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Incorrect output due to Tier 2 _LOAD_CONST_INLINE #117051
Description
Bug report
I've constructed a sneaky way to break the remove_globals() optimization, by executing a code object in two different globals dicts. (Credit goes to @brandtbucher who started the conversation about this topic, though this particular example is mine.)
Take this code:
src = """
def f():
global x
def inner(i):
a = 1
for _ in range(100):
a = x + i
return a
return inner
func = f()
"""
co = compile(src, __file__, "exec")
ns1 = {"x": 1000}
eval(co, ns1)
func1 = ns1["func"]
for i in range(1000):
x = func1(i)
print(x)
ns2 = {"x": 2000}
eval(co, ns2)
func2 = ns2["func"]
for i in range(1000):
x = func2(i)
print(x)This should print
1999
2999
(try it with Python 3.12, or Python 3.13 without JIT or -Xuops).
However with current main (EDIT: when using JIT or -Xuops) it prints
1999
1999
:-(
Activity
gvanrossum commentedon Mar 20, 2024
git bisect points its sneaky little finger at GH-116460.
A workaround would be to comment out the
remove_globals()call in_Py_uop_analyze_and_optimize().gvanrossum commentedon Mar 20, 2024
I was thinking that another workaround would be to leave in the first
_GUARD_GLOBALS_VERSION. In fact, I'm not sure why that isn't kept byremove_globals()? (The algorithm there is hard for me to follow.) Of course it ought to be moved to the top, before the start of the loop, which would require #117062 first.markshannon commentedon Jun 30, 2026
This seems to have been fixed. We add a
_GUARD_GLOBALS_VERSIONto check for this