GPT-5.6 helped trace a performance regression to an Intel CPU microcode workaround
charliermarsh · x · 2026-07-22
A developer reports that GPT-5.6 helped track down a mysterious performance regression to an Intel CPU microcode workaround.
- The bug was caused by a workaround for an Intel CPU issue.
- That workaround can slow conditional jumps that cross a 32-byte boundary.
- Rebuilding with -mbranches-within-32B-boundaries restored performance.
- The post frames the result as a striking example of AI-assisted debugging in real engineering work.
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