Separate dataflow analysis and results#140234

nnethercote · 2025-04-24T02:02:54Z

Analysis gets put into Results with EntryStates, by iterate_to_fixpoint. This has two problems:

Results is passed various places where only Analysis is needed.
EntryStates is passed around mutably everywhere even though it is immutable.

This commit mostly separates Analysis from Results and fixes these two problems.

Every `Results` contains an `Analysis`, but these methods only need the `Analysis`. No point passing them more data than they need.

`Results` contains and `Analysis` and an `EntryStates`. The unfortunate thing about this is that the analysis needs to be mutable everywhere (`&mut Analysis`) which forces the `Results` to be mutable everywhere, even though `EntryStates` is immutable everywhere. To fix this, this commit renames `Results` as `AnalysisAndResults`, renames `EntryStates` as `Results`, and separates the analysis and results as much as possible. (`AnalysisAndResults` doesn't get much use, it's mostly there to facilitate method chaining of `iterate_to_fixpoint`.) `Results` is immutable everywhere, which: - is a bit clearer on how the data is used, - avoids an unnecessary clone of entry states in `locals_live_across_suspend_points`, and - moves the results outside the `RefCell` in Formatter. The commit also reformulates `ResultsHandle` as the generic `CowMut`, which is simpler than `ResultsHandle` because it doesn't need the `'tcx` lifetime and the trait bounds. It also which sits nicely alongside the new use of `Cow` in `ResultsCursor`.

rustbot · 2025-04-24T02:03:00Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

The rustc-dev-guide subtree was changed. If this PR only touches the dev guide consider submitting a PR directly to rust-lang/rustc-dev-guide otherwise thank you for updating the dev guide with your changes.

cc @BoxyUwU, @jieyouxu, @Kobzol

nnethercote · 2025-04-24T02:04:47Z

@Jarcho: I hope this doesn't interfere with the uncommitted clippy analyses that you have. From our previous conversation, they required Analysis to be mutable and this PR doesn't change that.

Jarcho · 2025-04-24T10:29:23Z

This doesn't look like it will interfere with anything I have.

davidtwco · 2025-05-07T13:37:10Z

@bors r+

Apologies for the delay in getting to this

bors · 2025-05-07T13:37:13Z

📌 Commit 92799b6 has been approved by davidtwco

It is now in the queue for this repository.

…llaumeGomez Rollup of 8 pull requests Successful merges: - rust-lang#140234 (Separate dataflow analysis and results) - rust-lang#140614 (Correct warning message in restricted visibility) - rust-lang#140671 (Parser: Recover error from named params while parse_path) - rust-lang#140700 (Don't crash on error codes passed to `--explain` which exceed our internal limit of 9999 ) - rust-lang#140706 ([rustdoc] Ensure that temporary doctest folder is correctly removed even if doctests failed) - rust-lang#140734 (Fix regression from rust-lang#140393 for espidf / horizon / nuttx / vita) - rust-lang#140741 (add armv5te-unknown-linux-gnueabi target maintainer) - rust-lang#140745 (run-make-support: set rustc dylib path for cargo wrapper) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#140234 - nnethercote:separate-Analysis-and-Results, r=davidtwco Separate dataflow analysis and results `Analysis` gets put into `Results` with `EntryStates`, by `iterate_to_fixpoint`. This has two problems: - `Results` is passed various places where only `Analysis` is needed. - `EntryStates` is passed around mutably everywhere even though it is immutable. This commit mostly separates `Analysis` from `Results` and fixes these two problems. r? `@davidtwco`

`Results` used to contain an `Analysis`, but it was removed in rust-lang#140234. That change made sense because the analysis was mutable but the entry states were immutable and it was good to separate them so the mutability of the different pieces was clear. Now that analyses are immutable there is no need for the separation, lots of analysis+results pairs can be combined, and the names are going back to what they were before: - `Results` -> `EntryStates` - `AnalysisAndResults` -> `Results`

nnethercote added 2 commits April 24, 2025 11:34

Pass Analysis to visit_* instead of Results.

4ff5558

Every `Results` contains an `Analysis`, but these methods only need the `Analysis`. No point passing them more data than they need.

rustbot assigned davidtwco Apr 24, 2025

rustbot added A-rustc-dev-guide Area: rustc-dev-guide S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 24, 2025

davidtwco approved these changes May 7, 2025

View reviewed changes

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 7, 2025

GuillaumeGomez mentioned this pull request May 7, 2025

Rollup of 8 pull requests #140751

Merged

bors merged commit 82c99c4 into rust-lang:master May 8, 2025
6 checks passed

rustbot added this to the 1.88.0 milestone May 8, 2025

nnethercote deleted the separate-Analysis-and-Results branch May 8, 2025 04:32

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Separate dataflow analysis and results#140234