diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src/dataflow_const_prop.rs')
| -rw-r--r-- | compiler/rustc_mir_transform/src/dataflow_const_prop.rs | 163 |
1 files changed, 71 insertions, 92 deletions
diff --git a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs index d4db7e2de..7adfc9dff 100644 --- a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs +++ b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs @@ -70,22 +70,6 @@ struct ConstAnalysis<'a, 'tcx> { param_env: ty::ParamEnv<'tcx>, } -impl<'tcx> ConstAnalysis<'_, 'tcx> { - fn eval_discriminant( - &self, - enum_ty: Ty<'tcx>, - variant_index: VariantIdx, - ) -> Option<ScalarTy<'tcx>> { - if !enum_ty.is_enum() { - return None; - } - let discr = enum_ty.discriminant_for_variant(self.tcx, variant_index)?; - let discr_layout = self.tcx.layout_of(self.param_env.and(discr.ty)).ok()?; - let discr_value = Scalar::try_from_uint(discr.val, discr_layout.size)?; - Some(ScalarTy(discr_value, discr.ty)) - } -} - impl<'tcx> ValueAnalysis<'tcx> for ConstAnalysis<'_, 'tcx> { type Value = FlatSet<ScalarTy<'tcx>>; @@ -95,22 +79,22 @@ impl<'tcx> ValueAnalysis<'tcx> for ConstAnalysis<'_, 'tcx> { &self.map } - fn handle_statement(&self, statement: &Statement<'tcx>, state: &mut State<Self::Value>) { - match statement.kind { - StatementKind::SetDiscriminant { box ref place, variant_index } => { - state.flood_discr(place.as_ref(), &self.map); - if self.map.find_discr(place.as_ref()).is_some() { - let enum_ty = place.ty(self.local_decls, self.tcx).ty; - if let Some(discr) = self.eval_discriminant(enum_ty, variant_index) { - state.assign_discr( - place.as_ref(), - ValueOrPlace::Value(FlatSet::Elem(discr)), - &self.map, - ); - } - } + fn handle_set_discriminant( + &self, + place: Place<'tcx>, + variant_index: VariantIdx, + state: &mut State<Self::Value>, + ) { + state.flood_discr(place.as_ref(), &self.map); + if self.map.find_discr(place.as_ref()).is_some() { + let enum_ty = place.ty(self.local_decls, self.tcx).ty; + if let Some(discr) = self.eval_discriminant(enum_ty, variant_index) { + state.assign_discr( + place.as_ref(), + ValueOrPlace::Value(FlatSet::Elem(discr)), + &self.map, + ); } - _ => self.super_statement(statement, state), } } @@ -126,59 +110,55 @@ impl<'tcx> ValueAnalysis<'tcx> for ConstAnalysis<'_, 'tcx> { // we must make sure that all `target as Variant#i` are `Top`. state.flood(target.as_ref(), self.map()); - if let Some(target_idx) = self.map().find(target.as_ref()) { - let (variant_target, variant_index) = match **kind { - AggregateKind::Tuple | AggregateKind::Closure(..) => { - (Some(target_idx), None) - } - AggregateKind::Adt(def_id, variant_index, ..) => { - match self.tcx.def_kind(def_id) { - DefKind::Struct => (Some(target_idx), None), - DefKind::Enum => ( - self.map.apply(target_idx, TrackElem::Variant(variant_index)), - Some(variant_index), - ), - _ => (None, None), - } - } - _ => (None, None), - }; - if let Some(variant_target_idx) = variant_target { - for (field_index, operand) in operands.iter().enumerate() { - if let Some(field) = self.map().apply( - variant_target_idx, - TrackElem::Field(FieldIdx::from_usize(field_index)), - ) { - let result = self.handle_operand(operand, state); - state.insert_idx(field, result, self.map()); - } + let Some(target_idx) = self.map().find(target.as_ref()) else { return }; + + let (variant_target, variant_index) = match **kind { + AggregateKind::Tuple | AggregateKind::Closure(..) => (Some(target_idx), None), + AggregateKind::Adt(def_id, variant_index, ..) => { + match self.tcx.def_kind(def_id) { + DefKind::Struct => (Some(target_idx), None), + DefKind::Enum => ( + self.map.apply(target_idx, TrackElem::Variant(variant_index)), + Some(variant_index), + ), + _ => return, } } - if let Some(variant_index) = variant_index - && let Some(discr_idx) = self.map().apply(target_idx, TrackElem::Discriminant) - { - // We are assigning the discriminant as part of an aggregate. - // This discriminant can only alias a variant field's value if the operand - // had an invalid value for that type. - // Using invalid values is UB, so we are allowed to perform the assignment - // without