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bpo-39320: Handle unpacking of **values in compiler (GH-18141) 

* Add DICT_UPDATE and DICT_MERGE bytecodes. Use them for ** unpacking.

* Remove BUILD_MAP_UNPACK and BUILD_MAP_UNPACK_WITH_CALL, as they are now unused.

* Update magic number for ** unpacking opcodes.

* Update dis.rst to incorporate new bytecodes.

* Add blurb entry.
This commit is contained in:
Mark Shannon 2020-01-27 09:57:45 +00:00 committed by GitHub
parent 72b1004657
commit 8a4cd700a7
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
10 changed files with 3680 additions and 3672 deletions
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21
Doc/library/dis.rst
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@ -873,32 +873,25 @@ All of the following opcodes use their arguments.
.. versionadded:: 3.9
.. opcode:: SET_UPDATE
.. opcode:: SET_UPDATE (i)
Calls ``set.update(TOS1[-i], TOS)``. Used to build sets.
.. versionadded:: 3.9
.. opcode:: BUILD_MAP_UNPACK (count)
.. opcode:: DICT_UPDATE (i)
Pops *count* mappings from the stack, merges them into a single dictionary,
and pushes the result. Implements dictionary unpacking in dictionary
displays ``{**x, **y, **z}``.
Calls ``dict.update(TOS1[-i], TOS)``. Used to build dicts.
.. versionadded:: 3.5
.. versionadded:: 3.9
.. opcode:: BUILD_MAP_UNPACK_WITH_CALL (count)
.. opcode:: DICT_MERGE
This is similar to :opcode:`BUILD_MAP_UNPACK`,
but is used for ``f(**x, **y, **z)`` call syntax. The stack item at
position ``count + 2`` should be the corresponding callable ``f``.
Like :opcode:`DICT_UPDATE` but raises an exception for duplicate keys.
.. versionadded:: 3.5
.. versionchanged:: 3.6
The position of the callable is determined by adding 2 to the opcode
argument instead of encoding it in the second byte of the argument.
.. versionadded:: 3.9
.. opcode:: LOAD_ATTR (namei)

4
Include/opcode.h generated
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@ -117,8 +117,6 @@ extern "C" {
#define SET_ADD 146
#define MAP_ADD 147
#define LOAD_CLASSDEREF 148
#define BUILD_MAP_UNPACK 150
#define BUILD_MAP_UNPACK_WITH_CALL 151
#define SETUP_ASYNC_WITH 154
#define FORMAT_VALUE 155
#define BUILD_CONST_KEY_MAP 156
@ -127,6 +125,8 @@ extern "C" {
#define CALL_METHOD 161
#define LIST_EXTEND 162
#define SET_UPDATE 163
#define DICT_MERGE 164
#define DICT_UPDATE 165
/* EXCEPT_HANDLER is a special, implicit block type which is created when
entering an except handler. It is not an opcode but we define it here

3
Lib/importlib/_bootstrap_external.py
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@ -276,6 +276,7 @@ _code_type = type(_write_atomic.__code__)
# Python 3.9a0 3422 (remove BEGIN_FINALLY, END_FINALLY, CALL_FINALLY, POP_FINALLY bytecodes #33387)
# Python 3.9a2 3423 (add IS_OP, CONTAINS_OP and JUMP_IF_NOT_EXC_MATCH bytecodes #39156)
# Python 3.9a2 3424 (simplify bytecodes for *value unpacking)
# Python 3.9a2 3425 (simplify bytecodes for **value unpacking)
#
# MAGIC must change whenever the bytecode emitted by the compiler may no
@ -285,7 +286,7 @@ _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 = (3424).to_bytes(2, 'little') + b'\r\n'
MAGIC_NUMBER = (3425).to_bytes(2, 'little') + b'\r\n'
_RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little') # For import.c
_PYCACHE = '__pycache__'

5
Lib/opcode.py
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@ -200,9 +200,6 @@ hasfree.append(148)
def_op('EXTENDED_ARG', 144)
EXTENDED_ARG = 144
def_op('BUILD_MAP_UNPACK', 150)
def_op('BUILD_MAP_UNPACK_WITH_CALL', 151)
jrel_op('SETUP_ASYNC_WITH', 154)
def_op('FORMAT_VALUE', 155)
@ -214,5 +211,7 @@ def_op('CALL_METHOD', 161)
def_op('LIST_EXTEND', 162)
def_op('SET_UPDATE', 163)
def_op('DICT_MERGE', 164)
def_op('DICT_UPDATE', 165)
del def_op, name_op, jrel_op, jabs_op

