[bf16] support printing bf16 tensor (#39375)

python/paddle/fluid/tests/unittests/test_var_base.py

@@ -1094,6 +1094,20 @@ class TestVarBase(unittest.TestCase):
         self.assertEqual(a_str, expected)
         paddle.enable_static()
 
+    def test_tensor_str_bf16(self):
+        paddle.disable_static(paddle.CPUPlace())
+        a = paddle.to_tensor([[1.5, 1.0], [0, 0]])
+        a = paddle.cast(a, dtype=core.VarDesc.VarType.BF16)
+        paddle.set_printoptions(precision=4)
+        a_str = str(a)
+
+        expected = '''Tensor(shape=[2, 2], dtype=bfloat16, place=Place(cpu), stop_gradient=True,
+       [[1.5000, 1.    ],
+        [0.    , 0.    ]])'''
+
+        self.assertEqual(a_str, expected)
+        paddle.enable_static()
+
     def test_print_tensor_dtype(self):
         paddle.disable_static(paddle.CPUPlace())
         a = paddle.rand([1])

python/paddle/tensor/to_string.py

@@ -223,12 +223,18 @@ def _format_tensor(var, summary, indent=0, max_width=0, signed=False):
 def to_string(var, prefix='Tensor'):
     indent = len(prefix) + 1
 
+    dtype = convert_dtype(var.dtype)
+    if var.dtype == core.VarDesc.VarType.BF16:
+        dtype = 'bfloat16'
+
     _template = "{prefix}(shape={shape}, dtype={dtype}, place={place}, stop_gradient={stop_gradient},\n{indent}{data})"
 
     tensor = var.value().get_tensor()
     if not tensor._is_initialized():
         return "Tensor(Not initialized)"
 
+    if var.dtype == core.VarDesc.VarType.BF16:
+        var = var.astype('float32')
     np_var = var.numpy()
 
     if len(var.shape) == 0:
@@ -250,7 +256,7 @@ def to_string(var, prefix='Tensor'):
     return _template.format(
         prefix=prefix,
         shape=var.shape,
-        dtype=convert_dtype(var.dtype),
+        dtype=dtype,
         place=var._place_str,
         stop_gradient=var.stop_gradient,
         indent=' ' * indent,