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2009 18th International Conference on Parallel Architectures and Compilation Techniques (2009)
Raleigh, North Carolina, USA
Sept. 12, 2009 to Sept. 16, 2009
ISSN: 1089-795X
ISBN: 978-0-7695-3771-9
pp: 41-52
Load elimination is a classical compiler transformation that is increasing in importance for multi-core and many-core architectures. The effect of the transformation is to replace a memory access, such as a read of an object field or an array element, by a read of a compiler-generated temporary that can be allocated in faster and more energy-efficient storage structures such as registers and local memories (scratchpads). Unfortunately, current just-in-time and dynamic compilers perform load elimination only in limited situations. In particular, they usually make worst-case assumptions about potential side effects arising from parallel constructs and method calls. These two constraints interact with each other since parallel constructs are usually translated to low-level runtime library calls. In this paper, we introduce an interprocedural load elimination algorithm suitable for use in dynamic optimization of parallel programs. The main contributions of the paper include: a) an algorithm for load elimination in the presence of three core parallel constructs -- async, finish, and isolated, b) efficient side-effect analysis for method calls, c) extended side-effect analysis for parallel constructs using an Isolation Consistency memory model, and d) performance results to study the impact of load elimination on a set of standard benchmarks using an implementation of the algorithm in Jikes RVM for optimizing programs written in a subset of the X10 v1.5 language. Our performance results show decreases in dynamic counts for getfield operations of up to 99.99%, and performance improvements of up to 1.76x on 1 core, and 1.39x on 16 cores, when comparing the algorithm in this paper with the load elimination algorithm available in Jikes RVM.
Load elimination, scalar replacement, parallel program, dynamic compilation, dynamic optimization, memory model

V. Sarkar and R. Barik, "Interprocedural Load Elimination for Dynamic Optimization of Parallel Programs," 2009 18th International Conference on Parallel Architectures and Compilation Techniques(PACT), Raleigh, North Carolina, USA, 2009, pp. 41-52.
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