4
Misc/NEWS.d/next/Core and Builtins/2020-01-15-15-50-22.bpo-39320.oWARyk.rst Normal file
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@ -0,0 +1,4 @@
Replace two complex bytecodes for building dicts with two simpler ones.
The new bytecodes ``DICT_MERGE`` and ``DICT_UPDATE`` have been added
The old bytecodes ``BUILD_MAP_UNPACK`` and ``BUILD_MAP_UNPACK_WITH_CALL`` have been removed.

45
Python/ceval.c
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@ -2801,49 +2801,32 @@ main_loop:
DISPATCH();
}
case TARGET(BUILD_MAP_UNPACK): {
Py_ssize_t i;
PyObject *sum = PyDict_New();
if (sum == NULL)
goto error;
for (i = oparg; i > 0; i--) {
PyObject *arg = PEEK(i);
if (PyDict_Update(sum, arg) < 0) {
case TARGET(DICT_UPDATE): {
PyObject *update = POP();
PyObject *dict = PEEK(oparg);
if (PyDict_Update(dict, update) < 0) {
if (_PyErr_ExceptionMatches(tstate, PyExc_AttributeError)) {
_PyErr_Format(tstate, PyExc_TypeError,
"'%.200s' object is not a mapping",
arg->ob_type->tp_name);
update->ob_type->tp_name);
}
Py_DECREF(sum);
Py_DECREF(update);
goto error;
}
}
while (oparg--)
Py_DECREF(POP());
PUSH(sum);
Py_DECREF(update);
DISPATCH();
}
case TARGET(BUILD_MAP_UNPACK_WITH_CALL): {
Py_ssize_t i;
PyObject *sum = PyDict_New();
if (sum == NULL)
goto error;
case TARGET(DICT_MERGE): {
PyObject *update = POP();
PyObject *dict = PEEK(oparg);
for (i = oparg; i > 0; i--) {
PyObject *arg = PEEK(i);
if (_PyDict_MergeEx(sum, arg, 2) < 0) {
Py_DECREF(sum);
format_kwargs_error(tstate, PEEK(2 + oparg), arg);
if (_PyDict_MergeEx(dict, update, 2) < 0) {
format_kwargs_error(tstate, PEEK(2 + oparg), update);
Py_DECREF(update);
goto error;
}
}
while (oparg--)
Py_DECREF(POP());
PUSH(sum);
Py_DECREF(update);
PREDICT(CALL_FUNCTION_EX);
DISPATCH();
}

