Predicting the effects of optimization on a procedure body

Abstract

Practical application of procedure integration (inline expansion) as a program optimization requires some method for estimating the effects of subsequent optimization on the integrated procedure. A technique is described for predicting the code improvement that can be expected due to constant folding and test elision when a procedure call involving constant actual parameters is integrated. The technique is based on information collected during a single data flow analysis of each procedure body, and on execution frequency statistics for the procedure. This information can then be used to estimate the cost in code size and the benefit in execution speed of integrating each call to the procedure. The algorithm uses a syntax directed analysis technique suitable for structured programming languages without gotos.