Merge remote-tracking branch 'upstream/main' into expose_codegen

Author: iritkatriel

Doc/c-api/refcounting.rst

@@ -7,8 +7,8 @@
 Reference Counting
 ******************
 
-The macros in this section are used for managing reference counts of Python
-objects.
+The functions and macros in this section are used for managing reference counts
+of Python objects.
 
 
 .. c:function:: Py_ssize_t Py_REFCNT(PyObject *o)
@@ -129,6 +129,11 @@ objects.
    It is a good idea to use this macro whenever decrementing the reference
    count of an object that might be traversed during garbage collection.
 
+   .. versionchanged:: 3.12
+      The macro argument is now only evaluated once. If the argument has side
+      effects, these are no longer duplicated.
+
+
 .. c:function:: void Py_IncRef(PyObject *o)
 
    Increment the reference count for object *o*. A function version of :c:func:`Py_XINCREF`.
@@ -139,3 +144,40 @@ objects.
 
    Decrement the reference count for object *o*. A function version of :c:func:`Py_XDECREF`.
    It can be used for runtime dynamic embedding of Python.
+
+
+.. c:macro:: Py_SETREF(dst, src)
+
+   Macro safely decrementing the `dst` reference count and setting `dst` to
+   `src`.
+
+   As in case of :c:func:`Py_CLEAR`, "the obvious" code can be deadly::
+
+       Py_DECREF(dst);
+       dst = src;
+
+   The safe way is::
+
+        Py_SETREF(dst, src);
+
+   That arranges to set `dst` to `src` _before_ decrementing reference count of
+   *dst* old value, so that any code triggered as a side-effect of `dst`
+   getting torn down no longer believes `dst` points to a valid object.
+
+   .. versionadded:: 3.6
+
+   .. versionchanged:: 3.12
+      The macro arguments are now only evaluated once. If an argument has side
+      effects, these are no longer duplicated.
+
+
+.. c:macro:: Py_XSETREF(dst, src)
+
+   Variant of :c:macro:`Py_SETREF` macro that uses :c:func:`Py_XDECREF` instead
+   of :c:func:`Py_DECREF`.
+
+   .. versionadded:: 3.6
+
+   .. versionchanged:: 3.12
+      The macro arguments are now only evaluated once. If an argument has side
+      effects, these are no longer duplicated.

Doc/library/index.rst

@@ -27,8 +27,8 @@ as a collection of packages, so it may be necessary to use the packaging
 tools provided with the operating system to obtain some or all of the
 optional components.
 
-In addition to the standard library, there is a growing collection of
-several thousand components (from individual programs and modules to
+In addition to the standard library, there is an active collection of
+hundreds of thousands of components (from individual programs and modules to
 packages and entire application development frameworks), available from
 the `Python Package Index <https://pypi.org>`_.
 

Doc/whatsnew/3.12.rst

@@ -792,6 +792,11 @@ Porting to Python 3.12
   :class:`bytes` type is accepted for bytes strings.
   (Contributed by Victor Stinner in :gh:`98393`.)
 
+* The :c:macro:`Py_CLEAR`, :c:macro:`Py_SETREF` and :c:macro:`Py_XSETREF`
+  macros now only evaluate their argument once. If the argument has side
+  effects, these side effects are no longer duplicated.
+  (Contributed by Victor Stinner in :gh:`98724`.)
+
 Deprecated
 ----------
 

Include/cpython/object.h

@@ -41,15 +41,15 @@ typedef struct _Py_Identifier {
     Py_ssize_t index;
 } _Py_Identifier;
 
-#if defined(NEEDS_PY_IDENTIFIER) || !defined(Py_BUILD_CORE)
+#ifndef Py_BUILD_CORE
 // For now we are keeping _Py_IDENTIFIER for continued use
 // in non-builtin extensions (and naughty PyPI modules).
 
 #define _Py_static_string_init(value) { .string = (value), .index = -1 }
 #define _Py_static_string(varname, value)  static _Py_Identifier varname = _Py_static_string_init(value)
 #define _Py_IDENTIFIER(varname) _Py_static_string(PyId_##varname, #varname)
 
-#endif  /* NEEDS_PY_IDENTIFIER */
+#endif /* !Py_BUILD_CORE */
 
 typedef struct {
     /* Number implementations must check *both*
@@ -305,37 +305,41 @@ _PyObject_GenericSetAttrWithDict(PyObject *, PyObject *,
 
 PyAPI_FUNC(PyObject *) _PyObject_FunctionStr(PyObject *);
 
