JIT: assertion failure in _PyObject_GC_UNTRACK

[devdanzin]

Crash report

What happened?

It's possible to non-deterministically abort a special debug JIT build by running the code below, running from a Python executable from a venv where you installed two packages in editable mode.

For this special build, apply this diff:

index 454c8dde031..9e21c41421a 100644
--- a/Include/internal/pycore_backoff.h
+++ b/Include/internal/pycore_backoff.h
@@ -99,8 +99,8 @@ backoff_counter_triggers(_Py_BackoffCounter counter)
 // Must be larger than ADAPTIVE_COOLDOWN_VALUE, otherwise when JIT code is
 // invalidated we may construct a new trace before the bytecode has properly
 // re-specialized:
-#define JUMP_BACKWARD_INITIAL_VALUE 4095
-#define JUMP_BACKWARD_INITIAL_BACKOFF 12
+#define JUMP_BACKWARD_INITIAL_VALUE 63
+#define JUMP_BACKWARD_INITIAL_BACKOFF 6
 static inline _Py_BackoffCounter
 initial_jump_backoff_counter(void)
{
@@ -112,8 +112,8 @@ initial_jump_backoff_counter(void)
 * Must be larger than ADAPTIVE_COOLDOWN_VALUE,
 * otherwise when a side exit warms up we may construct
 * a new trace before the Tier 1 code has properly re-specialized. */
-#define SIDE_EXIT_INITIAL_VALUE 4095
-#define SIDE_EXIT_INITIAL_BACKOFF 12
+#define SIDE_EXIT_INITIAL_VALUE 63
+#define SIDE_EXIT_INITIAL_BACKOFF 6

 static inline _Py_BackoffCounter
 initial_temperature_backoff_counter(void)
diff --git a/Include/internal/pycore_optimizer.h b/Include/internal/pycore_optimizer.h
index 8b7f12bf03d..8cc51959063 100644
--- a/Include/internal/pycore_optimizer.h
+++ b/Include/internal/pycore_optimizer.h
@@ -163,7 +163,7 @@ static inline uint16_t uop_get_error_target(const _PyUOpInstruction *inst)
 // progress (and inserting a new ENTER_EXECUTOR instruction). In practice, this
 // is the "maximum amount of polymorphism" that an isolated trace tree can
 // handle before rejoining the rest of the program.
-#define MAX_CHAIN_DEPTH 4
+#define MAX_CHAIN_DEPTH 16

 /* Symbols */
 /* See explanation in optimizer_symbols.c */

This MRE must be invoked like this:

/path/to/venv/with/editable/installs/bin/python mre.py

Sorry about another long MRE, this code also seems stubbornly hard to reduce. MRE:

from random import randint

class UnstableHash_unstable_hash_object_v4:
 hash_count = 0

 def __hash__(self):
 self.hash_count += 1
 new_hash = 5 if self.hash_count < 70 else randint(0, 1024)
 print(new_hash)
 return new_hash
unstable_hash_object_v4 = UnstableHash_unstable_hash_object_v4()
tuple_v6 = (90.1433,)

def uop_harness_f1():

 class ShapeA_la_7776:
 payload = 123

 class ShapeB_la_7776:

 @property
 def payload(self):
 return 'property_payload'

 class ShapeC_la_7776:

 def payload(self):
 return id(self)

 class ShapeD_la_7776:
 __slots__ = ['payload']

 def __init__(self):
 self.payload = 'slot_payload'
 shapes_la_7776 = [ShapeA_la_7776(), ShapeB_la_7776(), ShapeC_la_7776(), ShapeD_la_7776()]
 for i in range(500):
 obj = shapes_la_7776[i % len(shapes_la_7776)]
 try:
 payload_val = obj.payload
 if callable(payload_val):
 payload_val()
 payload_val()
 payload_val()
 payload_val()
 except Exception:
 pass
{unstable_hash_object_v4, unstable_hash_object_v4}
{unstable_hash_object_v4, unstable_hash_object_v4}
{unstable_hash_object_v4, unstable_hash_object_v4}
{unstable_hash_object_v4, unstable_hash_object_v4}
 for i_loop_1589 in{2, 1, 2, 3, 4, 5, 6, 8, 10, 9, 12, 10, 12, 13, 14, 15, 17, 17}:
 x, *y = tuple_v6
 x, *y = tuple_v6
for i_f1 in range(300):
 try:
 uop_harness_f1()
 except Exception as e:
 break

