GeezerVison

@serhiy-storchaka
This is a draft. If use 5~7 days, it may achieve better quality.
I can wait until your PR "bpo-47152: Convert the re module into a package" is merged, then I redo this PR.

This PR has not been carefully checked yet, it will take a few days to do this.

Just want to ask your arrangement, is this PR merged first, or your PR first?
I tend to merge your PR first, then I can carefully check when you are preparing your PR.

I prefer to wait until this PR is merged. It is easy to redo my changes.

Ok, I will finish this PR in a few days.

In _compile() recursive function, it seems hard to return the number of REPEATs.

   def _compile(code, pattern, flags):
       # `code` is a list object
       # `pattern` and `flags` are input data
       ...

For counting the number of REPEATs, it's better at compile-time than parse-time.
Is it worth adding a parameter to _compile() function for this purpose?

You can save it as an attribute of pattern.state.

You can save it as an attribute of pattern.state.

In _compile() function, pattern.state is not accessable. pattern is SubPattern.data, not SubPattern.
I have an idea, I will try tommorw, time to sleep.

CompileData.diff changes code to a CompileData object, which may save intermediate states during compilation. Only apply this patch to main branch, MSVC2022 non-PGO release build runs test_re.py is 2.1% slower (0.277 sec -> 0.283 sec).

Another way is to temporarily store it in a field in SRE_OP_INFO, but this would make SRE_OP_INFO take up an unnecessary field.

To be honest, the whole patch is intricacy, so reviewing is harder than making it from zero. If you think so too, you may make a PR instead of this PR.

CompileData.diff.txt (.diff attachment is not supportted by GitHub, so I added .txt)

edit: below patch is faster a bit.

This simpler patch is faster (2.80 sec)
simple_patch.diff.txt

I can divide the patch into some commits, each commit only modify one simple step, which makes the review much easier. Then this PR will be closed.
I suggest merge your PR first.