-/* Safely decref `op` and set `op` to `op2`.
+/* Safely decref `dst` and set `dst` to `src`.
  *
  * As in case of Py_CLEAR "the obvious" code can be deadly:
  *
- *     Py_DECREF(op);
- *     op = op2;
+ *     Py_DECREF(dst);
+ *     dst = src;
  *
  * The safe way is:
  *
- *      Py_SETREF(op, op2);
+ *      Py_SETREF(dst, src);
  *
- * That arranges to set `op` to `op2` _before_ decref'ing, so that any code
- * triggered as a side-effect of `op` getting torn down no longer believes
- * `op` points to a valid object.
+ * That arranges to set `dst` to `src` _before_ decref'ing, so that any code
+ * triggered as a side-effect of `dst` getting torn down no longer believes
+ * `dst` points to a valid object.
  *
- * Py_XSETREF is a variant of Py_SETREF that uses Py_XDECREF instead of
- * Py_DECREF.
+ * gh-98724: Use the _tmp_dst_ptr variable to evaluate the 'dst' macro argument
+ * exactly once, to prevent the duplication of side effects in this macro.
  */
-
-#define Py_SETREF(op, op2)                      \
-    do {                                        \
-        PyObject *_py_tmp = _PyObject_CAST(op); \
-        (op) = (op2);                           \
-        Py_DECREF(_py_tmp);                     \
+#define Py_SETREF(dst, src)                                     \
+    do {                                                        \
+        PyObject **_tmp_dst_ptr = _Py_CAST(PyObject**, &(dst)); \
+        PyObject *_tmp_dst = (*_tmp_dst_ptr);                   \
+        *_tmp_dst_ptr = _PyObject_CAST(src);                    \
+        Py_DECREF(_tmp_dst);                                    \
     } while (0)
 
-#define Py_XSETREF(op, op2)                     \
-    do {                                        \
-        PyObject *_py_tmp = _PyObject_CAST(op); \
-        (op) = (op2);                           \
-        Py_XDECREF(_py_tmp);                    \
+/* Py_XSETREF() is a variant of Py_SETREF() that uses Py_XDECREF() instead of
+ * Py_DECREF().
+ */
+#define Py_XSETREF(dst, src)                                    \
+    do {                                                        \
+        PyObject **_tmp_dst_ptr = _Py_CAST(PyObject**, &(dst)); \
+        PyObject *_tmp_dst = (*_tmp_dst_ptr);                   \
+        *_tmp_dst_ptr = _PyObject_CAST(src);                    \
+        Py_XDECREF(_tmp_dst);                                   \
     } while (0)
 
 

Include/internal/pycore_code.h

@@ -91,8 +91,6 @@ typedef struct {
 
 #define INLINE_CACHE_ENTRIES_FOR_ITER CACHE_ENTRIES(_PyForIterCache)
 
-extern uint8_t _PyOpcode_Adaptive[256];
-
 // Borrowed references to common callables:
 struct callable_cache {
     PyObject *isinstance;
@@ -219,11 +217,14 @@ extern int _Py_Specialize_LoadAttr(PyObject *owner, _Py_CODEUNIT *instr,
                                    PyObject *name);
 extern int _Py_Specialize_StoreAttr(PyObject *owner, _Py_CODEUNIT *instr,
                                     PyObject *name);
-extern int _Py_Specialize_LoadGlobal(PyObject *globals, PyObject *builtins, _Py_CODEUNIT *instr, PyObject *name);
-extern int _Py_Specialize_BinarySubscr(PyObject *sub, PyObject *container, _Py_CODEUNIT *instr);
-extern int _Py_Specialize_StoreSubscr(PyObject *container, PyObject *sub, _Py_CODEUNIT *instr);
-extern int _Py_Specialize_Call(PyObject *callable, _Py_CODEUNIT *instr,
-                               int nargs, PyObject *kwnames);
+extern void _Py_Specialize_LoadGlobal(PyObject *globals, PyObject *builtins,
+                                      _Py_CODEUNIT *instr, PyObject *name);
+extern void _Py_Specialize_BinarySubscr(PyObject *sub, PyObject *container,
+                                        _Py_CODEUNIT *instr);
+extern void _Py_Specialize_StoreSubscr(PyObject *container, PyObject *sub,
+                                       _Py_CODEUNIT *instr);
+extern void _Py_Specialize_Call(PyObject *callable, _Py_CODEUNIT *instr,
+                                int nargs, PyObject *kwnames);
 extern void _Py_Specialize_BinaryOp(PyObject *lhs, PyObject *rhs, _Py_CODEUNIT *instr,
                                     int oparg, PyObject **locals);
 extern void _Py_Specialize_CompareOp(PyObject *lhs, PyObject *rhs,
@@ -377,8 +378,22 @@ write_location_entry_start(uint8_t *ptr, int code, int length)
 