extra flooding. - let enum_ty = target.ty(self.local_decls, self.tcx).ty; - if let Some(discr_val) = self.eval_discriminant(enum_ty, variant_index) { - state.insert_value_idx(discr_idx, FlatSet::Elem(discr_val), &self.map); + _ => return, + }; + if let Some(variant_target_idx) = variant_target { + for (field_index, operand) in operands.iter().enumerate() { + if let Some(field) = self.map().apply( + variant_target_idx, + TrackElem::Field(FieldIdx::from_usize(field_index)), + ) { + let result = self.handle_operand(operand, state); + state.insert_idx(field, result, self.map()); } } } + if let Some(variant_index) = variant_index + && let Some(discr_idx) = self.map().apply(target_idx, TrackElem::Discriminant) + { + // We are assigning the discriminant as part of an aggregate. + // This discriminant can only alias a variant field's value if the operand + // had an invalid value for that type. + // Using invalid values is UB, so we are allowed to perform the assignment + // without extra flooding. + let enum_ty = target.ty(self.local_decls, self.tcx).ty; + if let Some(discr_val) = self.eval_discriminant(enum_ty, variant_index) { + state.insert_value_idx(discr_idx, FlatSet::Elem(discr_val), &self.map); + } + } } Rvalue::CheckedBinaryOp(op, box (left, right)) => { // Flood everything now, so we can use `insert_value_idx` directly later. state.flood(target.as_ref(), self.map()); - let target = self.map().find(target.as_ref()); + let Some(target) = self.map().find(target.as_ref()) else { return }; - let value_target = target - .and_then(|target| self.map().apply(target, TrackElem::Field(0_u32.into()))); - let overflow_target = target - .and_then(|target| self.map().apply(target, TrackElem::Field(1_u32.into()))); + let value_target = self.map().apply(target, TrackElem::Field(0_u32.into())); + let overflow_target = self.map().apply(target, TrackElem::Field(1_u32.into())); if value_target.is_some() || overflow_target.is_some() { let (val, overflow) = self.binary_op(state, *op, left, right); @@ -228,8 +208,8 @@ impl<'tcx> ValueAnalysis<'tcx> for ConstAnalysis<'_, 'tcx> { _ => unreachable!(), } .map(|result| ValueOrPlace::Value(self.wrap_immediate(result, *ty))) - .unwrap_or(ValueOrPlace::top()), - _ => ValueOrPlace::top(), + .unwrap_or(ValueOrPlace::TOP), + _ => ValueOrPlace::TOP, }, Rvalue::BinaryOp(op, box (left, right)) => { // Overflows must be ignored here. @@ -323,7 +303,7 @@ impl<'tcx> std::fmt::Debug for ScalarTy<'tcx> { impl<'a, 'tcx> ConstAnalysis<'a, 'tcx> { pub fn new(tcx: TyCtxt<'tcx>, body: &'a Body<'tcx>, map: Map) -> Self { - let param_env = tcx.param_env(body.source.def_id()); + let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id()); Self { map, tcx, @@ -351,7 +331,7 @@ impl<'a, 'tcx> ConstAnalysis<'a, 'tcx> { } (FlatSet::Bottom, _) | (_, FlatSet::Bottom) => (FlatSet::Bottom, FlatSet::Bottom), (_, _) => { - // Could attempt some algebraic simplifcations here. + // Could attempt some algebraic simplifications here. (FlatSet::Top, FlatSet::Top) } } @@ -377,6 +357,20 @@ impl<'a, 'tcx> ConstAnalysis<'a, 'tcx> { } } + fn eval_discriminant( + &self, + enum_ty: Ty<'tcx>, + variant_index: VariantIdx, + ) -> Option<ScalarTy<'tcx>> { + if !enum_ty.is_enum() { + return None; + } + let discr = enum_ty.discriminant_for_variant(self.tcx, variant_index)?; + let discr_layout = self.tcx.layout_of(self.param_env.and(discr.ty)).ok()?; + let discr_value = Scalar::try_from_uint(discr.val, discr_layout.size)?; + Some(ScalarTy(discr_value, discr.ty)) + } + fn wrap_scalar(&self, scalar: Scalar, ty: Ty<'tcx>) -> FlatSet<ScalarTy<'tcx>> { FlatSet::Elem(ScalarTy(scalar, ty)) } @@ -520,21 +514,6 @@ impl<'tcx, 'map, 'a> Visitor<'tcx> for OperandCollector<'tcx, 'map, 'a> { _ => (), } } - - fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) { - match rvalue { - Rvalue::Discriminant(place) => { - match self.state.get_discr(place.as_ref(), self.visitor.map) { - FlatSet::Top => (), - FlatSet::Elem(value) => { - self.visitor.before_effect.insert((location, *place), value); - } - FlatSet::Bottom => (), - } - } - _ => self.super_rvalue(rvalue, location), - } - } } struct DummyMachine; |