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GeezerVison is showing github.com — gh-126910: Verify that JIT stencils preserve frame pointer by Fidget-Spinner · Pull Request #146524 · python/cpython

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@Fidget-Spinner

@Fidget-Spinner Fidget-Spinner commented Mar 27, 2026 •
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This PR introduces a lightweight assembly verifier that the JIT does not clobber the frame pointer.

I verified that without #146521 , this will fail JIT compilation on x86-64. Will use CI to test AArch64.

This is expected to fail JIT CI until that PR lands.

  • Issue: Supporting stack unwinding in the JIT compiler #126910

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@Fidget-Spinner
Verify that JIT stencils preserve frame pointer
fae87b9
@Fidget-Spinner
Fidget-Spinner requested review from brandtbucher, diegorusso and savannahostrowski as code owners March 27, 2026 15:18
@bedevere-app bedevere-app Bot added the awaiting core review label Mar 27, 2026
@bedevere-app bedevere-app Bot mentioned this pull request Mar 27, 2026
Supporting stack unwinding in the JIT compiler #126910
Open
@Fidget-Spinner Fidget-Spinner added the skip news label Mar 27, 2026
Fidget-Spinner added 4 commits March 27, 2026 23:22
@Fidget-Spinner
Update _optimizers.py
776e109
@Fidget-Spinner
Fix lint
8ad1774
@Fidget-Spinner
more linting
8c9fb56
@Fidget-Spinner
Merge remote-tracking branch 'upstream/main' into fp_verifier
a66c8cd
diegorusso
diegorusso approved these changes Mar 27, 2026
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LGTM, thanks!

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@bedevere-app bedevere-app Bot added awaiting merge and removed awaiting core review labels Mar 27, 2026
@Fidget-Spinner

Fidget-Spinner commented Mar 27, 2026 •
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Alright! Confirmed all platforms that currently support frame pointers (x64 and AArch64) fail, so this means it does work!
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Fidget-Spinner added 2 commits March 28, 2026 01:55
@Fidget-Spinner
Merge remote-tracking branch 'upstream/main' into fp_verifier
c3eaa2a
@Fidget-Spinner
Try a fix
bde6c5b
@Fidget-Spinner
Fidget-Spinner requested review from FFY00, ZeroIntensity and ericsnowcurrently as code owners March 27, 2026 18:47
@Fidget-Spinner
PEP 7
3e1199e
@Fidget-Spinner

Fidget-Spinner commented Mar 27, 2026

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Just an FYI: discussed with Mark on 26 Mar UK time that we should just remove the clever tricks to get the frame address and use a simple approximate one.
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Fidget-Spinner added 3 commits March 28, 2026 03:04
@Fidget-Spinner
Revert "PEP 7"
743cc6a 
This reverts commit 3e1199e.
@Fidget-Spinner
Revert "Try a fix"
d7a2d30 
This reverts commit bde6c5b.
@Fidget-Spinner
Apply Brandt's fix
108ea06
@Fidget-Spinner
Fidget-Spinner requested a review from markshannon as a code owner March 27, 2026 19:07
@Fidget-Spinner

Fidget-Spinner commented Mar 27, 2026 •
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Had to partially revert some of #146521 because the current recursion limit/stack overflow detection is working strangely after that with the JIT. Brandt's suggestion to just whack a Py_NO_INLINE on the function work. Good thing we have the verifier now so that we don't use one of the other recursion check functions and inadvertently introduce this again into the JIT.
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@Fidget-Spinner
Fidget-Spinner merged commit 1384f02 into python:main Mar 27, 2026
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@bedevere-app bedevere-app Bot removed the awaiting merge label Mar 27, 2026
@Fidget-Spinner
Fidget-Spinner deleted the fp_verifier branch March 27, 2026 19:39
@pablogsal pablogsal mentioned this pull request Apr 4, 2026
gh-130273: Fix traceback color output with unicode characters #142529
Merged
clin1234 pushed a commit to clin1234/cpython that referenced this pull request Apr 16, 2026
@Fidget-Spinner @clin1234
pythongh-126910: Verify that JIT stencils preserve frame pointer (pyt…
04ecc20 
…honGH-146524)
ljfp pushed a commit to ljfp/cpython that referenced this pull request Apr 25, 2026
@Fidget-Spinner @ljfp
pythongh-126910: Verify that JIT stencils preserve frame pointer (pyt…
0036cc1 
…honGH-146524)
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@diegorusso diegorusso diegorusso approved these changes
@brandtbucher brandtbucher Awaiting requested review from brandtbucher brandtbucher is a code owner
@savannahostrowski savannahostrowski Awaiting requested review from savannahostrowski
@ericsnowcurrently ericsnowcurrently Awaiting requested review from ericsnowcurrently ericsnowcurrently is a code owner
@ZeroIntensity ZeroIntensity Awaiting requested review from ZeroIntensity ZeroIntensity is a code owner
@FFY00 FFY00 Awaiting requested review from FFY00 FFY00 is a code owner
@markshannon markshannon Awaiting requested review from markshannon markshannon is a code owner

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@Fidget-Spinner @diegorusso
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