Object code optimizer

Last updated October 06, 2024

An object code optimizer, sometimes also known as a post pass optimizer or, for small sections of code, peephole optimizer, forms part of a software compiler. It takes the output from the source language compile step - the object code or binary file - and tries to replace identifiable sections of the code with replacement code that is more algorithmically efficient (usually improved speed).

Examples

The earliest "COBOL Optimizer" was developed by Capex Corporation in the mid 1970s for COBOL. This type of optimizer depended, in this case, upon knowledge of "weaknesses" in the standard IBM COBOL compiler, and actually replaced (or patched) sections of the object code with more efficient code. The replacement code might replace a linear table lookup with a binary search for example or sometimes simply replace a relatively slow instruction with a known faster one that was otherwise functionally equivalent within its context. This technique is now known as strength reduction. For example, on the IBM/360 hardware the CLI instruction was, depending on the particular model, between twice and 5 times as fast as a CLC instruction for single byte comparisons.^[1]^[2]

Advantages

The main advantage of re-optimizing existing programs was that the stock of already compiled customer programs (object code) could be improved almost instantly with minimal effort, reducing CPU resources at a fixed cost (the price of the proprietary software). A disadvantage was that new releases of COBOL, for example, would require (charged) maintenance to the optimizer to cater for possibly changed internal COBOL algorithms. However, since new releases of COBOL compilers frequently coincided with hardware upgrades, the faster hardware would usually more than compensate for the application programs reverting to their pre-optimized versions (until a supporting optimizer was released).

Other optimizers

Some binary optimizers do executable compression, which reduces the size of binary files using generic data compression techniques, reducing storage requirements and transfer and loading times, but not improving run-time performance. Actual consolidation of duplicate library modules would also reduce memory requirements.

Some binary optimizers utilize run-time metrics (profiling) to introspectively improve performance using techniques similar to JIT compilers.

Recent developments

More recently developed "binary optimizers" for various platforms, some claiming novelty but, nevertheless, essentially using the same (or similar) techniques described above, include:

IBM Automatic Binary Optimizer for z/OS (ABO) (2015)^[3]
IBM Automatic Binary Optimizer for z/OS (ABO) Trial Cloud Service (2020)^[4]
The Sun Studio Binary Code Optimizer ^[5] — which requires a profile phase beforehand
Design and Engineering of a Dynamic Binary Optimizer — from IBM T. J. Watson Res. Center (February 2005)^[6]^[7]
QuaC: Binary Optimization for Fast Runtime Code Generation in C ^[8] — (which appears to include some elements of JIT)
DynamoRIO
COBRA: An Adaptive Runtime Binary Optimization Framework for Multithreaded Applications^[9]
Spike Executable Optimizer (Unix kernel)^[10]
"SOLAR" Software Optimization at Link-time And Run-time^[11]
Dynimize: CPU Performance Virtualization^[12]
BOLT: post-link optimizer built on top of the LLVM framework. Utilizing sample-based profiling, BOLT improves the performance of real-world applications even for highly optimized binaries built with both Feedback Directed Optimization and Link-time optimization. For GCC and Clang compilers, BOLT speeds up their binaries by up to 20.4% on top of FDO and LTO, and up to 52.1% if the binaries are built without FDO and LTO.^[13]

Related Research Articles

In computing, a compiler is a computer program that translates computer code written in one programming language into another language. The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a low-level programming language to create an executable program.

<span class="mw-page-title-main">Linker (computing)</span> Computer program which combines multiple object files into a single file

In computing, a linker or link editor is a computer system program that takes one or more object files and combines them into a single executable file, library file, or another "object" file.

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In computer science, self-modifying code is code that alters its own instructions while it is executing – usually to reduce the instruction path length and improve performance or simply to reduce otherwise repetitively similar code, thus simplifying maintenance. The term is usually only applied to code where the self-modification is intentional, not in situations where code accidentally modifies itself due to an error such as a buffer overflow.

