`LOAD_FAST_BORROW; POP_TOP` pairs should be removed

Feature or enhancement

Proposal:

I noticed that

def f(x):
    x

produces these instructions:

  3           RESUME                   0

  4           LOAD_FAST_BORROW         0 (x)
              POP_TOP
              LOAD_COMMON_CONSTANT     7 (None)
              RETURN_VALUE

from dis import dis

def f(x):
    x

dis(f)

The compiler should get rid of any LOAD_FAST_BORROW; POP_TOP pairs.

I will work on this.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-152643

首先跟踪 CPython 编译器路径，该路径会为提供的函数复现用例生成 LOAD_FAST_BORROW 和 POP_TOP 指令。使用 dis(f) 验证这对指令已消失，同时函数仍返回 None；该 issue 还链接了 PR gh-152643，因此请在开始之前检查这项工作。