Binary translation

In computing, binary translation (or (binary) recompilation) is the emulation of one instruction set by another through translation of binary code. Sequences of instructions are translated from the source 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.

The two main types are static and dynamic binary translation. Translation can be done in hardware (for example, by circuits in a CPU) or in software (e.g. run-time engines, statical recompiler, emulators).

Motivation for using the complex process of binary translation is either that a compilation of the source code to the destination platform or instruction set is not available (or technically problematic) or when the source code is plainly not available anymore (Abandonware).

Performance-wise static recompilations have the potential to achieve a better performance than real emulation approaches as in optimal case one overhead introducing interface is removed.

A translator using static binary translation aims to convert all of the code of an executable file into code that runs on the target architecture without having to run the code first, as is done in dynamic binary translation. This is very difficult to do correctly, since not all the code can be discovered by the translator. For example, some parts of the executable may be reachable only through indirect branches, whose value is known only at run-time.

One such static binary translator uses universal superoptimizer peephole technology (developed by Sorav Bansal, and Alex Aiken from Stanford University) to perform efficient translation between possibly many source and target pairs, with considerably low development costs and high performance of the target binary. In experiments of PowerPC-to-x86 translations, some binaries even outperformed native versions, but on average they ran at two-thirds of native speed.

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