LAMBDA-SPLITTING - A HIGHER-ORDER APPROACH TO CROSS-MODULE OPTIMIZATIONS

We describe an algorithm for automatic inline expansion across module boundaries that works in the presence of higher-order functions and fr ee variables; it rearranges bindings and scopes as necessary to move n onexpansive code from one module to another. We describe-and implement -the algorithm as transformations on lambda-calculus. Our inliner inte racts well with separate compilation and is efficient, robust, and pra ctical enough for everyday use in the SML/NJ compiler. Inlining improv es performance by 4-8% on existing code, and makes it possible to use much more data abstraction by consistently eliminating penalties for m odularity.