Backtrace:

Python/optimizer.c:269: _PyObject_GC_UNTRACK: Assertion "_PyObject_GC_IS_TRACKED(((PyObject*)(op)))" failed: object not tracked by the garbage collector
Enable tracemalloc to get the memory block allocation traceback

object address : 0x555555f82230
object refcount : 0
object type : 0x555555c5e680
object type name: uop_executor
object repr : <refcnt 0 at 0x555555f82230>

Fatal Python error: _PyObject_AssertFailed: _PyObject_AssertFailed
Python runtime state: initialized

Current thread 0x00007ffff7ea8780 [python] (most recent call first):
 File "/home/danzin/crashers/jit/reduced_crash_retcode_child_15732_2.py", line 47 in uop_harness_f1
 File "/home/danzin/crashers/jit/reduced_crash_retcode_child_15732_2.py", line 56 in <module>

Program received signal SIGABRT, Aborted.

#0 __pthread_kill_implementation (threadid=<optimized out>, signo=6, no_tid=0) at ./nptl/pthread_kill.c:44
#1 __pthread_kill_internal (threadid=<optimized out>, signo=6) at ./nptl/pthread_kill.c:89
#2 __GI___pthread_kill (threadid=<optimized out>, signo=signo@entry=6) at ./nptl/pthread_kill.c:100
#3 0x00007ffff7c4579e in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#4 0x00007ffff7c288cd in __GI_abort () at ./stdlib/abort.c:73
#5 0x00005555558bba92 in fatal_error_exit (status=<optimized out>) at Python/pylifecycle.c:3155
#6 0x00005555558bd07d in fatal_error (fd=2, header=header@entry=1, prefix=prefix@entry=0x5555559f7e90 <__func__.11> "_PyObject_AssertFailed",
 msg=msg@entry=0x555555980fe5 "_PyObject_AssertFailed", status=status@entry=-1) at Python/pylifecycle.c:3371
#7 0x00005555558bd0ef in _Py_FatalErrorFunc (func=func@entry=0x5555559f7e90 <__func__.11> "_PyObject_AssertFailed",
 msg=msg@entry=0x555555980fe5 "_PyObject_AssertFailed") at Python/pylifecycle.c:3387
#8 0x00005555556dd237 in _PyObject_AssertFailed (obj=obj@entry=0x555555f82230,
 expr=expr@entry=0x5555559a9f60 "_PyObject_GC_IS_TRACKED(((PyObject*)(op)))",
 msg=msg@entry=0x5555559a9f30 "object not tracked by the garbage collector", file=file@entry=0x55555598c050 "Python/optimizer.c",
 line=line@entry=269, function=function@entry=0x555555a9c010 <__func__.9> "_PyObject_GC_UNTRACK") at Objects/object.c:3165
#9 0x00005555558a2303 in _PyObject_GC_UNTRACK (filename=filename@entry=0x55555598c050 "Python/optimizer.c", lineno=lineno@entry=269,
 op=op@entry=0x555555f82230) at ./Include/internal/pycore_gc.h:269
#10 0x00005555558a3198 in uop_dealloc (op=op@entry=0x555555f82230) at Python/optimizer.c:269
#11 0x00005555556dc978 in _Py_Dealloc (op=op@entry=0x555555f82230) at Objects/object.c:3206
#12 0x00005555557b47ab in Py_DECREF_MORTAL (filename=filename@entry=0x5555559aaec8 "./Include/internal/pycore_stackref.h", lineno=lineno@entry=701,
 op=0x555555f82230) at ./Include/internal/pycore_object.h:450
