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