40ae34194c
detects redundant imports that can be eliminated. for #117772 : In order to facilitate review and modification, split the checking code and removing redundant imports code into two PR.
72 lines
2.4 KiB
Rust
72 lines
2.4 KiB
Rust
//! Normalizes MIR in RevealAll mode.
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use rustc_middle::mir::visit::*;
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use rustc_middle::mir::*;
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use rustc_middle::ty::{self, Ty, TyCtxt};
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pub struct RevealAll;
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impl<'tcx> MirPass<'tcx> for RevealAll {
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fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
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let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id());
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RevealAllVisitor { tcx, param_env }.visit_body_preserves_cfg(body);
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}
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}
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struct RevealAllVisitor<'tcx> {
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tcx: TyCtxt<'tcx>,
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param_env: ty::ParamEnv<'tcx>,
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}
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impl<'tcx> MutVisitor<'tcx> for RevealAllVisitor<'tcx> {
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#[inline]
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fn tcx(&self) -> TyCtxt<'tcx> {
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self.tcx
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}
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#[inline]
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fn visit_place(
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&mut self,
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place: &mut Place<'tcx>,
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_context: PlaceContext,
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_location: Location,
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) {
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// Performance optimization: don't reintern if there is no `OpaqueCast` to remove.
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if place.projection.iter().all(|elem| !matches!(elem, ProjectionElem::OpaqueCast(_))) {
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return;
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}
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// `OpaqueCast` projections are only needed if there are opaque types on which projections are performed.
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// After the `RevealAll` pass, all opaque types are replaced with their hidden types, so we don't need these
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// projections anymore.
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place.projection = self.tcx.mk_place_elems(
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&place
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.projection
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.into_iter()
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.filter(|elem| !matches!(elem, ProjectionElem::OpaqueCast(_)))
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.collect::<Vec<_>>(),
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);
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self.super_place(place, _context, _location);
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}
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#[inline]
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fn visit_constant(&mut self, constant: &mut ConstOperand<'tcx>, location: Location) {
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// We have to use `try_normalize_erasing_regions` here, since it's
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// possible that we visit impossible-to-satisfy where clauses here,
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// see #91745
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if let Ok(c) = self.tcx.try_normalize_erasing_regions(self.param_env, constant.const_) {
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constant.const_ = c;
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}
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self.super_constant(constant, location);
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}
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#[inline]
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fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: TyContext) {
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// We have to use `try_normalize_erasing_regions` here, since it's
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// possible that we visit impossible-to-satisfy where clauses here,
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// see #91745
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if let Ok(t) = self.tcx.try_normalize_erasing_regions(self.param_env, *ty) {
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*ty = t;
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}
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}
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}
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