https://github.com/python/cpython/commit/5edfe55acf29f7c36f585bcff7f96c244c43f9ae
commit: 5edfe55acf29f7c36f585bcff7f96c244c43f9ae
branch: main
author: Donghee Na <[email protected]>
committer: corona10 <[email protected]>
date: 2025-09-09T09:51:08+09:00
summary:
gh-137838: Fix JIT trace buffer overrun by increasing possible exit stubs
(gh-138177)
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2025-08-27-17-51-38.gh-issue-137838.lK6T0j.rst
M Include/internal/pycore_optimizer.h
M Lib/test/test_sys_settrace.py
M Lib/test/test_trace.py
M Python/optimizer.c
diff --git a/Include/internal/pycore_optimizer.h
b/Include/internal/pycore_optimizer.h
index 01c98c36f052a9..94d01999f68d9d 100644
--- a/Include/internal/pycore_optimizer.h
+++ b/Include/internal/pycore_optimizer.h
@@ -119,7 +119,7 @@ PyAPI_FUNC(void)
_Py_Executors_InvalidateCold(PyInterpreterState *interp);
#define JIT_CLEANUP_THRESHOLD 100000
// This is the length of the trace we project initially.
-#define UOP_MAX_TRACE_LENGTH 800
+#define UOP_MAX_TRACE_LENGTH 1200
#define TRACE_STACK_SIZE 5
diff --git a/Lib/test/test_sys_settrace.py b/Lib/test/test_sys_settrace.py
index b3685a91c57ee7..199a9087dfe3bc 100644
--- a/Lib/test/test_sys_settrace.py
+++ b/Lib/test/test_sys_settrace.py
@@ -360,6 +360,8 @@ class TraceTestCase(unittest.TestCase):
# Disable gc collection when tracing, otherwise the
# deallocators may be traced as well.
def setUp(self):
+ if os.environ.get('PYTHON_UOPS_OPTIMIZE') == '0':
+ self.skipTest("Line tracing behavior differs when JIT optimizer is
disabled")
self.using_gc = gc.isenabled()
gc.disable()
self.addCleanup(sys.settrace, sys.gettrace())
diff --git a/Lib/test/test_trace.py b/Lib/test/test_trace.py
index bf54c9995376d6..19eee19bdea6d5 100644
--- a/Lib/test/test_trace.py
+++ b/Lib/test/test_trace.py
@@ -142,6 +142,8 @@ def test_traced_func_linear(self):
self.assertEqual(self.tracer.results().counts, expected)
+ @unittest.skipIf(os.environ.get('PYTHON_UOPS_OPTIMIZE') == '0',
+ "Line counts differ when JIT optimizer is disabled")
def test_traced_func_loop(self):
self.tracer.runfunc(traced_func_loop, 2, 3)
@@ -166,6 +168,8 @@ def test_traced_func_importing(self):
self.assertEqual(self.tracer.results().counts, expected)
+ @unittest.skipIf(os.environ.get('PYTHON_UOPS_OPTIMIZE') == '0',
+ "Line counts differ when JIT optimizer is disabled")
def test_trace_func_generator(self):
self.tracer.runfunc(traced_func_calling_generator)
@@ -236,6 +240,8 @@ def setUp(self):
self.my_py_filename = fix_ext_py(__file__)
self.addCleanup(sys.settrace, sys.gettrace())
+ @unittest.skipIf(os.environ.get('PYTHON_UOPS_OPTIMIZE') == '0',
+ "Line counts differ when JIT optimizer is disabled")
def test_exec_counts(self):
self.tracer = Trace(count=1, trace=0, countfuncs=0, countcallers=0)
code = r'''traced_func_loop(2, 5)'''
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2025-08-27-17-51-38.gh-issue-137838.lK6T0j.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2025-08-27-17-51-38.gh-issue-137838.lK6T0j.rst
new file mode 100644
index 00000000000000..3b8a2a88d4a5ec
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2025-08-27-17-51-38.gh-issue-137838.lK6T0j.rst
@@ -0,0 +1,2 @@
+Fix JIT trace buffer overrun by increasing possible exit stubs.
+Patch by Donghee Na.
diff --git a/Python/optimizer.c b/Python/optimizer.c
index bae5cfa50ead58..b82c790ffa9e69 100644
--- a/Python/optimizer.c
+++ b/Python/optimizer.c
@@ -591,9 +591,8 @@ translate_bytecode_to_trace(
for (;;) {
target = INSTR_IP(instr, code);
- // Need space for _DEOPT
- max_length--;
-
+ // One for possible _DEOPT, one because _CHECK_VALIDITY itself might
_DEOPT
+ max_length-=2;
uint32_t opcode = instr->op.code;
uint32_t oparg = instr->op.arg;
@@ -1283,6 +1282,11 @@ uop_optimize(
_Py_BloomFilter_Init(&dependencies);
_PyUOpInstruction buffer[UOP_MAX_TRACE_LENGTH];
OPT_STAT_INC(attempts);
+ char *env_var = Py_GETENV("PYTHON_UOPS_OPTIMIZE");
+ bool is_noopt = true;
+ if (env_var == NULL || *env_var == '\0' || *env_var > '0') {
+ is_noopt = false;
+ }
int length = translate_bytecode_to_trace(frame, instr, buffer,
UOP_MAX_TRACE_LENGTH, &dependencies, progress_needed);
if (length <= 0) {
// Error or nothing translated
@@ -1290,8 +1294,7 @@ uop_optimize(
}
assert(length < UOP_MAX_TRACE_LENGTH);
OPT_STAT_INC(traces_created);
- char *env_var = Py_GETENV("PYTHON_UOPS_OPTIMIZE");
- if (env_var == NULL || *env_var == '\0' || *env_var > '0') {
+ if (!is_noopt) {
length = _Py_uop_analyze_and_optimize(frame, buffer,
length,
curr_stackentries, &dependencies);
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