diff options
Diffstat (limited to 'compiler/rustc_mir_dataflow/src/impls/liveness.rs')
| -rw-r--r-- | compiler/rustc_mir_dataflow/src/impls/liveness.rs | 107 |
1 files changed, 66 insertions, 41 deletions
diff --git a/compiler/rustc_mir_dataflow/src/impls/liveness.rs b/compiler/rustc_mir_dataflow/src/impls/liveness.rs index 21132eb99..3e08a8799 100644 --- a/compiler/rustc_mir_dataflow/src/impls/liveness.rs +++ b/compiler/rustc_mir_dataflow/src/impls/liveness.rs @@ -23,12 +23,6 @@ use crate::{Analysis, AnalysisDomain, Backward, CallReturnPlaces, GenKill, GenKi /// [liveness]: https://en.wikipedia.org/wiki/Live_variable_analysis pub struct MaybeLiveLocals; -impl MaybeLiveLocals { - fn transfer_function<'a, T>(&self, trans: &'a mut T) -> TransferFunction<'a, T> { - TransferFunction(trans) - } -} - impl<'tcx> AnalysisDomain<'tcx> for MaybeLiveLocals { type Domain = ChunkedBitSet<Local>; type Direction = Backward; @@ -54,7 +48,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeLiveLocals { statement: &mir::Statement<'tcx>, location: Location, ) { - self.transfer_function(trans).visit_statement(statement, location); + TransferFunction(trans).visit_statement(statement, location); } fn terminator_effect( @@ -63,7 +57,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeLiveLocals { terminator: &mir::Terminator<'tcx>, location: Location, ) { - self.transfer_function(trans).visit_terminator(terminator, location); + TransferFunction(trans).visit_terminator(terminator, location); } fn call_return_effect( @@ -85,9 +79,11 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeLiveLocals { _resume_block: mir::BasicBlock, resume_place: mir::Place<'tcx>, ) { - if let Some(local) = resume_place.as_local() { - trans.kill(local); - } + YieldResumeEffect(trans).visit_place( + &resume_place, + PlaceContext::MutatingUse(MutatingUseContext::Yield), + Location::START, + ) } } @@ -98,28 +94,51 @@ where T: GenKill<Local>, { fn visit_place(&mut self, place: &mir::Place<'tcx>, context: PlaceContext, location: Location) { - let local = place.local; - - // We purposefully do not call `super_place` here to avoid calling `visit_local` for this - // place with one of the `Projection` variants of `PlaceContext`. - self.visit_projection(place.as_ref(), context, location); + if let PlaceContext::MutatingUse(MutatingUseContext::Yield) = context { + // The resume place is evaluated and assigned to only after generator resumes, so its + // effect is handled separately in `yield_resume_effect`. + return; + } match DefUse::for_place(*place, context) { - Some(DefUse::Def) => self.0.kill(local), - Some(DefUse::Use) => self.0.gen(local), + Some(DefUse::Def) => { + if let PlaceContext::MutatingUse( + MutatingUseContext::Call | MutatingUseContext::AsmOutput, + ) = context + { + // For the associated terminators, this is only a `Def` when the terminator returns + // "successfully." As such, we handle this case separately in `call_return_effect` + // above. However, if the place looks like `*_5`, this is still unconditionally a use of + // `_5`. + } else { + self.0.kill(place.local); + } + } + Some(DefUse::Use) => self.0.gen(place.local), None => {} } + + self.visit_projection(place.as_ref(), context, location); } fn visit_local(&mut self, local: Local, context: PlaceContext, _: Location) { - // Because we do not call `super_place` above, `visit_local` is only called for locals that - // do not appear as part of a `Place` in the MIR. This handles cases like the implicit use - // of the return place in a `Return` terminator or the index in an `Index` projection. - match DefUse::for_place(local.into(), context) { - Some(DefUse::Def) => self.0.kill(local), - Some(DefUse::Use) => self.0.gen(local), - None => {} - } + DefUse::apply(self.0, local.into(), context); + } +} + +struct YieldResumeEffect<'a, T>(&'a mut T); + +impl<'tcx, T> Visitor<'tcx> for YieldResumeEffect<'_, T> +where + T: GenKill<Local>, +{ + fn visit_place(&mut self, place: &mir::Place<'tcx>, context: PlaceContext, location: Location) { + DefUse::apply(self.0, *place, context); + self.visit_projection(place.as_ref(), context, location); + } + + fn visit_local(&mut self, local: Local, context: PlaceContext, _: Location) { + DefUse::apply(self.0, local.into(), context); } } @@ -130,11 +149,25 @@ enum DefUse { } impl DefUse { + fn apply<'tcx>(trans: &mut impl GenKill<Local>, place: Place<'tcx>, context: PlaceContext) { + match DefUse::for_place(place, context) { + Some(DefUse::Def) => trans.kill(place.local), + Some(DefUse::Use) => trans.gen(place.local), + None => {} + } + } + fn for_place<'tcx>(place: Place<'tcx>, context: PlaceContext) -> Option<DefUse> { match context { PlaceContext::NonUse(_) => None, - PlaceContext::MutatingUse(MutatingUseContext::Store | MutatingUseContext::Deinit) => { + PlaceContext::MutatingUse( + MutatingUseContext::Call + | MutatingUseContext::Yield + | MutatingUseContext::AsmOutput + | MutatingUseContext::Store + | MutatingUseContext::Deinit, + ) => { if place.is_indirect() { // Treat derefs as a use of the base local. `*p = 4` is not a def of `p` but a // use. @@ -152,16 +185,6 @@ impl DefUse { place.is_indirect().then_some(DefUse::Use) } - // For the associated terminators, this is only a `Def` when the terminator returns - // "successfully." As such, we handle this case separately in `call_return_effect` - // above. However, if the place looks like `*_5`, this is still unconditionally a use of - // `_5`. - PlaceContext::MutatingUse( - MutatingUseContext::Call - | MutatingUseContext::Yield - | MutatingUseContext::AsmOutput, - ) => place.is_indirect().then_some(DefUse::Use), - // All other contexts are uses... PlaceContext::MutatingUse( MutatingUseContext::AddressOf @@ -247,7 +270,7 @@ impl<'a, 'tcx> Analysis<'tcx> for MaybeTransitiveLiveLocals<'a> { | StatementKind::Retag(..) | StatementKind::AscribeUserType(..) | StatementKind::Coverage(..) - | StatementKind::CopyNonOverlapping(..) + | StatementKind::Intrinsic(..) | StatementKind::Nop => None, }; if let Some(destination) = destination { @@ -290,8 +313,10 @@ impl<'a, 'tcx> Analysis<'tcx> for MaybeTransitiveLiveLocals<'a> { _resume_block: mir::BasicBlock, resume_place: mir::Place<'tcx>, ) { - if let Some(local) = resume_place.as_local() { - trans.remove(local); - } + YieldResumeEffect(trans).visit_place( + &resume_place, + PlaceContext::MutatingUse(MutatingUseContext::Yield), + Location::START, + ) } } |