mir_build: Integrate "simplification" steps into match-pair-tree creation #137875
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r? @Noratrieb rustbot has assigned @Noratrieb. Use |
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cc @Nadrieril (Looks like I accidentally broke triagebot pings for |
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Actually, this seems more appropriate: r? Nadrieril |
Nadrieril
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Mar 5, 2025
Nadrieril
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Mar 5, 2025
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| /// | ||
| /// Invariant: Or-patterns must be sorted to the end. | ||
| subpairs: Vec<Self>, |
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I would prefer to remove this: the invariant is relevant for Candidates only; adding it here is potentially confusing. We could even remove it from FlatPat if we make sure to sort in the FlatPat -> Candidate conversion step.
Nadrieril
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Mar 5, 2025
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Some changes occurred in match lowering cc @Nadrieril |
What remained of this simplification process has been integrated into construction of the match-pair trees.
As the invariant indicated, this place could only be none for `TestCase::Irrefutable` nodes, which no longer exist.
Nadrieril
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Mar 5, 2025
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@bors r+ |
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Rollup of 20 pull requests Successful merges: - rust-lang#134063 (dec2flt: Clean up float parsing modules) - rust-lang#136581 (Retire the legacy `Makefile`-based `run-make` test infra) - rust-lang#136662 (Count char width at most once in `Formatter::pad`) - rust-lang#136764 (Make `ptr_cast_add_auto_to_object` lint into hard error) - rust-lang#136798 (Added documentation for flushing per rust-lang#74348) - rust-lang#136865 (Perform deeper compiletest path normalization for `$TEST_BUILD_DIR` to account for compare-mode/debugger cases, and normalize long type file filename hashes) - rust-lang#136975 (Look for `python3` first on MacOS, not `py`) - rust-lang#136977 (Upload Datadog metrics with citool) - rust-lang#137240 (Slightly reformat `std::fs::remove_dir_all` error docs) - rust-lang#137298 (Check signature WF when lowering MIR body) - rust-lang#137463 ([illumos] attempt to use posix_spawn to spawn processes) - rust-lang#137477 (uefi: Add Service Binding Protocol abstraction) - rust-lang#137569 (Stabilize `string_extend_from_within`) - rust-lang#137633 (Only use implied bounds hack if bevy, and use deeply normalize in implied bounds hack) - rust-lang#137679 (Various coretests improvements) - rust-lang#137723 (Make `rust.description` more general-purpose and pass `CFG_VER_DESCRIPTION`) - rust-lang#137728 (Remove unsizing coercions for tuples) - rust-lang#137731 (Resume one waiter at once in deadlock handler) - rust-lang#137875 (mir_build: Integrate "simplification" steps into match-pair-tree creation) - rust-lang#138028 (compiler: add `ExternAbi::is_rustic_abi`) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#137875 - Zalathar:irrefutable, r=Nadrieril mir_build: Integrate "simplification" steps into match-pair-tree creation The “simplification” step helps to prepare THIR patterns for lowering into MIR, and originally dates back to the earliest days of MIR in the compiler. Over time, various intermediate data structures have been introduced (e.g. `MatchPair`, later renamed to `MatchPairTree`) that reduce the need for a separate simplification step, because some of the necessary simplifications can be built into the construction of those intermediate structures instead. This PR continues that process to its logical conclusion and removes the simplification step entirely, by integrating its remaining responsibilities into match-pair-tree creation: flattening “irrefutable” nodes, collecting bindings/ascriptions in flat lists, and sorting or-patterns after other subpatterns. This has a few immediate benefits: - We can remove `TestCase::Irrefutable`, which was not allowed to exist after simplification, and was much larger than other test-case variants. - We can make `MatchPairTree::place` non-optional, because only irrefutable nodes could fail to have a place. In the future, this should also help with some ideas I have for simplifying how `AscribeUserType` and `ExpandedConstant` nodes are handled, by representing them as side-data keyed by THIR pattern ID, so that they are no longer their own kinds of THIR pattern node.
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The “simplification” step helps to prepare THIR patterns for lowering into MIR, and originally dates back to the earliest days of MIR in the compiler.
Over time, various intermediate data structures have been introduced (e.g.
MatchPair, later renamed toMatchPairTree) that reduce the need for a separate simplification step, because some of the necessary simplifications can be built into the construction of those intermediate structures instead. This PR continues that process to its logical conclusion and removes the simplification step entirely, by integrating its remaining responsibilities into match-pair-tree creation: flattening “irrefutable” nodes, collecting bindings/ascriptions in flat lists, and sorting or-patterns after other subpatterns.This has a few immediate benefits:
TestCase::Irrefutable, which was not allowed to exist after simplification, and was much larger than other test-case variants.MatchPairTree::placenon-optional, because only irrefutable nodes could fail to have a place.In the future, this should also help with some ideas I have for simplifying how
AscribeUserTypeandExpandedConstantnodes are handled, by representing them as side-data keyed by THIR pattern ID, so that they are no longer their own kinds of THIR pattern node.