#13 0x00005555557b485b in PyStackRef_CLOSE (ref=..., ref@entry=...) at ./Include/internal/pycore_stackref.h:701
#14 0x00005555557cfe33 in _PyEval_EvalFrameDefault (tstate=0x555555cca298 <_PyRuntime+331064>, frame=0x7fffffffce30, throwflag=0)
 at Python/generated_cases.c.h:7656
#15 0x00005555557dd559 in _PyEval_EvalFrame (tstate=tstate@entry=0x555555cca298 <_PyRuntime+331064>, frame=frame@entry=0x7ffff7fac180,
 throwflag=throwflag@entry=0) at ./Include/internal/pycore_ceval.h:119
#16 0x00005555557dd72a in _PyEval_Vector (tstate=0x555555cca298 <_PyRuntime+331064>, func=0x7ffff74e8650, locals=locals@entry=0x0,
 args=0x7fffffffd008, argcount=<optimized out>, kwnames=0x0) at Python/ceval.c:1977
#17 0x000055555567dc31 in _PyFunction_Vectorcall (func=<optimized out>, stack=<optimized out>, nargsf=<optimized out>, kwnames=<optimized out>)
 at Objects/call.c:413
#18 0x000055555567df88 in _PyObject_VectorcallTstate (tstate=0x555555cca298 <_PyRuntime+331064>, callable=callable@entry=0x7ffff74e8650,
 args=args@entry=0x7fffffffd008, nargsf=nargsf@entry=9223372036854775809, kwnames=kwnames@entry=0x0) at ./Include/internal/pycore_call.h:169
#19 0x000055555567e0b4 in PyObject_CallOneArg (func=func@entry=0x7ffff74e8650, arg=arg@entry=0x7ffff728c8a0) at Objects/call.c:395
#20 0x000055555570a05e in call_unbound_noarg (unbound=unbound@entry=1, func=func@entry=0x7ffff74e8650, self=self@entry=0x7ffff728c8a0)
 at Objects/typeobject.c:3019
#21 0x000055555571717f in maybe_call_special_no_args (self=self@entry=0x7ffff728c8a0, attr=<optimized out>,
 attr_is_none=attr_is_none@entry=0x7fffffffd084) at Objects/typeobject.c:3132
#22 0x000055555571746b in slot_tp_hash (self=0x7ffff728c8a0) at Objects/typeobject.c:10489
#23 0x00005555556dbf44 in PyObject_Hash (v=0x7ffff728c8a0) at Objects/object.c:1158
#24 0x00005555556fb0b2 in _PyObject_HashFast (op=op@entry=0x7ffff728c8a0) at ./Include/internal/pycore_object.h:872
#25 0x00005555556ffaaf in _PySet_AddTakeRef (so=0x7ffff72e5c70, key=0x7ffff728c8a0) at Objects/setobject.c:234
#26 0x00007ffff706a948 in ?? ()
#27 0xfffffffffffffffe in ?? ()
#28 0x0000555555cca298 in _PyRuntime ()
#29 0x00007fffffffd420 in ?? ()
#30 0x00007ffff70a9017 in ?? ()
#31 0x0000555555eb4dc0 in ?? ()
#32 0x00007ffff70a9000 in ?? ()
#33 0x0000555555cca298 in _PyRuntime ()
#34 0x00007ffff7fac0a0 in ?? ()
#35 0x00007ffff7fac160 in ?? ()
#36 0x00005555557ca1c0 in _PyEval_EvalFrameDefault (tstate=<error reading variable: Cannot access memory at address 0xfffffffffffffda0>,
 frame=0xffffffffffffffff, throwflag=<error reading variable: Cannot access memory at address 0xfffffffffffffd8c>)
 at Python/generated_cases.c.h:5598
Backtrace stopped: previous frame inner to this frame (corrupt stack?)

