gh-117139: Replace _PyList_FromArraySteal with stack ref variant (#122830)

colesbury · Fidget-Spinner · web-flow · commit ab094d1b2b34 · 2024-08-12T14:49:49.000-04:00
This replaces `_PyList_FromArraySteal` with `_PyList_FromStackRefSteal`.
It's functionally equivalent, but takes a `_PyStackRef` array instead of
an array of `PyObject` pointers.

Co-authored-by: Ken Jin &lt;kenjin@python.org&gt;
diff --git a/Include/internal/pycore_list.h b/Include/internal/pycore_list.h
@@ -56,7 +56,10 @@ typedef struct {
     PyListObject *it_seq; /* Set to NULL when iterator is exhausted */
 } _PyListIterObject;
 
-PyAPI_FUNC(PyObject *)_PyList_FromArraySteal(PyObject *const *src, Py_ssize_t n);
+union _PyStackRef;
+
+PyAPI_FUNC(PyObject *)_PyList_FromStackRefSteal(const union _PyStackRef *src, Py_ssize_t n);
+
 
 #ifdef __cplusplus
 }
diff --git a/Objects/listobject.c b/Objects/listobject.c
@@ -3142,7 +3142,7 @@ PyList_AsTuple(PyObject *v)
 }
 
 PyObject *
-_PyList_FromArraySteal(PyObject *const *src, Py_ssize_t n)
+_PyList_FromStackRefSteal(const _PyStackRef *src, Py_ssize_t n)
 {
     if (n == 0) {
         return PyList_New(0);
@@ -3151,13 +3151,15 @@ _PyList_FromArraySteal(PyObject *const *src, Py_ssize_t n)
     PyListObject *list = (PyListObject *)PyList_New(n);
     if (list == NULL) {
         for (Py_ssize_t i = 0; i < n; i++) {
-            Py_DECREF(src[i]);
+            PyStackRef_CLOSE(src[i]);
         }
         return NULL;
     }
 
     PyObject **dst = list->ob_item;
-    memcpy(dst, src, n * sizeof(PyObject *));
+    for (Py_ssize_t i = 0; i < n; i++) {
+        dst[i] = PyStackRef_AsPyObjectSteal(src[i]);
+    }
 
     return (PyObject *)list;
 }
diff --git a/Python/bytecodes.c b/Python/bytecodes.c
@@ -1666,13 +1666,7 @@ dummy_func(
         }
 
         inst(BUILD_LIST, (values[oparg] -- list)) {
-            STACKREFS_TO_PYOBJECTS(values, oparg, values_o);
-            if (CONVERSION_FAILED(values_o)) {
-                DECREF_INPUTS();
-                ERROR_IF(true, error);
-            }
-            PyObject *list_o = _PyList_FromArraySteal(values_o, oparg);
-            STACKREFS_TO_PYOBJECTS_CLEANUP(values_o);
+            PyObject *list_o = _PyList_FromStackRefSteal(values, oparg);
             ERROR_IF(list_o == NULL, error);
             list = PyStackRef_FromPyObjectSteal(list_o);
         }
diff --git a/Python/executor_cases.c.h b/Python/executor_cases.c.h
diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
diff --git a/Tools/cases_generator/analyzer.py b/Tools/cases_generator/analyzer.py
@@ -534,7 +534,7 @@ def has_error_without_pop(op: parser.InstDef) -> bool:
     "STACKREFS_TO_PYOBJECTS",
     "STACKREFS_TO_PYOBJECTS_CLEANUP",
     "CONVERSION_FAILED",
-    "_PyList_FromArraySteal",
+    "_PyList_FromStackRefSteal",
     "_PyTuple_FromArraySteal",
     "_PyTuple_FromStackRefSteal",
 )

Original file line number	Diff line number	Diff line change
`@@ -3142,7 +3142,7 @@ PyList_AsTuple(PyObject *v)`
`3142`	`3142`	`}`
`3143`	`3143`
`3144`	`3144`	`PyObject *`
`3145`		`-_PyList_FromArraySteal(PyObject const src, Py_ssize_t n)`
	`3145`	`+_PyList_FromStackRefSteal(const _PyStackRef *src, Py_ssize_t n)`
`3146`	`3146`	`{`
`3147`	`3147`	`if (n == 0) {`
`3148`	`3148`	`return PyList_New(0);`
`@@ -3151,13 +3151,15 @@ _PyList_FromArraySteal(PyObject const src, Py_ssize_t n)`
`3151`	`3151`	`PyListObject list = (PyListObject )PyList_New(n);`
`3152`	`3152`	`if (list == NULL) {`
`3153`	`3153`	`for (Py_ssize_t i = 0; i < n; i++) {`
`3154`		`- Py_DECREF(src[i]);`
	`3154`	`+ PyStackRef_CLOSE(src[i]);`
`3155`	`3155`	`}`
`3156`	`3156`	`return NULL;`
`3157`	`3157`	`}`
`3158`	`3158`
`3159`	`3159`	`PyObject **dst = list->ob_item;`
`3160`		`- memcpy(dst, src, n * sizeof(PyObject *));`
	`3160`	`+ for (Py_ssize_t i = 0; i < n; i++) {`
	`3161`	`+ dst[i] = PyStackRef_AsPyObjectSteal(src[i]);`
	`3162`	`+ }`
`3161`	`3163`
`3162`	`3164`	`return (PyObject *)list;`
`3163`	`3165`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1666,13 +1666,7 @@ dummy_func(`
`1666`	`1666`	`}`
`1667`	`1667`
`1668`	`1668`	`inst(BUILD_LIST, (values[oparg] -- list)) {`
`1669`		`- STACKREFS_TO_PYOBJECTS(values, oparg, values_o);`
`1670`		`- if (CONVERSION_FAILED(values_o)) {`
`1671`		`- DECREF_INPUTS();`
`1672`		`- ERROR_IF(true, error);`
`1673`		`- }`
`1674`		`- PyObject *list_o = _PyList_FromArraySteal(values_o, oparg);`
`1675`		`- STACKREFS_TO_PYOBJECTS_CLEANUP(values_o);`
	`1669`	`+ PyObject *list_o = _PyList_FromStackRefSteal(values, oparg);`
`1676`	`1670`	`ERROR_IF(list_o == NULL, error);`
`1677`	`1671`	`list = PyStackRef_FromPyObjectSteal(list_o);`
`1678`	`1672`	`}`
Original file line number	Diff line number	Diff line change
`@@ -534,7 +534,7 @@ def has_error_without_pop(op: parser.InstDef) -> bool:`
`534`	`534`	`"STACKREFS_TO_PYOBJECTS",`
`535`	`535`	`"STACKREFS_TO_PYOBJECTS_CLEANUP",`
`536`	`536`	`"CONVERSION_FAILED",`
`537`		`- "_PyList_FromArraySteal",`
	`537`	`+ "_PyList_FromStackRefSteal",`
`538`	`538`	`"_PyTuple_FromArraySteal",`
`539`	`539`	`"_PyTuple_FromStackRefSteal",`
`540`	`540`	`)`