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Auto merge of #98145 - ouz-a:some_branch, r=oli-obk

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Pull Derefer before ElaborateDrops

_Follow up work to #97025 #96549 #96116 #95887 #95649_

This moves `Derefer` before `ElaborateDrops` and creates a new `Rvalue` called `VirtualRef` that allows us to bypass many constraints for `DerefTemp`.

r? `@oli-obk`
This commit is contained in:
bors 2022-07-13 14:32:33 +00:00
commit 42bd138126
43 changed files with 401 additions and 227 deletions
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4
compiler/rustc_borrowck/src/invalidation.rs
View file

@ -289,6 +289,10 @@ impl<'cx, 'tcx> InvalidationGenerator<'cx, 'tcx> {
| Rvalue::ShallowInitBox(ref operand, _ /*ty*/) => {
self.consume_operand(location, operand)
}
Rvalue::CopyForDeref(ref place) => {
let op = &Operand::Copy(*place);
self.consume_operand(location, op);
}
Rvalue::Len(place) | Rvalue::Discriminant(place) => {
let af = match *rvalue {

17
compiler/rustc_borrowck/src/lib.rs
View file

@ -1236,6 +1236,23 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
| Rvalue::ShallowInitBox(ref operand, _ /*ty*/) => {
self.consume_operand(location, (operand, span), flow_state)
}
Rvalue::CopyForDeref(place) => {
self.access_place(
location,
(place, span),
(Deep, Read(ReadKind::Copy)),
LocalMutationIsAllowed::No,
flow_state,
);
// Finally, check if path was already moved.
self.check_if_path_or_subpath_is_moved(
location,
InitializationRequiringAction::Use,
(place.as_ref(), span),
flow_state,
);
}
Rvalue::Len(place) | Rvalue::Discriminant(place) => {
let af = match *rvalue {

5
compiler/rustc_borrowck/src/type_check/mod.rs
View file

@ -2269,6 +2269,10 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
Rvalue::Use(operand) | Rvalue::UnaryOp(_, operand) => {
self.check_operand(operand, location);
}
Rvalue::CopyForDeref(place) => {
let op = &Operand::Copy(*place);
self.check_operand(op, location);
}
Rvalue::BinaryOp(_, box (left, right))
| Rvalue::CheckedBinaryOp(_, box (left, right)) => {
@ -2299,6 +2303,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
| Rvalue::BinaryOp(..)
| Rvalue::CheckedBinaryOp(..)
| Rvalue::NullaryOp(..)
| Rvalue::CopyForDeref(..)
| Rvalue::UnaryOp(..)
| Rvalue::Discriminant(..) => None,

5
compiler/rustc_codegen_cranelift/src/base.rs
View file

@ -503,6 +503,11 @@ fn codegen_stmt<'tcx>(
let val = codegen_operand(fx, operand);
lval.write_cvalue(fx, val);
}
Rvalue::CopyForDeref(place) => {
let cplace = codegen_place(fx, place);
let val = cplace.to_cvalue(fx);
lval.write_cvalue(fx, val)
}
Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
let place = codegen_place(fx, place);
let ref_ = place.place_ref(fx, lval.layout());

6
compiler/rustc_codegen_ssa/src/mir/rvalue.rs
View file

@ -8,6 +8,7 @@ use crate::traits::*;
use crate::MemFlags;
use rustc_middle::mir;
use rustc_middle::mir::Operand;
use rustc_middle::ty::cast::{CastTy, IntTy};
use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf};
use rustc_middle::ty::{self, adjustment::PointerCast, Instance, Ty, TyCtxt};
@ -344,6 +345,10 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
self.codegen_place_to_pointer(bx, place, mk_ref)
}
mir::Rvalue::CopyForDeref(place) => {
let operand = self.codegen_operand(&mut bx, &Operand::Copy(place));
(bx, operand)
}
mir::Rvalue::AddressOf(mutability, place) => {
let mk_ptr = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| {
tcx.mk_ptr(ty::TypeAndMut { ty, mutbl: mutability })
@ -698,6 +703,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
pub fn rvalue_creates_operand(&self, rvalue: &mir::Rvalue<'tcx>, span: Span) -> bool {
match *rvalue {
mir::Rvalue::Ref(..) |
mir::Rvalue::CopyForDeref(..) |
mir::Rvalue::AddressOf(..) |
mir::Rvalue::Len(..) |
mir::Rvalue::Cast(..) | // (*)

