Basic support for OpenCL (experimental)

Basic support for OpenCL

Problem: OpenCL cannot import stdint.h. Temporary fix: define custom opencl_stdint.h (defines currently only int64_t `)

TODO:

• implement opencl_stdint.h
• implement shard_mem, textures, built-in functions
• avoid CUDA intrinsics (fast_div)

pystencils/backends/cbackend.py

@@ -58,6 +58,9 @@ def generate_c(ast_node: Node, signature_only: bool = False, dialect='c', custom
     elif dialect == 'cuda':
         from pystencils.backends.cuda_backend import CudaBackend
         printer = CudaBackend(signature_only=signature_only)
+    elif dialect == 'opencl':
+        from pystencils.backends.opencl_backend import OpenClBackend
+        printer = OpenClBackend(signature_only=signature_only)
     else:
         raise ValueError("Unknown dialect: " + str(dialect))
     code = printer(ast_node)
@@ -165,14 +168,19 @@ class CBackend:
         return result
 
     def _print(self, node):
+        if isinstance(node, str):
+            return node
         for cls in type(node).__mro__:
             method_name = "_print_" + cls.__name__
             if hasattr(self, method_name):
                 return getattr(self, method_name)(node)
         raise NotImplementedError(self.__class__.__name__ + " does not support node of type " + node.__class__.__name__)
 
+    def _print_Type(self, node):
+        return str(node)
+
     def _print_KernelFunction(self, node):
-        function_arguments = ["%s %s" % (str(s.symbol.dtype), s.symbol.name) for s in node.get_parameters()]
+        function_arguments = ["%s %s" % (self._print(s.symbol.dtype), s.symbol.name) for s in node.get_parameters()]
         launch_bounds = ""
         if self._dialect == 'cuda':
             max_threads = node.indexing.max_threads_per_block()
@@ -207,7 +215,11 @@ class CBackend:
 
     def _print_SympyAssignment(self, node):
         if node.is_declaration:
-            data_type = "const " + str(node.lhs.dtype) + " " if node.is_const else str(node.lhs.dtype) + " "
+            if node.is_const:
+                prefix = 'const '
+            else:
+                prefix = ''
+            data_type = prefix + self._print(node.lhs.dtype) + " "
             return "%s%s = %s;" % (data_type, self.sympy_printer.doprint(node.lhs),
                                    self.sympy_printer.doprint(node.rhs))
         else:
@@ -276,10 +288,10 @@ class CBackend:
                                   ]
         destructuring_bindings.sort()  # only for code aesthetics
         return "{\n" + self._indent + \
-            ("\n" + self._indent).join(destructuring_bindings) + \
-            "\n" + self._indent + \
-            ("\n" + self._indent).join(self._print(node.body).splitlines()) + \
-            "\n}"
+               ("\n" + self._indent).join(destructuring_bindings) + \
+               "\n" + self._indent + \
+               ("\n" + self._indent).join(self._print(node.body).splitlines()) + \
+               "\n}"
 
 
 # ------------------------------------------ Helper function & classes -------------------------------------------------