macro-op vs. micro-op

Article: Inside Barcelona: AMD's Next Generation
By: David Kanter (dkanter.delete@this.realworldtech.com), May 21, 2007 4:38 pm
Room: Moderated Discussions
dess (dess@nospam.com) on 5/21/07 wrote:
---------------------------
>The article speak about (as well as the figures indicate) >micro-ops at some places,
>where - IMHO - there should be macro-op, instead. F.ex.:
>"The pack buffer, which is part of the decoding phase, is >responsible for sending
>groups of exactly 3 micro-ops to the re-order buffer (ROB)."
>An exerpt from the Software Optimization Guide for AMD 10h >Processors:
>"Early decoding produces three macro-ops per cycle from >either path. The outputs
>of both decoders are multiplexed together and passed to the >next stage in the pipeline, the instruction control unit."
>(AFAIK a macro-op can contain several micro-ops.)

In talking with architects, some use the terminology micro-op to refer to what AMD used to call RISCops (Rops), but are most accurately described as internal operations. Some of their documentation refers to macro-ops as the internal operations. I don't really think it matters. I choose the term that makes it easiest for the folks at AMD to edit/revise/comment on my article and questions.

However, Intel is a different story. First of all, the term is uop, not micro-op, which refers to the internal operations. In Intel terminology a macro-op is an x86 instruction. So macro-op fusion is the fusing of two x86 instruction (CMP+JMP).

>Now I'm confused whether this happened at some places for >the Core 2 as well, or
>those are really 4 micro-ops, in which case the Barcelona >is the wider one.

Decoding always maps the contents of the Icache (x86 instructions) to the internal operations and operands of the processor in question.

AMD has 3 decoders, Intel has 4 decoders. AMD can 3 operations/cycle, Intel can rename 4. Counting execution units is a little tricky since AMD likes to count their separate AGUs as functional units, while Intel considers them part of the memory pipelines. Intel can retire 4 operations, AMD can retire 3.

At the end of the day, the Core2 is theoretically wider. However, it's unclear to what extent this will be true in practice.

DK
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    Yes, I left out a sentence there. Fixed (NT)David Kanter2007/05/16 12:07 PM
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  microops vs macroops on page 4Peter Lund2007/05/17 12:04 PM
    microops vs macroops on page 4David Kanter2007/05/21 04:51 PM
      microops vs macroops on page 4EduardoS2007/05/21 05:42 PM
        microops vs macroops on page 4dess2007/05/21 07:00 PM
  Barcelona Article OnlinePeter Lund2007/05/17 12:25 PM
  macro-op vs. micro-opdess2007/05/21 07:24 AM
    macro-op vs. micro-opDavid Kanter2007/05/21 04:38 PM
      macro-op vs. micro-opdess2007/05/21 06:15 PM
        macro-op vs. micro-opDavid Kanter2007/05/22 12:11 AM
          macro-op vs. micro-opdess2007/05/22 03:56 AM
            macro-op vs. micro-opGipsel2007/05/22 05:05 AM
              macro-op vs. micro-opdess2007/05/22 05:52 AM
                macro-op vs. micro-opanonymous2007/05/22 06:14 AM
                  macro-op vs. micro-opdess2007/05/22 06:44 AM
                    macro-op vs. micro-opEduardoS2007/05/22 02:19 PM
                      macro-op vs. micro-opdess2007/05/24 08:52 AM
            Stop comparing apples to orangesEduardoS2007/05/22 02:30 PM
              Stop comparing apples to orangesdess2007/05/22 04:09 PM
                Stop comparing apples to orangesdess2007/05/22 04:30 PM
                Stop comparing apples to orangesEduardoS2007/05/22 04:31 PM
                  Stop comparing... apples to oranges?dess2007/05/24 09:30 AM
              Stop comparing apples to orangesanonymous2007/05/22 08:12 PM
                Stop comparing apples to orangesEduardoS2007/05/23 02:50 PM
          macro-op vs. micro-opanonymous2007/05/22 06:08 AM
            macro-op vs. micro-opdess2007/05/22 06:40 AM
              macro-op vs. micro-opanonymous2007/05/22 06:48 AM
      macro-op vs. micro-opdess2007/05/21 08:30 PM
        macro-op vs. micro-opanonymous2007/05/22 06:44 AM
          macro-op vs. micro-opdess2007/05/24 09:38 AM
      macro-op vs. micro-opMichael S2007/05/22 05:26 AM
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