compiler: fix array padding and linearization

Author: mloubout

devito/passes/clusters/buffering.py

@@ -404,12 +404,8 @@ def generate_buffers(clusters, key, sregistry, options, **kwargs):
         # Finally create the actual buffer
         cls = callback or Array
         name = sregistry.make_name(prefix=f'{f.name}b')
-        # We specify the padding to match the input Function's one, so that
-        # the array can be used in place of the Function with valid strides
-        # Plain Array do not track mapped so we default to no padding
-        padding = 0 if cls is Array else f.padding
         mapper[f] = cls(name=name, dimensions=dimensions, dtype=f.dtype,
-                        padding=padding, grid=f.grid, halo=f.halo,
+                        grid=f.grid, halo=f.halo,
                         space='mapped', mapped=f, f=f)
 
     return mapper

devito/types/array.py

@@ -165,7 +165,10 @@ def __dtype_setup__(cls, **kwargs):
     def __padding_setup__(self, **kwargs):
         padding = kwargs.get('padding')
         if padding is None:
-            padding = ((0, 0),)*self.ndim
+            if self.is_autopaddable:
+                padding = self.__padding_setup_smart__(**kwargs)
+            else:
+                padding = ((0, 0),)*self.ndim
         elif isinstance(padding, DimensionTuple):
             padding = tuple(padding[d] for d in self.dimensions)
         elif is_integer(padding):
@@ -244,7 +247,7 @@ class MappedArrayMixin:
 
 
 class ArrayMapped(MappedArrayMixin, Array):
-    pass
+    is_autopaddable = True
 
 
 class ArrayObject(ArrayBasic):

tests/test_linearize.py

@@ -663,6 +663,21 @@ def test_int64_array(order):
         assert f'({2*order} + {long}y_size)*({2*order} + {long}x_size))' in str(op)
 
 
+@switchconfig(autopadding=np.float32)
+def test_mapped_array_symbolic_autopad():
+    grid = Grid(shape=(30, 30))
+    f = Function(name='f', grid=grid, space_order=4)
+
+    a = Array(name='ab', dimensions=grid.dimensions, dtype=f.dtype,
+              grid=grid, halo=f.halo, space='mapped')
+
+    assert type(a).__name__ == 'ArrayMapped'
+    assert a.is_autopaddable
+    pad = a.padding[-1][1]
+    assert not pad.is_Integer
+    assert pad.free_symbols == {grid.dimensions[-1].symbolic_size}
+
+
 def test_cire_n_strides():
     grid = Grid(shape=(4, 4, 4))