84
Python/compile.c
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@ -1007,9 +1007,6 @@ stack_effect(int opcode, int oparg, int jump)
case BUILD_SET:
case BUILD_STRING:
return 1-oparg;
case BUILD_MAP_UNPACK:
case BUILD_MAP_UNPACK_WITH_CALL:
return 1 - oparg;
case BUILD_MAP:
return 1 - 2*oparg;
case BUILD_CONST_KEY_MAP:
@ -1125,6 +1122,8 @@ stack_effect(int opcode, int oparg, int jump)
return 0;
case LIST_EXTEND:
case SET_UPDATE:
case DICT_MERGE:
case DICT_UPDATE:
return -1;
default:
return PY_INVALID_STACK_EFFECT;
@ -3868,37 +3867,58 @@ static int
compiler_dict(struct compiler *c, expr_ty e)
{
Py_ssize_t i, n, elements;
int containers;
int have_dict;
int is_unpacking = 0;
n = asdl_seq_LEN(e->v.Dict.values);
containers = 0;
have_dict = 0;
elements = 0;
for (i = 0; i < n; i++) {
is_unpacking = (expr_ty)asdl_seq_GET(e->v.Dict.keys, i) == NULL;
if (elements == 0xFFFF || (elements && is_unpacking)) {
if (!compiler_subdict(c, e, i - elements, i))
if (is_unpacking) {
if (elements) {
if (!compiler_subdict(c, e, i - elements, i)) {
return 0;
containers++;
}
if (have_dict) {
ADDOP_I(c, DICT_UPDATE, 1);
}
have_dict = 1;
elements = 0;
}
if (is_unpacking) {
if (have_dict == 0) {
ADDOP_I(c, BUILD_MAP, 0);
have_dict = 1;
}
VISIT(c, expr, (expr_ty)asdl_seq_GET(e->v.Dict.values, i));
containers++;
ADDOP_I(c, DICT_UPDATE, 1);
}
else {
if (elements == 0xFFFF) {
if (!compiler_subdict(c, e, i - elements, i)) {
return 0;
}
if (have_dict) {
ADDOP_I(c, DICT_UPDATE, 1);
}
have_dict = 1;
elements = 0;
}
else {
elements++;
}
}
if (elements || containers == 0) {
if (!compiler_subdict(c, e, n - elements, n))
return 0;
containers++;
}
/* If there is more than one dict, they need to be merged into a new
* dict. If there is one dict and it's an unpacking, then it needs
* to be copied into a new dict." */
if (containers > 1 || is_unpacking) {
ADDOP_I(c, BUILD_MAP_UNPACK, containers);
if (elements) {
if (!compiler_subdict(c, e, n - elements, n)) {
return 0;
}
if (have_dict) {
ADDOP_I(c, DICT_UPDATE, 1);
}
have_dict = 1;
}
if (!have_dict) {
ADDOP_I(c, BUILD_MAP, 0);
}
return 1;
}
@ -4263,8 +4283,8 @@ ex_call:
}
/* Then keyword arguments */
if (nkwelts) {
/* the number of dictionaries on the stack */
Py_ssize_t nsubkwargs = 0;
/* Has a new dict been pushed */
int have_dict = 0;
nseen = 0; /* the number of keyword arguments on the stack following */
for (i = 0; i < nkwelts; i++) {
@ -4272,13 +4292,18 @@ ex_call:
if (kw->arg == NULL) {
/* A keyword argument unpacking. */
if (nseen) {
if (!compiler_subkwargs(c, keywords, i - nseen, i))
if (!compiler_subkwargs(c, keywords, i - nseen, i)) {
return 0;
nsubkwargs++;
}
have_dict = 1;
nseen = 0;
}
if (!have_dict) {
ADDOP_I(c, BUILD_MAP, 0);
have_dict = 1;
}
VISIT(c, expr, kw->value);
nsubkwargs++;
ADDOP_I(c, DICT_MERGE, 1);
}
else {
nseen++;
@ -4286,14 +4311,15 @@ ex_call:
}
if (nseen) {
/* Pack up any trailing keyword arguments. */
if (!compiler_subkwargs(c, keywords, nkwelts - nseen, nkwelts))
if (!compiler_subkwargs(c, keywords, nkwelts - nseen, nkwelts)) {
return 0;
nsubkwargs++;
}
if (nsubkwargs > 1) {
/* Pack it all up */
ADDOP_I(c, BUILD_MAP_UNPACK_WITH_CALL, nsubkwargs);
if (have_dict) {
ADDOP_I(c, DICT_MERGE, 1);
}
have_dict = 1;
}
assert(have_dict);
}
ADDOP_I(c, CALL_FUNCTION_EX, nkwelts > 0);
return 1;

2854
Python/importlib.h generated
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File diff suppressed because it is too large Load Diff

4308
Python/importlib_external.h generated
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File diff suppressed because it is too large Load Diff

8
Python/opcode_targets.h generated
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@ -149,8 +149,8 @@ static void *opcode_targets[256] = {
&&TARGET_MAP_ADD,
&&TARGET_LOAD_CLASSDEREF,
&&_unknown_opcode,
&&TARGET_BUILD_MAP_UNPACK,
&&TARGET_BUILD_MAP_UNPACK_WITH_CALL,
&&_unknown_opcode,
&&_unknown_opcode,
&&_unknown_opcode,
&&_unknown_opcode,
&&TARGET_SETUP_ASYNC_WITH,
@ -163,8 +163,8 @@ static void *opcode_targets[256] = {
&&TARGET_CALL_METHOD,
&&TARGET_LIST_EXTEND,
&&TARGET_SET_UPDATE,
&&_unknown_opcode,
&&_unknown_opcode,
&&TARGET_DICT_MERGE,
&&TARGET_DICT_UPDATE,
&&_unknown_opcode,
&&_unknown_opcode,
&&_unknown_opcode,