Better error message for ghost layer misalignment

pystencils/cpu/cpujit.py

@@ -356,7 +356,7 @@ def equal_size_check(fields):
     return template_size_check.format(cond=cond)
 
 
-def create_function_boilerplate_code(parameter_info, name, insert_checks=True):
+def create_function_boilerplate_code(parameter_info, name, ast_node, insert_checks=True):
     pre_call_code = ""
     parameters = []
     post_call_code = ""
@@ -374,6 +374,19 @@ def create_function_boilerplate_code(parameter_info, name, insert_checks=True):
                 np_dtype = field.dtype.numpy_dtype
                 item_size = np_dtype.itemsize
 
+                if ast_node.instruction_set:
+                    byte_width = ast_node.instruction_set['width'] * item_size
+                    offset = max(max(ast_node.ghost_layers)) * item_size
+                    offset_cond = f"(((uintptr_t) buffer_{field.name}.buf) + {offset}) % {byte_width} == 0"
+
+                    message = str(offset) + ". This is probably due to a different number of ghost_layers chosen for " \
+                                            "the arrays and the kernel creation. If the number of ghost layers for the " \
+                                            "kernel creation is not specified it will choose a suitable value " \
+                                            "automatically. This value might not " \
+                                            "be compatible with the allocated arrays."
+                    pre_call_code += template_check_array.format(cond=offset_cond, what="offset", name=field.name,
+                                                                 expected=message)
+
                 if (np_dtype.isbuiltin and FieldType.is_generic(field)
                         and not np.issubdtype(field.dtype.numpy_dtype, np.complexfloating)):
                     dtype_cond = "buffer_{name}.format[0] == '{format}'".format(name=field.name,
@@ -504,7 +517,7 @@ class ExtensionModuleCode:
             old_name = ast.function_name
             ast.function_name = "kernel_" + name
             print(generate_c(ast, custom_backend=self._custom_backend), file=file)
-            print(create_function_boilerplate_code(ast.get_parameters(), name), file=file)
+            print(create_function_boilerplate_code(ast.get_parameters(), name, ast), file=file)
             ast.function_name = old_name
         print(create_module_boilerplate_code(self.module_name, self._function_names), file=file)