ENH: properly fix unaligned load of complex types

juliantaylor · juliantaylor · commit c9bf9b0b1c8a · 2013-06-10T23:03:05.000+02:00
the workaround of setting the aligned to false unconditionally makes
copying strided complex data extremely slow as it will always do
unaligned elementwise memmoves.
Instead set the alignment requirement for complex types correct in the
dtype to begin with.

Note that on 32 bit gcc complex double will still be aligned to 8 bytes
unless compiled with -malign-double.

It is possible this will introduce new segfaults on architectures
without unaligned loads, but this now indicates a missing alignment
check in the affected code as the array description is correct.
diff --git a/numpy/core/src/multiarray/arraytypes.c.src b/numpy/core/src/multiarray/arraytypes.c.src
@@ -3817,9 +3817,9 @@ NPY_NO_EXPORT PyArray_Descr @from@_Descr = {
     /* type_num */
     NPY_@from@,
     /* elsize */
-    @num@*sizeof(@fromtype@),
+    @num@ * sizeof(@fromtype@),
     /* alignment */
-    _ALIGN(@fromtype@),
+    @num@ * _ALIGN(@fromtype@),
     /* subarray */
     NULL,
     /* fields */
@@ -4150,6 +4150,7 @@ set_typeinfo(PyObject *dict)
      *         CFLOAT, CDOUBLE, CLONGDOUBLE#
      * #Name = Half, Float, Double, LongDouble,
      *         CFloat, CDouble, CLongDouble#
+     * #num  = 1, 1, 1, 1, 2, 2, 2#
      */
 
     PyDict_SetItemString(infodict, "@name@",
@@ -4160,7 +4161,7 @@ set_typeinfo(PyObject *dict)
 #endif
                 NPY_@name@,
                 NPY_BITSOF_@name@,
-                _ALIGN(@type@),
+                @num@ * _ALIGN(@type@),
                 (PyObject *) &Py@Name@ArrType_Type));
     Py_DECREF(s);
 
diff --git a/numpy/core/src/multiarray/dtype_transfer.c b/numpy/core/src/multiarray/dtype_transfer.c
@@ -3574,13 +3574,6 @@ PyArray_GetDTypeTransferFunction(int aligned,
                     PyArray_ISNBO(dst_dtype->byteorder)) {
 
         if (PyArray_EquivTypenums(src_type_num, dst_type_num)) {
-            /*
-             * For complex numbers, the alignment is smaller than the
-             * type size, so we turn off the aligned flag then.
-             */
-            if (src_dtype->kind == 'c' || dst_dtype->kind == 'c') {
-                aligned = 0;
-            }
             *out_stransfer = PyArray_GetStridedCopyFn(aligned,
                                         src_stride, dst_stride,
                                         src_itemsize);
@@ -3677,13 +3670,6 @@ PyArray_GetDTypeTransferFunction(int aligned,
         /* This is a straight copy */
         if (src_itemsize == 1 || PyArray_ISNBO(src_dtype->byteorder) ==
                                  PyArray_ISNBO(dst_dtype->byteorder)) {
-            /*
-             * For complex numbers, the alignment is smaller than the
-             * type size, so we turn off the aligned flag then.
-             */
-            if (src_dtype->kind == 'c' || dst_dtype->kind == 'c') {
-                aligned = 0;
-            }
             *out_stransfer = PyArray_GetStridedCopyFn(aligned,
                                         src_stride, dst_stride,
                                         src_itemsize);
