ENH: Optimize array creation by avoiding errors

4 files changed, 126 insertions, 64 deletions

diff --git a/numpy/core/src/multiarray/common.c b/numpy/core/src/multiarray/common.c
index 01bf9cd74..4787c6482 100644
--- a/numpy/core/src/multiarray/common.c
+++ b/numpy/core/src/multiarray/common.c
@@ -27,6 +27,60 @@
  * be allowed under the NPY_SAME_KIND_CASTING rules, and if not we issue a
  * warning (that people's code will be broken in a future release.)
  */
+
+/*
+ * PyArray_GetAttrString_SuppressException:
+ *
+ * Stripped down version of PyObject_GetAttrString,
+ * avoids lookups for None, tuple, and List objects,
+ * and doesn't create a PyErr since this code ignores it.
+ *
+ * This can be much faster then PyObject_GetAttrString where
+ * exceptions are not used by caller.
+ *
+ * 'obj' is the object to search for attribute.
+ *
+ * 'name' is the attribute to search for.
+ *
+ * Returns attribute value on success, 0 on failure.
+ */
+PyObject *
+PyArray_GetAttrString_SuppressException(PyObject *obj, char *name)
+{
+    PyTypeObject *tp = Py_TYPE(obj);
+    PyObject *res = (PyObject *)NULL;
+    if (/* Is not trivial type */
+        obj != Py_None &&
+        !PyList_CheckExact(obj) &&
+        !PyTuple_CheckExact(obj)) {
+        /* Attribute referenced by (char *)name */
+        if (tp->tp_getattr != NULL) {
+            res = (*tp->tp_getattr)(obj, name);
+            if (res == NULL) {
+                PyErr_Clear();
+            }
+        }
+        /* Attribute referenced by (PyObject *)name */
+        else if (tp->tp_getattro != NULL) {
+#if defined(NPY_PY3K)
+            PyObject *w = PyUnicode_InternFromString(name);
+#else
+            PyObject *w = PyString_InternFromString(name);
+#endif
+            if (w == NULL)
+                return (PyObject *)NULL;
+            Py_DECREF(w);
+            res = (*tp->tp_getattro)(obj, w);
+            if (res == NULL) {
+                PyErr_Clear();
+            }
+        }
+    }
+    return res;
+}
+
+
+
 NPY_NO_EXPORT NPY_CASTING NPY_DEFAULT_ASSIGN_CASTING = NPY_INTERNAL_UNSAFE_CASTING_BUT_WARN_UNLESS_SAME_KIND;
 
 
@@ -156,8 +210,17 @@ PyArray_DTypeFromObjectHelper(PyObject *obj, int maxdims,
         goto promote_types;
     }
 
+    /* See if it's a python None */
+    if (obj == Py_None) {
+        dtype = PyArray_DescrFromType(NPY_OBJECT);
+        if (dtype == NULL) {
+            goto fail;
+        }
+        Py_INCREF(dtype);
+        goto promote_types;
+    }
     /* Check if it's a NumPy scalar */
-    if (PyArray_IsScalar(obj, Generic)) {
+    else if (PyArray_IsScalar(obj, Generic)) {
         if (!string_type) {
             dtype = PyArray_DescrFromScalar(obj);
             if (dtype == NULL) {
@@ -308,32 +371,35 @@ PyArray_DTypeFromObjectHelper(PyObject *obj, int maxdims,
     }
 
     /* PEP 3118 buffer interface */
-    memset(&buffer_view, 0, sizeof(Py_buffer));
-    if (PyObject_GetBuffer(obj, &buffer_view, PyBUF_FORMAT|PyBUF_STRIDES) == 0 ||
-        PyObject_GetBuffer(obj, &buffer_view, PyBUF_FORMAT) == 0) {
-
-        PyErr_Clear();
-        dtype = _descriptor_from_pep3118_format(buffer_view.format);
-        PyBuffer_Release(&buffer_view);
-        if (dtype) {
+    if (PyObject_CheckBuffer(obj) == 1) {
+        memset(&buffer_view, 0, sizeof(Py_buffer));
+        if (PyObject_GetBuffer(obj, &buffer_view,
+                               PyBUF_FORMAT|PyBUF_STRIDES) == 0 ||
+            PyObject_GetBuffer(obj, &buffer_view, PyBUF_FORMAT) == 0) {
+    
+            PyErr_Clear();
+            dtype = _descriptor_from_pep3118_format(buffer_view.format);
+            PyBuffer_Release(&buffer_view);
+            if (dtype) {
+                goto promote_types;
+            }
+        }
+        else if (PyObject_GetBuffer(obj, &buffer_view, PyBUF_STRIDES) == 0 ||
+                 PyObject_GetBuffer(obj, &buffer_view, PyBUF_SIMPLE) == 0) {
+    
+            PyErr_Clear();
+            dtype = PyArray_DescrNewFromType(NPY_VOID);
+            dtype->elsize = buffer_view.itemsize;
+            PyBuffer_Release(&buffer_view);
             goto promote_types;
         }
-    }
-    else if (PyObject_GetBuffer(obj, &buffer_view, PyBUF_STRIDES) == 0 ||
-             PyObject_GetBuffer(obj, &buffer_view, PyBUF_SIMPLE) == 0) {
-
-        PyErr_Clear();
-        dtype = PyArray_DescrNewFromType(NPY_VOID);
-        dtype->elsize = buffer_view.itemsize;
-        PyBuffer_Release(&buffer_view);
-        goto promote_types;
-    }
-    else {
-        PyErr_Clear();
+        else {
+            PyErr_Clear();
+        }
     }
 
