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ZeroIntensity merged 3 commits into from
Nov 24, 2025
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gh-141004: Document stack effect APIs #141843

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e73dfcd
Document stack effect APIs.
ZeroIntensity Nov 22, 2025
1bb20e3
Document the jump parameter.
ZeroIntensity Nov 22, 2025
ebc1d47
Update Doc/c-api/veryhigh.rst
ZeroIntensity Nov 24, 2025
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40 changes: 40 additions & 0 deletions Doc/c-api/veryhigh.rst
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Expand Up@@ -396,3 +396,43 @@ Available start symbols
* :pep:`484`

.. versionadded:: 3.8


Stack Effects
^^^^^^^^^^^^^
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@vstinnervstinnerNov 24, 2025

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I'm not sure that these funtions belong to "The Very High Level Layer", but I cannot find a better home for them. So I'm fine with documenting them in this file.

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@ZeroIntensityZeroIntensityNov 24, 2025

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The ideal solution would be to move all the compiler functions to their own file, but unfortunately, we're not allowed to do that without the EB approving it (see #141811 (comment)).


.. seealso::
:py:func:`dis.stack_effect`


.. c:macro:: PY_INVALID_STACK_EFFECT

Sentinel value representing an invalid stack effect.

This is currently equivalent to ``INT_MAX``.

.. versionadded:: 3.8


.. c:function:: int PyCompile_OpcodeStackEffect(int opcode, int oparg)

Compute the stack effect of *opcode* with argument *oparg*.

On success, this function returns the stack effect; on failure, this
returns :c:macro:`PY_INVALID_STACK_EFFECT`.

.. versionadded:: 3.4


.. c:function:: int PyCompile_OpcodeStackEffectWithJump(int opcode, int oparg, int jump)

Similar to :c:func:`PyCompile_OpcodeStackEffect`, but don't include the
stack effect of jumping if *jump* is zero.

If *jump* is ``0``, this will not include the stack effect of jumping, but
if *jump* is ``1`` or ``-1``, this will include it.

On success, this function returns the stack effect; on failure, this
returns :c:macro:`PY_INVALID_STACK_EFFECT`.

.. versionadded:: 3.8
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