Here are the outputs from running with PYTHON_OPT_DEBUG=4 and PYTHON_LLTRACE=4, since they are too long I've attached them as files:

opt_debug_15732.txt
lltrace_15732.txt

Found using lafleur.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

Python 3.15.0a0 (heads/main-dirty:6bf1c0ab349, Jul 22 2025, 11:26:33) [GCC 14.2.0]

Linked PRs

• gh-137007: Track executor before any possible deallocations #137016
• [3.14] gh-137007: Track executor before any possible deallocations (GH-137016) #142541

[Fidget-Spinner]

I cannot seem to reproduce this with a debug build of the JIT and with a patch applied, for the reproducer. The reproducer runs till completion for me.

[Fidget-Spinner]

Wait sorry, I didn't see that you need two packages in editable mode for this. Re-investigating.

[brandtbucher]

I feel like that part is probably a red herring. Probably the import machinery is taking a different path to find random when that's the case, causing GC to happen or something.

[Fidget-Spinner]

I feel like that part is probably a red herring. Probably the import machinery is taking a different path to find random when that's the case, causing GC to happen or something.

I tried tweaking GC thresholds and don't get anything either. It's not a GC problem. I narrowed it down to the code path in the executor code deallocating the executor when it's not yet tracked by GC.

[devdanzin]

I was able to reproduce this by (cloning, then) installing pip and pypa/sampleproject as editable. However, it somehow led to a segfault this time:

Program received signal SIGSEGV, Segmentation fault.
_PyObject_GC_UNTRACK (op=0x555555e448a0) at ./Include/internal/pycore_gc.h:279
279 _PyGCHead_SET_NEXT(prev, next);

#0 _PyObject_GC_UNTRACK (op=0x555555e448a0) at ./Include/internal/pycore_gc.h:279
#1 uop_dealloc (op=0x555555e448a0) at Python/optimizer.c:269
#2 0x00005555556c059d in _Py_Dealloc (op=0x555555e448a0) at Objects/object.c:3206
#3 0x00005555557c86de in Py_DECREF_MORTAL (op=<optimized out>) at ./Include/internal/pycore_object.h:482
#4 PyStackRef_CLOSE (ref=...) at ./Include/internal/pycore_stackref.h:701
#5 _PyEval_EvalFrameDefault (tstate=<optimized out>, frame=<optimized out>, throwflag=<optimized out>) at Python/generated_cases.c.h:7656
#6 0x00005555557d2b3c in _PyEval_EvalFrame (tstate=0x555555bb9a48 <_PyRuntime+315048>, frame=<optimized out>, throwflag=0)
 at ./Include/internal/pycore_ceval.h:119
#7 _PyEval_Vector (tstate=0x555555bb9a48 <_PyRuntime+315048>, func=0x7ffff7496fb0, locals=0x0, args=0x7fffffffd178, argcount=<optimized out>,
 kwnames=<optimized out>) at Python/ceval.c:1977
#8 0x000055555564905b in _PyObject_VectorcallTstate (tstate=0x555555bb9a48 <_PyRuntime+315048>, callable=0x7ffff7496fb0, args=0x7fffffffd178,
 nargsf=9223372036854775809, kwnames=0x0) at ./Include/internal/pycore_call.h:169
#9 PyObject_CallOneArg (func=func@entry=0x7ffff7496fb0, arg=arg@entry=0x7ffff7333b60) at Objects/call.c:395
#10 0x00005555556feed2 in call_unbound_noarg (unbound=<optimized out>, func=0x7ffff7496fb0, self=0x7ffff7333b60) at Objects/typeobject.c:3019
#11 maybe_call_special_no_args (self=0x7ffff7333b60, attr=<optimized out>, attr_is_none=<synthetic pointer>) at Objects/typeobject.c:3132
#12 slot_tp_hash (self=0x7ffff7333b60) at Objects/typeobject.c:10489
#13 0x00005555556e8e95 in _PyObject_HashFast (op=0x7ffff7333b60) at ./Include/internal/pycore_object.h:872
#14 _PySet_AddTakeRef (so=0x7ffff73bd2a0, key=0x7ffff7333b60) at Objects/setobject.c:234
#15 0x00007ffff71c0225 in ?? ()
#16 0x00007fffffffd590 in ?? ()
#17 0xfffffffffffffffe in ?? ()
#18 0x00007fffffffd590 in ?? ()
#19 0x00007ffff71c7017 in ?? ()
#20 0x00007ffff7fac0a0 in ?? ()
#21 0x00007ffff7fac160 in ?? ()
#22 0x0000555555c720c0 in ?? ()
#23 0x0000555555b70319 in _PyRuntime ()
#24 0x0000555555d11116 in ?? ()
#25 0x00005555557ca888 in _PyEval_EvalFrameDefault (tstate=<error reading variable: Cannot access memory at address 0xfffffffffffffd58>,
 frame=<optimized out>, throwflag=<optimized out>) at Python/generated_cases.c.h:5598
Backtrace stopped: previous frame inner to this frame (corrupt stack?)

Can you reproduce by installing those two packages?

