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Mar 6, 2025
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gh-128563: Clarify wording in Whats new for Tail call #130911

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6 changes: 3 additions & 3 deletions Doc/whatsnew/3.14.rst
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Expand Up @@ -301,11 +301,11 @@ For further information on how to build Python, see
cautiously revised down to 3-5%. While we expect performance results to be better
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@hauntsaninja hauntsaninja Mar 7, 2025 •
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thanks for updating the docs! it's been interesting following along the journey :-)
maybe a silly question, why do we expect performance numbers to be better than what we report?

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The computed goto bug in theory shouldnt affect modern systems that much, but it's unclear for now so I just put that therr.

than what we report, our estimates are more conservative due to a
`compiler bug <https://github.com/llvm/llvm-project/issues/106846>`_ found in
Clang/LLVM 19. We were unaware of this bug, and it artifically boosted
our numbers, resulting in inaccurate results. We sincerely apologize for
Clang/LLVM 19, which causes the normal interpreter to be slower. We were unaware of this bug,
resulting in inaccurate results. We sincerely apologize for
communicating results that were only accurate for certain versions of LLVM 19
and 20. At the time of writing, this bug has not yet been fixed in LLVM 19-21. Thus
any benchmarks with those versions of LLVM may produce artifically inflated numbers.
any benchmarks with those versions of LLVM may produce inaccurate numbers.
(Thanks to Nelson Elhage for bringing this to light.)

(Contributed by Ken Jin in :gh:`128563`, with ideas on how to implement this
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