Profile Guided Optimization

Definitions

1. A two-pass compiler optimization technique where the program is first compiled with instrumentation, then run against representative workloads to collect runtime profiling data (branch frequencies, hot paths, cache behavior), and finally recompiled using that data to make better inlining, code layout, and branch prediction decisions.

   In plain English: A way to make software faster by first observing how it actually runs, then recompiling it with that knowledge to optimize the most-used paths.

   Example: "PGO shaved 15% off our server's p99 latency because the compiler could lay out the hot path without any branches."

Related Terms

• Tail Call Optimization
• Cache
• JIT
• Profile
• Vectorization
• Hot Path
• Tail Call Optimization
• Intermediate Representation
• AOT Compilation
• Loop Unrolling
• Unrolling