Agner`s CPU blog

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Stop the instruction set war
Author:  Date: 2016-04-17 03:31
Why do different vendors have to maintain nonoverlapping encodings of instructions? Shouldn't support for particular instruction set be queried via CPUID before the code using them would be executed? It seems it'd be quite OK to have a particular opcode mean one thing on a CPU supporting feature X and not Y, and another thing on a CPU supporting feature Y and not X if these features are from different vendors. Why the battle for opcode space then?
 
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