npbackend: the target_bhc now ignore zero-sized operations. Fixes issue

#10

bridge/npbackend/ndarray.pyx

@@ -180,23 +180,28 @@ def get_bhc(ary):
         raise ValueError("Bohrium arrays must be aligned, writeable, and in machine byte-order")
     if not dtype_equal(ary, base):
         raise ValueError("Bohrium base and view must have same data type")
-    if not base.ctypes.data <= ary.ctypes.data < base.ctypes.data + base.nbytes:
-        raise ValueError("The view must point to data within the base array")
-
-    # Lets make sure that 'ary' has a Bohrium-C base array
-    if base.bhc_ary is None:
-        base._data_np2bhc()
-
-    offset = (ary.ctypes.data - base.ctypes.data) / base.itemsize
-    if (ary.ctypes.data - base.ctypes.data) % base.itemsize != 0:
-        raise TypeError("The view offset must be element aligned")
-    if not 0 <= offset < base.size:
-        raise TypeError("The view offset is greater than the total number of elements in the base!")
-    strides = []
-    for stride in ary.strides:
-        strides.append(stride / base.itemsize)
-        if stride % base.itemsize != 0:
-            raise TypeError("The strides must be element aligned")
+
+    if 0 in ary.shape:#Lets use a dummy strides and offset for zero-sized views
+        strides = [0]*ary.ndim
+        offset = 0
+    else:
+        if not base.ctypes.data <= ary.ctypes.data < base.ctypes.data + base.nbytes:
+            raise ValueError("The view must point to data within the base array")
+
+        # Lets make sure that 'ary' has a Bohrium-C base array
+        if base.bhc_ary is None:
+            base._data_np2bhc()
+
+        offset = (ary.ctypes.data - base.ctypes.data) / base.itemsize
+        if (ary.ctypes.data - base.ctypes.data) % base.itemsize != 0:
+            raise TypeError("The view offset must be element aligned")
+        if not 0 <= offset < base.size:
+            raise TypeError("The view offset is greater than the total number of elements in the base!")
+        strides = []
+        for stride in ary.strides:
+            strides.append(stride / base.itemsize)
+            if stride % base.itemsize != 0:
+                raise TypeError("The strides must be element aligned")
 
     ndim = ary.ndim if ary.ndim > 0 else 1
     shape = ary.shape if len(ary.shape) > 0 else (1,)

bridge/npbackend/target/target_bhc.py

@@ -6,19 +6,25 @@
 from .. import bhc
 from .._util import dtype_name
 from . import interface
+import functools
+import operator
 
 class Base(interface.Base):
     """base array handle"""
 
     def __init__(self, size, dtype, bhc_obj=None):
         super(Base, self).__init__(size, dtype)
+        if size == 0:
+            return
 
         if bhc_obj is None:
             func = eval("bhc.bh_multi_array_%s_new_empty" % dtype_name(dtype))
-            bhc_obj = bhc_exec(func, 1, (size,))
+            bhc_obj = _bhc_exec(func, 1, (size,))
         self.bhc_obj = bhc_obj
 
     def __del__(self):
+        if self.size == 0:
+            return
         exec("bhc.bh_multi_array_%s_destroy(self.bhc_obj)" %
              dtype_name(self.dtype)
         )
@@ -28,16 +34,21 @@ class View(interface.View):
 
     def __init__(self, ndim, start, shape, strides, base):
         super(View, self).__init__(ndim, start, shape, strides, base)
+        self.size = functools.reduce(operator.mul, shape, 1)
+        if self.size == 0:
+            return
         dtype = dtype_name(self.dtype)
         func = eval("bhc.bh_multi_array_%s_new_view" % dtype)
         self.bhc_obj = func(base.bhc_obj, ndim, start, shape, strides)
 
     def __del__(self):
+        if self.size == 0:
+            return
         exec("bhc.bh_multi_array_%s_destroy(self.bhc_obj)" % dtype_name(
             self.dtype
         ))
 
