article: ARM Goes 64-bitanon08/14/12 05:32 AM
            New Article: ARM Goes 64-bitEduardoS08/14/12 06:06 AM
          New Article: ARM Goes 64-bitnone08/14/12 05:40 AM
            AArch64 select better than cmovPaul A. Clayton08/14/12 06:08 AM
            New Article: ARM Goes 64-bitanon08/14/12 06:12 AM
              New Article: ARM Goes 64-bitnone08/14/12 06:25 AM
                Predicated ld/store are usefulPaul A. Clayton08/14/12 06:48 AM
                  Predicated ld/store are usefulnone08/14/12 06:56 AM
                    Predicated ld/store are usefulanon08/14/12 07:07 AM
                    Predicated stores might not be that badPaul A. Clayton08/14/12 07:27 AM
                      Predicated stores might not be that badDavid Kanter08/15/12 01:14 AM
                        Predicated stores might not be that badMichael S08/15/12 11:41 AM
                        Predicated stores might not be that badR Byron08/17/12 04:09 AM
                New Article: ARM Goes 64-bitanon08/14/12 06:54 AM
                  New Article: ARM Goes 64-bitnone08/14/12 07:04 AM
                    New Article: ARM Goes 64-bitanon08/14/12 07:43 AM
          New Article: ARM Goes 64-bitEduardoS08/14/12 06:07 AM
            New Article: ARM Goes 64-bitanon08/14/12 06:20 AM
              New Article: ARM Goes 64-bitnone08/14/12 06:29 AM
                New Article: ARM Goes 64-bitanon08/14/12 07:00 AM
            New Article: ARM Goes 64-bitMichael S08/14/12 03:43 PM
        New Article: ARM Goes 64-bitRichard Cownie08/14/12 06:53 AM
          OT: Conrad's "Youth"Richard Cownie08/14/12 07:20 AM
      New Article: ARM Goes 64-bitEduardoS08/14/12 06:04 AM
        New Article: ARM Goes 64-bitmpx08/14/12 08:59 AM
          New Article: ARM Goes 64-bitAntti-Ville Tuunainen08/14/12 09:16 AM
        New Article: ARM Goes 64-bitanonymou508/14/12 11:03 AM
          New Article: ARM Goes 64-bitname9911/17/12 03:31 PM
            Microarchitecting a counter registerPaul A. Clayton11/17/12 07:37 PM
    New Article: ARM Goes 64-bitbakaneko08/14/12 04:21 AM
      New Article: ARM Goes 64-bitname9911/17/12 03:40 PM
        New Article: ARM Goes 64-bitEduardoS11/17/12 04:52 PM
        New Article: ARM Goes 64-bitDoug S11/17/12 05:48 PM
        New Article: ARM Goes 64-bitbakaneko11/18/12 05:40 PM
          New Article: ARM Goes 64-bitWilco11/19/12 07:59 AM
            New Article: ARM Goes 64-bitEduardoS11/19/12 08:23 AM
              New Article: ARM Goes 64-bitWilco11/19/12 09:31 AM
                Downloading µarch-specific binaries?Paul A. Clayton11/19/12 11:21 AM
                New Article: ARM Goes 64-bitEduardoS11/19/12 11:41 AM
                  New Article: ARM Goes 64-bitWilco11/21/12 07:44 AM
                    JIT vs. static compilation (Was: New Article: ARM Goes 64-bit)VMguy11/22/12 03:21 AM
                      JIT vs. static compilation (Was: New Article: ARM Goes 64-bit)David Kanter11/22/12 12:12 PM
                        JIT vs. static compilation (Was: New Article: ARM Goes 64-bit)Gabriele Svelto11/23/12 03:50 AM
                    New Article: ARM Goes 64-bitEduardoS11/23/12 10:09 AM
                      New Article: ARM Goes 64-bitEBFE11/26/12 01:24 AM
                        New Article: ARM Goes 64-bitGabriele Svelto11/26/12 03:33 AM
                          New Article: ARM Goes 64-bitEBFE11/27/12 11:17 PM
                            New Article: ARM Goes 64-bitGabriele Svelto11/28/12 02:32 AM
                        New Article: ARM Goes 64-bitEduardoS11/26/12 12:16 PM
                          New Article: ARM Goes 64-bitEBFE11/28/12 12:33 AM
                            New Article: ARM Goes 64-bitEduardoS11/28/12 05:53 AM
                              New Article: ARM Goes 64-bitMichael S11/28/12 06:15 AM
                                New Article: ARM Goes 64-bitEduardoS11/28/12 07:33 AM
                                  New Article: ARM Goes 64-bitMichael S11/28/12 09:16 AM
