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I am looking for a reference on the "evolution" of x86 instruction set. Mainly, which newer commands make older commands redundant and unusable and a breakdown of the instruction according to their functionality and not to the time/processor they were added at.

Also, is there a reference talking about the usage percentage of x86 commands in recent years software development (meaning, which commands are no longer used in modern day programs)?

SIMEL
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  • I think it is necessary to distinguish opcode assignments from register set from assembly language mnemonic. Each has evolved somewhat independently. Also, the CPU's operating mode has a great effect on which instructions are used simply because the flat modes require much less loading/shuffling of segment registers. – wallyk Apr 15 '12 at 07:24
  • Decimal math hasn't been used in decades and got killed by AMD64. Complex instructions aren't used as much anymore due to poor performance. MMX and FPU code are slowly being replaced by SSE code, but both still have certain advantages over SSE. – harold Apr 15 '12 at 12:25

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That sounds more like a research question than a programming question.

Your best bet is to go to, say, the Wikipedia article that lists the x86 instructions for the processors in the lineage, figure out what each instruction does and categorise them according to functionality.

As for trends in the use of instructions, no idea. It's a rather loaded question. It's not much different than asking, "which english words are more common in modern day usage?" Which instructions are used depends on the application.

Michael Slade
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