In computing, binary translation is a form of binary recompilation where sequences of instructions are translated from a source instruction set to the target instruction set. In some cases such as instruction set simulation, the target instruction set may be the same as the source instruction set, providing testing and debugging features such as instruction trace, conditional breakpoints and hot spot detection.

In computing, just-in-time (JIT) compilation is compilation during execution of a program rather than before execution. This may consist of source code translation but is more commonly bytecode translation to machine code, which is then executed directly. A system implementing a JIT compiler typically continuously analyses the code being executed and identifies parts of the code where the speedup gained from compilation or recompilation would outweigh the overhead of compiling that code.

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In software engineering, profiling is a form of dynamic program analysis that measures, for example, the space (memory) or time complexity of a program, the usage of particular instructions, or the frequency and duration of function calls. Most commonly, profiling information serves to aid program optimization, and more specifically, performance engineering.

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Capex Corporation was an American computer software company in existence from 1969 through 1982 and based in Phoenix, Arizona. It made a variety of software products, mostly system utilities for the IBM mainframe platform, and was known for its Optimizer add-on to the IBM COBOL compiler. Capex was acquired by Computer Associates in 1982.

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<span class="mw-page-title-main">IBM COBOL</span>

IBM has offered the computer programming language COBOL on many platforms, starting with the IBM 1400 series and IBM 7000 series, continuing into the industry-dominant IBM System/360 and IBM System/370 mainframe systems, and then through IBM Power Systems (AIX), IBM Z, and x86 (Linux).

References

↑ "Archived copy" (PDF). Archived from the original (PDF) on 2010-07-11. Retrieved 2010-01-07.{{cite web}}: CS1 maint: archived copy as title (link)
↑ Evans, Michael (1982-12-01). "Software engineering for the Cobol environment". Communications of the ACM. 25 (12): 874–882. doi: 10.1145/358728.358732 . S2CID 17268690.
↑ "IBM Automatic Binary Optimizer for z/OS - Overview". www.ibm.com. 2015. Archived from the original on 2020-10-18. Retrieved 2020-05-15.
↑ "IBM Automatic Binary Optimizer for z/OS Trial Cloud Service". optimizer.ibm.com. 2020. Archived from the original on 2021-01-19. Retrieved 2021-10-27.
↑ "The Binary Code Optimizer". Archived from the original on 2010-07-22. Retrieved 2010-01-07.
↑ Duesterwald, E. (2005). "Design and Engineering of a Dynamic Binary Optimizer". Proceedings of the IEEE. 93 (2): 436–448. doi:10.1109/JPROC.2004.840302. S2CID 2217101.
↑ Xu, Chaohao; Li, Jianhui; Bao, Tao; Wang, Yun; Huang, Bo (2007-06-13). "Metadata driven memory optimizations in dynamic binary translator". Proceedings of the 3rd international conference on Virtual execution environments - VEE '07. Association for Computing Machinery. pp. 148–157. doi:10.1145/1254810.1254831. ISBN 978-1-59593630-1. S2CID 15234434. Archived from the original on 2021-10-27. Retrieved 2021-10-27– via ACM Digital Library.
↑ "Archived copy" (PDF). Archived (PDF) from the original on 2009-04-19. Retrieved 2010-01-07.{{cite web}}: CS1 maint: archived copy as title (link)
↑ Kim, Jinpyo; Hsu, Wei-Chung; Yew, Pen-Chung (2007). "COBRA: An Adaptive Runtime Binary Optimization Framework for Multithreaded Applications". 2007 International Conference on Parallel Processing (ICPP 2007). p. 25. doi:10.1109/ICPP.2007.23. ISBN 978-0-7695-2933-2. S2CID 15079211.
↑ "Archived copy" (PDF). Archived from the original (PDF) on 2010-09-11. Retrieved 2010-01-07.{{cite web}}: CS1 maint: archived copy as title (link)
↑ ""SOLAR" Software Optimization at Link-time And Run-time". Archived from the original on 2016-02-14.
↑ "Dynimize Product Overview". dynimize.com. Archived from the original on 2021-10-25. Retrieved 2021-04-26.
↑ Panchenko, Maksim; Auler, Rafael; Nell, Bill; Ottoni, Guilherme (2019-02-16). "BOLT: A Practical Binary Optimizer for Data Centers and Beyond". 2019 IEEE/ACM International Symposium on Code Generation and Optimization (CGO). pp. 2–14. arXiv: 1807.06735 . doi:10.1109/CGO.2019.8661201. ISBN 978-1-7281-1436-1. S2CID 49869552.

