Convert the signed 32-bit integer b to a single-precision (32-bit) floating-point element, store the result in the lower element, and copy the upper 3 packed elements from a to the upper elements of the result.
See Implementation
Convert the signed 32-bit integer b to a single-precision (32-bit) floating-point element, store the result in the lower element, and copy the upper 3 packed elements from a to the upper elements of the result.