[Paddle C++ API] Remapping input and output tensors after XPU op has fallen back to CPU op (#50625)

* fix accurary diff issue when XPU op batch_norm is added to XPU blacklist

* remap op output tensor to input tensor when the op has fallen back to CPU

* rename function name and fix bug causing by InplaceCounter

paddle/phi/api/yaml/generator/api_base.py

@@ -1179,6 +1179,11 @@ PADDLE_API {self.get_return_type(inplace_flag=True)} {api_func_name}({self.get_d
     ):
         return None, None, None
 
+    def reset_view_after_fallback(
+        self, out_dtype_list, code_indent='', inplace_flag=False
+    ):
+        return ''
+
     def gen_kernel_code(self, kernel_name, code_indent, inplace_flag=False):
         kernel_dispatch = self.kernel['dispatch'][kernel_name]
         input_tensors, kernel_args, kernel_signature = self.get_kernel_args(
@@ -1227,6 +1232,7 @@ PADDLE_API {self.get_return_type(inplace_flag=True)} {api_func_name}({self.get_d
 {code_indent}  }}
 {code_indent}  if (kernel_result.has_fallback_cpu) {{
 {fallback_kernel_output_trans}
+{self.reset_view_after_fallback(self.outputs['types'], code_indent, inplace_flag)}
 {code_indent}  }}
 {code_indent}  {self.gene_return_code()}"""
 

paddle/phi/api/yaml/generator/api_gen.py

@@ -312,6 +312,36 @@ class ForwardAPI(BaseAPI):
 
         return kernel_output, output_names, output_create
 
+    def reset_view_after_fallback(
+        self, out_dtype_list, code_indent='', inplace_flag=False
+    ):
+        remap_code = ''
+
+        if len(out_dtype_list) == 1:
+            if (
+                not inplace_flag
+                and self.view_map is not None
+                and self.outputs['names'][0] in self.view_map
+            ):
+                remap_code += f"""
+{code_indent}    phi::DenseTensor * {self.view_map[self.outputs['names'][0]]}_remap = static_cast<phi::DenseTensor*>({self.view_map[self.outputs['names'][0]]}.impl().get());
+{code_indent}    {self.view_map[self.outputs['names'][0]]}_remap->ShareBufferWith(*kernel_out);
+{code_indent}    kernel_out->ShareInplaceVersionCounterWith(*{self.view_map[self.outputs['names'][0]]}_remap);
+"""
+        elif len(out_dtype_list) > 1:
+            for i in range(len(out_dtype_list)):
+                if (
+                    not inplace_flag
+                    and self.view_map is not None
+                    and self.outputs['names'][i] in self.view_map
+                ):
+                    remap_code += f"""
+{code_indent}    phi::DenseTensor * {self.view_map[self.outputs['names'][i]]}_remap = static_cast<phi::DenseTensor*>({self.view_map[self.outputs['names'][i]]}.impl().get());
+{code_indent}    {self.view_map[self.outputs['names'][i]]}_remap->ShareBufferWith(*kernel_out_{i});
+{code_indent}    kernel_out_{i}->ShareInplaceVersionCounterWith(*{self.view_map[self.outputs['names'][i]]}_remap);
+"""
+        return remap_code
+
 
 def header_include():
     return """