[devdanzin]

Here's a reproducer for the segfault in a JIT non-debug build without the need of installing packages, please use this diff:

index 454c8dde031..9e21c41421a 100644
--- a/Include/internal/pycore_backoff.h
+++ b/Include/internal/pycore_backoff.h
@@ -99,8 +99,8 @@ backoff_counter_triggers(_Py_BackoffCounter counter)
 // Must be larger than ADAPTIVE_COOLDOWN_VALUE, otherwise when JIT code is
 // invalidated we may construct a new trace before the bytecode has properly
 // re-specialized:
-#define JUMP_BACKWARD_INITIAL_VALUE 4095
-#define JUMP_BACKWARD_INITIAL_BACKOFF 12
+#define JUMP_BACKWARD_INITIAL_VALUE 63
+#define JUMP_BACKWARD_INITIAL_BACKOFF 6
 static inline _Py_BackoffCounter
 initial_jump_backoff_counter(void)
{
@@ -112,8 +112,8 @@ initial_jump_backoff_counter(void)
 * Must be larger than ADAPTIVE_COOLDOWN_VALUE,
 * otherwise when a side exit warms up we may construct
 * a new trace before the Tier 1 code has properly re-specialized. */
-#define SIDE_EXIT_INITIAL_VALUE 4095
-#define SIDE_EXIT_INITIAL_BACKOFF 12
+#define SIDE_EXIT_INITIAL_VALUE 63
+#define SIDE_EXIT_INITIAL_BACKOFF 6

 static inline _Py_BackoffCounter
 initial_temperature_backoff_counter(void)
diff --git a/Include/internal/pycore_optimizer.h b/Include/internal/pycore_optimizer.h
index 8b7f12bf03d..fee929f122f 100644
--- a/Include/internal/pycore_optimizer.h
+++ b/Include/internal/pycore_optimizer.h
@@ -121,7 +121,7 @@ PyAPI_FUNC(void) _Py_Executors_InvalidateCold(PyInterpreterState *interp);
 // This is the length of the trace we project initially.
 #define UOP_MAX_TRACE_LENGTH 800

-#define TRACE_STACK_SIZE 5
+#define TRACE_STACK_SIZE 10

 int _Py_uop_analyze_and_optimize(_PyInterpreterFrame *frame,
 _PyUOpInstruction *trace, int trace_len, int curr_stackentries,
@@ -152,7 +152,7 @@ static inline uint16_t uop_get_error_target(const _PyUOpInstruction *inst)
 }

 // Holds locals, stack, locals, stack ... co_consts (in that order)
-#define MAX_ABSTRACT_INTERP_SIZE 4096
+#define MAX_ABSTRACT_INTERP_SIZE 8192

 #define TY_ARENA_SIZE (UOP_MAX_TRACE_LENGTH * 5)

@@ -163,7 +163,7 @@ static inline uint16_t uop_get_error_target(const _PyUOpInstruction *inst)
 // progress (and inserting a new ENTER_EXECUTOR instruction). In practice, this
 // is the "maximum amount of polymorphism" that an isolated trace tree can
 // handle before rejoining the rest of the program.
-#define MAX_CHAIN_DEPTH 4
+#define MAX_CHAIN_DEPTH 16

 /* Symbols */
 /* See explanation in optimizer_symbols.c */

And this reproducer:

import sys
from importlib.machinery import all_suffixes as module_suffixes # Not sure why, but this unused import seems necessary
from importlib.util import spec_from_file_location

class _EditableFinder:
 @classmethod
 def _find_spec(cls, fullname, candidate_path):
 return spec_from_file_location(fullname, candidate_path.with_suffix("pyc"))

class _EditableFinder2:
 @classmethod
 def _find_spec(cls, fullname, candidate_path):
 return spec_from_file_location(fullname, candidate_path.with_suffix("py"))

sys.meta_path.append(_EditableFinder)
sys.meta_path.append(_EditableFinder2)

from random import randint

class UnstableHash_unstable_hash_object_v4:
 hash_count = 0

 def __hash__(self):
 self.hash_count += 1
 new_hash = 5 if self.hash_count < 70 else randint(0, 1024)
 print(new_hash)
 return new_hash
unstable_hash_object_v4 = UnstableHash_unstable_hash_object_v4()
tuple_v6 = (90.1433,)

def uop_harness_f1():

 class ShapeA_la_7776:
 payload = 123

 class ShapeB_la_7776:

