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gh-105481: remove regen-opcode. Generated _PyOpcode_Caches in regen-cases. #108367

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Merged
merged 5 commits into from
Aug 23, 2023

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iritkatriel
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@iritkatriel iritkatriel commented Aug 23, 2023

if instr.cache_offset > 0:
self.out.emit(f'[{name}] = {instr.cache_offset},')
# Irregular case:
self.out.emit('[JUMP_BACKWARD] = 1,')
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How should we deal with this case?

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Put JUMP_BACKWARD in a family of its own, and add the cache effect notation to its instr? Or is that a problem because it's also part of the JUMP pseudo?

If it's complicated I'm fine with leaving this special case.

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Alas, it looks like it's in a pseudo with JUMP_FORWARD and those are required to have the same size. Maybe that requirement is too strict?

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In an offline discussion with @markshannon we decided to add a family for JUMP_BACKWARD which would declare its cache size. This causes the generator to emit an assertion that the cache size declared for the family (1) is equal to that which is calculated from the instruction signature (0). If I add the cache to the signature, then I get an error about the pseudo-instructions for JUMP (JUMP_FORWARD and JUMP_BACKWARD) not having the same instruction format.

So there is something here that we need to resolve, and it's not a trivial change. I suggest we commit this PR (which is large enough) with the workaround on line 553, and resolve it in a separate PR.

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Agreed. LGTM.

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Ah, I didn't see your comment before I wrote this ^. Yes, we seem to agree.

@iritkatriel iritkatriel requested a review from gvanrossum August 23, 2023 13:58
if instr.cache_offset > 0:
self.out.emit(f'[{name}] = {instr.cache_offset},')
# Irregular case:
self.out.emit('[JUMP_BACKWARD] = 1,')
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Put JUMP_BACKWARD in a family of its own, and add the cache effect notation to its instr? Or is that a problem because it's also part of the JUMP pseudo?

If it's complicated I'm fine with leaving this special case.

Co-authored-by: Guido van Rossum <gvanrossum@gmail.com>
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There's a new commit after the PR has been approved.

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

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Generate opcode metadata from bytecodes.c instead of opcode.py
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