bpo-44032: Move data stack to thread from FrameObject.

Include/cpython/code.h

@@ -40,8 +40,8 @@ struct PyCodeObject {
  PyObject *co_name; /* unicode (name, for reference) */
  PyObject *co_linetable; /* string (encoding addr<->lineno mapping) See
  Objects/lnotab_notes.txt for details. */
+ int co_nlocalsplus; /* Number of locals + free + cell variables */
  PyObject *co_exceptiontable; /* Byte string encoding exception handling table */
- void *co_zombieframe; /* for optimization only (see frameobject.c) */
  PyObject *co_weakreflist; /* to support weakrefs to code objects */
  /* Scratch space for extra data relating to the code object.
  Type is a void* to keep the format private in codeobject.c to force

Include/cpython/frameobject.h

@@ -20,12 +20,9 @@ enum _framestate {
 typedef signed char PyFrameState;
 
 struct _frame {
-PyObject_VAR_HEAD
+PyObject_HEAD
  struct _frame *f_back; /* previous frame, or NULL */
  PyCodeObject *f_code; /* code segment */
- PyObject *f_builtins; /* builtin symbol table (PyDictObject) */
- PyObject *f_globals; /* global symbol table (PyDictObject) */
- PyObject *f_locals; /* local symbol table (any mapping) */
  PyObject **f_valuestack; /* points after the last local */
  PyObject *f_trace; /* Trace function */
  /* Borrowed reference to a generator, or NULL */
@@ -36,7 +33,8 @@ struct _frame {
  PyFrameState f_state; /* What state the frame is in */
  char f_trace_lines; /* Emit per-line trace events? */
  char f_trace_opcodes; /* Emit per-opcode trace events? */
- PyObject *f_localsplus[1]; /* locals+stack, dynamically sized */
+ char f_own_locals_memory; /* This frame owns the memory for the locals */
+ PyObject **f_localsptr; /* Pointer to locals, cells, free */
 };
 
 static inline int _PyFrame_IsRunnable(struct _frame *f) {
@@ -62,7 +60,7 @@ PyAPI_FUNC(PyFrameObject *) PyFrame_New(PyThreadState *, PyCodeObject *,
 
 /* only internal use */
 PyFrameObject*
-_PyFrame_New_NoTrack(PyThreadState *, PyFrameConstructor *, PyObject *);
+_PyFrame_New_NoTrack(PyThreadState *, PyFrameConstructor *, PyObject *, PyObject **);
 
 
 /* The rest of the interface is specific for frame objects */

Include/cpython/pystate.h

@@ -57,6 +57,12 @@ typedef struct _err_stackitem {
 
 } _PyErr_StackItem;
 
+typedef struct _stack_chunk {
+ struct _stack_chunk *previous;
+ size_t size;
+ size_t top;
+ PyObject * data[1]; /* Variable sized */
+} _PyStackChunk;
 
 // The PyThreadState typedef is in Include/pystate.h.
 struct _ts {
@@ -149,6 +155,9 @@ struct _ts {
 
  CFrame root_cframe;
 
+ _PyStackChunk *datastack_chunk;
+ PyObject **datastack_top;
+ PyObject **datastack_limit;
  /* XXX signal handlers should also be here */
 
 };

Include/genobject.h

@@ -18,7 +18,7 @@ extern "C" {
  /* Note: gi_frame can be NULL if the generator is "finished" */ \
  PyFrameObject *prefix##_frame; \
  /* The code object backing the generator */ \
-PyObject *prefix##_code; \
+PyCodeObject *prefix##_code; \
  /* List of weak reference. */ \
  PyObject *prefix##_weakreflist; \
  /* Name of the generator. */ \

Include/internal/pycore_frame.h

@@ -0,0 +1,38 @@
+#ifndef Py_INTERNAL_FRAME_H
+#define Py_INTERNAL_FRAME_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+enum {
+ FRAME_SPECIALS_GLOBALS_OFFSET = 0,
+ FRAME_SPECIALS_BUILTINS_OFFSET = 1,
+ FRAME_SPECIALS_LOCALS_OFFSET = 2,
+ FRAME_SPECIALS_SIZE = 3
+};
+
+static inline PyObject **
+_PyFrame_Specials(PyFrameObject *f) {
+ return &f->f_valuestack[-FRAME_SPECIALS_SIZE];
+}
+
+/* Returns a *borrowed* reference. */
+static inline PyObject *
+_PyFrame_GetGlobals(PyFrameObject *f)
+{
+ return _PyFrame_Specials(f)[FRAME_SPECIALS_GLOBALS_OFFSET];
+}
+
+/* Returns a *borrowed* reference. */
+static inline PyObject *
+_PyFrame_GetBuiltins(PyFrameObject *f)
+{
+ return _PyFrame_Specials(f)[FRAME_SPECIALS_BUILTINS_OFFSET];
+}
+
+int _PyFrame_TakeLocals(PyFrameObject *f);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_INTERNAL_FRAME_H */

