Currently, we specializeFOR_ITER for both tuple and list. We also handle tuple and lists specially inGET_ITER to support this specialization.

We should extend this specialization of iteration over sequences, using virtual iterators tobytes,str,bytesarray and others.
To do this, we should:

• Add atp_getiteritem slots toPyTypeObject for sequences that can be efficiently indexed and cannot raise except for out-of-bounds access.
• Add a specialization ofFOR_ITER for these classes.
• SpecializeGET_ITER for:
  • iterators
  • indexable sequences (those classes with atp_getiteritem slot)
• SpecializeSEND for indexable sequences which should also improve JIT coverage, as unspecialized_SEND is currently a major cause of jit optimization failures.

Combined with#145667 this will allow effective specialization of a wider range of iterables and allow that specialization not only forfor loops, but also foryield from loops.
It will add 3 instructions (4 new, 1 removed) which a reasonable

Linked PRs

• gh-145668: Optimize FOR_ITER virtual iterators for bytes, bytearray, … #145670