Arithmetic Shifting Considered Harmful

Abstract

For more than a decade there has been great confusion over the semantics of the standard "arithmetic right shift" instruction. This confusion particularly afflicts authors of computer reference handbooks and of optimizing compilers. The fact that shifting is not always equivalent to division has been red iscovered over and over again over the years, but has never been publicized. This paper quotes a large number of sources to prove the widespread extent of this confusion, and then proceeds to a short discussion of the problem itself and what to do about it.