     /* The array interface */
-    ip = PyObject_GetAttrString(obj, "__array_interface__");
+    ip = PyArray_GetAttrString_SuppressException(obj, "__array_interface__");
     if (ip != NULL) {
         if (PyDict_Check(ip)) {
             PyObject *typestr;
@@ -364,12 +430,9 @@ PyArray_DTypeFromObjectHelper(PyObject *obj, int maxdims,
         }
         Py_DECREF(ip);
     }
-    else {
-        PyErr_Clear();
-    }
 
     /* The array struct interface */
-    ip = PyObject_GetAttrString(obj, "__array_struct__");
+    ip = PyArray_GetAttrString_SuppressException(obj, "__array_struct__");
     if (ip != NULL) {
         PyArrayInterface *inter;
         char buf[40];
@@ -389,9 +452,6 @@ PyArray_DTypeFromObjectHelper(PyObject *obj, int maxdims,
         }
         Py_DECREF(ip);
     }
-    else {
-        PyErr_Clear();
-    }
 
     /* The old buffer interface */
 #if !defined(NPY_PY3K)
@@ -407,7 +467,9 @@ PyArray_DTypeFromObjectHelper(PyObject *obj, int maxdims,
 #endif
 
     /* The __array__ attribute */
-    if (PyObject_HasAttrString(obj, "__array__")) {
+    ip = PyArray_GetAttrString_SuppressException(obj, "__array__");
+    if (ip != NULL) {
+        Py_DECREF(ip);
         ip = PyObject_CallMethod(obj, "__array__", NULL);
         if(ip && PyArray_Check(ip)) {
             dtype = PyArray_DESCR((PyArrayObject *)ip);
diff --git a/numpy/core/src/multiarray/common.h b/numpy/core/src/multiarray/common.h
index a474cf820..68f8d246d 100644
--- a/numpy/core/src/multiarray/common.h
+++ b/numpy/core/src/multiarray/common.h
@@ -25,6 +25,9 @@ NPY_NO_EXPORT int
 PyArray_DTypeFromObjectHelper(PyObject *obj, int maxdims,
                               PyArray_Descr **out_dtype, int string_status);
 
+NPY_NO_EXPORT PyObject *
+PyArray_GetAttrString_SuppressException(PyObject *v, char *name);
+
 /*
  * Returns NULL without setting an exception if no scalar is matched, a
  * new dtype reference otherwise.
diff --git a/numpy/core/src/multiarray/ctors.c b/numpy/core/src/multiarray/ctors.c
index 5c692bd02..c96258417 100644
--- a/numpy/core/src/multiarray/ctors.c
+++ b/numpy/core/src/multiarray/ctors.c
@@ -646,32 +646,35 @@ discover_dimensions(PyObject *obj, int *maxndim, npy_intp *d, int check_it,
     /* obj is a PEP 3118 buffer */
 #if PY_VERSION_HEX >= 0x02060000
     /* PEP 3118 buffer interface */
-    memset(&buffer_view, 0, sizeof(Py_buffer));
-    if (PyObject_GetBuffer(obj, &buffer_view, PyBUF_STRIDES) == 0 ||
-        PyObject_GetBuffer(obj, &buffer_view, PyBUF_ND) == 0) {
-        int nd = buffer_view.ndim;
-        if (nd < *maxndim) {
-            *maxndim = nd;
+    if (PyObject_CheckBuffer(obj) == 1) {
+        memset(&buffer_view, 0, sizeof(Py_buffer));
+        if (PyObject_GetBuffer(obj, &buffer_view, PyBUF_STRIDES) == 0 ||
+            PyObject_GetBuffer(obj, &buffer_view, PyBUF_ND) == 0) {
+            int nd = buffer_view.ndim;
+            if (nd < *maxndim) {
+                *maxndim = nd;
+            }
+            for (i=0; i<*maxndim; i++) {
+                d[i] = buffer_view.shape[i];
+            }
+            PyBuffer_Release(&buffer_view);
+            return 0;
         }
-        for (i=0; i<*maxndim; i++) {
-            d[i] = buffer_view.shape[i];
+        else if (PyObject_GetBuffer(obj, &buffer_view, PyBUF_SIMPLE) == 0) {
+            d[0] = buffer_view.len;
+            *maxndim = 1;
+            PyBuffer_Release(&buffer_view);
+            return 0;
+        }
+        else {
+            PyErr_Clear();
         }
-        PyBuffer_Release(&buffer_view);
-        return 0;
-    }
-    else if (PyObject_GetBuffer(obj, &buffer_view, PyBUF_SIMPLE) == 0) {
-        d[0] = buffer_view.len;
-        *maxndim = 1;
-        PyBuffer_Release(&buffer_view);
-        return 0;
-    }
-    else {
-        PyErr_Clear();
     }
 #endif
 
