A compiler framework for speculative analysis and optimizations

Lin, Jin; Chen, Tong; Hsu, Wei-Chung; Yew, Pen-Chung; Ju, Roy; Ngai, Tin-Fook; Chan, Sin-Lam

doi:10.1145/780822.781164

Cited by 18 publications

(26 citation statements)

References 25 publications

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“…Finally, we want to stress that PRE techniques are applicable to other areas of optimization such as load/store elimination by combining both control and data speculation [Lin et al 2003], load/store elimination for binaries [Fernández and Espasa 2004], communication optimization [Knoop and Mehofer 2002], and thread-level synchronization cost elimination [Zhai et al 2002]. Significant performance gains can be expected from these optimizations, leveraging the benefits of a more application-specific PRE technique that may be derived from our algorithm.…”

Section: Resultsmentioning

confidence: 99%

“…Their algorithm performs no worse than if speculation is not used, but is not optimal. Lin et al [2003] incorporate alias profiling information to support data speculation in the SSAPRE framework.…”

Section: Related Workmentioning

confidence: 99%

“…This paper presents the first algorithm that achieves both computational and lifetime optimal results simultaneously. Presently, many existing compiler frameworks have incorporated and used profiling information to support control speculation (and data speculation [Lin et al 2003]). As increasingly more aggressive profile-guided optimizations are being employed, the profiling overhead can be better amortized (or shared).…”

Section: Introductionmentioning

confidence: 99%

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A lifetime optimal algorithm for speculative PRE

Xue

Cai

2006

ACM Trans. Archit. Code Optim.

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A lifetime optimal algorithm, called MC-PRE, is presented for the first time that performs speculative PRE based on edge profiles. In addition to being computationally optimal in the sense that the total number of dynamic computations for an expression in the transformed code is minimized, MC-PRE is also lifetime optimal since the lifetimes of introduced temporaries are also minimized. The key in achieving lifetime optimality lies not only in finding a unique minimum cut on a transformed graph of a given CFG, but also in performing a data-flow analysis directly on the CFG to avoid making unnecessary code insertions and deletions. The lifetime optimal results are rigorously proved. We evaluate our algorithm in GCC against three previously published PRE algorithms, namely, MC-PRE comp (Qiong and Xue's computationally optimal version of MC-PRE), LCM (Knoop, Rüthing, and Steffen's lifetime optimal algorithm for performing nonspeculative classic PRE), and CMP-PRE (Bodik, Gupta, and Soffa's PRE algorithm based on code-motion preventing (CMP) regions, which is speculative but not computationally optimal). We report and analyze our experimental results, obtained from both actual program execution and instrumentation, for all 22 C, C++ and FORTRAN 77 benchmarks from SPECcpu2000 on an Itanium 2 computer system. Our results show that MC-PRE (or MC-PRE comp ) is capable of eliminating more partial redundancies than both LCM and CMP-PRE (especially in functions with complex control flow), and, in addition, MC-PRE inserts temporaries with shorter lifetimes than MC-PRE comp . Each of both benefits has contributed to the performance improvements in benchmark programs at the costs of only small compile-time and code-size increases in some benchmarks.

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Section: Resultsmentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A lifetime optimal algorithm for speculative PRE

Xue

Cai

2006

ACM Trans. Archit. Code Optim.

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“…Aside from mitigating deficiencies in alias analysis, data speculation can also allow the compiler to manage even "known-sometimes" dependences. Other researchers have shown opportunities to exist for profitable integration of data speculation into optimizations [17]. Table 1 shows estimated SPECint2000 performance ratios (higher is better) for GNU and IMPACT compilers on a Linux system (implying 64-bit pointers, which affect data cache performance).…”

Section: Ia-64 and Structural Transformsmentioning

confidence: 99%

Field-testing IMPACT EPIC research results in Itanium 2

Sias

Ueng

Kent

et al. 2004

SIGARCH Comput. Archit. News

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Explicitly-Parallel Instruction Computing (EPIC) provides architectural features, including predication and explicit control speculation, intended to enhance the compiler's ability to expose instruction-level parallelism (ILP) in control-intensive programs. Aggressive structural transformations using these features, though described in the literature, have not yet been fully characterized in complete systems. Using the Intel Itanium 2 microprocessor, the SPECint2000 benchmarks and the IMPACT Compiler for IA-64, a research compiler competitive with the best commercial compilers on the platform, we provide an in situ evaluation of code generated using aggressive, EPIC-enabled techniques in a reality-constrained microarchitecture. Our work shows a 1.13 average speedup (up to 1.50) due to these compilation techniques, relative to traditionally-optimized code at the same inlining and pointer analysis levels, and a 1.55 speedup (up to 2.30) relative to GNU GCC, a solid traditional compiler. Detailed results show that the structural compilation approach provides benefits far beyond a decrease in branch misprediction penalties and that it both positively and negatively impacts instruction cache performance. We also demonstrate the increasing significance of runtime effects, such as data cache and TLB, in determining end performance and the interaction of these effects with control speculation.

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“…Control and data speculation [Heggy et al 1990;Bringmann et al 1993;Mahlke et al 1993;Wu et al 1994;Postiff et al 2000;Ju et al 2000;Mahadevan et al 2000;Lin et al 2003Lin et al , 2004 has been used effectively to improve program performance. Ju et al [2000] proposed a unified framework to exploit both control and data speculation targeting specifically for memory latency hiding.…”

Section: Introductionmentioning

confidence: 99%

Recovery code generation for general speculative optimizations

Lin

Hsu

Yew

et al. 2006

ACM Trans. Archit. Code Optim.

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A general framework that integrates both control and data speculation using alias profiling and/or compiler heuristic rules has shown to improve CPU2000 performance on Itanium systems. However, speculative optimizations require check instructions and recovery code to ensure correct execution when speculation fails at runtime. How to generate check instructions and their associated recovery code efficiently and effectively is an issue yet to be well studied. It is also, very important that the recovery code generated in the earlier phases integrate gracefully in the later optimization phases. At the very least, it should not hinder later optimizations, thus, ensuring overall performance improvement. This paper proposes a framework that uses an if-block structure to facilitate check instructions and recovery code generation for general speculative optimizations. It allows speculative instructions and their recovery code generated in the early compiler optimization phases to be integrated effectively with the subsequent optimization phases. It also allows multilevel speculation for multilevel pointers and multilevel expression trees to be handled with no additional complexity. The proposed recovery code generation framework has been implemented and evaluated in the Open Research Compiler (ORC).

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A compiler framework for speculative analysis and optimizations

Cited by 18 publications

References 25 publications

A lifetime optimal algorithm for speculative PRE

A lifetime optimal algorithm for speculative PRE

Field-testing IMPACT EPIC research results in Itanium 2

Recovery code generation for general speculative optimizations

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