Get rid of conditional inputs and outputs for instructions in bytecodes.c

[markshannon]

We should remove the conditional stack effects in instruction definitions in bytecodes.c

Conditional stack effects already complicate code generation and that is only going to get worse with top-of-stack caching and other interpreter/JIT optimizations.

There were two reasons for having conditional stack effects:

1. Ease of porting the old ceval code to bytecodes.c
2. Performance

Reason 1 no longer applies. Instructions are much more regular now and it isn't that much work to remove the remaining conditional stack effects.

That leaves performance. I experimentally removed the conditional stack effects for LOAD_GLOBAL and LOAD_ATTR which is the worse possible case for performance as it makes no attempt to mitigate the extra dispatch costs and possibly worse specialization.
The results are here
Overall we see a 0.8% slowdown. It seems that specialization is not significantly worse, but there is a large increase in PUSH_NULL following LOAD_GLOBAL that appears to responsible for the slowdown. An extra specialization should fix that.

Prior discussion

Linked PRs

• GH-128914: Remove conditional stack effects from bytecodes.c and the code generators #128918

[picnixz]

(Tagging it as a performance change even though we would end up with a slowdown. However, this is still something that is performance-related)