gh-106581: Split `CALL_PY_EXACT_ARGS` into uops by gvanrossum · Pull Request #107760 · python/cpython

This is only the first step for doing `CALL` in Tier 2.
The next step involves tracing into the called code object.
After that we'll have to do the remaining `CALL` specialization.
Finally we'll have to tweak various things like `KW_NAMES`,
and possibly move the `NULL` (for method calls) *above* the callable.
But those are things for future PRs.

Note: this moves setting `frame->return_offset` directly in front of
`DISPATCH_INLINED()`, to make it easier to move it into `_PUSH_FRAME`.

Instead, the special case is an opcode using SAVE_FRAME_STATE().
Introducing #if TIER_ONE and #if TIER_TWO so we can implement
_PUSH_FRAME differently for both tiers.

Instead, we special-case SAVE_IP:
- Its Tier 2 expansion sets oparg to the instruction offset
- In Tier 1 it is a no-op (and skipped if present in a macro)

This finishes the work begun in gh-107760. When, while projecting a superblock, we encounter a call to a short, simple function, the superblock will now enter the function using `_PUSH_FRAME`, continue through it, and leave it using `_POP_FRAME`, and then continue through the original code. Multiple frame pushes and pops are even possible. It is also possible to stop appending to the superblock in the middle of a called function, when running out of space or encountering an unsupported bytecode.