     /* obj has the __array_struct__ interface */
-    if ((e = PyObject_GetAttrString(obj, "__array_struct__")) != NULL) {
+    e = PyArray_GetAttrString_SuppressException(obj, "__array_struct__");
+    if (e != NULL) {
         int nd = -1;
         if (NpyCapsule_Check(e)) {
             PyArrayInterface *inter;
@@ -693,12 +696,10 @@ discover_dimensions(PyObject *obj, int *maxndim, npy_intp *d, int check_it,
             return 0;
         }
     }
-    else {
-        PyErr_Clear();
-    }
 
     /* obj has the __array_interface__ interface */
-    if ((e = PyObject_GetAttrString(obj, "__array_interface__")) != NULL) {
+    e = PyArray_GetAttrString_SuppressException(obj, "__array_interface__");
+    if (e != NULL) {
         int nd = -1;
         if (PyDict_Check(e)) {
             PyObject *new;
@@ -728,9 +729,6 @@ discover_dimensions(PyObject *obj, int *maxndim, npy_intp *d, int check_it,
             return 0;
         }
     }
-    else {
-        PyErr_Clear();
-    }
 
     n = PySequence_Size(obj);
 
@@ -1934,9 +1932,8 @@ PyArray_FromStructInterface(PyObject *input)
     PyArrayObject *ret;
     char endian = NPY_NATBYTE;
 
-    attr = PyObject_GetAttrString(input, "__array_struct__");
+    attr = PyArray_GetAttrString_SuppressException(input, "__array_struct__");
     if (attr == NULL) {
-        PyErr_Clear();
         return Py_NotImplemented;
     }
     if (!NpyCapsule_Check(attr)) {
@@ -2009,9 +2006,9 @@ PyArray_FromInterface(PyObject *origin)
     /* Get the memory from __array_data__ and __array_offset__ */
     /* Get the strides */
 
-    iface = PyObject_GetAttrString(origin, "__array_interface__");
+    iface = PyArray_GetAttrString_SuppressException(origin,
+						    "__array_interface__");
     if (iface == NULL) {
-        PyErr_Clear();
         return Py_NotImplemented;
     }
     if (!PyDict_Check(iface)) {
@@ -2226,9 +2223,8 @@ PyArray_FromArrayAttr(PyObject *op, PyArray_Descr *typecode, PyObject *context)
     PyObject *new;
     PyObject *array_meth;
 
-    array_meth = PyObject_GetAttrString(op, "__array__");
+    array_meth = PyArray_GetAttrString_SuppressException(op, "__array__");
     if (array_meth == NULL) {
-        PyErr_Clear();
         return Py_NotImplemented;
     }
     if (context == NULL) {
diff --git a/numpy/core/src/multiarray/multiarraymodule.c b/numpy/core/src/multiarray/multiarraymodule.c
index 7332a26d0..426ab695c 100644
--- a/numpy/core/src/multiarray/multiarraymodule.c
+++ b/numpy/core/src/multiarray/multiarraymodule.c
@@ -52,6 +52,7 @@ NPY_NO_EXPORT int NPY_NUMUSERTYPES = 0;
 #include "shape.h"
 #include "ctors.h"
 #include "array_assign.h"
+#include "common.h"
 
 /* Only here for API compatibility */
 NPY_NO_EXPORT PyTypeObject PyBigArray_Type;
@@ -68,7 +69,7 @@ PyArray_GetPriority(PyObject *obj, double default_)
     if (PyArray_CheckExact(obj))
         return priority;
 
-    ret = PyObject_GetAttrString(obj, "__array_priority__");
+    ret = PyArray_GetAttrString_SuppressException(obj, "__array_priority__");
     if (ret != NULL) {
         priority = PyFloat_AsDouble(ret);
     }