gh-141976: Check stack bounds in JIT optimizer

[Fidget-Spinner]

I verified this fixes the repro given in the issue. I'm not adding the repro because it's not self-contained, and so might change if asyncio changes.

• Issue: JIT: Assertion failure for WITHIN_STACK_BOUNDS() in optimize_uops #141976

[markshannon]

Why the extra code in optimizer_genrator.py when we're just changing assert(WITHIN_STACK_BOUNDS()) to CHECK_STACK_BOUNDS()?

You can reduce the amount of extra code by making the assertion/check code an attribute of the Stack object.

[markshannon]

One piece of code left from the earlier version that should be removed.
Otherwise, LGTM.

[markshannon]

This is now just a copy of the overridden method, so it can be removed.

[bedevere-app]

When you're done making the requested changes, leave the comment: I have made the requested changes; please review again.

[Fidget-Spinner]

Actually, there's a serious flaw with this approach.

It should be checking the stack bound before we write and increment the stack pointer. Otherwise, we might be writing to invalid memory.

[Fidget-Spinner]

I have made the requested changes; please review again

[bedevere-app]

Thanks for making the requested changes!

@markshannon: please review the changes made to this pull request.

[markshannon]

LGTM.

The extra checks probably aren't strictly necessary for safety, since we are writing into the middle of a huge buffer.
But, they're not wrong and a bit of extra safety is a good thing.