5
compiler/rustc_const_eval/src/interpret/step.rs
View file

@ -172,6 +172,11 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
self.copy_op(&op, &dest, /*allow_transmute*/ false)?;
}
CopyForDeref(ref place) => {
let op = self.eval_place_to_op(*place, Some(dest.layout))?;
self.copy_op(&op, &dest, /* allow_transmute*/ false)?;
}
BinaryOp(bin_op, box (ref left, ref right)) => {
let layout = binop_left_homogeneous(bin_op).then_some(dest.layout);
let left = self.read_immediate(&self.eval_operand(left, layout)?)?;

1
compiler/rustc_const_eval/src/transform/check_consts/check.rs
View file

@ -446,6 +446,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
Rvalue::ThreadLocalRef(_) => self.check_op(ops::ThreadLocalAccess),
Rvalue::Use(_)
| Rvalue::CopyForDeref(..)
| Rvalue::Repeat(..)
| Rvalue::Discriminant(..)
| Rvalue::Len(_)

2
compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
View file

@ -260,6 +260,8 @@ where
in_place::<Q, _>(cx, in_local, place.as_ref())
}
Rvalue::CopyForDeref(place) => in_place::<Q, _>(cx, in_local, place.as_ref()),
Rvalue::Use(operand)
| Rvalue::Repeat(operand, _)
| Rvalue::UnaryOp(_, operand)

1
compiler/rustc_const_eval/src/transform/check_consts/resolver.rs
View file

@ -199,6 +199,7 @@ where
mir::Rvalue::Cast(..)
| mir::Rvalue::ShallowInitBox(..)
| mir::Rvalue::Use(..)
| mir::Rvalue::CopyForDeref(..)
| mir::Rvalue::ThreadLocalRef(..)
| mir::Rvalue::Repeat(..)
| mir::Rvalue::Len(..)

4
compiler/rustc_const_eval/src/transform/promote_consts.rs
View file

@ -494,6 +494,10 @@ impl<'tcx> Validator<'_, 'tcx> {
Rvalue::Use(operand) | Rvalue::Repeat(operand, _) => {
self.validate_operand(operand)?;
}
Rvalue::CopyForDeref(place) => {
let op = &Operand::Copy(*place);
self.validate_operand(op)?
}
Rvalue::Discriminant(place) | Rvalue::Len(place) => {
self.validate_place(place.as_ref())?

11
compiler/rustc_const_eval/src/transform/validate.rs
View file

@ -382,7 +382,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
};
}
match rvalue {
Rvalue::Use(_) => {}
Rvalue::Use(_) | Rvalue::CopyForDeref(_) => {}
Rvalue::Aggregate(agg_kind, _) => {
let disallowed = match **agg_kind {
AggregateKind::Array(..) => false,
@ -592,6 +592,15 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
),
);
}
if let Rvalue::CopyForDeref(place) = rvalue {
if !place.ty(&self.body.local_decls, self.tcx).ty.builtin_deref(true).is_some()
{
self.fail(
location,
"`CopyForDeref` should only be used for dereferenceable types",
)
}
}
// FIXME(JakobDegen): Check this for all rvalues, not just this one.
if let Rvalue::Use(Operand::Copy(src) | Operand::Move(src)) = rvalue {
// The sides of an assignment must not alias. Currently this just checks whether

14
compiler/rustc_middle/src/mir/mod.rs
View file

@ -61,7 +61,7 @@ mod syntax;
pub use syntax::*;
mod switch_sources;
pub mod tcx;
mod terminator;
pub mod terminator;
pub use terminator::*;
pub mod traversal;
@ -925,6 +925,15 @@ impl<'tcx> LocalDecl<'tcx> {
}
}
/// Returns `true` if this is a DerefTemp
pub fn is_deref_temp(&self) -> bool {
match self.local_info {
Some(box LocalInfo::DerefTemp) => return true,
_ => (),
}
return false;
}
/// Returns `true` is the local is from a compiler desugaring, e.g.,
/// `__next` from a `for` loop.
#[inline]
@ -1795,6 +1804,7 @@ impl<'tcx> Rvalue<'tcx> {
Rvalue::Cast(CastKind::PointerExposeAddress, _, _) => false,
Rvalue::Use(_)
| Rvalue::CopyForDeref(_)
| Rvalue::Repeat(_, _)
| Rvalue::Ref(_, _, _)
| Rvalue::ThreadLocalRef(_)
@ -1889,6 +1899,8 @@ impl<'tcx> Debug for Rvalue<'tcx> {
write!(fmt, "&{}{}{:?}", region, kind_str, place)
}
CopyForDeref(ref place) => write!(fmt, "deref_copy {:#?}", place),
AddressOf(mutability, ref place) => {
let kind_str = match mutability {
Mutability::Mut => "mut",

