Google migrates billions of lines of code to Arm with the help of AI

"The report makes it clear that the difficulty of such migrations no longer lies in translating machine language or rewriting source code. Whereas in the past, a lot of attention was paid to binary translation, the reality today is that modern compilers and open-source ecosystems make this step largely unnecessary. The real challenge lies in the enormous number of small, often trivial adjustments scattered across millions of lines of code and thousands of configuration files."

"Google analyzed a total of 38,000 code commits that were part of the migration. This revealed that only a fraction related to actual code translation, while the majority consisted of adjustments to build systems, test configurations, and infrastructure settings. The researchers emphasize that these tasks are simple in themselves, but their scale and distribution across the entire code base pose a huge coordination challenge."

"To address this problem, Google deployed its internal automation system, Rosie. This enabled the company to automatically generate, test, and submit thousands of small changes to the appropriate teams. Another system, CHAMP, then checked whether the new Arm versions of software ran as stably and reliably as their x86 counterparts. Thanks to this approach, most of the migration took place without the direct intervention of developers."

Google migrated its software ecosystem from x86 processors to Arm at warehouse scale. Modern compilers and open-source ecosystems eliminated most need for binary translation or massive source rewrites. The main difficulty came from millions of small, trivial adjustments spread across code, build systems, tests, and configuration files rather than code translation. Analysis of 38,000 migration-related commits showed only a fraction involved code translation, with the majority modifying build systems, test configurations, and infrastructure settings. Google automated the migration using internal systems—Rosie to generate, test, and submit changes, CHAMP to validate Arm stability, and CogniPort to autonomously repair failed builds and tests.

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