64 lines
3.0 KiB
Rust
64 lines
3.0 KiB
Rust
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use crate::MirPass;
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use rustc_middle::mir::patch::MirPatch;
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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 fn deref_finder<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
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let mut patch = MirPatch::new(body);
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let (basic_blocks, local_decl) = body.basic_blocks_and_local_decls_mut();
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for (block, data) in basic_blocks.iter_enumerated_mut() {
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for (i, stmt) in data.statements.iter_mut().enumerate() {
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match stmt.kind {
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StatementKind::Assign(box (og_place, Rvalue::Ref(region, borrow_knd, place))) => {
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if borrow_knd == (BorrowKind::Mut { allow_two_phase_borrow: false }) {
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for (idx, (p_ref, p_elem)) in place.iter_projections().enumerate() {
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if p_elem == ProjectionElem::Deref {
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// The type that we are derefing
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let ty = p_ref.ty(local_decl, tcx).ty;
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let temp = patch.new_temp(ty, stmt.source_info.span);
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// Because we are assigning this right before original statement
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// we are using index i of statement
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let loc = Location { block: block, statement_index: i };
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patch.add_statement(loc, StatementKind::StorageLive(temp));
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// We are adding current p_ref's projections to our
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// temp value
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let deref_place =
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Place::from(p_ref.local).project_deeper(p_ref.projection, tcx);
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patch.add_assign(
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loc,
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Place::from(temp),
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Rvalue::Use(Operand::Move(deref_place)),
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);
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// We are creating a place by using our temp value's location
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// and copying derefed values we need to it
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let temp_place =
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Place::from(temp).project_deeper(&place.projection[idx..], tcx);
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patch.add_assign(
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loc,
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og_place,
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Rvalue::Ref(region, borrow_knd, temp_place),
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);
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// We have to delete the original statement since we just
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// replaced it
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stmt.make_nop();
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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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}
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}
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patch.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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