[D2SCinn]Support deliver skip_gc_vars into Graph (#49411)

* [D2SCinn]Support deliver skip_gc_vars into Graph

* fix unittest

* fix copy

python/paddle/jit/dy2static/partial_program.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from copy import deepcopy
+
 import numpy as np
 
 import paddle
@@ -699,19 +701,32 @@ class PartialProgramLayer:
     def _get_forward_backward_program_form(
         self, whole_program, forward_end_op_index
     ):
-        forward_builded_program = add_build_strategy_for(
-            whole_program, 0, forward_end_op_index, self._build_strategy
-        )
+        # NOTE(dev): We apply build_strategy for backward firstly to
+        # avoid skipping more gc variables.
         backward_start_op_index = forward_end_op_index + 2 * len(
             self._outputs.var_ids
         )
         backward_end_op_index = whole_program.desc.block(0).op_size()
+        backward_skip_vars = self._parse_skip_gc_vars(whole_program)
         backward_builded_program = add_build_strategy_for(
             whole_program,
             backward_start_op_index,
             backward_end_op_index,
             self._build_strategy,
+            backward_skip_vars,
+        )
+
+        forward_skip_vars = self._parse_skip_gc_vars(
+            whole_program, backward_builded_program
+        )
+        forward_builded_program = add_build_strategy_for(
+            whole_program,
+            0,
+            forward_end_op_index,
+            self._build_strategy,
+            forward_skip_vars,
         )
+
         self._apply_inplace_pass(
             forward_builded_program, backward_builded_program
         )
@@ -726,26 +741,10 @@ class PartialProgramLayer:
         empty_startup_program = paddle.static.Program()
         use_cuda = True if core.is_compiled_with_cuda() else False
         # skip data var
-        forward_mem_opt_skip_vars = []
-        backward_mem_opt_skip_vars = []
-        for var_name, var in forward_program.global_block().vars.items():
-            if var.is_data:
-                forward_mem_opt_skip_vars.append(var_name)
-        for var_name, var in backward_program.global_block().vars.items():
-            if var.is_data:
-                backward_mem_opt_skip_vars.append(var_name)
-        for var in self._inputs:
-            if isinstance(var, paddle.fluid.framework.Variable):
-                forward_mem_opt_skip_vars.append(var.desc.name())
-                backward_mem_opt_skip_vars.append(var.desc.name())
-        for var in self._outputs:
-            if isinstance(var, paddle.fluid.framework.Variable):
-                forward_mem_opt_skip_vars.append(var.desc.name())
-                backward_mem_opt_skip_vars.append(var.desc.name())
-        for var_name in core.parse_safe_eager_deletion_skip_vars(
-            backward_program.desc
-        ):
-            forward_mem_opt_skip_vars.append(var_name)
+        forward_mem_opt_skip_vars = self._parse_skip_gc_vars(
+            forward_program, backward_program
+        )
+        backward_mem_opt_skip_vars = self._parse_skip_gc_vars(forward_program)
         attrs = {
             "use_cuda": use_cuda,
             "mem_opt_skip_vars": forward_mem_opt_skip_vars,
@@ -771,6 +770,38 @@ class PartialProgramLayer:
             attr_types,
         )
 
+    @LazyInitialized
+    def _inout_var_names(self):
+        """
+        Returns Variable Names from self._inputs and self.outputs
+        """
+        var_names = []
+        for var in self._inputs:
+            if isinstance(var, paddle.fluid.framework.Variable):
+                var_names.append(var.desc.name())
+        for var in self._outputs:
+            if isinstance(var, paddle.fluid.framework.Variable):
+                var_names.append(var.desc.name())
+        return var_names
+
+    def _parse_skip_gc_vars(self, program, backward_program=None):
+        """
+        Parse variables that need to skip GC after execute it.
+        If specify backward_program, it will keep the variables used in backward.
+        """
+        # skip data var, DO NOT ignore this deepcopy
+        skip_vars = deepcopy(self._inout_var_names)
+        for var_name, var in program.global_block().vars.items():
+            if var.is_data:
+                skip_vars.append(var_name)
+
+        if backward_program:
+            for var_name in core.parse_safe_eager_deletion_skip_vars(
+                backward_program.desc
+            ):
+                skip_vars.append(var_name)
+        return skip_vars
+
     def _prepare(self, inputs):
         """
         Prepare inputs, outputs, attrs.
@@ -1055,13 +1086,16 @@ def partial_program_from(concrete_program):
 
 @switch_to_static_graph
 def add_build_strategy_for(
-    program, start_op_index, end_op_index, build_strategy=None
+    program, start_op_index, end_op_index, build_strategy=None, skip_vars=None
 ):
     if start_op_index < end_op_index:
         compiled_program = paddle.static.CompiledProgram(
             core.Graph(program.desc, start_op_index, end_op_index),
             build_strategy=build_strategy,
         )
+        if skip_vars:
+            # TODO(Aurelius84): Need to unify name with C++, such as kSkipVarNames.
+            compiled_program._graph.set("skip_gc_vars", set(skip_vars))
         compiled_program._compile(
             core.Scope(), framework._current_expected_place()
         )