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Code Issues Projects Releases Packages Wiki Activity Actions 13

gh-91276: Make JUMP_IF_TRUE_OR_POP/JUMP_IF_FALSE_OR_POP relative (GH-32215)

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Irit Katriel 2022-04-15 20:19:24 +01:00 • committed by GitHub
parent 5d421d7342
commit ea2ae02607
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8 changed files with 38 additions and 12 deletions
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13
Doc/library/dis.rst
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@ -993,21 +993,26 @@ iterations of the loop.
.. versionadded:: 3.11
.. opcode:: JUMP_IF_TRUE_OR_POP (target)
.. opcode:: JUMP_IF_TRUE_OR_POP (delta)
If TOS is true, sets the bytecode counter to *target* and leaves TOS on the
If TOS is true, increments the bytecode counter by *delta* and leaves TOS on the
stack. Otherwise (TOS is false), TOS is popped.
.. versionadded:: 3.1
.. versionchanged:: 3.11
The oparg is now a relative delta rather than an absolute target.
.. opcode:: JUMP_IF_FALSE_OR_POP (target)
.. opcode:: JUMP_IF_FALSE_OR_POP (delta)
If TOS is false, sets the bytecode counter to *target* and leaves TOS on the
If TOS is false, increments the bytecode counter by *delta* and leaves TOS on the
stack. Otherwise (TOS is true), TOS is popped.
.. versionadded:: 3.1
.. versionchanged:: 3.11
The oparg is now a relative delta rather than an absolute target.
.. opcode:: FOR_ITER (delta)

3
Doc/whatsnew/3.11.rst
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@ -787,6 +787,9 @@ CPython bytecode changes
:opcode:`POP_JUMP_FORWARD_IF_NONE` and :opcode:`POP_JUMP_BACKWARD_IF_NONE`
opcodes to speed up conditional jumps.
* :opcode:`JUMP_IF_TRUE_OR_POP` and :opcode:`JUMP_IF_FALSE_OR_POP` are now
relative rather than absolute.
Deprecated
==========

2
Include/opcode.h generated
View file

@ -199,7 +199,7 @@ static const uint32_t _PyOpcode_RelativeJump[8] = {
0U,
0U,
536870912U,
135020544U,
135118848U,
4163U,
122880U,
0U,

4
Lib/importlib/_bootstrap_external.py
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@ -401,6 +401,7 @@ _code_type = type(_write_atomic.__code__)
# Python 3.11a6 3491 (remove JUMP_IF_NOT_EG_MATCH, add CHECK_EG_MATCH,
# add JUMP_BACKWARD_NO_INTERRUPT, make JUMP_NO_INTERRUPT virtual)
# Python 3.11a7 3492 (make POP_JUMP_IF_NONE/NOT_NONE/TRUE/FALSE relative)
# Python 3.11a7 3493 (Make JUMP_IF_TRUE_OR_POP/JUMP_IF_FALSE_OR_POP relative)
# Python 3.12 will start with magic number 3500
@ -415,7 +416,8 @@ _code_type = type(_write_atomic.__code__)
# Whenever MAGIC_NUMBER is changed, the ranges in the magic_values array
# in PC/launcher.c must also be updated.
MAGIC_NUMBER = (3492).to_bytes(2, 'little') + b'\r\n'
MAGIC_NUMBER = (3493).to_bytes(2, 'little') + b'\r\n'
_RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little') # For import.c
_PYCACHE = '__pycache__'

4
Lib/opcode.py
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@ -131,8 +131,8 @@ hascompare.append(107)
name_op('IMPORT_NAME', 108) # Index in name list
name_op('IMPORT_FROM', 109) # Index in name list
jrel_op('JUMP_FORWARD', 110) # Number of words to skip
jabs_op('JUMP_IF_FALSE_OR_POP', 111) # Target byte offset from beginning of code
jabs_op('JUMP_IF_TRUE_OR_POP', 112) # ""
jrel_op('JUMP_IF_FALSE_OR_POP', 111) # Number of words to skip
jrel_op('JUMP_IF_TRUE_OR_POP', 112) # ""
jrel_op('POP_JUMP_FORWARD_IF_FALSE', 114)
jrel_op('POP_JUMP_FORWARD_IF_TRUE', 115)
name_op('LOAD_GLOBAL', 116, 5) # Index in name list

1
Misc/NEWS.d/next/Core and Builtins/2022-03-31-14-33-48.bpo-47120.6S_uoU.rst Normal file
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@ -0,0 +1 @@
Make opcodes :opcode:`JUMP_IF_TRUE_OR_POP` and :opcode:`JUMP_IF_FALSE_OR_POP` relative rather than absolute.

8
Python/ceval.c
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@ -4081,7 +4081,7 @@ handle_eval_breaker:
DISPATCH();
}
if (Py_IsFalse(cond)) {
JUMPTO(oparg);
JUMPBY(oparg);
DISPATCH();
}
err = PyObject_IsTrue(cond);
@ -4090,7 +4090,7 @@ handle_eval_breaker:
Py_DECREF(cond);
}
else if (err == 0)
JUMPTO(oparg);
JUMPBY(oparg);
else
goto error;
DISPATCH();
@ -4105,12 +4105,12 @@ handle_eval_breaker:
DISPATCH();
}
if (Py_IsTrue(cond)) {
JUMPTO(oparg);
JUMPBY(oparg);
DISPATCH();
}
err = PyObject_IsTrue(cond);
if (err > 0) {
JUMPTO(oparg);
JUMPBY(oparg);
}
else if (err == 0) {
STACK_SHRINK(1);

15
Python/compile.c
View file

@ -7672,6 +7672,21 @@ normalize_jumps(struct assembler *a)
last->i_opcode = is_forward ?
POP_JUMP_FORWARD_IF_TRUE : POP_JUMP_BACKWARD_IF_TRUE;
break;
case JUMP_IF_TRUE_OR_POP:
case JUMP_IF_FALSE_OR_POP:
if (!is_forward) {
/* As far as we can tell, the compiler never emits
* these jumps with a backwards target. If/when this
* exception is raised, we have found a use case for
* a backwards version of this jump (or to replace
* it with the sequence (COPY 1, POP_JUMP_IF_T/F, POP)
*/
PyErr_Format(PyExc_SystemError,
"unexpected %s jumping backwards",
last->i_opcode == JUMP_IF_TRUE_OR_POP ?
"JUMP_IF_TRUE_OR_POP" : "JUMP_IF_FALSE_OR_POP");
}
break;
}
}
}