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

まず issue #132508、リンクされている pull request #157353、および参照されている Discourse の議論を読んで、提案されているタグ付きポインタ表現と現在の作業状況を理解してください。issue にはファイル、テスト、または範囲が限定された実装タスクが記載されていません。完了するには、より広範なインタープリターと VM の設計を定義し、検証する必要があります。