16
compiler/rustc_middle/src/mir/syntax.rs
View file

@ -52,6 +52,8 @@ pub enum MirPhase {
/// of the `mir_promoted` query), these promoted elements are available in the `promoted_mir`
/// query.
ConstsPromoted = 2,
/// After this projections may only contain deref projections as the first element.
Derefered = 3,
/// Beginning with this phase, the following variants are disallowed:
/// * [`TerminatorKind::DropAndReplace`]
/// * [`TerminatorKind::FalseUnwind`]
@ -66,9 +68,7 @@ pub enum MirPhase {
/// Furthermore, `Drop` now uses explicit drop flags visible in the MIR and reaching a `Drop`
/// terminator means that the auto-generated drop glue will be invoked. Also, `Copy` operands
/// are allowed for non-`Copy` types.
DropsLowered = 3,
/// After this projections may only contain deref projections as the first element.
Derefered = 4,
DropsLowered = 4,
/// Beginning with this phase, the following variant is disallowed:
/// * [`Rvalue::Aggregate`] for any `AggregateKind` except `Array`
///
@ -1051,6 +1051,16 @@ pub enum Rvalue<'tcx> {
/// initialized but its content as uninitialized. Like other pointer casts, this in general
/// affects alias analysis.
ShallowInitBox(Operand<'tcx>, Ty<'tcx>),
/// A CopyForDeref is equivalent to a read from a place at the
/// codegen level, but is treated specially by drop elaboration. When such a read happens, it
/// is guaranteed (via nature of the mir_opt `Derefer` in rustc_mir_transform/src/deref_separator)
/// that the only use of the returned value is a deref operation, immediately
/// followed by one or more projections. Drop elaboration treats this rvalue as if the
/// read never happened and just projects further. This allows simplifying various MIR
/// optimizations and codegen backends that previously had to handle deref operations anywhere
/// in a place.
CopyForDeref(Place<'tcx>),
}
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]

1
compiler/rustc_middle/src/mir/tcx.rs
View file

@ -211,6 +211,7 @@ impl<'tcx> Rvalue<'tcx> {
}
},
Rvalue::ShallowInitBox(_, ty) => tcx.mk_box(ty),
Rvalue::CopyForDeref(ref place) => place.ty(local_decls, tcx).ty,
}
}

1
compiler/rustc_middle/src/mir/type_foldable.rs
View file

@ -122,6 +122,7 @@ impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
Ref(region, bk, place) => {
Ref(region.try_fold_with(folder)?, bk, place.try_fold_with(folder)?)
}
CopyForDeref(place) => CopyForDeref(place.try_fold_with(folder)?),
AddressOf(mutability, place) => AddressOf(mutability, place.try_fold_with(folder)?),
Len(place) => Len(place.try_fold_with(folder)?),
Cast(kind, op, ty) => Cast(kind, op.try_fold_with(folder)?, ty.try_fold_with(folder)?),

4
compiler/rustc_middle/src/mir/type_visitable.rs
View file

@ -78,6 +78,10 @@ impl<'tcx> TypeVisitable<'tcx> for Rvalue<'tcx> {
use crate::mir::Rvalue::*;
match *self {
Use(ref op) => op.visit_with(visitor),
CopyForDeref(ref place) => {
let op = &Operand::Copy(*place);
op.visit_with(visitor)
}
Repeat(ref op, _) => op.visit_with(visitor),
ThreadLocalRef(did) => did.visit_with(visitor),
Ref(region, _, ref place) => {

7
compiler/rustc_middle/src/mir/visit.rs
View file

@ -711,6 +711,13 @@ macro_rules! make_mir_visitor {
};
self.visit_place(path, ctx, location);
}
Rvalue::CopyForDeref(place) => {
self.visit_place(
place,
PlaceContext::NonMutatingUse(NonMutatingUseContext::Inspect),
location
);
}
Rvalue::AddressOf(m, path) => {
let ctx = match m {

