About the Author 4 Future Directions

Memory disambiguation is a technique for remov-ing spurious data dependences that severely limitthe compiler’s freedom of code-scheduling.Though dependence tests for linear array refer-ences work well in many scientific applications,they are incapable of handling pointer derefer-ences, which are very common in general-purposeapplications written in C-like languages. This paper1 is a survey of several recentlyproposed memory disambiguation schemes thatcan handle pointer dereferences. They areclassified as either static or dynamic. Staticdisambiguation uses data-flow analysis to computean approximation of the set of memory aliases ateach program point. Four static disambiguators arecompared. Some evidences show that they mayhave already achieved high accuracy in practice. Dynamic disambiguation resolves at run-timeany ambiguous data dependences that cannot bedetermined during compilation. A pure software-based and two hardware-assisted dynamic disam-biguators are examined. While they can bridgepart of the gap between a raw static disambiguatorand a perfect one, there is still room for improve-ment. Based on our studies, we propose a number offuture directions to develop memory disambigua-tors of better performance/cost. 1. The IBM contact for this paper is Graham War-ren, manager, TOBEY Compiler Development,Compiler Back-End Technology, IBM CanadaLaboratory.