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[3.6] bpo-27169: The __debug__ constant is now optimized out at compile time. (GH-4880) #4882

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Merged
serhiy-storchaka merged 1 commit into from
Dec 15, 2017
Merged

[3.6] bpo-27169: The __debug__ constant is now optimized out at compile time. (GH-4880) #4882

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16 changes: 8 additions & 8 deletions Lib/test/test_builtin.py
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Original file line number Diff line number Diff line change
Expand Up @@ -331,16 +331,16 @@ def test_compile(self):
try:
assert False
except AssertionError:
return (True, f.__doc__)
return (True, f.__doc__, __debug__)
else:
return (False, f.__doc__)
return (False, f.__doc__, __debug__)
'''
def f(): """doc"""
values = [(-1, __debug__, f.__doc__),
(0, True, 'doc'),
(1, False, 'doc'),
(2, False, None)]
for optval, debugval, docstring in values:
values = [(-1, __debug__, f.__doc__, __debug__),
(0, True, 'doc', True),
(1, False, 'doc', False),
(2, False, None, False)]
for optval, *expected in values:
# test both direct compilation and compilation via AST
codeobjs = []
codeobjs.append(compile(codestr, "<test>", "exec", optimize=optval))
Expand All @@ -350,7 +350,7 @@ def f(): """doc"""
ns = {}
exec(code, ns)
rv = ns['f']()
self.assertEqual(rv, (debugval, docstring))
self.assertEqual(rv, tuple(expected))

def test_delattr(self):
sys.spam = 1
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1 change: 1 addition & 0 deletions Lib/test/test_compile.py
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ def test_debug_assignment(self):
import builtins
prev = builtins.__debug__
setattr(builtins, '__debug__', 'sure')
self.assertEqual(__debug__, prev)
setattr(builtins, '__debug__', prev)

def test_argument_handling(self):
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2017-12-15-11-50-06.bpo-27169.VO84fQ.rst
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@@ -0,0 +1,2 @@
The ``__debug__`` constant is now optimized out at compile time. This fixes also
bpo-22091.
45 changes: 15 additions & 30 deletions Python/compile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1343,13 +1343,15 @@ is_const(expr_ty e)
case Ellipsis_kind:
case NameConstant_kind:
return 1;
case Name_kind:
return _PyUnicode_EqualToASCIIString(e->v.Name.id, "__debug__");
default:
return 0;
}
}

static PyObject *
get_const_value(expr_ty e)
get_const_value(struct compiler *c, expr_ty e)
{
switch (e->kind) {
case Constant_kind:
Expand All @@ -1364,6 +1366,9 @@ get_const_value(expr_ty e)
return Py_Ellipsis;
case NameConstant_kind:
return e->v.NameConstant.value;
case Name_kind:
assert(_PyUnicode_EqualToASCIIString(e->v.Name.id, "__debug__"));
return c->c_optimize ? Py_False : Py_True;
default:
assert(!is_const(e));
return NULL;
Expand Down Expand Up @@ -3035,6 +3040,11 @@ compiler_nameop(struct compiler *c, identifier name, expr_context_ty ctx)
!_PyUnicode_EqualToASCIIString(name, "True") &&
!_PyUnicode_EqualToASCIIString(name, "False"));

if (ctx == Load && _PyUnicode_EqualToASCIIString(name, "__debug__")) {
ADDOP_O(c, LOAD_CONST, c->c_optimize ? Py_False : Py_True, consts);
return 1;
}

op = 0;
optype = OP_NAME;
scope = PyST_GetScope(c->u->u_ste, mangled);
Expand Down Expand Up @@ -3298,7 +3308,7 @@ compiler_subdict(struct compiler *c, expr_ty e, Py_ssize_t begin, Py_ssize_t end
return 0;
}
for (i = begin; i < end; i++) {
key = get_const_value((expr_ty)asdl_seq_GET(e->v.Dict.keys, i));
key = get_const_value(c, (expr_ty)asdl_seq_GET(e->v.Dict.keys, i));
Py_INCREF(key);
PyTuple_SET_ITEM(keys, i - begin, key);
}
Expand Down Expand Up @@ -4044,35 +4054,10 @@ compiler_visit_keyword(struct compiler *c, keyword_ty k)
static int
expr_constant(struct compiler *c, expr_ty e)
{
char *id;
switch (e->kind) {
case Ellipsis_kind:
return 1;
case Constant_kind:
return PyObject_IsTrue(e->v.Constant.value);
case Num_kind:
return PyObject_IsTrue(e->v.Num.n);
case Str_kind:
return PyObject_IsTrue(e->v.Str.s);
case Name_kind:
/* optimize away names that can't be reassigned */
id = PyUnicode_AsUTF8(e->v.Name.id);
if (id && strcmp(id, "__debug__") == 0)
return !c->c_optimize;
return -1;
case NameConstant_kind: {
PyObject *o = e->v.NameConstant.value;
if (o == Py_None)
return 0;
else if (o == Py_True)
return 1;
else if (o == Py_False)
return 0;
}
/* fall through */
default:
return -1;
if (is_const(e)) {
return PyObject_IsTrue(get_const_value(c, e));
}
return -1;
}


Expand Down