gh-142543: Mark tracer functions as Py_NO_INLINE (GH-142846)

Author: Fidget-Spinner

Misc/NEWS.d/next/Core_and_Builtins/2025-12-16-23-26-41.gh-issue-142543.wJKjBs.rst

@@ -0,0 +1 @@
+Fix a stack overflow on Clang JIT build configurations with full LTO.

Python/optimizer.c

@@ -582,7 +582,8 @@ is_terminator(const _PyUOpInstruction *uop)
 
 /* Returns 1 on success (added to trace), 0 on trace end.
  */
-int
+// gh-142543: inlining this function causes stack overflows
+Py_NO_INLINE int
 _PyJit_translate_single_bytecode_to_trace(
     PyThreadState *tstate,
     _PyInterpreterFrame *frame,
@@ -994,7 +995,8 @@ _PyJit_translate_single_bytecode_to_trace(
 }
 
 // Returns 0 for do not enter tracing, 1 on enter tracing.
-int
+// gh-142543: inlining this function causes stack overflows
+Py_NO_INLINE int
 _PyJit_TryInitializeTracing(
     PyThreadState *tstate, _PyInterpreterFrame *frame, _Py_CODEUNIT *curr_instr,
     _Py_CODEUNIT *start_instr, _Py_CODEUNIT *close_loop_instr, int curr_stackdepth, int chain_depth,
@@ -1066,7 +1068,7 @@ _PyJit_TryInitializeTracing(
     return 1;
 }
 
-void
+Py_NO_INLINE void
 _PyJit_FinalizeTracing(PyThreadState *tstate)
 {
     _PyThreadStateImpl *_tstate = (_PyThreadStateImpl *)tstate;