Comments by "Lawrence D’Oliveiro" (@lawrencedoliveiro9104) on "assembly instructions are WILD" video.

  1. Are these short forms really worth using, though? Often, when you benchmark things, you find that longer, simpler instruction sequences are faster. Which is why RISC architectures have the performance edge that they do.
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  2. I suspect that benchmarks will show that simpler instructions are faster.
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  3.  @ABaumstumpf  RISC absolutely has a performance advantage. Look at the current list of the world’s most powerful supercomputers: you don’t see anything x86 until 5th place.
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  4.  @ABaumstumpf  ARM and POWER and the Chinese machine are all RISC. Like I said, the highest that x86 could get was 5th place.
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  5. It was a performance issue. Those complex instructions were too hard to make fast.
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  6.  @brycemw  In other words, these clever CISC-isms are a complete waste of time. This is why we have RISC.
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  7.  @brycemw  I doubt Linus Torvalds said any such thing. x86 backward compatibility was basically an albatross around the neck of Intel. If it had “focused on what mattered the most”, it would never have gone down the Itanium dead end, and left the door open for AMD to take the lead with AMD64. I just checked some (early) AMD64 docs, and the REPxx prefixes are listed in the “legacy” category -- not something you would use in new code.
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