Re-block SRoA on SIMD types by scottmcm · Pull Request #144665 · rust-lang/rust

scottmcm · 2025-07-30T03:41:59Z

Fixes 144621

rustbot · 2025-07-30T03:42:05Z

rustbot has assigned @saethlin.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

rustbot · 2025-07-30T03:42:07Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

compiler-errors · 2025-07-30T03:52:38Z

compiler/rustc_mir_transform/src/sroa.rs

        }
        if let ty::Adt(def, _args) = ty.kind()
-            && tcx.is_lang_item(def.did(), LangItem::DynMetadata)
+            && (def.repr().simd() || tcx.is_lang_item(def.did(), LangItem::DynMetadata))


Please update the doc comment on this function.

Also, could you rename this function? Calling it escaping_locals seems a bit misleading given it has opt-outs for locals that are not necessarily escaping.

compiler-errors

I'm pretty confused about how this was refactored. This code distinguishes escaping and excluded, but AFAICT escaping is a superset of the two that shouldn't change. Is there something I'm misunderstanding about the code, or are there further simplifications we can do here?

compiler-errors · 2025-07-30T17:22:13Z

compiler/rustc_mir_transform/src/sroa.rs

        let mut excluded = excluded_locals(body);
        let typing_env = body.typing_env(tcx);
        loop {
+            add_type_based_exclusions(tcx, &mut excluded, body);


Does this need to happen in the loop? The set of excluded locals based off of type exclusions shouldn't change, right?

Since we're in a loop I think it can because SRoA might add extra locals in the loop?

We can SRoA a (__m128, __m128), adding new locals which themselves need to not get SRoA'd.

compiler-errors · 2025-07-30T17:22:57Z

compiler/rustc_mir_transform/src/sroa.rs

    body: &Body<'tcx>,
-) -> DenseBitSet<Local> {
+) {
    let is_excluded_ty = |ty: Ty<'tcx>| {


Why not just inline this closure? It's just a simple match on ADT, even if it's not written like that today.

compiler-errors · 2025-07-30T17:23:24Z

compiler/rustc_mir_transform/src/sroa.rs

    let mut set = DenseBitSet::new_empty(body.local_decls.len());
    set.insert_range(RETURN_PLACE..=Local::from_usize(body.arg_count));
-    for (local, decl) in body.local_decls().iter_enumerated() {
-        if excluded.contains(local) || is_excluded_ty(decl.ty) {
+    for local in body.local_decls().indices() {
+        if excluded.contains(local) {
            set.insert(local);
        }
    }


This is morally just a clone of excluded, right?

Hmm, probably. I'll give it a shot. (I don't know if there's potentially different lengths because of changing numbers of locals.)

scottmcm · 2025-07-30T22:08:21Z

Actually, @compiler-errors, would you be ok with just doing the first commit here for now -- since beta branches in 2 days and we should have a fix for this -- as a partial revert of #144543, and then doing the refactor in another PR?

compiler-errors · 2025-07-30T22:09:42Z

Sure

compiler-errors · 2025-07-30T22:10:12Z

r=me on the first commit

scottmcm · 2025-07-31T07:58:33Z

@bors r=compiler-errors

bors · 2025-07-31T07:58:36Z

📌 Commit fe08ba0 has been approved by compiler-errors

It is now in the queue for this repository.

Rollup of 3 pull requests Successful merges: - #144657 (fix: Only "close the window" when its the last annotated file) - #144665 (Re-block SRoA on SIMD types) - #144713 (`rustc_middle::ty` cleanups) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #144665 - scottmcm:restore-sroa-simd-check, r=compiler-errors Re-block SRoA on SIMD types Fixes #144621

scottmcm · 2025-07-31T15:44:44Z

I've been thinking about the structure here and pondering whether there's some useful loop invariants that can simplify the refactor. Notably, since we're already blocking &_3.1 from SRoA'ing _3 at all, I think we don't actually need to check the escaping for the new locals we introduce when expanding a local, since the parts can't be borrowed either.

Still TBD on trying that out and seeing how it feels, though.

Rollup of 3 pull requests Successful merges: - rust-lang/rust#144657 (fix: Only "close the window" when its the last annotated file) - rust-lang/rust#144665 (Re-block SRoA on SIMD types) - rust-lang/rust#144713 (`rustc_middle::ty` cleanups) r? `@ghost` `@rustbot` modify labels: rollup

Re-block SRoA on SIMD types

fe08ba0

Fixes 144621

rustbot assigned saethlin Jul 30, 2025

rustbot added 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 Jul 30, 2025

scottmcm mentioned this pull request Jul 30, 2025

ICE building glam: Projecting into SIMD type std::arch::aarch64::float32x4_t is banned by MCP#838 #144621

Closed

compiler-errors reviewed Jul 30, 2025

View reviewed changes

This comment has been minimized.

Sign in to view

scottmcm force-pushed the restore-sroa-simd-check branch 2 times, most recently from d942a9d to ec7e4f9 Compare July 30, 2025 06:53

compiler-errors reviewed Jul 30, 2025

View reviewed changes

scottmcm force-pushed the restore-sroa-simd-check branch from ec7e4f9 to fe08ba0 Compare July 31, 2025 06:32

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 Jul 31, 2025

Zalathar mentioned this pull request Jul 31, 2025

Rollup of 3 pull requests #144723

Merged

bors merged commit 8cca6bc into rust-lang:master Jul 31, 2025
20 checks passed

rustbot added this to the 1.90.0 milestone Jul 31, 2025

rust-timer added a commit that referenced this pull request Jul 31, 2025

Unrolled build for #144665

eed7cb8

Rollup merge of #144665 - scottmcm:restore-sroa-simd-check, r=compiler-errors Re-block SRoA on SIMD types Fixes #144621

scottmcm deleted the restore-sroa-simd-check branch July 31, 2025 15:38

stefanboca mentioned this pull request Jul 31, 2025

blink.cmp build fail on Arch Linux (latest rustup version for rust-nightly) saghen/blink.cmp#2053

Closed

2 tasks

Uh oh!

Conversation

scottmcm commented Jul 30, 2025 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

rustbot commented Jul 30, 2025

Uh oh!

rustbot commented Jul 30, 2025

Uh oh!

compiler-errors Jul 30, 2025

Choose a reason for hiding this comment

Uh oh!

This comment has been minimized.

compiler-errors left a comment

Choose a reason for hiding this comment

Uh oh!

compiler-errors Jul 30, 2025

Choose a reason for hiding this comment

Uh oh!

scottmcm Jul 30, 2025

Choose a reason for hiding this comment

Uh oh!

compiler-errors Jul 30, 2025

Choose a reason for hiding this comment

Uh oh!

compiler-errors Jul 30, 2025

Choose a reason for hiding this comment

Uh oh!

scottmcm Jul 30, 2025

Choose a reason for hiding this comment

Uh oh!

scottmcm commented Jul 30, 2025

Uh oh!

compiler-errors commented Jul 30, 2025

Uh oh!

compiler-errors commented Jul 30, 2025

Uh oh!

scottmcm commented Jul 31, 2025

Uh oh!

bors commented Jul 31, 2025

Uh oh!

Uh oh!

scottmcm commented Jul 31, 2025

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

6 participants

scottmcm commented Jul 30, 2025 •

edited by rustbot

Loading