1. A computer implemented method for using Superword-Level Parallelism (SLP) in processing a plurality of statements, wherein the statements are associated with an array having a number of array positions, and each statement includes one or more expressions, said method comprising the steps of: gathering the expressions for each of said statements into a structure comprising at least a single merge stream, said single merge stream being furnished with a location for each gathered expression, wherein the location for a given expression is associated with one of said positions of said array; selectively identifying a plurality of said expressions in said single merge stream, and applying SLP packing operations to said identified expressions, in order to merge respective identified expressions into one or more isomorphic sub-streams; selectively combining the expressions of said isomorphic sub-streams, and other expressions of said single merge stream, into a number of input vectors that are substantially equal in length to one another; generating a location vector containing the respective locations for all of the expressions in said single merge stream; and generating an output stream comprising the expressions of said input vectors, wherein said expressions are arranged in an order in said output stream that is determined by the respective locations contained in said location vector.