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gh-95913: Edit, expand & format Bytecode sect in 3.11 WhatsNew (GH-98559)
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‎Doc/whatsnew/3.11.rst‎

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@@ -1481,58 +1481,100 @@ contributors are volunteers from the community.
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CPython bytecode changes
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========================
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* The bytecode now contains inline cache entries, which take the form of
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:opcode:`CACHE` instructions. Many opcodes expect to be followed by an exact
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number of caches, and instruct the interpreter to skip over them at runtime.
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Populated caches can look like arbitrary instructions, so great care should be
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taken when reading or modifying raw, adaptive bytecode containing quickened
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data.
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The bytecode now contains inline cache entries,
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which take the form of the newly-added :opcode:`CACHE` instructions.
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Many opcodes expect to be followed by an exact number of caches,
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and instruct the interpreter to skip over them at runtime.
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Populated caches can look like arbitrary instructions,
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so great care should be taken when reading or modifying
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raw, adaptive bytecode containing quickened data.
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* Replaced all numeric ``BINARY_*`` and ``INPLACE_*`` instructions with a single
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:opcode:`BINARY_OP` implementation.
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* Replaced the three call instructions: :opcode:`CALL_FUNCTION`,
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:opcode:`CALL_FUNCTION_KW` and :opcode:`CALL_METHOD` with
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:opcode:`PUSH_NULL`, :opcode:`PRECALL`, :opcode:`CALL`,
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and :opcode:`KW_NAMES`.
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This decouples the argument shifting for methods from the handling of
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keyword arguments and allows better specialization of calls.
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.. _whatsnew311-added-opcodes:
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* Removed ``COPY_DICT_WITHOUT_KEYS`` and ``GEN_START``.
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New opcodes
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-----------
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* :opcode:`ASYNC_GEN_WRAP`, :opcode:`RETURN_GENERATOR` and :opcode:`SEND`,
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used in generators and co-routines.
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* :opcode:`MATCH_CLASS` and :opcode:`MATCH_KEYS` no longer push an additional
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boolean value indicating whether the match succeeded or failed. Instead, they
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indicate failure with :const:`None` (where a tuple of extracted values would
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otherwise be).
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* :opcode:`COPY_FREE_VARS`,
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which avoids needing special caller-side code for closures.
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* Replace several stack manipulation instructions (``DUP_TOP``, ``DUP_TOP_TWO``,
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``ROT_TWO``, ``ROT_THREE``, ``ROT_FOUR``, and ``ROT_N``) with new
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:opcode:`COPY` and :opcode:`SWAP` instructions.
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* :opcode:`JUMP_BACKWARD_NO_INTERRUPT`,
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for use in certain loops where handling interrupts is undesirable.
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* Replaced :opcode:`JUMP_IF_NOT_EXC_MATCH` by :opcode:`CHECK_EXC_MATCH` which
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performs the check but does not jump.
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* :opcode:`MAKE_CELL`, to create :ref:`cell-objects`.
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* Replaced :opcode:`JUMP_IF_NOT_EG_MATCH` by :opcode:`CHECK_EG_MATCH` which
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performs the check but does not jump.
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* :opcode:`CHECK_EG_MATCH` and :opcode:`PREP_RERAISE_STAR`,
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to handle the :ref:`new exception groups and except* <whatsnew311-pep654>`
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added in :pep:`654`.
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* Replaced :opcode:`JUMP_ABSOLUTE` by the relative :opcode:`JUMP_BACKWARD`.
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* :opcode:`PUSH_EXC_INFO`, for use in exception handlers.
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* Added :opcode:`JUMP_BACKWARD_NO_INTERRUPT`, which is used in certain loops where it
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is undesirable to handle interrupts.
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* :opcode:`RESUME`, a no-op,
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for internal tracing, debugging and optimization checks.
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* Replaced :opcode:`POP_JUMP_IF_TRUE` and :opcode:`POP_JUMP_IF_FALSE` by
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the relative :opcode:`POP_JUMP_FORWARD_IF_TRUE`, :opcode:`POP_JUMP_BACKWARD_IF_TRUE`,
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:opcode:`POP_JUMP_FORWARD_IF_FALSE` and :opcode:`POP_JUMP_BACKWARD_IF_FALSE`.