3
compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
View file

@ -102,7 +102,8 @@ where
| mir::Rvalue::NullaryOp(..)
| mir::Rvalue::UnaryOp(..)
| mir::Rvalue::Discriminant(..)
| mir::Rvalue::Aggregate(..) => {}
| mir::Rvalue::Aggregate(..)
| mir::Rvalue::CopyForDeref(..) => {}
}
}

1
compiler/rustc_mir_dataflow/src/lib.rs
View file

@ -38,6 +38,7 @@ pub mod impls;
pub mod move_paths;
pub mod rustc_peek;
pub mod storage;
pub mod un_derefer;
pub(crate) mod indexes {
pub(crate) use super::move_paths::MovePathIndex;

30
compiler/rustc_mir_dataflow/src/move_paths/builder.rs
View file

@ -1,3 +1,4 @@
use crate::un_derefer::UnDerefer;
use rustc_index::vec::IndexVec;
use rustc_middle::mir::tcx::RvalueInitializationState;
use rustc_middle::mir::*;
@ -19,6 +20,7 @@ struct MoveDataBuilder<'a, 'tcx> {
param_env: ty::ParamEnv<'tcx>,
data: MoveData<'tcx>,
errors: Vec<(Place<'tcx>, MoveError<'tcx>)>,
un_derefer: UnDerefer<'tcx>,
}
impl<'a, 'tcx> MoveDataBuilder<'a, 'tcx> {
@ -32,6 +34,7 @@ impl<'a, 'tcx> MoveDataBuilder<'a, 'tcx> {
tcx,
param_env,
errors: Vec::new(),
un_derefer: UnDerefer { tcx: tcx, derefer_sidetable: Default::default() },
data: MoveData {
moves: IndexVec::new(),
loc_map: LocationMap::new(body),
@ -94,6 +97,11 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
///
/// Maybe we should have separate "borrowck" and "moveck" modes.
fn move_path_for(&mut self, place: Place<'tcx>) -> Result<MovePathIndex, MoveError<'tcx>> {
if let Some(new_place) = self.builder.un_derefer.derefer(place.as_ref(), self.builder.body)
{
return self.move_path_for(new_place);
}
debug!("lookup({:?})", place);
let mut base = self.builder.data.rev_lookup.locals[place.local];
@ -276,6 +284,12 @@ struct Gatherer<'b, 'a, 'tcx> {
impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
fn gather_statement(&mut self, stmt: &Statement<'tcx>) {
match &stmt.kind {
StatementKind::Assign(box (place, Rvalue::CopyForDeref(reffed))) => {
assert!(place.projection.is_empty());
if self.builder.body.local_decls[place.local].is_deref_temp() {
self.builder.un_derefer.derefer_sidetable.insert(place.local, *reffed);
}
}
StatementKind::Assign(box (place, rval)) => {
self.create_move_path(*place);
if let RvalueInitializationState::Shallow = rval.initialization_state() {
@ -294,7 +308,10 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
}
StatementKind::StorageLive(_) => {}
StatementKind::StorageDead(local) => {
self.gather_move(Place::from(*local));
// DerefTemp locals (results of CopyForDeref) don't actually move anything.
if !self.builder.un_derefer.derefer_sidetable.contains_key(&local) {
self.gather_move(Place::from(*local));
}
}
StatementKind::SetDiscriminant { .. } | StatementKind::Deinit(..) => {
span_bug!(
@ -328,6 +345,7 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
self.gather_operand(operand);
}
}
Rvalue::CopyForDeref(..) => unreachable!(),
Rvalue::Ref(..)
| Rvalue::AddressOf(..)
| Rvalue::Discriminant(..)
@ -439,6 +457,11 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
fn gather_move(&mut self, place: Place<'tcx>) {
debug!("gather_move({:?}, {:?})", self.loc, place);
if let Some(new_place) = self.builder.un_derefer.derefer(place.as_ref(), self.builder.body)
{
self.gather_move(new_place);
return;
}
if let [ref base @ .., ProjectionElem::Subslice { from, to, from_end: false }] =
**place.projection
@ -494,6 +517,11 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
fn gather_init(&mut self, place: PlaceRef<'tcx>, kind: InitKind) {
debug!("gather_init({:?}, {:?})", self.loc, place);
if let Some(new_place) = self.builder.un_derefer.derefer(place, self.builder.body) {
self.gather_init(new_place.as_ref(), kind);
return;
}
let mut place = place;
// Check if we are assigning into a field of a union, if so, lookup the place

