Merge pull request #19259 from seberg/maint-ufunc-refactor-masked-not…

…-duplicate

MAINT: Align masked with normal ufunc loops

doc/release/upcoming_changes/19259.c_api.rst

@@ -0,0 +1,12 @@
+Masked inner-loops cannot be customized anymore
+-----------------------------------------------
+The masked inner-loop selector is now never used.  A warning
+will be given in the unlikely event that it was customized.
+
+We do not expect that any code uses this.  If you do use it,
+you must unset the selector on newer NumPy version.
+Please also contact the NumPy developers, we do anticipate
+providing a new, more specific, mechanism.
+
+The customization was part of a never-implemented feature to allow
+for faster masked operations.

numpy/core/include/numpy/ufuncobject.h

@@ -66,27 +66,14 @@ typedef int (PyUFunc_TypeResolutionFunc)(
                                 PyArray_Descr **out_dtypes);
 
 /*
- * Given an array of DTypes as returned by the PyUFunc_TypeResolutionFunc,
- * and an array of fixed strides (the array will contain NPY_MAX_INTP for
- * strides which are not necessarily fixed), returns an inner loop
- * with associated auxiliary data.
- *
- * For backwards compatibility, there is a variant of the inner loop
- * selection which returns an inner loop irrespective of the strides,
- * and with a void* static auxiliary data instead of an NpyAuxData *
- * dynamically allocatable auxiliary data.
+ * Legacy loop selector. (This should NOT normally be used and we can expect
+ * that only the `PyUFunc_DefaultLegacyInnerLoopSelector` is ever set).
+ * However, unlike the masked version, it probably still works.
  *
  * ufunc:             The ufunc object.
  * dtypes:            An array which has been populated with dtypes,
  *                    in most cases by the type resolution function
  *                    for the same ufunc.
- * fixed_strides:     For each input/output, either the stride that
- *                    will be used every time the function is called
- *                    or NPY_MAX_INTP if the stride might change or
- *                    is not known ahead of time. The loop selection
- *                    function may use this stride to pick inner loops
- *                    which are optimized for contiguous or 0-stride
- *                    cases.
  * out_innerloop:     Should be populated with the correct ufunc inner
  *                    loop for the given type.
  * out_innerloopdata: Should be populated with the void* data to
@@ -101,15 +88,7 @@ typedef int (PyUFunc_LegacyInnerLoopSelectionFunc)(
                             PyUFuncGenericFunction *out_innerloop,
                             void **out_innerloopdata,
                             int *out_needs_api);
-typedef int (PyUFunc_MaskedInnerLoopSelectionFunc)(
-                            struct _tagPyUFuncObject *ufunc,
-                            PyArray_Descr **dtypes,
-                            PyArray_Descr *mask_dtype,
-                            npy_intp *fixed_strides,
-                            npy_intp fixed_mask_stride,
-                            PyUFunc_MaskedStridedInnerLoopFunc **out_innerloop,
-                            NpyAuxData **out_innerloopdata,
-                            int *out_needs_api);
+
 
 typedef struct _tagPyUFuncObject {
         PyObject_HEAD
@@ -199,10 +178,8 @@ typedef struct _tagPyUFuncObject {
     #else
         void *reserved2;
     #endif
-        /*
-         * A function which returns a masked inner loop for the ufunc.
-         */
-        PyUFunc_MaskedInnerLoopSelectionFunc *masked_inner_loop_selector;
+        /* Was previously the `PyUFunc_MaskedInnerLoopSelectionFunc` */
+        void *_always_null_previously_masked_innerloop_selector;
 
         /*
          * List of flags for each operand when ufunc is called by nditer object.