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Created on 2021-11-09 19:56 by brandtbucher, last changed 2022-04-11 14:59 by admin. This issue is now closed.
| Pull Requests | |||
|---|---|---|---|
| URL | Status | Linked | Edit |
| PR 29505 | merged | brandtbucher, 2021-11-09 21:13 | |
| PR 29526 | merged | brandtbucher, 2021-11-11 19:51 | |
| PR 31066 | merged | brandtbucher, 2022-02-01 23:13 | |
| PR 31101 | merged | miss-islington, 2022-02-03 15:29 | |
| Messages (6) | |||
|---|---|---|---|
| msg406046 - (view) | Author: Brandt Bucher (brandtbucher) *  |
Date: 2021-11-09 19:56 | |
The following code hangs during compilation on 3.11 and 3.10:
>>> while True or spam: pass
Our peepholer gets stuck in a loop, repeatedly "optimizing" instruction 4 (POP_JUMP_IF_TRUE -> JUMP_ABSOLUTE):
1 0 JUMP_ABSOLUTE 0 (to 0)
2 LOAD_NAME 0 (spam)
4 POP_JUMP_IF_TRUE 0 (to 0)
After optimizing jumps to jumps like these, we always back up and attempt to optimize the same instruction again (which makes it possible to optimize three or more chained jumps on the same line). The issue is that this particular optimization doesn't actually change the instruction, since both jumps target the same exact block. Since nothing changes, we loop forever.
The fix is really simple: just skip the optimization if instr->i_target == target->i_target. We already do this for several other types of jumps; it just looks like POP_JUMP_IF_TRUE and POP_JUMP_IF_FALSE might have been missed.
I'll have a PR up soon.
|
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| msg406174 - (view) | Author: Brandt Bucher (brandtbucher) * |
Date: 2021-11-11 19:44 | |
New changeset 27b69e60daa7b191ee6bc76fb6d5fb7d793062ab by Brandt Bucher in branch 'main': bpo-45773: Stop "optimizing" certain jump patterns (GH-29505) https://github.com/python/cpython/commit/27b69e60daa7b191ee6bc76fb6d5fb7d793062ab |
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| msg406179 - (view) | Author: Brandt Bucher (brandtbucher) * |
Date: 2021-11-11 21:52 | |
New changeset a89bbde83fe7f8cc347341e7ec57cda3ba312530 by Brandt Bucher in branch '3.10': [3.10] bpo-45773: Stop "optimizing" certain jump patterns (GH-29526) https://github.com/python/cpython/commit/a89bbde83fe7f8cc347341e7ec57cda3ba312530 |
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| msg412318 - (view) | Author: Brandt Bucher (brandtbucher) * |
Date: 2022-02-01 23:13 | |
My fix for this seems to have erroneously added two invalid new jump threads: POP_JUMP_IF_FALSE(a) to JUMP_IF_FALSE_OR_POP(b) is folded into POP_JUMP_IF_FALSE(b) POP_JUMP_IF_TRUE(a) to JUMP_IF_TRUE_OR_POP(b) is folded into POP_JUMP_IF_TRUE(b) The good news is that I can't get the compiler to actually emit these particular jump sequences. It still needs to be fixed ASAP, though. |
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| msg412433 - (view) | Author: Mark Shannon (Mark.Shannon) * |
Date: 2022-02-03 10:14 | |
New changeset e0433c1e70254d4d0357a9e14596929a04bdf769 by Brandt Bucher in branch 'main': bpo-45773: Remove invalid peephole optimizations (GH-31066) https://github.com/python/cpython/commit/e0433c1e70254d4d0357a9e14596929a04bdf769 |
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| msg412447 - (view) | Author: miss-islington (miss-islington) | Date: 2022-02-03 15:54 | |
New changeset ff6948b1286c854ee77dfc0b23b9d828b36873e4 by Miss Islington (bot) in branch '3.10': bpo-45773: Remove invalid peephole optimizations (GH-31066) https://github.com/python/cpython/commit/ff6948b1286c854ee77dfc0b23b9d828b36873e4 |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:59:52 | admin | set | github: 89931 |
| 2022-02-03 16:04:53 | brandtbucher | set | priority: release blocker -> status: open -> closed resolution: fixed stage: patch review -> resolved |
| 2022-02-03 15:54:59 | miss-islington | set | messages: + msg412447 |
| 2022-02-03 15:29:01 | miss-islington | set | nosy:
+ miss-islington pull_requests: + pull_request29284 |
| 2022-02-03 10:14:48 | Mark.Shannon | set | messages: + msg412433 |
| 2022-02-01 23:13:54 | brandtbucher | set | pull_requests: + pull_request29251 |
| 2022-02-01 23:13:36 | brandtbucher | set | status: closed -> open priority: high -> release blocker type: crash -> behavior nosy: + pablogsal messages: + msg412318 resolution: fixed -> (no value) stage: resolved -> patch review |
| 2021-12-10 09:39:14 | iritkatriel | set | status: pending -> closed |
| 2021-11-13 15:46:18 | brandtbucher | set | status: open -> pending resolution: fixed stage: patch review -> resolved |
| 2021-11-11 21:52:53 | brandtbucher | set | messages: + msg406179 |
| 2021-11-11 19:51:33 | brandtbucher | set | pull_requests: + pull_request27776 |
| 2021-11-11 19:44:39 | brandtbucher | set | messages: + msg406174 |
| 2021-11-09 21:13:45 | brandtbucher | set | keywords:
+ patch stage: patch review pull_requests: + pull_request27756 |
| 2021-11-09 19:56:22 | brandtbucher | create | |