From: Ken Jin <kenjin@python.org>
Date: Wed, 3 Sep 2025 18:05:06 +0000 (+0800)
Subject: gh-138431: JIT Optimizer --- Fix round-tripping references for str and tuple (GH... 
X-Git-Tag: v3.15.0a1~500
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2402f84665df41732c94db2ccd6f90dd13479fa8;p=thirdparty%2FPython%2Fcpython.git

gh-138431: JIT Optimizer --- Fix round-tripping references for str and tuple (GH-138458)

Co-authored-by: Mark Shannon <9448417+markshannon@users.noreply.github.com>
---

diff --git a/Include/internal/pycore_optimizer.h b/Include/internal/pycore_optimizer.h
index 3a5ae0a054ed..01c98c36f052 100644
--- a/Include/internal/pycore_optimizer.h
+++ b/Include/internal/pycore_optimizer.h
@@ -251,6 +251,12 @@ PyJitRef_Wrap(JitOptSymbol *sym)
     return (JitOptRef){.bits=(uintptr_t)sym};
 }
 
+static inline JitOptRef
+PyJitRef_StripReferenceInfo(JitOptRef ref)
+{
+    return PyJitRef_Wrap(PyJitRef_Unwrap(ref));
+}
+
 static inline JitOptRef
 PyJitRef_Borrow(JitOptRef ref)
 {
diff --git a/Lib/test/test_capi/test_opt.py b/Lib/test/test_capi/test_opt.py
index c796b0dd4b5b..ffd65dbb1464 100644
--- a/Lib/test/test_capi/test_opt.py
+++ b/Lib/test/test_capi/test_opt.py
@@ -2501,6 +2501,22 @@ class TestUopsOptimization(unittest.TestCase):
         # For now... until we constant propagate it away.
         self.assertIn("_BINARY_OP", uops)
 
+    def test_reference_tracking_across_call_doesnt_crash(self):
+
+        def f1():
+            for _ in range(TIER2_THRESHOLD + 1):
+                # Choose a value that won't occur elsewhere to avoid sharing
+                str("value that won't occur elsewhere to avoid sharing")
+
+        f1()
+
+        def f2():
+            for _ in range(TIER2_THRESHOLD + 1):
+                # Choose a value that won't occur elsewhere to avoid sharing
+                tuple((31, -17, 25, "won't occur elsewhere"))
+
+        f2()
+
 
 def global_identity(x):
     return x
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-09-03-15-35-34.gh-issue-138431.EUsrtA.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-09-03-15-35-34.gh-issue-138431.EUsrtA.rst
new file mode 100644
index 000000000000..11fc3c05d5aa
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-09-03-15-35-34.gh-issue-138431.EUsrtA.rst
@@ -0,0 +1 @@
+Fix a bug in the JIT optimizer when round-tripping strings and tuples.
diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index 781296dc7f48..eccbddf0546a 100644
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -762,9 +762,8 @@ dummy_func(void) {
     }
 
     op(_RETURN_VALUE, (retval -- res)) {
-        // We wrap and unwrap the value to mimic PyStackRef_MakeHeapSafe
-        // in bytecodes.c
-        JitOptRef temp = PyJitRef_Wrap(PyJitRef_Unwrap(retval));
+        // Mimics PyStackRef_MakeHeapSafe in the interpreter.
+        JitOptRef temp = PyJitRef_StripReferenceInfo(retval);
         DEAD(retval);
         SAVE_STACK();
         ctx->frame->stack_pointer = stack_pointer;
@@ -925,7 +924,9 @@ dummy_func(void) {
     op(_CALL_STR_1, (unused, unused, arg -- res)) {
         if (sym_matches_type(arg, &PyUnicode_Type)) {
             // e.g. str('foo') or str(foo) where foo is known to be a string
-            res = arg;
+            // Note: we must strip the reference information because it goes
+            // through str() which strips the reference information from it.
+            res = PyJitRef_StripReferenceInfo(arg);
         }
         else {
             res = sym_new_type(ctx, &PyUnicode_Type);
@@ -1065,7 +1066,9 @@ dummy_func(void) {
     op(_CALL_TUPLE_1, (callable, null, arg -- res)) {
         if (sym_matches_type(arg, &PyTuple_Type)) {
             // e.g. tuple((1, 2)) or tuple(foo) where foo is known to be a tuple
-            res = arg;
+            // Note: we must strip the reference information because it goes
+            // through tuple() which strips the reference information from it.
+            res = PyJitRef_StripReferenceInfo(arg);
         }
         else {
             res = sym_new_type(ctx, &PyTuple_Type);
diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
index 14e985b42ea0..8617355e25f4 100644
--- a/Python/optimizer_cases.c.h
+++ b/Python/optimizer_cases.c.h
@@ -1060,7 +1060,7 @@
             JitOptRef retval;
             JitOptRef res;
             retval = stack_pointer[-1];
-            JitOptRef temp = PyJitRef_Wrap(PyJitRef_Unwrap(retval));
+            JitOptRef temp = PyJitRef_StripReferenceInfo(retval);
             stack_pointer += -1;
             assert(WITHIN_STACK_BOUNDS());
             ctx->frame->stack_pointer = stack_pointer;
@@ -2496,7 +2496,7 @@
             JitOptRef res;
             arg = stack_pointer[-1];
             if (sym_matches_type(arg, &PyUnicode_Type)) {
-                res = arg;
+                res = PyJitRef_StripReferenceInfo(arg);
             }
             else {
                 res = sym_new_type(ctx, &PyUnicode_Type);
@@ -2522,7 +2522,7 @@
             JitOptRef res;
             arg = stack_pointer[-1];
             if (sym_matches_type(arg, &PyTuple_Type)) {
-                res = arg;
+                res = PyJitRef_StripReferenceInfo(arg);
             }
             else {
                 res = sym_new_type(ctx, &PyTuple_Type);