Mixed-width SIMD operations using even/odd register pairs for wide data elements

Systems and methods relate to a mixed-width single instruction multiple data (SIMD) instruction which has at least a source vector operand comprising data elements of a first bit-width and a destination vector operand comprising data elements of a second bit-width, wherein the second bit-width is either half of or twice the first bit-width. Correspondingly, one of the source or destination vector operands is expressed as a pair of registers, a first register and a second register. The other vector operand is expressed as a single register. Data elements of the first register correspond to even-numbered data elements of the other vector operand expressed as a single register, and data elements of the second register correspond to data elements of the other vector operand expressed as a single register.