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| author | Camille Gillot <gillot.camille@gmail.com> | 2025-09-14 13:04:53 +0000 |
|---|---|---|
| committer | Camille Gillot <gillot.camille@gmail.com> | 2025-09-14 13:27:46 +0000 |
| commit | 8811344f22e0c015aaa45367b6462e3ecdcb22b5 (patch) | |
| tree | 3c31f52154cbf4f76e2eb63c7ca1103e8e8b2eb9 /compiler/rustc_mir_transform/src | |
| parent | aee7d703c58b68611785684bbb8e402c1471992b (diff) | |
| download | rust-8811344f22e0c015aaa45367b6462e3ecdcb22b5.tar.gz rust-8811344f22e0c015aaa45367b6462e3ecdcb22b5.zip | |
Elaborate comment.
Diffstat (limited to 'compiler/rustc_mir_transform/src')
| -rw-r--r-- | compiler/rustc_mir_transform/src/dest_prop.rs | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/compiler/rustc_mir_transform/src/dest_prop.rs b/compiler/rustc_mir_transform/src/dest_prop.rs index 7e6f39881b8..b9ab0a9feee 100644 --- a/compiler/rustc_mir_transform/src/dest_prop.rs +++ b/compiler/rustc_mir_transform/src/dest_prop.rs @@ -590,8 +590,12 @@ fn save_as_intervals<'tcx>( twostep = TwoStepIndex::from_u32(twostep.as_u32() + 1); debug_assert_eq!(twostep, two_step_loc(loc, Effect::After)); append_at(&mut values, &state, twostep); - // Ensure we have a non-zero live range even for dead stores. This is done by marking - // all the written-to locals as live in the second half of the statement. + // Like terminators, ensure we have a non-zero live range even for dead stores. + // Some rvalues interleave reads and writes, for instance `Rvalue::Aggregate`, see + // https://github.com/rust-lang/rust/issues/146383. By precaution, treat statements + // as behaving so by default. + // We make an exception for simple assignments `_a.stuff = {copy|move} _b.stuff`, + // as marking `_b` live here would prevent unification. let is_simple_assignment = matches!(stmt.kind, StatementKind::Assign(box (_, Rvalue::Use(_)))); VisitPlacesWith(|place: Place<'tcx>, ctxt| { |