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bpo-38328: Speed up the creation time of constant list and set display. (GH-17114)

This commit is contained in:
Brandt Bucher 2019-11-25 22:16:53 -08:00 committed by Inada Naoki
parent e4db1f05e9
commit 6dd9b64770
3 changed files with 25 additions and 1 deletions
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2
Lib/test/test_sys.py
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@ -1222,7 +1222,7 @@ class SizeofTest(unittest.TestCase):
# list
samples = [[], [1,2,3], ['1', '2', '3']]
for sample in samples:
check(sample, vsize('Pn') + len(sample)*self.P)
check(list(sample), vsize('Pn') + len(sample)*self.P)
# sortwrapper (list)
# XXX
# cmpwrapper (list)

2
Misc/NEWS.d/next/Core and Builtins/2019-11-11-23-44-15.bpo-38328.IFrrjq.rst Normal file
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@ -0,0 +1,2 @@
Sped up the creation time of constant :class:`list` and :class:`set` displays.
Patch by Brandt Bucher.

22
Python/compile.c
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@ -197,6 +197,7 @@ static int compiler_visit_slice(struct compiler *, slice_ty,
expr_context_ty);
static int inplace_binop(struct compiler *, operator_ty);
static int are_all_items_const(asdl_seq *, Py_ssize_t, Py_ssize_t);
static int expr_constant(expr_ty);
static int compiler_with(struct compiler *, stmt_ty, int);
@ -3655,6 +3656,27 @@ starunpack_helper(struct compiler *c, asdl_seq *elts,
{
Py_ssize_t n = asdl_seq_LEN(elts);
Py_ssize_t i, nsubitems = 0, nseen = 0;
if (n > 2 && are_all_items_const(elts, 0, n)) {
PyObject *folded = PyTuple_New(n);
if (folded == NULL) {
return 0;
}
PyObject *val;
for (i = 0; i < n; i++) {
val = ((expr_ty)asdl_seq_GET(elts, i))->v.Constant.value;
Py_INCREF(val);
PyTuple_SET_ITEM(folded, i, val);
}
if (outer_op == BUILD_SET_UNPACK) {
Py_SETREF(folded, PyFrozenSet_New(folded));
if (folded == NULL) {
return 0;
}
}
ADDOP_LOAD_CONST_NEW(c, folded);
ADDOP_I(c, outer_op, 1);
return 1;
}
for (i = 0; i < n; i++) {
expr_ty elt = asdl_seq_GET(elts, i);
if (elt->kind == Starred_kind) {