python / python/cpython

JIT coverage can be improved considerably

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#142,982 5 comments 0 reactions 2 assignees View on GitHub

@Fidget-Spinner is already working on this.

Since Dec 29, 2025.

interpreter-core topic-JIT type-feature
Dominant language
Python
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Description

JIT coverage is still quite variable. For some benchmarks, e.g. richards it is close to 100%.
For others, much lower:

https://github.com/savannahostrowski/pyperf_bench/blob/main/profiling/jit.svg

Note: A fair bit of the time attributed to the interpreter is frame cleanup, so makes the interpreter fractions look larger than they are.

We can increase JIT coverage, by:

  • Treating dynamic exits, like side exits: warming up and compiling a new side trace.
  • Adding possible jit entry points at function entries, as well as backward edges.
Linked PRs
  • gh-143391
  • gh-143977

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