What is Vector SIMD?
The AltiVec unit is classified as a vector SIMD unit, since it operates on multiple elements (in a vector register) with one instruction (SIMD = single instruction, multiple data). For example, array A is a 16 bit integer with 8 elements: 1 2 3 4 5 6 7 8 And array B has these 8 elements: 80 70 60 50 40 30 20 10 If we want to add these arrays together, then if they are each fetched into a vector register, one vector SIMD instruction can provide the result: 81 72 63 54 45 36 27 18 Many modern microprocessors are including vector SIMD capabilities, so restructuring a program to make it more vectorizable may be useful for lots of target systems.
