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GeezerVison is showing github.com — gh-148211: decompose `_POP_TOP_LOAD_CONST_INLINE(_BORROW)` in JIT by NekoAsakura · Pull Request #148230 · python/cpython

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NekoAsakura commented Apr 7, 2026 •

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The composite uop definitions in bytecodes.c are kept for now — remove_unneeded_uops still produces them as intermediate forms during push/pop cancellation.

cpython/Python/optimizer_analysis.c

Lines 610 to 653 in 4ff8b07

	const uint16_t op_without_push[MAX_UOP_ID + 1] = {
	[_COPY] = _NOP,
	[_LOAD_CONST_INLINE] = _NOP,
	[_LOAD_CONST_INLINE_BORROW] = _NOP,
	[_LOAD_CONST_UNDER_INLINE] = _POP_TOP_LOAD_CONST_INLINE,
	[_LOAD_CONST_UNDER_INLINE_BORROW] = _POP_TOP_LOAD_CONST_INLINE_BORROW,
	[_LOAD_FAST] = _NOP,
	[_LOAD_FAST_BORROW] = _NOP,
	[_LOAD_SMALL_INT] = _NOP,
	[_POP_TOP_LOAD_CONST_INLINE] = _POP_TOP,
	[_POP_TOP_LOAD_CONST_INLINE_BORROW] = _POP_TOP,
	[_POP_TWO_LOAD_CONST_INLINE_BORROW] = _POP_TWO,
	[_POP_CALL_ONE_LOAD_CONST_INLINE_BORROW] = _POP_CALL_ONE,
	[_POP_CALL_TWO_LOAD_CONST_INLINE_BORROW] = _POP_CALL_TWO,
	[_SHUFFLE_2_LOAD_CONST_INLINE_BORROW] = _POP_CALL_ONE_LOAD_CONST_INLINE_BORROW,
	};

	const bool op_skip[MAX_UOP_ID + 1] = {
	[_NOP] = true,
	[_CHECK_VALIDITY] = true,
	[_CHECK_PERIODIC] = true,
	[_SET_IP] = true,
	};

	const uint16_t op_without_pop[MAX_UOP_ID + 1] = {
	[_POP_TOP] = _NOP,
	[_POP_TOP_NOP] = _NOP,
	[_POP_TOP_INT] = _NOP,
	[_POP_TOP_FLOAT] = _NOP,
	[_POP_TOP_UNICODE] = _NOP,
	[_POP_TOP_LOAD_CONST_INLINE] = _LOAD_CONST_INLINE,
	[_POP_TOP_LOAD_CONST_INLINE_BORROW] = _LOAD_CONST_INLINE_BORROW,
	[_POP_TWO] = _POP_TOP,
	[_POP_TWO_LOAD_CONST_INLINE_BORROW] = _POP_TOP_LOAD_CONST_INLINE_BORROW,
	[_POP_CALL_TWO_LOAD_CONST_INLINE_BORROW] = _POP_CALL_ONE_LOAD_CONST_INLINE_BORROW,
	[_POP_CALL_ONE_LOAD_CONST_INLINE_BORROW] = _POP_CALL_LOAD_CONST_INLINE_BORROW,
	[_POP_CALL_TWO] = _POP_CALL_ONE,
	[_POP_CALL_ONE] = _POP_CALL,
	};

	const uint16_t op_without_pop_null[MAX_UOP_ID + 1] = {
	[_POP_CALL] = _POP_TOP,
	[_POP_CALL_LOAD_CONST_INLINE_BORROW] = _POP_TOP_LOAD_CONST_INLINE_BORROW,
	};

Specifically, these composites chain through _POP_TOP_LOAD_CONST_INLINE_BORROW in the op_without_push / op_without_pop / op_without_pop_null tables:

_POP_TWO_LOAD_CONST_INLINE_BORROW
_POP_CALL_LOAD_CONST_INLINE_BORROW
_POP_CALL_ONE_LOAD_CONST_INLINE_BORROW
_POP_CALL_TWO_LOAD_CONST_INLINE_BORROW
_SHUFFLE_2_LOAD_CONST_INLINE_BORROW

Additionally, _LOAD_CONST_UNDER_INLINE(_BORROW) references _POP_TOP_LOAD_CONST_INLINE(_BORROW) as a target in op_without_push — those table entries would need updating too.

Once these dependents are decomposed, the definitions can be fully removed.

Issue: Refactor the JIT uops #148211

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          pythongh-148211: decompose _POP_TOP_LOAD_CONST_INLINE(_BORROW) in JIT

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NekoAsakura requested review from Fidget-Spinner, markshannon, savannahostrowski and tomasr8 as code owners

April 7, 2026 19:35

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Apr 7, 2026

Refactor the JIT uops #148211

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Fidget-Spinner commented Apr 7, 2026

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Feel free to remove the composite uops altogether, including removing them from remove_unneeded_uops!

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Apr 7, 2026

Fidget-Spinner commented Apr 7, 2026

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Ah wait, it seems this is quite hard to remove from the unneeded ops pass without modifying it heavily. So let's skip that for now. Thanks!

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Fidget-Spinner approved these changes

Apr 7, 2026

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LGTM. Thanks a lot!

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Python/optimizer_analysis.c Resolved

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bedevere-app Bot added awaiting merge and removed awaiting review labels

Apr 7, 2026

NekoAsakura mentioned this pull request

Apr 8, 2026

Remove duplicate uops _LOAD_CONST_UNDER_INLINE(_BORROW) in JIT #148235

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Fidget-Spinner commented Apr 8, 2026

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Please fix the merge conflicts from the other PR. Thank you!

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          Merge branch 'main' into pythongh-148211/decompose-pop-top

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NekoAsakura commented Apr 8, 2026

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Done :)

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NekoAsakura added 2 commits

April 8, 2026 21:32


          Merge branch 'main' into pythongh-148211/decompose-pop-top

a8abce8


          pythongh-148211: decompose _POP_TOP_LOAD_CONST_INLINE(_BORROW) in JIT

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Fidget-Spinner merged commit d2fa4b2 into python:main

Apr 8, 2026

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bedevere-app Bot removed the awaiting merge label

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NekoAsakura deleted the gh-148211/decompose-pop-top branch

April 8, 2026 15:22

NekoAsakura mentioned this pull request

Apr 9, 2026

gh-148211: decompose [_POP_CALL_X/_SHUFFLE_2]_LOAD_CONST_INLINE_BORROW in JIT #148313

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ljfp pushed a commit to ljfp/cpython that referenced this pull request

Apr 25, 2026


          pythongh-148211: decompose _POP_TOP_LOAD_CONST_INLINE(_BORROW) in J…

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…IT (pythonGH-148230)

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NekoAsakura commented Apr 7, 2026 •

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