 @property
 def payload(self):
 return 'property_payload'

 class ShapeC_la_7776:

 def payload(self):
 return id(self)

 class ShapeD_la_7776:
 __slots__ = ['payload']

 def __init__(self):
 self.payload = 'slot_payload'
 shapes_la_7776 = [ShapeA_la_7776(), ShapeB_la_7776(), ShapeC_la_7776(), ShapeD_la_7776()]
 for i in range(500):
 obj = shapes_la_7776[i % len(shapes_la_7776)]
 try:
 payload_val = obj.payload
 if callable(payload_val):
 payload_val()
 payload_val()
 payload_val()
 payload_val()
 except Exception:
 pass
{unstable_hash_object_v4, unstable_hash_object_v4}
{unstable_hash_object_v4, unstable_hash_object_v4}
{unstable_hash_object_v4, unstable_hash_object_v4}
{unstable_hash_object_v4, unstable_hash_object_v4}
 for i_loop_1589 in{2, 1, 2, 3, 4, 5, 6, 8, 10, 9, 12, 10, 12, 13, 14, 15, 17, 17}:
 x, *y = tuple_v6
 x, *y = tuple_v6
for i_f1 in range(300):
 try:
 uop_harness_f1()
 except Exception as e:
 break

[brandtbucher]

Here's a reproducer for the segfault in a JIT non-debug build without the need of installing packages, please use this diff:

Hm, this isn't working for me. Non-debug build, patches applied, no venv.

[devdanzin]

Hm, this isn't working for me. Non-debug build, patches applied, no venv.

This isn't my make-it-reliably-reproducible day, is it? It doesn't work without a venv for me either, and it turns out I had lafleur installed when I though I didn't and removing it stops reproducing. What a mess. Sorry again. I will spend a lot more time making sure any reports are reproducible.

So here's how it's working for me:

(release_jit_cpython_venv) :~ $ pip3 list
Package Version Editable project location
---------- ------- -----------------------------
lafleur 0.0.1 /home/danzin/projects/lafleur
peppercorn 0.6
pip 25.1.1
(release_jit_cpython_venv) :~ $ ~/venvs/release_jit_cpython_venv/bin/python ~/crashers/jit/reduced_crash_retcode_child_15732_2.py
5
5
5
5
[... a bunch of numbers]
427
493
35
Segmentation fault (core dumped)

I hope it works now.

[brandtbucher]

Also, for the future, setting a random seed really helps when randomness is involved. ;)

[devdanzin]

Also, for the future, setting a random seed really helps when randomness is involved. ;)

There's a seed for the mutations (that is, test case generation is reproducible), it just never occurred to me to add it to the fuzzing script (that is, doh)🤦. Thanks, will adopt it :)

Are you able to reproduce it with latest instructions?

Here's a small reduction I got, that shows calling randint isn't necessary:

import gc
gc.set_threshold(10) # Doesn't seem to work with 1 or most numbers, but 10 works
from random import randint # Seems necessary to get GC to where we want


class _EditableFinder:
 @classmethod
 def _find_spec(cls, fullname, candidate_path):
 pass


class UnstableHash_unstable_hash_object_v4:
 def __hash__(self):
 print(5, end=" ", flush=True) # If we don't flush, no crash. If we do a bare print, it also crashes.
 return 5
unstable_hash_object_v4 = UnstableHash_unstable_hash_object_v4()

tuple_v6 = (90.1433,)

def uop_harness_f1():

 class ShapeA_la_7776:
 payload = 123

 class ShapeB_la_7776:
 @property
 def payload(self):
 return 'property_payload'

 class ShapeC_la_7776:
 def payload(self):
 return id(self)

 class ShapeD_la_7776:
 __slots__ = ['payload']
 def __init__(self):
 self.payload = 'slot_payload'

 shapes_la_7776 = [ShapeA_la_7776(), ShapeB_la_7776(), ShapeC_la_7776(), ShapeD_la_7776()]
 for i in range(500):
 obj = shapes_la_7776[i % len(shapes_la_7776)]
 payload_val = obj.payload
 if callable(payload_val):
 payload_val()

{unstable_hash_object_v4, unstable_hash_object_v4, unstable_hash_object_v4}

 for i_loop_1589 in{2, 1, 2, 3, 4, 5, 6, 8, 10, 9, 12, 10, 12, 13, 14, 15, 15, 17}:
 x, *y = tuple_v6

for i_f1 in range(100):
 uop_harness_f1()