| use crate::MirPass; |
| use rustc_index::IndexVec; |
| use rustc_middle::mir::patch::MirPatch; |
| use rustc_middle::mir::visit::NonUseContext::VarDebugInfo; |
| use rustc_middle::mir::visit::{MutVisitor, PlaceContext}; |
| use rustc_middle::mir::*; |
| use rustc_middle::ty::TyCtxt; |
| |
| pub struct Derefer; |
| |
| pub struct DerefChecker<'a, 'tcx> { |
| tcx: TyCtxt<'tcx>, |
| patcher: MirPatch<'tcx>, |
| local_decls: &'a IndexVec<Local, LocalDecl<'tcx>>, |
| } |
| |
| impl<'a, 'tcx> MutVisitor<'tcx> for DerefChecker<'a, 'tcx> { |
| fn tcx(&self) -> TyCtxt<'tcx> { |
| self.tcx |
| } |
| |
| fn visit_place(&mut self, place: &mut Place<'tcx>, cntxt: PlaceContext, loc: Location) { |
| if !place.projection.is_empty() |
| && cntxt != PlaceContext::NonUse(VarDebugInfo) |
| && place.projection[1..].contains(&ProjectionElem::Deref) |
| { |
| let mut place_local = place.local; |
| let mut last_len = 0; |
| let mut last_deref_idx = 0; |
| |
| for (idx, elem) in place.projection[0..].iter().enumerate() { |
| if *elem == ProjectionElem::Deref { |
| last_deref_idx = idx; |
| } |
| } |
| |
| for (idx, (p_ref, p_elem)) in place.iter_projections().enumerate() { |
| if !p_ref.projection.is_empty() && p_elem == ProjectionElem::Deref { |
| let ty = p_ref.ty(self.local_decls, self.tcx).ty; |
| let temp = self.patcher.new_local_with_info( |
| ty, |
| self.local_decls[p_ref.local].source_info.span, |
| LocalInfo::DerefTemp, |
| ); |
| |
| // We are adding current p_ref's projections to our |
| // temp value, excluding projections we already covered. |
| let deref_place = Place::from(place_local) |
| .project_deeper(&p_ref.projection[last_len..], self.tcx); |
| |
| self.patcher.add_assign( |
| loc, |
| Place::from(temp), |
| Rvalue::CopyForDeref(deref_place), |
| ); |
| place_local = temp; |
| last_len = p_ref.projection.len(); |
| |
| // Change `Place` only if we are actually at the Place's last deref |
| if idx == last_deref_idx { |
| let temp_place = |
| Place::from(temp).project_deeper(&place.projection[idx..], self.tcx); |
| *place = temp_place; |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| pub fn deref_finder<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { |
| let patch = MirPatch::new(body); |
| let mut checker = DerefChecker { tcx, patcher: patch, local_decls: &body.local_decls }; |
| |
| for (bb, data) in body.basic_blocks.as_mut_preserves_cfg().iter_enumerated_mut() { |
| checker.visit_basic_block_data(bb, data); |
| } |
| |
| checker.patcher.apply(body); |
| } |
| |
| impl<'tcx> MirPass<'tcx> for Derefer { |
| fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { |
| deref_finder(tcx, body); |
| } |
| } |