diff --git a/compiler/rustc_mir_transform/src/const_prop_lint.rs b/compiler/rustc_mir_transform/src/const_prop_lint.rs index 76c8cdcc271..8bbb81354d8 100644 --- a/compiler/rustc_mir_transform/src/const_prop_lint.rs +++ b/compiler/rustc_mir_transform/src/const_prop_lint.rs @@ -101,15 +101,24 @@ fn from(v: ImmTy<'tcx>) -> Self { } impl<'tcx> Value<'tcx> { - fn project(&self, proj: impl Iterator>>) -> Option<&Value<'tcx>> { + fn project( + &self, + proj: &[PlaceElem<'tcx>], + prop: &ConstPropagator<'_, 'tcx>, + ) -> Option<&Value<'tcx>> { let mut this = self; for proj in proj { - this = match (proj?, this) { - (ProjectionElem::Field(idx, _), Value::Aggregate { fields, .. }) => { + this = match (*proj, this) { + (PlaceElem::Field(idx, _), Value::Aggregate { fields, .. }) => { fields.get(idx).unwrap_or(&Value::Uninit) } + (PlaceElem::Index(idx), Value::Aggregate { fields, .. }) => { + let idx = prop.get_const(idx.into())?.immediate()?; + let idx = prop.ecx.read_target_usize(idx).ok()?; + fields.get(FieldIdx::from_u32(idx.try_into().ok()?)).unwrap_or(&Value::Uninit) + } ( - ProjectionElem::ConstantIndex { offset, min_length: 1, from_end: false }, + PlaceElem::ConstantIndex { offset, min_length: 1, from_end: false }, Value::Aggregate { fields, .. }, ) => fields .get(FieldIdx::from_u32(offset.try_into().ok()?)) @@ -204,8 +213,7 @@ fn local_decls(&self) -> &'mir LocalDecls<'tcx> { } fn get_const(&self, place: Place<'tcx>) -> Option<&Value<'tcx>> { - self.locals[place.local] - .project(place.projection.iter().map(|proj| self.try_eval_index_offset(proj))) + self.locals[place.local].project(&place.projection, self) } /// Remove `local` from the pool of `Locals`. Allows writing to them, @@ -696,21 +704,6 @@ fn eval_rvalue( Some(()) } - - fn try_eval_index_offset(&self, proj: PlaceElem<'tcx>) -> Option> { - Some(match proj { - ProjectionElem::Index(local) => { - let val = self.get_const(local.into())?; - let op = val.immediate()?; - ProjectionElem::ConstantIndex { - offset: self.ecx.read_target_usize(op).ok()?, - min_length: 1, - from_end: false, - } - } - other => other, - }) - } } impl<'tcx> Visitor<'tcx> for ConstPropagator<'_, 'tcx> {