fix paddle.where broadcast bug (#39182)

python/paddle/tensor/search.py

@@ -585,26 +585,49 @@ def where(condition, x=None, y=None, name=None):
     condition_shape = list(condition.shape)
     x_shape = list(x.shape)
     y_shape = list(y.shape)
+
     if x_shape == y_shape and condition_shape == x_shape:
+        broadcast_condition = condition
+        broadcast_x = x
+        broadcast_y = y
+    else:
+        if core.is_compiled_with_xpu():
+            cond_int = layers.cast(condition, x.dtype)
+            cond_not_int = layers.cast(layers.logical_not(condition), x.dtype)
+            out1 = layers.elementwise_mul(x, cond_int)
+            out2 = layers.elementwise_mul(y, cond_not_int)
+            out = layers.elementwise_add(out1, out2)
+            return out
+
+        zeros_like_x = layers.zeros_like(x)
+        zeros_like_y = layers.zeros_like(y)
+        zeros_like_condition = layers.zeros_like(condition)
+        zeros_like_condition = layers.cast(zeros_like_condition, x.dtype)
+        cast_cond = layers.cast(condition, x.dtype)
+
+        broadcast_zeros = layers.elementwise_add(zeros_like_x, zeros_like_y)
+        broadcast_zeros = layers.elementwise_add(broadcast_zeros,
+                                                 zeros_like_condition)
+        broadcast_x = layers.elementwise_add(x, broadcast_zeros)
+        broadcast_y = layers.elementwise_add(y, broadcast_zeros)
+        broadcast_condition = layers.elementwise_add(cast_cond, broadcast_zeros)
+        broadcast_condition = layers.cast(broadcast_condition, 'bool')
+
     if in_dygraph_mode():
-            return _C_ops.where(condition, x, y)
+        return _C_ops.where(broadcast_condition, broadcast_x, broadcast_y)
     else:
         helper = LayerHelper("where", **locals())
         out = helper.create_variable_for_type_inference(dtype=x.dtype)
 
         helper.append_op(
             type='where',
-                inputs={'Condition': condition,
-                        'X': x,
-                        'Y': y},
+            inputs={
+                'Condition': broadcast_condition,
+                'X': broadcast_x,
+                'Y': broadcast_y
+            },
             outputs={'Out': [out]})
-            return out
-    else:
-        cond_int = layers.cast(condition, x.dtype)
-        cond_not_int = layers.cast(layers.logical_not(condition), x.dtype)
-        out1 = layers.elementwise_mul(x, cond_int)
-        out2 = layers.elementwise_mul(y, cond_not_int)
-        out = layers.elementwise_add(out1, out2)
+
         return out