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* Added :opcode:`POP_JUMP_FORWARD_IF_NOT_NONE`, :opcode:`POP_JUMP_BACKWARD_IF_NOT_NONE`,
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:opcode:`POP_JUMP_FORWARD_IF_NONE` and :opcode:`POP_JUMP_BACKWARD_IF_NONE`
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opcodes to speed up conditional jumps.
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.. _whatsnew311-replaced-opcodes:
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* :opcode:`JUMP_IF_TRUE_OR_POP` and :opcode:`JUMP_IF_FALSE_OR_POP` are now
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relative rather than absolute.
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Replaced opcodes
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----------------
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* :opcode:`RESUME` has been added. It is a no-op. Performs internal tracing,
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debugging and optimization checks.
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+------------------------------------+-----------------------------------+-----------------------------------------+
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| Replaced Opcode(s) | New Opcode(s) | Notes |
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+====================================+===================================+=========================================+
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| | :opcode:`!BINARY_*` | :opcode:`BINARY_OP` | Replaced all numeric binary/in-place |
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| | :opcode:`!INPLACE_*` | | opcodes with a single opcode |
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+------------------------------------+-----------------------------------+-----------------------------------------+
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| | :opcode:`!CALL_FUNCTION` | | :opcode:`CALL` | Decouples argument shifting for methods |
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| | :opcode:`!CALL_FUNCTION_KW` | | :opcode:`KW_NAMES` | from handling of keyword arguments; |
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| | :opcode:`!CALL_METHOD` | | :opcode:`PRECALL` | allows better specialization of calls |
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| | | :opcode:`PUSH_NULL` | |
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+------------------------------------+-----------------------------------+-----------------------------------------+
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| | :opcode:`!DUP_TOP` | | :opcode:`COPY` | Stack manipulation instructions |
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| | :opcode:`!DUP_TOP_TWO` | | :opcode:`SWAP` | |
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| | :opcode:`!ROT_TWO` | | |
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| | :opcode:`!ROT_THREE` | | |
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| | :opcode:`!ROT_FOUR` | | |
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| | :opcode:`!ROT_N` | | |
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+------------------------------------+-----------------------------------+-----------------------------------------+
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| | :opcode:`!JUMP_IF_NOT_EXC_MATCH` | | :opcode:`CHECK_EXC_MATCH` | Now performs check but doesn't jump |
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+------------------------------------+-----------------------------------+-----------------------------------------+
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| | :opcode:`!JUMP_ABSOLUTE` | | :opcode:`JUMP_BACKWARD` | See [#bytecode-jump]_; |
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| | :opcode:`!POP_JUMP_IF_FALSE` | | :opcode:`POP_JUMP_BACKWARD_IF_* | ``TRUE``, ``FALSE``, |
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| | :opcode:`!POP_JUMP_IF_TRUE` | <POP_JUMP_BACKWARD_IF_TRUE>` | ``NONE`` and ``NOT_NONE`` variants |
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| | | :opcode:`POP_JUMP_FORWARD_IF_* | for each direction |
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| | <POP_JUMP_FORWARD_IF_TRUE>` | |
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+------------------------------------+-----------------------------------+-----------------------------------------+
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| | :opcode:`!SETUP_WITH` | :opcode:`BEFORE_WITH` | :keyword:`with` block setup |
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| | :opcode:`!SETUP_ASYNC_WITH` | | |
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+------------------------------------+-----------------------------------+-----------------------------------------+
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.. [#bytecode-jump] All jump opcodes are now relative, including the
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existing :opcode:`JUMP_IF_TRUE_OR_POP` and :opcode:`JUMP_IF_FALSE_OR_POP`.
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The argument is now an offset from the current instruction
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rather than an absolute location.
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.. _whatsnew311-changed-opcodes:
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.. _whatsnew311-removed-opcodes:
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.. _whatsnew311-changed-removed-opcodes:
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Changed/removed opcodes
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-----------------------
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* Changed :opcode:`MATCH_CLASS` and :opcode:`MATCH_KEYS`
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to no longer push an additional boolean value to indicate success/failure.
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Instead, ``None`` is pushed on failure
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in place of the tuple of extracted values.
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* Changed opcodes that work with exceptions to reflect them
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now being represented as one item on the stack instead of three
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(see :gh:`89874`).
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* Removed :opcode:`!COPY_DICT_WITHOUT_KEYS`, :opcode:`!GEN_START`,
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:opcode:`!POP_BLOCK`, :opcode:`!SETUP_FINALLY` and :opcode:`!YIELD_FROM`.
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.. _whatsnew311-deprecated:

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