[SOT][FasterGuard] add ExprNodeBase cleanup func

[gouzil]

PR Category

Performance Optimization

PR Types

Performance

Description

添加清理方法，用于解决过程中临时变量的清理

TODO:

• 加个东西 check 一下？不过这样是不是会更慢了，而且需要考虑 immortal

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[Copilot]

Pull Request Overview

This PR introduces a cleanup mechanism within expression nodes to ensure temporary Python objects are properly released, thereby improving performance.

• Introduces a virtual cleanup() method in ExprNodeBase and corresponding overrides in AttributeExprNode and ItemExprNode.
• Implements a macro (DELAYED_CLEAN) to decrement reference counts and clean up stored Python objects.
• Updates evaluation functions to record cleanupable objects during attribute and item access.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
paddle/fluid/pybind/sot/guards.h	Added cleanup() methods and storage vectors in expression nodes.
paddle/fluid/pybind/sot/guards.cc	Introduced DELAYED_CLEAN macro and updated eval methods.

Comments suppressed due to low confidence (1)

paddle/fluid/pybind/sot/guards.h:354

• [nitpick] Consider renaming 'clean_py_obj_' to 'cleanup_py_objects_' to improve clarity regarding its purpose.

std::vector<PyObject*> clean_py_obj_;

[Copilot]

Calling Py_REFCNT on a PyObject immediately after a Py_DECREF may cause undefined behavior if the object is deallocated when its reference count reaches zero. Consider updating the cleanup logic to avoid accessing deallocated memory.

Suggested change

	bool should_erase = true; \
	if (*it) { \
	Py_DECREF(*it); \
	should_erase = (Py_REFCNT(*it) <= 0); \
	} \
	it = should_erase ? clean_py_obj_.erase(it) : ++it; \
	} \
	if (*it) { \
	PyObject* temp = *it; \
	Py_DECREF(temp); \
	it = clean_py_obj_.erase(it); \
	} else { \
	++it; \
	} \