36
compiler/rustc_mir_dataflow/src/un_derefer.rs Normal file
View file

@ -0,0 +1,36 @@
use rustc_data_structures::stable_map::FxHashMap;
use rustc_middle::mir::*;
use rustc_middle::ty::TyCtxt;
/// Used for reverting changes made by `DerefSeparator`
pub struct UnDerefer<'tcx> {
pub tcx: TyCtxt<'tcx>,
pub derefer_sidetable: FxHashMap<Local, Place<'tcx>>,
}
impl<'tcx> UnDerefer<'tcx> {
pub fn derefer(&self, place: PlaceRef<'tcx>, body: &Body<'tcx>) -> Option<Place<'tcx>> {
let reffed = self.derefer_sidetable.get(&place.local)?;
let new_place = reffed.project_deeper(place.projection, self.tcx);
if body.local_decls[new_place.local].is_deref_temp() {
return self.derefer(new_place.as_ref(), body);
}
Some(new_place)
}
pub fn ref_finder(&mut self, body: &Body<'tcx>) {
for (_bb, data) in body.basic_blocks().iter_enumerated() {
for stmt in data.statements.iter() {
match stmt.kind {
StatementKind::Assign(box (place, Rvalue::CopyForDeref(reffed))) => {
if body.local_decls[place.local].is_deref_temp() {
self.derefer_sidetable.insert(place.local, reffed);
}
}
_ => (),
}
}
}
}
}

13
compiler/rustc_mir_transform/src/add_retag.rs
View file

@ -70,17 +70,6 @@ fn may_contain_reference<'tcx>(ty: Ty<'tcx>, depth: u32, tcx: TyCtxt<'tcx>) -> b
}
}
/// Determines whether or not this LocalDecl is temp, if not it needs retagging.
fn is_not_temp<'tcx>(local_decl: &LocalDecl<'tcx>) -> bool {
if let Some(local_info) = &local_decl.local_info {
match local_info.as_ref() {
LocalInfo::DerefTemp => return false,
_ => (),
};
}
return true;
}
impl<'tcx> MirPass<'tcx> for AddRetag {
fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
sess.opts.debugging_opts.mir_emit_retag
@ -98,7 +87,7 @@ impl<'tcx> MirPass<'tcx> for AddRetag {
// a temporary and retag on that.
is_stable(place.as_ref())
&& may_contain_reference(place.ty(&*local_decls, tcx).ty, /*depth*/ 3, tcx)
&& is_not_temp(&local_decls[place.local])
&& !local_decls[place.local].is_deref_temp()
};
let place_base_raw = |place: &Place<'tcx>| {
// If this is a `Deref`, get the type of what we are deref'ing.

1
compiler/rustc_mir_transform/src/const_prop.rs
View file

@ -621,6 +621,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
// There's no other checking to do at this time.
Rvalue::Aggregate(..)
| Rvalue::Use(..)
| Rvalue::CopyForDeref(..)
| Rvalue::Repeat(..)
| Rvalue::Len(..)
| Rvalue::Cast(..)

1
compiler/rustc_mir_transform/src/const_prop_lint.rs
View file

@ -693,6 +693,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
// There's no other checking to do at this time.
Rvalue::Aggregate(..)
| Rvalue::Use(..)
| Rvalue::CopyForDeref(..)
| Rvalue::Repeat(..)
| Rvalue::Len(..)
| Rvalue::Cast(..)

3
compiler/rustc_mir_transform/src/deref_separator.rs
View file

@ -35,6 +35,7 @@ impl<'tcx> MutVisitor<'tcx> for DerefChecker<'tcx> {
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;
@ -54,7 +55,7 @@ impl<'tcx> MutVisitor<'tcx> for DerefChecker<'tcx> {
self.patcher.add_assign(
loc,
Place::from(temp),
Rvalue::Use(Operand::Move(deref_place)),
Rvalue::CopyForDeref(deref_place),
);
place_local = temp;
last_len = p_ref.projection.len();