Include/internal/pycore_pymem.h

@@ -94,6 +94,11 @@ struct _PyTraceMalloc_Config {
 
 PyAPI_DATA(struct _PyTraceMalloc_Config) _Py_tracemalloc_config;
 
+/* Allocate memory directly from the O/S virtual memory system,
+ * where supported. Otherwise fallback on malloc */
+void *_PyObject_VirtualAlloc(size_t size);
+void _PyObject_VirtualFree(void *, size_t size);
+
 
 #ifdef __cplusplus
 }

Include/internal/pycore_pystate.h

@@ -147,6 +147,9 @@ PyAPI_FUNC(int) _PyState_AddModule(
 
 PyAPI_FUNC(int) _PyOS_InterruptOccurred(PyThreadState *tstate);
 
+PyObject **_PyThreadState_PushLocals(PyThreadState *, int size);
+void _PyThreadState_PopLocals(PyThreadState *, PyObject **);
+
 #ifdef __cplusplus
 }
 #endif

Lib/test/test_gdb.py

@@ -666,15 +666,16 @@ def test_builtin_method(self):
 
  def test_frames(self):
  gdb_output = self.get_stack_trace('''
+import sys
 def foo(a, b, c):
-pass
+return sys._getframe(0)
 
-foo(3, 4, 5)
-id(foo.__code__)''',
+f = foo(3, 4, 5)
+id(f)''',
  breakpoint='builtin_id',
- cmds_after_breakpoint=['print (PyFrameObject*)(((PyCodeObject*)v)->co_zombieframe)']
+ cmds_after_breakpoint=['print (PyFrameObject*)v']
  )
- self.assertTrue(re.match(r'.*\s+\$1 =\s+Frame 0x-?[0-9a-f]+, for file <string>, line 3, in foo \(\)\s+.*',
+ self.assertTrue(re.match(r'.*\s+\$1 =\s+Frame 0x-?[0-9a-f]+, for file <string>, line 4, in foo \(a=3.*',
  gdb_output,
  re.DOTALL),
  'Unexpected gdb representation: %r\n%s' % (gdb_output, gdb_output))

Lib/test/test_sys.py

@@ -1274,11 +1274,7 @@ class C(object): pass
  # frame
  import inspect
  x = inspect.currentframe()
- ncells = len(x.f_code.co_cellvars)
- nfrees = len(x.f_code.co_freevars)
- localsplus = x.f_code.co_stacksize + x.f_code.co_nlocals +\
- ncells + nfrees
- check(x, vsize('8P3i3c' + localsplus*'P'))
+ check(x, size('5P3i4cP'))
  # function
  def func(): pass
  check(func, size('14P'))

Misc/NEWS.d/next/Core and Builtins/2021-05-14-20-03-32.bpo-44032.OzT1ob.rst

@@ -0,0 +1,2 @@
+Move 'fast' locals and other variables from the frame object to a per-thread
+datastack.

Objects/codeobject.c

@@ -239,6 +239,8 @@ PyCode_NewWithPosOnlyArgs(int argcount, int posonlyargcount, int kwonlyargcount,
  co->co_posonlyargcount = posonlyargcount;
  co->co_kwonlyargcount = kwonlyargcount;
  co->co_nlocals = nlocals;
+ co->co_nlocalsplus = nlocals +
+ (int)PyTuple_GET_SIZE(freevars) + (int)PyTuple_GET_SIZE(cellvars);
  co->co_stacksize = stacksize;
  co->co_flags = flags;
  Py_INCREF(code);
@@ -263,7 +265,6 @@ PyCode_NewWithPosOnlyArgs(int argcount, int posonlyargcount, int kwonlyargcount,
  co->co_linetable = linetable;
  Py_INCREF(exceptiontable);
  co->co_exceptiontable = exceptiontable;
- co->co_zombieframe = NULL;
  co->co_weakreflist = NULL;
  co->co_extra = NULL;
 
@@ -674,8 +675,6 @@ code_dealloc(PyCodeObject *co)
  Py_XDECREF(co->co_exceptiontable);
  if (co->co_cell2arg != NULL)
  PyMem_Free(co->co_cell2arg);
- if (co->co_zombieframe != NULL)
- PyObject_GC_Del(co->co_zombieframe);
  if (co->co_weakreflist != NULL)
  PyObject_ClearWeakRefs((PyObject*)co);
  PyObject_Free(co);