gh-160852: Re-read the bytecode after JIT stop_tracing

Misc/NEWS.d/next/Core_and_Builtins/2026-10-28-22-15-00.gh-issue-160852.st0pTr.rst

@@ -0,0 +1,2 @@
+Fix a crash in the experimental JIT when a finalizer invalidates an
+executor while ``stop_tracing`` leaves the tracer.

Python/bytecodes.c

@@ -6636,6 +6636,16 @@ dummy_func(
             LEAVE_TRACING();
             int err = stop_tracing_and_jit(tstate, frame);
             ERROR_IF(err < 0);
+            /* stop_tracing_and_jit() can drop the last reference to a
+               temporary and run a finalizer. A ResourceWarning then writes
+               __warningregistry__ into a watched globals dict, and
+               executor_invalidate() restores this instruction and clears its
+               executor slot. Dispatching the ENTER_EXECUTOR opcode sampled
+               above calls _PyJIT_Entry(NULL). Keep any EXTENDED_ARG bits
+               already accumulated in oparg; only the low byte lives in the
+               code unit. */
+            opcode = next_instr->op.code;
+            oparg = (oparg & ~255) | next_instr->op.arg;
             DISPATCH_GOTO_NON_TRACING();
 #else
             Py_FatalError("JIT label executed in non-jit build.");