HP Labs Technical Reports

Techniques for Critical Path Reduction of Scalar Programs

Schlanaker, Michael ; Kathail, Vinod

HPL-95-112
December, 1995

Keyword(s): critical path reduction, control height reduction, data height reduction, blocked control substitution, instruction level parallelism

Abstract: Scalar performance on processors with instruction level parallelism (ISP) is often limited by control and data dependencies. This report describes a family of compiler techniques , called critical path reduction (CPR) techiques, which reduce the length of critical paths through control and data dependencies. Control CPR reduces the number of branches of the critical path and improves the performance of branch intensive codes on processors with inadequate branch throughput or excessive branch latency. Data CPR reduces the number of arithmetic operations on the critical path. Optimization and scheduling are adapted to support CPR.

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