                                    New Article: ARM Goes 64-bitEduardoS11/28/12 09:53 AM
                                    New Article: ARM Goes 64-bitEugene Nalimov11/28/12 05:58 PM
                                      Amazing!EduardoS11/28/12 07:25 PM
                                        Amazing! (non-italic response)EduardoS11/28/12 07:25 PM
                                        Amazing!EBFE11/28/12 08:20 PM
                                          Undefined behaviour doubles downEduardoS11/28/12 09:10 PM
                              New Article: ARM Goes 64-bitEBFE11/28/12 07:54 PM
                                New Article: ARM Goes 64-bitEduardoS11/28/12 09:21 PM
                Have you heard of Transmeta?David Kanter11/19/12 03:47 PM
            New Article: ARM Goes 64-bitbakaneko11/19/12 09:08 AM
            New Article: ARM Goes 64-bitDavid Kanter11/19/12 03:40 PM
              Semantic Dictionary EncodingRay11/19/12 10:37 PM
              New Article: ARM Goes 64-bitRohit11/20/12 04:48 PM
                New Article: ARM Goes 64-bitDavid Kanter11/20/12 11:07 PM
                  New Article: ARM Goes 64-bitWilco11/21/12 06:41 AM
                    New Article: ARM Goes 64-bitDavid Kanter11/21/12 10:12 AM
                    A JIT exampleMark Roulo11/21/12 10:30 AM
                      A JIT exampleWilco11/21/12 07:04 PM
                        A JIT examplerwessel11/21/12 09:05 PM
                        A JIT exampleGabriele Svelto11/23/12 03:53 AM
                        A JIT exampleEduardoS11/23/12 10:13 AM
                          A JIT exampleWilco11/23/12 01:41 PM
                            A JIT exampleEduardoS11/23/12 02:06 PM
                            A JIT exampleGabriele Svelto11/23/12 04:09 PM
                              A JIT exampleSymmetry11/26/12 05:58 AM
            New Article: ARM Goes 64-bitRay11/19/12 10:27 PM
    New Article: ARM Goes 64-bitDavid Kanter08/14/12 09:11 AM
  v7-M is Thumb-onlyPaul A. Clayton08/14/12 06:58 AM
  Minor suggested correctionPaul A. Clayton08/14/12 08:33 AM
    Minor suggested correctionanon08/14/12 08:57 AM
  New Article: ARM Goes 64-bitExophase08/14/12 08:33 AM
    New Article: ARM Goes 64-bitDavid Kanter08/14/12 09:16 AM
      New Article: ARM Goes 64-bitjigal08/15/12 01:49 PM
  Correction re ARM and BBC MicroPaul08/14/12 08:59 PM
    Correction re ARM and BBC MicroPer Hesselgren08/15/12 03:27 AM
  Memory BW so lowPer Hesselgren08/15/12 03:14 AM
    Memory BW so lownone08/15/12 11:16 AM
  New Article: ARM Goes 64-bitdado08/15/12 10:25 AM
  Number of GPRsKenneth Jonsson08/16/12 02:35 PM
    Number of GPRsExophase08/16/12 02:52 PM
      Number of GPRsKenneth Jonsson08/17/12 02:41 AM
        Ooops, missing link...Kenneth Jonsson08/17/12 02:44 AM
        64-bit pointers eat some performancePaul A. Clayton08/17/12 06:19 AM
          64-bit pointers eat some performancebakaneko08/17/12 08:37 AM
            Brute force seems to workPaul A. Clayton08/17/12 10:08 AM
              Brute force seems to workbakaneko08/17/12 11:15 AM
          64-bit pointers eat some performanceRichard Cownie08/17/12 08:46 AM
            Pointer compression is atypicalPaul A. Clayton08/17/12 10:43 AM
              Pointer compression is atypicalRichard Cownie08/17/12 12:57 PM
                Pointer compression is atypicalHoward Chu08/22/12 10:17 PM
                  Pointer compression is atypicalRichard Cownie08/23/12 04:48 AM
                    Pointer compression is atypicalHoward Chu08/23/12 06:51 AM
              Pointer compression is atypicalWilco08/17/12 02:41 PM
                Pointer compression is atypicalRichard Cownie08/17/12 04:13 PM
                  Pointer compression is atypicalRicardo B08/19/12 10:44 AM
                  Pointer compression is atypicalHoward Chu08/22/12 10:08 PM
                    Unified libraries?Paul A. Clayton08/23/12 07:49 AM
