bjoernager/rust
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Do not clone dominator tree for SSA analysis.

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This commit is contained in:
Camille GILLOT 2023-05-17 10:45:12 +00:00
parent fa8598cb50
commit ada7f1c2c4
1 changed files with 8 additions and 11 deletions
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19
compiler/rustc_mir_transform/src/ssa.rs
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@ -31,11 +31,11 @@ pub struct SsaLocals {
/// We often encounter MIR bodies with 1 or 2 basic blocks. In those cases, it's unnecessary to /// We often encounter MIR bodies with 1 or 2 basic blocks. In those cases, it's unnecessary to
/// actually compute dominators, we can just compare block indices because bb0 is always the first /// actually compute dominators, we can just compare block indices because bb0 is always the first
/// block, and in any body all other blocks are always dominated by bb0. /// block, and in any body all other blocks are always dominated by bb0.
struct SmallDominators { struct SmallDominators<'a> {
inner: Option<Dominators<BasicBlock>>, inner: Option<&'a Dominators<BasicBlock>>,
} }
impl SmallDominators { impl SmallDominators<'_> {
fn dominates(&self, first: Location, second: Location) -> bool { fn dominates(&self, first: Location, second: Location) -> bool {
if first.block == second.block { if first.block == second.block {
first.statement_index <= second.statement_index first.statement_index <= second.statement_index
@ -68,11 +68,8 @@ impl SsaLocals {
let assignment_order = Vec::with_capacity(body.local_decls.len()); let assignment_order = Vec::with_capacity(body.local_decls.len());
let assignments = IndexVec::from_elem(Set1::Empty, &body.local_decls); let assignments = IndexVec::from_elem(Set1::Empty, &body.local_decls);
let dominators = if body.basic_blocks.len() > 2 { let dominators =
Some(body.basic_blocks.dominators().clone()) if body.basic_blocks.len() > 2 { Some(body.basic_blocks.dominators()) } else { None };
} else {
None
};
let dominators = SmallDominators { inner: dominators }; let dominators = SmallDominators { inner: dominators };
let direct_uses = IndexVec::from_elem(0, &body.local_decls); let direct_uses = IndexVec::from_elem(0, &body.local_decls);
@ -201,14 +198,14 @@ enum LocationExtended {
Arg, Arg,
} }
struct SsaVisitor { struct SsaVisitor<'a> {
dominators: SmallDominators, dominators: SmallDominators<'a>,
assignments: IndexVec<Local, Set1<LocationExtended>>, assignments: IndexVec<Local, Set1<LocationExtended>>,
assignment_order: Vec<Local>, assignment_order: Vec<Local>,
direct_uses: IndexVec<Local, u32>, direct_uses: IndexVec<Local, u32>,
} }
impl<'tcx> Visitor<'tcx> for SsaVisitor { impl<'tcx> Visitor<'tcx> for SsaVisitor<'_> {
fn visit_local(&mut self, local: Local, ctxt: PlaceContext, loc: Location) { fn visit_local(&mut self, local: Local, ctxt: PlaceContext, loc: Location) {
match ctxt { match ctxt {
PlaceContext::MutatingUse(MutatingUseContext::Projection) PlaceContext::MutatingUse(MutatingUseContext::Projection)