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[IBM-1] "Archived copy" (PDF). Archived from the original (PDF) on 2010-07-11. Retrieved 2010-01-07.{{cite web}}: CS1 maint: archived copy as title (link)

[Evans_1982-2] Evans, Michael (1982-12-01). "Software engineering for the Cobol environment". Communications of the ACM. 25 (12): 874–882. doi: 10.1145/358728.358732 . S2CID 17268690.

[IBM_ABO_2015-3] "IBM Automatic Binary Optimizer for z/OS - Overview". www.ibm.com. 2015. Archived from the original on 2020-10-18. Retrieved 2020-05-15.

[IBM_ABO_2020-4] "IBM Automatic Binary Optimizer for z/OS Trial Cloud Service". optimizer.ibm.com. 2020. Archived from the original on 2021-01-19. Retrieved 2021-10-27.

[Binopt-5] "The Binary Code Optimizer". Archived from the original on 2010-07-22. Retrieved 2010-01-07.

[Duesterwald_2005-6] Duesterwald, E. (2005). "Design and Engineering of a Dynamic Binary Optimizer". Proceedings of the IEEE. 93 (2): 436–448. doi:10.1109/JPROC.2004.840302. S2CID 2217101.

[Xu-Li-Bao-Wang-Huang_2007-7] Xu, Chaohao; Li, Jianhui; Bao, Tao; Wang, Yun; Huang, Bo (2007-06-13). "Metadata driven memory optimizations in dynamic binary translator". Proceedings of the 3rd international conference on Virtual execution environments - VEE '07. Association for Computing Machinery. pp. 148–157. doi:10.1145/1254810.1254831. ISBN 978-1-59593630-1. S2CID 15234434. Archived from the original on 2021-10-27. Retrieved 2021-10-27– via ACM Digital Library.

[CSD_1994-8] "Archived copy" (PDF). Archived (PDF) from the original on 2009-04-19. Retrieved 2010-01-07.{{cite web}}: CS1 maint: archived copy as title (link)

[Kim-Hse-Yew_2007-9] Kim, Jinpyo; Hsu, Wei-Chung; Yew, Pen-Chung (2007). "COBRA: An Adaptive Runtime Binary Optimization Framework for Multithreaded Applications". 2007 International Conference on Parallel Processing (ICPP 2007). p. 25. doi:10.1109/ICPP.2007.23. ISBN 978-0-7695-2933-2. S2CID 15079211.

[Spike_2010-10] "Archived copy" (PDF). Archived from the original (PDF) on 2010-09-11. Retrieved 2010-01-07.{{cite web}}: CS1 maint: archived copy as title (link)

[SOLAR-11] ""SOLAR" Software Optimization at Link-time And Run-time". Archived from the original on 2016-02-14.

[Dynimize-12] "Dynimize Product Overview". dynimize.com. Archived from the original on 2021-10-25. Retrieved 2021-04-26.

[Panchenko-Auler_2019-13] Panchenko, Maksim; Auler, Rafael; Nell, Bill; Ottoni, Guilherme (2019-02-16). "BOLT: A Practical Binary Optimizer for Data Centers and Beyond". 2019 IEEE/ACM International Symposium on Code Generation and Optimization (CGO). pp. 2–14. arXiv: 1807.06735 . doi:10.1109/CGO.2019.8661201. ISBN 978-1-7281-1436-1. S2CID 49869552.

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