bpo-38328: Speed up the creation time of constant list and set display. (GH-17114)
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 9961dee..947c935 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -1222,7 +1222,7 @@
# 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)
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-11-11-23-44-15.bpo-38328.IFrrjq.rst b/Misc/NEWS.d/next/Core and Builtins/2019-11-11-23-44-15.bpo-38328.IFrrjq.rst
new file mode 100644
index 0000000..e0c5ca7
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-11-11-23-44-15.bpo-38328.IFrrjq.rst
@@ -0,0 +1,2 @@
+Sped up the creation time of constant :class:`list` and :class:`set` displays.
+Patch by Brandt Bucher.
diff --git a/Python/compile.c b/Python/compile.c
index f56c015..98a4afa 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -197,6 +197,7 @@
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 @@
{
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) {