Evolution of SIMD extensions

The evolution of SIMD extensions is extremely rapid.

For the SSE and then AVX extensions, this meant the successive addition of new instructions to make up for the shortcomings of previous versions, using technological advances to integrate ever more transistors, and therefore functionality, into a chip. The transition from SSE to AVX extensions saw the move from 128-bit to 256-bit registers.

It can be somewhat anarchic. For example, starting with the Altivec extension, there are now four versions (table 1 ) which differ in the number of...