gh-131798: Split FOR_ITER_GEN into smaller uops

[Sacul0457]

I'm not sure how the optimizer knows the symbolic type on the first guard but it seems to work?

• Issue: Better uop coverage in the JIT optimizer #131798

[Fidget-Spinner]

I'm not sure how the optimizer knows the symbolic type on the first guard but it seems to work?

Uh oh. you just caught a bug in the JIT optimizer. Would you like to fix it?

The problem is that this line is wrong https://github.com/python/cpython/blob/main/Python/optimizer_symbols.c#L807 it should not be returning PyGen_Type, but rather NULL. Instead, _Py_uop_sym_get_probable_type should be the one returning PyGen_Type.

If you want to fix it, just move the lines around amend this small test to !, and copy the same line and change it to probable type https://github.com/python/cpython/blob/main/Python/optimizer_symbols.c#L2214

[Sacul0457]

Sure!
Should I fix it in this PR or create a new issue and open a separate PR?

[Fidget-Spinner]

Please open an issue and fix it in that PR. Thank you.