-def bhc_exec(func, *args):
+def _bhc_exec(func, *args):
     """execute the 'func' with the bhc objects in 'args'"""
 
     args = list(args)
@@ -48,6 +59,8 @@ def bhc_exec(func, *args):
 
 def get_data_pointer(ary, allocate=False, nullify=False):
     """Retrieves the data pointer from Bohrium Runtime."""
+    if ary.size == 0 or ary.base.size == 0:
+        return 0
 
     dtype = dtype_name(ary)
     ary = ary.bhc_obj
@@ -94,6 +107,9 @@ def ufunc(op, *args):
                 scalar_str = "_scalar" + ("_rhs" if len(args) > 2 else "")
         elif i > 0:
             in_dtype = arg.dtype#overwrite with a non-scalar input
+            #Do nothing on zero-sized arguments
+            if arg.size == 0 or arg.base.size == 0:
+                return
 
     if op.info['name'] == "identity":#Identity is a special case
         cmd = "bhc.bh_multi_array_%s_identity_%s" % (
@@ -105,19 +121,21 @@ def ufunc(op, *args):
             dtype_name(in_dtype), op.info['name']
         )
     cmd += scalar_str
-    bhc_exec(eval(cmd), *args)
+    _bhc_exec(eval(cmd), *args)
 
 def reduce(op, out, ary, axis):
     """
     reduce 'axis' dimension of 'ary' and write the result to out
 
     :op npbackend.ufunc.Ufunc: Instance of a Ufunc.
     """
+    if ary.size == 0 or ary.base.size == 0:
+        return
 
     func = eval("bhc.bh_multi_array_%s_%s_reduce" % (
         dtype_name(ary), op.info['name']
     ))
-    bhc_exec(func, out, ary, axis)
+    _bhc_exec(func, out, ary, axis)
 
 def accumulate(op, out, ary, axis):
     """
@@ -129,11 +147,13 @@ def accumulate(op, out, ary, axis):
     :in2 ?:
     :rtype: None
     """
+    if ary.size == 0 or ary.base.size == 0:
+        return
 
     func = eval("bhc.bh_multi_array_%s_%s_accumulate" % (
         dtype_name(ary), op.info['name'])
     )
-    bhc_exec(func, out, ary, axis)
+    _bhc_exec(func, out, ary, axis)
 
 def extmethod(name, out, in1, in2):
     """
@@ -146,13 +166,15 @@ def extmethod(name, out, in1, in2):
     :in2 ?:
     :rtype: None
     """
+    if out.size == 0 or out.base.size == 0:
+        return
 
     func = eval("bhc.bh_multi_array_extmethod_%s_%s_%s" % (
         dtype_name(out),
         dtype_name(in1),
         dtype_name(in2)
     ))
-    ret = bhc_exec(func, name, out, in1, in2)
+    ret = _bhc_exec(func, name, out, in1, in2)
 
     if ret != 0:
         raise NotImplementedError("The current runtime system does not support "
@@ -167,10 +189,12 @@ def range(size, dtype):
     :rtype: None
     """
 
-    func = eval("bhc.bh_multi_array_%s_new_range" % dtype_name(dtype))
-    bhc_obj = bhc_exec(func, size)
+    if size > 0:
+        func = eval("bhc.bh_multi_array_%s_new_range"%dtype_name(dtype))
+        bhc_obj = _bhc_exec(func, size)
+    else:
+        bhc_obj = None
     base = Base(size, dtype, bhc_obj)
-
     return View(1, 0, (size,), (dtype.itemsize,), base)
 
 def random123(size, start_index, key):
@@ -180,9 +204,11 @@ def random123(size, start_index, key):
     """
 
     dtype = numpy.dtype("uint64")
-    func = eval("bhc.bh_multi_array_uint64_new_random123")
-    bhc_obj = bhc_exec(func, size, start_index, key)
+    if size > 0:
+        func = eval("bhc.bh_multi_array_uint64_new_random123")
+        bhc_obj = _bhc_exec(func, size, start_index, key)
+    else:
+        bhc_obj = None
     base = Base(size, dtype, bhc_obj)
-
     return View(1, 0, (size,), (dtype.itemsize,), base)
 

test/python/test_emptiness.py

@@ -0,0 +1,17 @@
+import numpy as np
+import bohrium as bh
+from numpytest import numpytest,gen_views,TYPES
+
+
+class test_empty(numpytest):
+
+    def init(self):
+        a = {}
+        cmd = "a[0] = bh.array([]);a[1] = bh.array([])"
+        exec(cmd)
+        yield (a, cmd)
+
+    def test_add(self,a):
+        cmd = "res = a[0] + a[1]"
+        exec(cmd)
+        return (res,cmd)