Draft: feat: implement `__cuda_array_interface__`

https://numba.readthedocs.io/en/stable/cuda/cuda_array_interface.html

This is supported by:

• pycuda
• numba
• cupy
• torch
• nvcv https://github.com/CvCuda/CV-CUDA
• maybe by tensorflow in future: https://github.com/tensorflow/tensorflow/issues/29039

Also allow to execute with cupy (https://docs.cupy.dev/en/stable/index.html) instead of pycuda

TODO:

• check that pointers in correct CUDA context and if not import into current
• make execution with pycuda aware of __cuda_array_interface__
• what/how to test

pystencils/gpucuda/cudajit.py

@@ -2,17 +2,19 @@ import numpy as np
 
 from pystencils.backends.cbackend import get_headers
 from pystencils.backends.cuda_backend import generate_cuda
-from pystencils.typing import StructType
 from pystencils.field import FieldType
 from pystencils.include import get_pycuda_include_path, get_pystencils_include_path
 from pystencils.kernel_wrapper import KernelWrapper
+from pystencils.typing import StructType
 from pystencils.typing.typed_sympy import FieldPointerSymbol
+from pystencils.utils import DotDict
 
 USE_FAST_MATH = True
+USE_PYCUDA = False
 
 
 def get_cubic_interpolation_include_paths():
-    from os.path import join, dirname
+    from os.path import dirname, join
 
     return [join(dirname(__file__), "CubicInterpolationCUDA", "code"),
             join(dirname(__file__), "CubicInterpolationCUDA", "code", "internal")]
@@ -32,9 +34,6 @@ def make_python_function(kernel_function_node, argument_dict=None, custom_backen
     Returns:
         compiled kernel as Python function
     """
-    import pycuda.autoinit  # NOQA
-    from pycuda.compiler import SourceModule
-
     if argument_dict is None:
         argument_dict = {}
 
@@ -42,17 +41,25 @@ def make_python_function(kernel_function_node, argument_dict=None, custom_backen
     includes = "\n".join([f"#include {include_file}" for include_file in header_list])
 
     code = includes + "\n"
-    code += "#define FUNC_PREFIX __global__\n"
+    code += "#define FUNC_PREFIX extern \"C\" __global__\n"
     code += "#define RESTRICT __restrict__\n\n"
     code += str(generate_cuda(kernel_function_node, custom_backend=custom_backend))
 
-    nvcc_options = ["-w", "-std=c++11", "-Wno-deprecated-gpu-targets"]
+    nvcc_options = ["-w", "-std=c++11"]
     if USE_FAST_MATH:
         nvcc_options.append("-use_fast_math")
 
-    mod = SourceModule(code, options=nvcc_options, include_dirs=[
-                       get_pystencils_include_path(), get_pycuda_include_path()])
-    func = mod.get_function(kernel_function_node.function_name)
+    if USE_PYCUDA:
+        import pycuda.autoinit  # NOQA
+        from pycuda.compiler import SourceModule
+        nvcc_options.append("-Wno-deprecated-gpu-targets")
+        mod = SourceModule(code, options=nvcc_options, include_dirs=[
+                           get_pystencils_include_path(), get_pycuda_include_path()])
+        func = mod.get_function(kernel_function_node.function_name)
+    else:
+        import cupy
+        nvcc_options.append("-I" + get_pystencils_include_path())
+        func = cupy.RawKernel(code, kernel_function_node.function_name, options=tuple(nvcc_options), jitify=True)
 
     parameters = kernel_function_node.get_parameters()
 
@@ -78,13 +85,19 @@ def make_python_function(kernel_function_node, argument_dict=None, custom_backen
             args = _build_numpy_argument_list(parameters, full_arguments)
             cache[key] = (args, block_and_thread_numbers)
             cache_values.append(kwargs)  # keep objects alive such that ids remain unique
-            func(*args, **block_and_thread_numbers)
+            if USE_PYCUDA:
+                func(*args, **block_and_thread_numbers)
+            else:
+                func(block_and_thread_numbers['grid'],
+                     block_and_thread_numbers['block'], [cupy.asarray(a) for a in args])
+
         # import pycuda.driver as cuda
         # cuda.Context.synchronize() # useful for debugging, to get errors right after kernel was called
     ast = kernel_function_node
     parameters = kernel_function_node.get_parameters()
     wrapper = KernelWrapper(wrapper, parameters, ast)
-    wrapper.num_regs = func.num_regs
+    if USE_PYCUDA:
+        wrapper.num_regs = func.num_regs
     return wrapper
 
 
@@ -95,7 +108,15 @@ def _build_numpy_argument_list(parameters, argument_dict):
     for param in parameters:
         if param.is_field_pointer:
             array = argument_dict[param.field_name]
-            actual_type = array.dtype
+            if hasattr(array, "__cuda_array_interface__"):
+                interface = DotDict()
+                interface.shape = array.__cuda_array_interface__["shape"]
+                interface.dtype = np.dtype(array.__cuda_array_interface__["typestr"])
+                interface.strides = array.__cuda_array_interface__["strides"]
+                interface.data = array.__cuda_array_interface__["data"][0]
+            else:
+                interface = array
+            actual_type = interface.dtype
             expected_type = param.fields[0].dtype.numpy_dtype
             if expected_type != actual_type:
                 raise ValueError("Data type mismatch for field '%s'. Expected '%s' got '%s'." %
@@ -136,6 +157,14 @@ def _check_arguments(parameter_specification, argument_dict):
             except KeyError:
                 raise KeyError("Missing field parameter for kernel call " + str(symbolic_field))
 
+            if hasattr(field_arr, "__cuda_array_interface__"):
+                field_interface = DotDict()
+                field_interface.shape = field_arr.__cuda_array_interface__["shape"]
+                field_interface.dtype = np.dtype(field_arr.__cuda_array_interface__["typestr"])
+                field_interface.strides = field_arr.__cuda_array_interface__["strides"]
+                field_interface.data = field_arr.__cuda_array_interface__["data"][0]
+                field_arr = field_interface
+
             if symbolic_field.has_fixed_shape:
                 symbolic_field_shape = tuple(int(i) for i in symbolic_field.shape)
                 if isinstance(symbolic_field.dtype, StructType):
@@ -147,7 +176,7 @@ def _check_arguments(parameter_specification, argument_dict):
                 symbolic_field_strides = tuple(int(i) * field_arr.dtype.itemsize for i in symbolic_field.strides)
                 if isinstance(symbolic_field.dtype, StructType):
                     symbolic_field_strides = symbolic_field_strides[:-1]
-                if symbolic_field_strides != field_arr.strides:
+                if field_arr.strides and symbolic_field_strides != field_arr.strides:
                     raise ValueError("Passed array '%s' has strides %s which does not match expected strides %s" %
                                      (symbolic_field.name, str(field_arr.strides), str(symbolic_field_strides)))