Add placeholder code for bfloat16 in Python (halide#6849) (halide#6850)

* Add placeholder code for bfloat16 in Python (halide#6849)

This is a no-op change; I just want to mark the place(s) in the Python bindings that need attention if/when it becomes possible to support bfloat16 in Python buffers.

* Update PyBinaryOperators.h

python_bindings/src/PyBinaryOperators.h

@@ -61,6 +61,7 @@ HANDLE_SCALAR_TYPE(int8_t)
 HANDLE_SCALAR_TYPE(int16_t)
 HANDLE_SCALAR_TYPE(int32_t)
 HANDLE_SCALAR_TYPE(int64_t)
+// HANDLE_SCALAR_TYPE(bfloat16_t) TODO: https://github.com/halide/Halide/issues/6849
 HANDLE_SCALAR_TYPE(float16_t)
 HANDLE_SCALAR_TYPE(float)
 HANDLE_SCALAR_TYPE(double)

python_bindings/src/PyBuffer.cpp

@@ -57,6 +57,12 @@ inline float16_t value_cast<float16_t>(const py::object &value) {
  return float16_t(value.cast<double>());
 }
 
+// TODO: https://github.com/halide/Halide/issues/6849
+// template<>
+// inline bfloat16_t value_cast<bfloat16_t>(const py::object &value) {
+// return bfloat16_t(value.cast<double>());
+// }
+
 template<typename T>
 inline std::string format_descriptor() {
  return py::format_descriptor<T>::format();
@@ -67,6 +73,12 @@ inline std::string format_descriptor<float16_t>() {
  return "e";
 }
 
+// TODO: https://github.com/halide/Halide/issues/6849
+// template<>
+// inline std::string format_descriptor<bfloat16_t>() {
+// return there-is-no-python-buffer-format-descriptor-for-bfloat16;
+// }
+
 void call_fill(Buffer<> &b, const py::object &value) {
 
 #define HANDLE_BUFFER_TYPE(TYPE) \
@@ -84,6 +96,8 @@ void call_fill(Buffer<> &b, const py::object &value) {
  HANDLE_BUFFER_TYPE(int16_t)
  HANDLE_BUFFER_TYPE(int32_t)
  HANDLE_BUFFER_TYPE(int64_t)
+ // TODO: https://github.com/halide/Halide/issues/6849
+ // HANDLE_BUFFER_TYPE(bfloat16_t)
  HANDLE_BUFFER_TYPE(float16_t)
  HANDLE_BUFFER_TYPE(float)
  HANDLE_BUFFER_TYPE(double)
@@ -109,6 +123,8 @@ bool call_all_equal(Buffer<> &b, const py::object &value) {
  HANDLE_BUFFER_TYPE(int16_t)
  HANDLE_BUFFER_TYPE(int32_t)
  HANDLE_BUFFER_TYPE(int64_t)
+ // TODO: https://github.com/halide/Halide/issues/6849
+ // HANDLE_BUFFER_TYPE(bfloat16_t)
  HANDLE_BUFFER_TYPE(float16_t)
  HANDLE_BUFFER_TYPE(float)
  HANDLE_BUFFER_TYPE(double)
@@ -133,6 +149,8 @@ std::string type_to_format_descriptor(const Type &type) {
  HANDLE_BUFFER_TYPE(int16_t)
  HANDLE_BUFFER_TYPE(int32_t)
  HANDLE_BUFFER_TYPE(int64_t)
+ // TODO: https://github.com/halide/Halide/issues/6849
+ // HANDLE_BUFFER_TYPE(bfloat16_t)
  HANDLE_BUFFER_TYPE(float16_t)
  HANDLE_BUFFER_TYPE(float)
  HANDLE_BUFFER_TYPE(double)
@@ -159,6 +177,8 @@ Type format_descriptor_to_type(const std::string &fd) {
  HANDLE_BUFFER_TYPE(int16_t)
  HANDLE_BUFFER_TYPE(int32_t)
  HANDLE_BUFFER_TYPE(int64_t)
+ // TODO: https://github.com/halide/Halide/issues/6849
+ // HANDLE_BUFFER_TYPE(bfloat16_t)
  HANDLE_BUFFER_TYPE(float16_t)
  HANDLE_BUFFER_TYPE(float)
  HANDLE_BUFFER_TYPE(double)
@@ -196,6 +216,8 @@ py::object buffer_getitem_operator(Buffer<> &buf, const std::vector<int> &pos) {
  HANDLE_BUFFER_TYPE(int16_t)
  HANDLE_BUFFER_TYPE(int32_t)
  HANDLE_BUFFER_TYPE(int64_t)
+ // TODO: https://github.com/halide/Halide/issues/6849
+ // HANDLE_BUFFER_TYPE(bfloat16_t)
  HANDLE_BUFFER_TYPE(float16_t)
  HANDLE_BUFFER_TYPE(float)
  HANDLE_BUFFER_TYPE(double)
@@ -224,6 +246,8 @@ py::object buffer_setitem_operator(Buffer<> &buf, const std::vector<int> &pos, c
  HANDLE_BUFFER_TYPE(int16_t)
  HANDLE_BUFFER_TYPE(int32_t)
  HANDLE_BUFFER_TYPE(int64_t)
+ // TODO: https://github.com/halide/Halide/issues/6849
+ // HANDLE_BUFFER_TYPE(bfloat16_t)
  HANDLE_BUFFER_TYPE(float16_t)
  HANDLE_BUFFER_TYPE(float)
  HANDLE_BUFFER_TYPE(double)

python_bindings/test/correctness/buffer.py

@@ -130,6 +130,20 @@ def test_float16():
  hl_img = hl.Buffer(array_in)
  array_out = np.array(hl_img, copy = False)
 
+# TODO: https://github.com/halide/Halide/issues/6849
+# def test_bfloat16():
+# try:
+# from tensorflow.python.lib.core import _pywrap_bfloat16
+# bfloat16 = _pywrap_bfloat16.TF_bfloat16_type()
+# array_in = np.zeros((256, 256, 3), dtype=bfloat16, order='F')
+# hl_img = hl.Buffer(array_in)
+# array_out = np.array(hl_img, copy = False)
+# except ModuleNotFoundError as e:
+# print("skipping test_bfloat16() because tensorflow was not found: %s" % str(e))
+# return
+# else:
+# assert False, "This should not happen"
+
 def test_int64():
  array_in = np.zeros((256, 256, 3), dtype=np.int64, order='F')
  hl_img = hl.Buffer(array_in)
@@ -279,6 +293,8 @@ def test_scalar_buffers():
  test_for_each_element()
  test_fill_all_equal()
  test_bufferinfo_sharing()
+ # TODO: https://github.com/halide/Halide/issues/6849
+ # test_bfloat16()
  test_float16()
  test_int64()
  test_reorder()