gh-120642: Move private PyCode APIs to the internal C API (#120643)

* Move _Py_CODEUNIT and related functions to pycore_code.h.
* Move _Py_BackoffCounter to pycore_backoff.h.
* Move Include/cpython/optimizer.h content to pycore_optimizer.h.
* Remove Include/cpython/optimizer.h.
* Remove PyUnstable_Replace_Executor().

Rename functions:

* PyUnstable_GetExecutor() => _Py_GetExecutor()
* PyUnstable_GetOptimizer() => _Py_GetOptimizer()
* PyUnstable_SetOptimizer() => _Py_SetTier2Optimizer()
* PyUnstable_Optimizer_NewCounter() => _PyOptimizer_NewCounter()
* PyUnstable_Optimizer_NewUOpOptimizer() => _PyOptimizer_NewUOpOptimizer()

1 files changed, 0 insertions, 52 deletions

diff --git a/Include/cpython/code.h b/Include/cpython/code.h
index ef8f930..07ed520 100644
--- a/Include/cpython/code.h
+++ b/Include/cpython/code.h
@@ -24,58 +24,6 @@ typedef struct _Py_GlobalMonitors {
     uint8_t tools[_PY_MONITORING_UNGROUPED_EVENTS];
 } _Py_GlobalMonitors;
 
-typedef struct {
-    union {
-        struct {
-            uint16_t backoff : 4;
-            uint16_t value : 12;
-        };
-        uint16_t as_counter;  // For printf("%#x", ...)
-    };
-} _Py_BackoffCounter;
-
-/* Each instruction in a code object is a fixed-width value,
- * currently 2 bytes: 1-byte opcode + 1-byte oparg.  The EXTENDED_ARG
- * opcode allows for larger values but the current limit is 3 uses
- * of EXTENDED_ARG (see Python/compile.c), for a maximum
- * 32-bit value.  This aligns with the note in Python/compile.c
- * (compiler_addop_i_line) indicating that the max oparg value is
- * 2**32 - 1, rather than INT_MAX.
- */
-
-typedef union {
-    uint16_t cache;
-    struct {
-        uint8_t code;
-        uint8_t arg;
-    } op;
-    _Py_BackoffCounter counter;  // First cache entry of specializable op
-} _Py_CODEUNIT;
-
-
-/* These macros only remain defined for compatibility. */
-#define _Py_OPCODE(word) ((word).op.code)
-#define _Py_OPARG(word) ((word).op.arg)
-
-static inline _Py_CODEUNIT
-_py_make_codeunit(uint8_t opcode, uint8_t oparg)
-{
-    // No designated initialisers because of C++ compat
-    _Py_CODEUNIT word;
-    word.op.code = opcode;
-    word.op.arg = oparg;
-    return word;
-}
-
-static inline void
-_py_set_opcode(_Py_CODEUNIT *word, uint8_t opcode)
-{
-    word->op.code = opcode;
-}
-
-#define _Py_MAKE_CODEUNIT(opcode, oparg) _py_make_codeunit((opcode), (oparg))
-#define _Py_SET_OPCODE(word, opcode) _py_set_opcode(&(word), (opcode))
-
 
 typedef struct {
     PyObject *_co_code;