bpo-43683: Handle generator entry in bytecode by markshannon · Pull Request #25138 · python/cpython
Adds GEN_START bytecode to handle checking for None when starting a generator or coroutine.
This means that:
send()doesn't need to check the state of the generator.- Should speed up iteration as check is only performed once per generator, not once per iteration.
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LGTM
…o bytecode. Document new bytecode and make it fail gracefully if mis-compiled. Add NEWS item Bump magic number.
| entryblock = b; | ||
| } | ||
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| if (insert_generator_prefix(c, entryblock)) { |
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If we're compiling a generator (or coroutine etc.) the new function assumes (without asserting) that entryblock is not NULL. But evidently it could be, since below on line 6690 there's a check whether it could be. I don't know how it could be NULL - that would mean there's no code in the function at all, but it seems there's code above that always adds at least one instruction (RETURN_VALUE on line 6668). So maybe the check for entryblock == NULL below can be replaced by an assert? (I'd place that assert right underneath the for-loop above on lines 6683-6686.
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entryblock cannot be NULL. I'll add the assert.