                    Pointer compression is atypicalRichard Cownie08/23/12 08:44 AM
                      Pointer compression is atypicalHoward Chu08/23/12 05:17 PM
                        Pointer compression is atypicalanon08/23/12 08:15 PM
                          Pointer compression is atypicalHoward Chu08/23/12 09:33 PM
            64-bit pointers eat some performanceFoo_08/18/12 12:09 PM
              64-bit pointers eat some performanceRichard Cownie08/18/12 05:25 PM
                64-bit pointers eat some performanceRichard Cownie08/18/12 05:32 PM
            Page-related benefit of small pointersPaul A. Clayton08/23/12 08:36 AM
        Number of GPRsWilco08/17/12 06:31 AM
          Number of GPRsKenneth Jonsson08/17/12 11:54 AM
            Number of GPRsExophase08/17/12 12:44 PM
              Number of GPRsKenneth Jonsson08/17/12 01:22 PM
                Number of GPRsWilco08/17/12 02:53 PM
        What about dynamic utilization?Exophase08/17/12 09:30 AM
          Compiler vs. assembly aliasing knowledge?Paul A. Clayton08/17/12 10:20 AM
            Compiler vs. assembly aliasing knowledge?Exophase08/17/12 11:09 AM
            Compiler vs. assembly aliasing knowledge?anon08/18/12 02:23 AM
              Compiler vs. assembly aliasing knowledge?Ricardo B08/19/12 11:02 AM
                Compiler vs. assembly aliasing knowledge?anon08/19/12 06:07 PM
                  Compiler vs. assembly aliasing knowledge?Ricardo B08/19/12 07:26 PM
                    Compiler vs. assembly aliasing knowledge?anon08/19/12 10:03 PM
                      Compiler vs. assembly aliasing knowledge?anon08/20/12 01:59 AM
        Number of GPRsDavid Kanter08/17/12 12:46 PM
          RAT issues as part of reason 1Paul A. Clayton08/17/12 02:18 PM
        Number of GPRsname9911/17/12 06:37 PM
          Large ARFs increase renaming costPaul A. Clayton11/17/12 09:23 PM
    Number of GPRsDavid Kanter08/16/12 03:31 PM
    Number of GPRsRichard Cownie08/16/12 05:17 PM
    32 GPRs ~2-3%Paul A. Clayton08/16/12 06:27 PM
      Oops, Message-ID: aaed6e38-c7bd-467e-ba41-f40cf1020e5e@googlegroups.com (NT)Paul A. Clayton08/16/12 06:29 PM
      32 GPRs ~2-3%Exophase08/16/12 10:06 PM
        R31 as SP/zero is kind of neat (NT)Paul A. Clayton08/17/12 06:23 AM
        32 GPRs ~2-3%rwessel08/17/12 08:24 AM
          32 GPRs ~2-3%Exophase08/17/12 09:16 AM
            32 GPRs ~2-3%Max08/17/12 04:19 PM
      32 GPRs ~2-3%name9911/17/12 07:43 PM
    Number of GPRsmpx08/17/12 01:11 AM
      Latency and powerPaul A. Clayton08/17/12 06:54 AM
    Number of GPRsbakaneko08/17/12 03:09 AM
  New Article: ARM Goes 64-bitSteve08/17/12 02:12 PM
    New Article: ARM Goes 64-bitDavid Kanter08/19/12 12:42 PM
      New Article: ARM Goes 64-bitDoug S08/19/12 02:02 PM
      New Article: ARM Goes 64-bitAnon08/19/12 07:16 PM
      New Article: ARM Goes 64-bitSteve08/30/12 07:51 AM
  Scalar vs Vector registersRobert David Graham08/19/12 05:19 PM
    Scalar vs Vector registersDavid Kanter08/19/12 05:29 PM
  New Article: ARM Goes 64-bitBaserock ARM servers08/21/12 04:13 PM
    Baserock ARM serversSysanon08/21/12 04:14 PM
    A-15 virtualization and LPAE?Paul A. Clayton08/21/12 06:13 PM
      A-15 virtualization and LPAE?Anon08/21/12 07:13 PM
        Half-depth advantages?Paul A. Clayton08/21/12 08:42 PM
          Half-depth advantages?Anon08/22/12 03:33 PM
            Thanks for the information (NT)Paul A. Clayton08/22/12 04:04 PM
      A-15 virtualization and LPAE?C. Ladisch08/23/12 11:12 AM
        A-15 virtualization and LPAE?Paul08/23/12 03:17 PM
        Excessive pessimismPaul A. Clayton08/23/12 04:08 PM
          Excessive pessimismDavid Kanter08/23/12 05:05 PM
    New Article: ARM Goes 64-bitMichael S08/22/12 07:12 AM
      BTW, Baserock==product, Codethink==company (NT)Paul A. Clayton08/22/12 08:56 AM
  New Article: ARM Goes 64-bitReinoud Zandijk08/21/12 11:27 PM
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