diff options
| -rw-r--r-- | Include/objimpl.h | 52 | ||||
| -rw-r--r-- | Modules/gcmodule.c | 16 | ||||
| -rw-r--r-- | Objects/object.c | 8 | ||||
| -rw-r--r-- | Objects/typeobject.c | 4 |
4 files changed, 32 insertions, 48 deletions
diff --git a/Include/objimpl.h b/Include/objimpl.h index 2ea3ad5..db4cb6d 100644 --- a/Include/objimpl.h +++ b/Include/objimpl.h @@ -173,40 +173,36 @@ extern DL_IMPORT(void) _PyObject_Del(PyObject *); #define _PyObject_SIZE(typeobj) ( (typeobj)->tp_basicsize ) -/* _PyObject_VAR_SIZE computes the amount of memory allocated for a vrbl- - size object with nitems items, exclusive of gc overhead (if any). The - value is rounded up to the closest multiple of sizeof(void *), in order - to ensure that pointer fields at the end of the object are correctly - aligned for the platform (this is of special importance for subclasses - of, e.g., str or long, so that pointers can be stored after the embedded - data). - - Note that there's no memory wastage in doing this, as malloc has to - return (at worst) pointer-aligned memory anyway - - However, writing the macro to *return* the result is clumsy due to the - calculations needed. Instead you must pass the result lvalue as the first - argument, and it should be of type size_t (both because that's the - correct conceptual type, and because using an unsigned type allows the - compiler to generate faster code for the mod computation inside the - macro). +/* _PyObject_VAR_SIZE returns the number of bytes (as size_t) allocated for a + vrbl-size object with nitems items, exclusive of gc overhead (if any). The + value is rounded up to the closest multiple of sizeof(void *), in order to + ensure that pointer fields at the end of the object are correctly aligned + for the platform (this is of special importance for subclasses of, e.g., + str or long, so that pointers can be stored after the embedded data). + + Note that there's no memory wastage in doing this, as malloc has to + return (at worst) pointer-aligned memory anyway. */ -#define _PyObject_VAR_SIZE(result, typeobj, nitems) \ - do { \ - size_t mod; \ - (result) = (size_t) (typeobj)->tp_basicsize; \ - (result) += (size_t) ((nitems)*(typeobj)->tp_itemsize); \ - mod = (result) % SIZEOF_VOID_P; \ - if (mod) \ - (result) += SIZEOF_VOID_P - mod; \ - } while(0) +#if ((SIZEOF_VOID_P - 1) & SIZEOF_VOID_P) != 0 +# error "_PyObject_VAR_SIZE requires SIZEOF_VOID_P be a power of 2" +#endif + +#define _PyObject_VAR_SIZE(typeobj, nitems) \ + (size_t) \ + ( ( (typeobj)->tp_basicsize + \ + (nitems)*(typeobj)->tp_itemsize + \ + (SIZEOF_VOID_P - 1) \ + ) & ~(SIZEOF_VOID_P - 1) \ + ) #define PyObject_NEW(type, typeobj) \ ( (type *) PyObject_Init( \ (PyObject *) PyObject_MALLOC( _PyObject_SIZE(typeobj) ), (typeobj)) ) -#define PyObject_NEW_VAR(type, typeobj, nitems) \ - ((type *) _PyObject_NewVar(typeobj, nitems)) +#define PyObject_NEW_VAR(type, typeobj, n) \ +( (type *) PyObject_InitVar( \ + (PyVarObject *) PyObject_MALLOC(_PyObject_VAR_SIZE((typeobj),(n)) ),\ + (typeobj), (n)) ) #define PyObject_DEL(op) PyObject_FREE(op) diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c index 63a2370..34503e4 100644 --- a/Modules/gcmodule.c +++ b/Modules/gcmodule.c @@ -801,14 +801,10 @@ PyObject * _PyObject_GC_Malloc(PyTypeObject *tp, int nitems) { PyObject *op; - size_t basicsize; + const size_t basicsize = _PyObject_VAR_SIZE(tp, nitems); #ifdef WITH_CYCLE_GC - size_t nbytes; - PyGC_Head *g; - - _PyObject_VAR_SIZE(basicsize, tp, nitems); - nbytes = sizeof(PyGC_Head) + basicsize; - g = PyObject_MALLOC(nbytes); + const size_t nbytes = sizeof(PyGC_Head) + basicsize; + PyGC_Head *g = PyObject_MALLOC(nbytes); if (g == NULL) return (PyObject *)PyErr_NoMemory(); g->gc_next = NULL; @@ -824,7 +820,6 @@ _PyObject_GC_Malloc(PyTypeObject *tp, int nitems) } op = FROM_GC(g); #else - _PyObject_VAR_SIZE(basicsize, tp, nitems); op = PyObject_MALLOC(basicsize); if (op == NULL) return (PyObject *)PyErr_NoMemory(); @@ -850,17 +845,14 @@ _PyObject_GC_NewVar(PyTypeObject *tp, int nitems) PyVarObject * _PyObject_GC_Resize(PyVarObject *op, int nitems) { - size_t basicsize; + const size_t basicsize = _PyObject_VAR_SIZE(op->ob_type, nitems); #ifdef WITH_CYCLE_GC PyGC_Head *g = AS_GC(op); - - _PyObject_VAR_SIZE(basicsize, op->ob_type, nitems); g = PyObject_REALLOC(g, sizeof(PyGC_Head) + basicsize); if (g == NULL) return (PyVarObject *)PyErr_NoMemory(); op = (PyVarObject *) FROM_GC(g); #else - _PyObject_VAR_SIZE(basicsize, op->ob_type, nitems); op = PyObject_REALLOC(op, basicsize); if (op == NULL) return (PyVarObject *)PyErr_NoMemory(); diff --git a/Objects/object.c b/Objects/object.c index 0237234..be8eb07 100644 --- a/Objects/object.c +++ b/Objects/object.c @@ -130,9 +130,7 @@ PyVarObject * _PyObject_NewVar(PyTypeObject *tp, int nitems) { PyVarObject *op; - size_t size; - - _PyObject_VAR_SIZE(size, tp, nitems); + const size_t size = _PyObject_VAR_SIZE(tp, nitems); op = (PyVarObject *) PyObject_MALLOC(size); if (op == NULL) return (PyVarObject *)PyErr_NoMemory(); @@ -1158,8 +1156,8 @@ _PyObject_GetDictPtr(PyObject *obj) if (dictoffset == 0) return NULL; if (dictoffset < 0) { - size_t size; - _PyObject_VAR_SIZE(size, tp, ((PyVarObject *)obj)->ob_size); + const size_t size = _PyObject_VAR_SIZE(tp, + ((PyVarObject *)obj)->ob_size); dictoffset += (long)size; assert(dictoffset > 0); assert(dictoffset % SIZEOF_VOID_P == 0); diff --git a/Objects/typeobject.c b/Objects/typeobject.c index 0342e71..0ec8175 100644 --- a/Objects/typeobject.c +++ b/Objects/typeobject.c @@ -191,9 +191,7 @@ PyObject * PyType_GenericAlloc(PyTypeObject *type, int nitems) { PyObject *obj; - size_t size; - - _PyObject_VAR_SIZE(size, type, nitems); + const size_t size = _PyObject_VAR_SIZE(type, nitems); if (PyType_IS_GC(type)) obj = _PyObject_GC_Malloc(type, nitems); |