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gh-135447: Document NOT_TAKEN & POP_ITER bytecode instructions #135803

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Merged
merged 25 commits into from
Sep 28, 2025
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gh-135447: Document NOT_TAKEN & POP_ITER bytecode instructions #135803

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Document BUILD_TEMPLATE
Yzi-Li Jun 22, 2025
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Document BUILD_INTERPOLATION
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Use it
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Document NOT_TAKEN
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Fix according to bytecodes.c
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Fix a small error
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Update Doc/library/dis.rst
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Document BUILD_TEMPLATE
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Document BUILD_INTERPOLATION
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Use it
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Document NOT_TAKEN
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Fix according to bytecodes.c
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Fix a small error
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Merge branch 'main' into fix-issue-135447
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Merge branch 'main' into fix-issue-135447
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Merge branch 'main' into fix-issue-135447
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Remove duplicate BUILD_INTERPOLATION/BUILD_TEMPLATE; clarify NOT_TAKE…
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27 changes: 27 additions & 0 deletions Doc/library/dis.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -585,6 +585,12 @@ operations on it as if it was a Python list. The top of the stack corresponds to
generate line tracing events.


.. opcode:: NOT_TAKEN
Do nothing code. Used as a hint to the interpreter that a branch was predicted
as not taken.
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I forgot what NOT_TAKEN does, but the rest look good. Maybe @iritkatriel knows?

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It indeed does nothing. Not sure it's related to prediction though. It think it's to give tracing applications like code coverage a way to distinguish between the taken/not taken branches.

CC @markshannon

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pure inst(NOP, (--)) {
}

family(RESUME, 0) = {
    RESUME_CHECK,
};

macro(NOT_TAKEN) = NOP;

Can we consider its behavior to be the same as NOP?

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Yes its a NOP but I forgot if its a hint or not.

.. versionadded:: 3.14


.. opcode:: POP_TOP

Removes the top-of-stack item::
Expand Down Expand Up @@ -1163,6 +1169,27 @@ iterations of the loop.
.. versionadded:: 3.6


.. opcode:: BUILD_INTERPOLATION

It expects as stack inputs (from top of stack down):

* ``format``: ``STACK[oparg & 1]``
* ``str``: ``STACK[-1 - (oparg & 1)]``
* ``value``: ``STACK[-2 - (oparg & 1)]``

It outputs the interpolation object to ``STACK[-1]`` after consuming its inputs.

.. versionadded:: 3.14


.. opcode:: BUILD_TEMPLATE

It consumes ``STACK[-1]``(string) and ``STACK[-2]``(interpolations) and
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Nice, this is pretty close. One small error: it's the other way around, interpolations is STACK[-1], string is STACK[-2]. This is because the bytecode definition file models a stack (LIFO), which means the rightmost element is the top of the stack.

outputs the template object to ``STACK[-1]``.

.. versionadded:: 3.14


.. opcode:: LIST_EXTEND (i)

Implements::
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