From 45aa17935483ee8314ae54719ea21fdd43e65378 Mon Sep 17 00:00:00 2001 From: Lzu Tao Date: Sun, 16 Jun 2024 10:00:23 +0000 Subject: [PATCH] Prefer Struct-of-array --- .../rustc_mir_transform/src/promote_consts.rs | 52 ++++++++----------- 1 file changed, 23 insertions(+), 29 deletions(-) diff --git a/compiler/rustc_mir_transform/src/promote_consts.rs b/compiler/rustc_mir_transform/src/promote_consts.rs index 2f7d8d96eaccc..e73db1014149c 100644 --- a/compiler/rustc_mir_transform/src/promote_consts.rs +++ b/compiler/rustc_mir_transform/src/promote_consts.rs @@ -58,9 +58,10 @@ impl<'tcx> MirPass<'tcx> for PromoteTemps<'tcx> { } let ccx = ConstCx::new(tcx, body); - let (mut temps, all_candidates) = collect_temps_and_candidates(&ccx); + let (mut temps, mut all_candidates) = collect_temps_and_candidates(&ccx); - let promotable_candidates = validate_candidates(&ccx, &mut temps, &all_candidates); + validate_candidates(&ccx, &mut temps, &mut all_candidates); + let promotable_candidates = &all_candidates.0[..]; let promoted = promote_candidates(body, tcx, temps, promotable_candidates); self.promoted_fragments.set(promoted); @@ -83,18 +84,16 @@ enum TempState { PromotedOut, } -/// A "root candidate" for promotion, which will become the -/// returned value in a promoted MIR, unless it's a subset -/// of a larger candidate. -#[derive(Copy, Clone, PartialEq, Eq, Debug)] -struct Candidate { - location: Location, -} +/// Each `[Location]` is a "root candidate" for promotion, which will become +/// the returned value in a promoted MIR, unless it's a subset of a larger +/// candidate. +#[derive(Clone, Debug)] +struct Candidates(Vec); struct Collector<'a, 'tcx> { ccx: &'a ConstCx<'a, 'tcx>, temps: IndexVec, - candidates: Vec, + candidates: Candidates, } impl<'tcx> Visitor<'tcx> for Collector<'_, 'tcx> { @@ -141,24 +140,23 @@ impl<'tcx> Visitor<'tcx> for Collector<'_, 'tcx> { } TempState::Unpromotable | TempState::PromotedOut => TempState::Unpromotable, }; - debug!(?temp); } fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) { self.super_rvalue(rvalue, location); if let Rvalue::Ref(..) = *rvalue { - self.candidates.push(Candidate { location }); + self.candidates.0.push(location); } } } fn collect_temps_and_candidates<'tcx>( ccx: &ConstCx<'_, 'tcx>, -) -> (IndexVec, Vec) { +) -> (IndexVec, Candidates) { let mut collector = Collector { temps: IndexVec::from_elem(TempState::Undefined, &ccx.body.local_decls), - candidates: vec![], + candidates: Candidates(vec![]), ccx, }; for (bb, data) in traversal::reverse_postorder(ccx.body) { @@ -192,8 +190,8 @@ impl<'a, 'tcx> std::ops::Deref for Validator<'a, 'tcx> { struct Unpromotable; impl<'tcx> Validator<'_, 'tcx> { - fn validate_candidate(&mut self, candidate: Candidate) -> Result<(), Unpromotable> { - let Left(statement) = self.body.stmt_at(candidate.location) else { bug!() }; + fn validate_candidate(&mut self, candidate: Location) -> Result<(), Unpromotable> { + let Left(statement) = self.body.stmt_at(candidate) else { bug!() }; let Some((_, Rvalue::Ref(_, kind, place))) = statement.kind.as_assign() else { bug!() }; // We can only promote interior borrows of promotable temps (non-temps @@ -691,15 +689,11 @@ impl<'tcx> Validator<'_, 'tcx> { fn validate_candidates( ccx: &ConstCx<'_, '_>, temps: &mut IndexSlice, - candidates: &[Candidate], -) -> Vec { + candidates: &mut Candidates, +) { let mut validator = Validator { ccx, temps, promotion_safe_blocks: None }; - candidates - .iter() - .copied() - .filter(|&candidate| validator.validate_candidate(candidate).is_ok()) - .collect() + candidates.0.retain(|&candidate| validator.validate_candidate(candidate).is_ok()); } struct Promoter<'a, 'tcx> { @@ -854,7 +848,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> { new_temp } - fn promote_candidate(mut self, candidate: Candidate, next_promoted_id: usize) -> Body<'tcx> { + fn promote_candidate(mut self, candidate: Location, next_promoted_id: usize) -> Body<'tcx> { let def = self.source.source.def_id(); let (mut rvalue, promoted_op) = { let promoted = &mut self.promoted; @@ -871,7 +865,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> { let blocks = self.source.basic_blocks.as_mut(); let local_decls = &mut self.source.local_decls; - let loc = candidate.location; + let loc = candidate; let statement = &mut blocks[loc.block].statements[loc.statement_index]; let StatementKind::Assign(box (_, Rvalue::Ref(region, borrow_kind, place))) = &mut statement.kind @@ -965,7 +959,7 @@ fn promote_candidates<'tcx>( body: &mut Body<'tcx>, tcx: TyCtxt<'tcx>, mut temps: IndexVec, - candidates: Vec, + candidates: &[Location], ) -> IndexVec> { // Visit candidates in reverse, in case they're nested. debug!(promote_candidates = ?candidates); @@ -978,8 +972,8 @@ fn promote_candidates<'tcx>( let mut promotions = IndexVec::new(); let mut extra_statements = vec![]; - for candidate in candidates.into_iter().rev() { - let Location { block, statement_index } = candidate.location; + for candidate in candidates.iter().copied().rev() { + let Location { block, statement_index } = candidate; if let StatementKind::Assign(box (place, _)) = &body[block].statements[statement_index].kind { if let Some(local) = place.as_local() { @@ -993,7 +987,7 @@ fn promote_candidates<'tcx>( // Declare return place local so that `mir::Body::new` doesn't complain. let initial_locals = iter::once(LocalDecl::new(tcx.types.never, body.span)).collect(); - let mut scope = body.source_scopes[body.source_info(candidate.location).scope].clone(); + let mut scope = body.source_scopes[body.source_info(candidate).scope].clone(); scope.parent_scope = None; let mut promoted = Body::new(