During code-gen, the compiler makes sure that any opcode that does not HAVE_ARG get an oparg value of 0.

Then, during optimizations some instructions become NOPs but their oparg is not set to 0, so when we come to emit code we need to check HAS_ARG again. It would be better to preserve the invariant in the optimizer instead.

Linked PRs

• gh-99876: make optimizer maintain the invariant that oparg == 0 for an instruction that does not have an arg #99877