Use tagged pointers for more efficient integer operations.

Feature or enhancement

Proposal:

From the discourse discussion:

Integers are ubiquitous, both in Python code and the virtual machine.
However our representation of integers is somewhat clunky and inefficient.

There is an old technique for handling ints efficiently in dynamic language VMs, called tagged pointers.
A normal object pointer always has its low bits set to zero, as objects are 8 or 16 byte aligned in memory.
We can use those low bits as “tags” to denote the meaning of the high bits.
Historically, the low bit has been set to zero to indicate that the high bits are a pointer, and to 1 to indicate that the high bits are an integer.

We already use another tagging scheme within the interpreter and in the frame stack, the tag indicating whether the reference is borrowed.

I expect to start small with this, initially just fixing https://github.com/python/cpython/issues/132508 then improving the performance of iteration over lists and tuples.

Has this already been discussed elsewhere?

I have already discussed this feature proposal on Discourse

Links to previous discussion of this feature:

https://discuss.python.org/t/using-tagged-pointers-to-support-efficient-integer-operations/87950

Linked PRs

• gh-157353

Bắt đầu bằng cách đọc issue #132508, pull request được liên kết #157353 và cuộc thảo luận Discourse được tham chiếu để hiểu biểu diễn con trỏ được gắn thẻ được đề xuất và công việc hiện tại. Issue không nêu tên tệp, kiểm thử hoặc một tác vụ triển khai có phạm vi giới hạn; để hoàn thành sẽ cần xác định và kiểm định một thiết kế interpreter và VM rộng hơn.