From b8591faf4fe3ef5c4935e109f61f4f8295e3096a Mon Sep 17 00:00:00 2001
From: ooooo <3164076421@qq.com>
Date: Wed, 23 Jul 2025 18:15:18 +0800
Subject: [PATCH 1/2] [Accuracy diff No.141] Fix accuracy diff for
 paddle.Tensor.__mul__ API

---
 .../phi/kernels/funcs/elementwise_grad_base.h | 52 +++++++++++++------
 test/legacy_test/test_multiply.py             | 21 ++++++++
 2 files changed, 57 insertions(+), 16 deletions(-)

diff --git a/paddle/phi/kernels/funcs/elementwise_grad_base.h b/paddle/phi/kernels/funcs/elementwise_grad_base.h
index 26d3195f6a5bfb..21d27a7f85e1d1 100644
--- a/paddle/phi/kernels/funcs/elementwise_grad_base.h
+++ b/paddle/phi/kernels/funcs/elementwise_grad_base.h
@@ -64,18 +64,28 @@ void CommonGradBroadcastCPU(const DenseTensor &x,
                             const CPUContext &dev_ctx,
                             DX_OP dx_op,
                             DY_OP dy_op) {
+  using MPType = typename phi::dtype::MPTypeTrait<T>::Type;
+
   std::vector<int64_t> index_array(max_dim, 0);
   const T *x_data = x.data<T>();
   const T *y_data = y.data<T>();
   const Tout *out_data = out.data<Tout>();
   const Tout *dout_data = dout.data<Tout>();
-  T *dx_data = dx == nullptr ? nullptr : dev_ctx.Alloc<T>(dx);
-  T *dy_data = dy == nullptr ? nullptr : dev_ctx.Alloc<T>(dy);
-  if (dx_data != nullptr) {
-    memset(dx_data, 0, dx->numel() * sizeof(T));
+
+  DenseTensor dx_mp, dy_mp;
+  MPType *dx_mp_data = nullptr;
+  MPType *dy_mp_data = nullptr;
+  if (dx != nullptr) {
+    dx_mp.Resize(dx->dims());
+    dev_ctx.Alloc<MPType>(&dx_mp);
+    dx_mp_data = dx_mp.data<MPType>();
+    memset(dx_mp_data, 0, dx->numel() * sizeof(MPType));
   }
-  if (dy_data != nullptr) {
-    memset(dy_data, 0, dy->numel() * sizeof(T));
+  if (dy != nullptr) {
+    dy_mp.Resize(dy->dims());
+    dev_ctx.Alloc<MPType>(&dy_mp);
+    dy_mp_data = dy_mp.data<MPType>();
+    memset(dy_mp_data, 0, dy->numel() * sizeof(MPType));
   }
   const int64_t out_size = std::accumulate(out_dims_array,
                                            out_dims_array + max_dim,
@@ -87,22 +97,32 @@ void CommonGradBroadcastCPU(const DenseTensor &x,
         GetElementwiseIndex<int64_t>(x_dims_array, max_dim, index_array.data());
     y_index =
         GetElementwiseIndex<int64_t>(y_dims_array, max_dim, index_array.data());
-    if (dx_data != nullptr) {
-      dx_data[x_index] += dx_op(x_data[x_index],
-                                y_data[y_index],
-                                out_data[out_index],
-                                dout_data[out_index]);
+    if (dx_mp_data != nullptr) {
+      dx_mp_data[x_index] += static_cast<MPType>(dx_op(x_data[x_index],
+                                                       y_data[y_index],
+                                                       out_data[out_index],
+                                                       dout_data[out_index]));
     }
-    if (dy_data != nullptr) {
-      dy_data[y_index] += dy_op(x_data[x_index],
-                                y_data[y_index],
-                                out_data[out_index],
-                                dout_data[out_index]);
+    if (dy_mp_data != nullptr) {
+      dy_mp_data[y_index] += static_cast<MPType>(dy_op(x_data[x_index],
+                                                       y_data[y_index],
+                                                       out_data[out_index],
+                                                       dout_data[out_index]));
     }
 
     UpdateElementwiseIndexArray<int64_t>(
         out_dims_array, max_dim, index_array.data());
   }
+  if (dx != nullptr) {
+    dev_ctx.Alloc<T>(dx);
+    phi::CastKernel<MPType, CPUContext>(
+        dev_ctx, dx_mp, phi::CppTypeToDataType<T>::Type(), dx);
+  }
+  if (dy != nullptr) {
+    dev_ctx.Alloc<T>(dy);
+    phi::CastKernel<MPType, CPUContext>(
+        dev_ctx, dy_mp, phi::CppTypeToDataType<T>::Type(), dy);
+  }
 }
 
 template <typename T, typename DX_OP, typename DY_OP, typename Tout = T>
diff --git a/test/legacy_test/test_multiply.py b/test/legacy_test/test_multiply.py
index 59702400db8e55..b82438e8aa4634 100755
--- a/test/legacy_test/test_multiply.py
+++ b/test/legacy_test/test_multiply.py
@@ -290,5 +290,26 @@ def init_shapes(self):
         self.y_shape = [5, 1]
 
 
+class TestMultiplyApiBF16(unittest.TestCase):
+    # Now only check the successful run of multiply with bfloat16 and backward.
+    def setUp(self):
+        paddle.device.set_device('cpu')
+
+    def test_multiply(self):
+        self.x_shape = [1, 1024, 32, 128]
+        self.y_shape = [1, 1024, 1, 128]
+        x = paddle.rand(self.x_shape, dtype='bfloat16')
+        x.stop_gradient = False
+        y = paddle.rand(self.y_shape, dtype='bfloat16')
+        y.stop_gradient = False
+        res = paddle.multiply(x, y)
+        loss = res.sum()
+        loss.backward()
+        assert x.grad is not None
+        assert x.grad.dtype == paddle.bfloat16
+        assert y.grad is not None
+        assert y.grad.dtype == paddle.bfloat16
+
+
 if __name__ == '__main__':
     unittest.main()

From 244e7d0323fa105bb97203c45a005eb274400352 Mon Sep 17 00:00:00 2001
From: ooooo <3164076421@qq.com>
Date: Wed, 23 Jul 2025 18:32:19 +0800
Subject: [PATCH 2/2] add headfile

---
 paddle/phi/kernels/funcs/elementwise_grad_base.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/paddle/phi/kernels/funcs/elementwise_grad_base.h b/paddle/phi/kernels/funcs/elementwise_grad_base.h
index 21d27a7f85e1d1..300aeaac2626b8 100644
--- a/paddle/phi/kernels/funcs/elementwise_grad_base.h
+++ b/paddle/phi/kernels/funcs/elementwise_grad_base.h
@@ -21,6 +21,7 @@ limitations under the License. */
 #include "paddle/phi/common/amp_type_traits.h"
 #include "paddle/phi/common/memory_utils.h"
 #include "paddle/phi/core/dense_tensor.h"
+#include "paddle/phi/kernels/cast_kernel.h"
 #include "paddle/phi/kernels/funcs/common_shape.h"
 #include "paddle/phi/kernels/funcs/elementwise_utils.h"
 #include "paddle/phi/kernels/funcs/for_range.h"