1. A computer implemented method for a compiler to compile a single source program to employ multiple SIMD accelerators, the computer implemented method comprising: receiving, by the compiler, the single source program; identifying vectorizable loop code in the single source program; extracting the vectorizable loop code from the single source program to form extracted vectorizable loop code; compiling the extracted vectorizable loop code to form executable vectorized instruction sequences; and compiling a remainder of the single source program for a principal processor to form an executable main program, wherein the executable main program controls operation of the executable vectorized instruction sequences on the plurality of ancillary SIMD accelerators.