 /* With a 16-bit counter, we have 12 bits for the counter value, and 4 bits for the backoff */
 #define ADAPTIVE_BACKOFF_BITS 4
-/* The initial counter value is 1 == 2**ADAPTIVE_BACKOFF_START - 1 */
-#define ADAPTIVE_BACKOFF_START 1
+
+// A value of 1 means that we attempt to specialize the *second* time each
+// instruction is executed. Executing twice is a much better indicator of
+// "hotness" than executing once, but additional warmup delays only prevent
+// specialization. Most types stabilize by the second execution, too:
+#define ADAPTIVE_WARMUP_VALUE 1
+#define ADAPTIVE_WARMUP_BACKOFF 1
+
+// A value of 52 means that we attempt to re-specialize after 53 misses (a prime
+// number, useful for avoiding artifacts if every nth value is a different type
+// or something). Setting the backoff to 0 means that the counter is reset to
+// the same state as a warming-up instruction (value == 1, backoff == 1) after
+// deoptimization. This isn't strictly necessary, but it is bit easier to reason
+// about when thinking about the opcode transitions as a state machine:
+#define ADAPTIVE_COOLDOWN_VALUE 52
+#define ADAPTIVE_COOLDOWN_BACKOFF 0
 
 #define MAX_BACKOFF_VALUE (16 - ADAPTIVE_BACKOFF_BITS)
 
@@ -390,9 +405,15 @@ adaptive_counter_bits(int value, int backoff) {
 }
 
 static inline uint16_t
-adaptive_counter_start(void) {
-    unsigned int value = (1 << ADAPTIVE_BACKOFF_START) - 1;
-    return adaptive_counter_bits(value, ADAPTIVE_BACKOFF_START);
+adaptive_counter_warmup(void) {
+    return adaptive_counter_bits(ADAPTIVE_WARMUP_VALUE,
+                                 ADAPTIVE_WARMUP_BACKOFF);
+}
+
+static inline uint16_t
+adaptive_counter_cooldown(void) {
+    return adaptive_counter_bits(ADAPTIVE_COOLDOWN_VALUE,
+                                 ADAPTIVE_COOLDOWN_BACKOFF);
 }
 
 static inline uint16_t
@@ -435,6 +456,16 @@ _PyCode_LineNumberFromArray(PyCodeObject *co, int index)
     }
 }
 
+typedef struct _PyShimCodeDef {
+    const uint8_t *code;
+    int codelen;
+    int stacksize;
+    const char *cname;
+} _PyShimCodeDef;
+
+extern PyCodeObject *
+_Py_MakeShimCode(const _PyShimCodeDef *code);
+
 
 #ifdef __cplusplus
 }

Include/internal/pycore_frame.h

@@ -42,27 +42,27 @@ typedef enum _framestate {
 enum _frameowner {
     FRAME_OWNED_BY_THREAD = 0,
     FRAME_OWNED_BY_GENERATOR = 1,
-    FRAME_OWNED_BY_FRAME_OBJECT = 2
+    FRAME_OWNED_BY_FRAME_OBJECT = 2,
+    FRAME_OWNED_BY_CSTACK = 3,
 };
 
 typedef struct _PyInterpreterFrame {
     /* "Specials" section */
-    PyObject *f_funcobj; /* Strong reference */
-    PyObject *f_globals; /* Borrowed reference */
-    PyObject *f_builtins; /* Borrowed reference */
-    PyObject *f_locals; /* Strong reference, may be NULL */
+    PyObject *f_funcobj; /* Strong reference. Only valid if not on C stack */
+    PyObject *f_globals; /* Borrowed reference. Only valid if not on C stack */
+    PyObject *f_builtins; /* Borrowed reference. Only valid if not on C stack */
+    PyObject *f_locals; /* Strong reference, may be NULL. Only valid if not on C stack */
     PyCodeObject *f_code; /* Strong reference */
-    PyFrameObject *frame_obj; /* Strong reference, may be NULL */
+    PyFrameObject *frame_obj; /* Strong reference, may be NULL. Only valid if not on C stack */
     /* Linkage section */
     struct _PyInterpreterFrame *previous;
     // NOTE: This is not necessarily the last instruction started in the given
     // frame. Rather, it is the code unit *prior to* the *next* instruction. For
     // example, it may be an inline CACHE entry, an instruction we just jumped
     // over, or (in the case of a newly-created frame) a totally invalid value:
     _Py_CODEUNIT *prev_instr;
-    int stacktop;     /* Offset of TOS from localsplus  */
+    int stacktop;  /* Offset of TOS from localsplus  */
     uint16_t yield_offset;
-    bool is_entry;  // Whether this is the "root" frame for the current _PyCFrame.
     char owner;
     /* Locals and stack */
     PyObject *localsplus[1];
@@ -110,7 +110,6 @@ _PyFrame_InitializeSpecials(
     frame->stacktop = code->co_nlocalsplus;
     frame->frame_obj = NULL;
     frame->prev_instr = _PyCode_CODE(code) - 1;
-    frame->is_entry = false;
     frame->yield_offset = 0;
     frame->owner = FRAME_OWNED_BY_THREAD;
 }