Merge branch 'auto-for-assignments' into 'master'

Auto for assignments

See merge request pycodegen/pystencils!95

pystencils/astnodes.py

@@ -518,12 +518,13 @@ class LoopOverCoordinate(Node):
 
 
 class SympyAssignment(Node):
-    def __init__(self, lhs_symbol, rhs_expr, is_const=True):
+    def __init__(self, lhs_symbol, rhs_expr, is_const=True, use_auto=False):
         super(SympyAssignment, self).__init__(parent=None)
         self._lhs_symbol = lhs_symbol
         self.rhs = sp.sympify(rhs_expr)
         self._is_const = is_const
         self._is_declaration = self.__is_declaration()
+        self.use_auto = use_auto
 
     def __is_declaration(self):
         if isinstance(self._lhs_symbol, cast_func):

pystencils/backends/cbackend.py

@@ -33,9 +33,9 @@ def generate_c(ast_node: Node,
                with_globals=True) -> str:
     """Prints an abstract syntax tree node as C or CUDA code.
 
-    This function does not need to distinguish between C, C++ or CUDA code, it just prints 'C-like' code as encoded
-    in the abstract syntax tree (AST). The AST is built differently for C or CUDA by calling different create_kernel
-    functions.
+    This function does not need to distinguish for most AST nodes between C, C++ or CUDA code, it just prints 'C-like'
+    code as encoded in the abstract syntax tree (AST). The AST is built differently for C or CUDA by calling different
+    create_kernel functions.
 
     Args:
         ast_node:
@@ -230,11 +230,15 @@ class CBackend:
 
     def _print_SympyAssignment(self, node):
         if node.is_declaration:
-            if node.is_const:
-                prefix = 'const '
+            if node.use_auto:
+                data_type = 'auto '
             else:
-                prefix = ''
-            data_type = prefix + self._print(node.lhs.dtype).replace(' const', '') + " "
+                if node.is_const:
+                    prefix = 'const '
+                else:
+                    prefix = ''
+                data_type = prefix + self._print(node.lhs.dtype).replace(' const', '') + " "
+
             return "%s%s = %s;" % (data_type,
                                    self.sympy_printer.doprint(node.lhs),
                                    self.sympy_printer.doprint(node.rhs))

pystencils/kernelcreation.py

@@ -26,7 +26,8 @@ def create_kernel(assignments,
                   gpu_indexing='block',
                   gpu_indexing_params=MappingProxyType({}),
                   use_textures_for_interpolation=True,
-                  cpu_prepend_optimizations=[]):
+                  cpu_prepend_optimizations=[],
+                  use_auto_for_assignments=False):
     """
     Creates abstract syntax tree (AST) of kernel, using a list of update equations.
 
@@ -102,12 +103,10 @@ def create_kernel(assignments,
                 vectorize(ast, **cpu_vectorize_info)
             else:
                 raise ValueError("Invalid value for cpu_vectorize_info")
-        return ast
     elif target == 'llvm':
         from pystencils.llvm import create_kernel
         ast = create_kernel(assignments, type_info=data_type, split_groups=split_groups,
                             iteration_slice=iteration_slice, ghost_layers=ghost_layers)
-        return ast
     elif target == 'gpu':
         from pystencils.gpucuda import create_cuda_kernel
         ast = create_cuda_kernel(assignments, type_info=data_type,
@@ -115,10 +114,15 @@ def create_kernel(assignments,
                                  iteration_slice=iteration_slice, ghost_layers=ghost_layers,
                                  skip_independence_check=skip_independence_check,
                                  use_textures_for_interpolation=use_textures_for_interpolation)
-        return ast
     else:
         raise ValueError("Unknown target %s. Has to be one of 'cpu', 'gpu' or 'llvm' " % (target,))
 
+    if use_auto_for_assignments:
+        for a in ast.atoms(SympyAssignment):
+            a.use_auto = True
+
+    return ast
+
 
 def create_indexed_kernel(assignments,
                           index_fields,