36
compiler/rustc_mir_transform/src/elaborate_drops.rs
View file

@ -1,3 +1,4 @@
use crate::deref_separator::deref_finder;
use crate::MirPass;
use rustc_data_structures::fx::FxHashMap;
use rustc_index::bit_set::BitSet;
@ -9,6 +10,7 @@ use rustc_mir_dataflow::elaborate_drops::{DropElaborator, DropFlagMode, DropStyl
use rustc_mir_dataflow::impls::{MaybeInitializedPlaces, MaybeUninitializedPlaces};
use rustc_mir_dataflow::move_paths::{LookupResult, MoveData, MovePathIndex};
use rustc_mir_dataflow::on_lookup_result_bits;
use rustc_mir_dataflow::un_derefer::UnDerefer;
use rustc_mir_dataflow::MoveDataParamEnv;
use rustc_mir_dataflow::{on_all_children_bits, on_all_drop_children_bits};
use rustc_mir_dataflow::{Analysis, ResultsCursor};
@ -26,6 +28,8 @@ impl<'tcx> MirPass<'tcx> for ElaborateDrops {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
debug!("elaborate_drops({:?} @ {:?})", body.source, body.span);
let mut un_derefer = UnDerefer { tcx: tcx, derefer_sidetable: Default::default() };
un_derefer.ref_finder(body);
let def_id = body.source.def_id();
let param_env = tcx.param_env_reveal_all_normalized(def_id);
let move_data = match MoveData::gather_moves(body, tcx, param_env) {
@ -41,7 +45,7 @@ impl<'tcx> MirPass<'tcx> for ElaborateDrops {
let elaborate_patch = {
let body = &*body;
let env = MoveDataParamEnv { move_data, param_env };
let dead_unwinds = find_dead_unwinds(tcx, body, &env);
let dead_unwinds = find_dead_unwinds(tcx, body, &env, &un_derefer);
let inits = MaybeInitializedPlaces::new(tcx, body, &env)
.into_engine(tcx, body)
@ -65,10 +69,12 @@ impl<'tcx> MirPass<'tcx> for ElaborateDrops {
init_data: InitializationData { inits, uninits },
drop_flags: Default::default(),
patch: MirPatch::new(body),
un_derefer: un_derefer,
}
.elaborate()
};
elaborate_patch.apply(body);
deref_finder(tcx, body);
}
}
@ -79,6 +85,7 @@ fn find_dead_unwinds<'tcx>(
tcx: TyCtxt<'tcx>,
body: &Body<'tcx>,
env: &MoveDataParamEnv<'tcx>,
und: &UnDerefer<'tcx>,
) -> BitSet<BasicBlock> {
debug!("find_dead_unwinds({:?})", body.span);
// We only need to do this pass once, because unwind edges can only
@ -92,7 +99,9 @@ fn find_dead_unwinds<'tcx>(
for (bb, bb_data) in body.basic_blocks().iter_enumerated() {
let place = match bb_data.terminator().kind {
TerminatorKind::Drop { ref place, unwind: Some(_), .. }
| TerminatorKind::DropAndReplace { ref place, unwind: Some(_), .. } => place,
| TerminatorKind::DropAndReplace { ref place, unwind: Some(_), .. } => {
und.derefer(place.as_ref(), body).unwrap_or(*place)
}
_ => continue,
};
@ -256,6 +265,7 @@ struct ElaborateDropsCtxt<'a, 'tcx> {
init_data: InitializationData<'a, 'tcx>,
drop_flags: FxHashMap<MovePathIndex, Local>,
patch: MirPatch<'tcx>,
un_derefer: UnDerefer<'tcx>,
}
impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
@ -298,7 +308,9 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
let terminator = data.terminator();
let place = match terminator.kind {
TerminatorKind::Drop { ref place, .. }
| TerminatorKind::DropAndReplace { ref place, .. } => place,
| TerminatorKind::DropAndReplace { ref place, .. } => {
self.un_derefer.derefer(place.as_ref(), self.body).unwrap_or(*place)
}
_ => continue,
};
@ -312,12 +324,17 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
LookupResult::Parent(None) => continue,
LookupResult::Parent(Some(parent)) => {
let (_maybe_live, maybe_dead) = self.init_data.maybe_live_dead(parent);
if self.body.local_decls[place.local].is_deref_temp() {
continue;
}
if maybe_dead {
self.tcx.sess.delay_span_bug(
terminator.source_info.span,
&format!(
"drop of untracked, uninitialized value {:?}, place {:?} ({:?})",
bb, place, path,
bb, place, path
),
);
}
@ -348,7 +365,11 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
let resume_block = self.patch.resume_block();
match terminator.kind {
TerminatorKind::Drop { place, target, unwind } => {
TerminatorKind::Drop { mut place, target, unwind } => {
if let Some(new_place) = self.un_derefer.derefer(place.as_ref(), self.body) {
place = new_place;
}
self.init_data.seek_before(loc);
match self.move_data().rev_lookup.find(place.as_ref()) {
LookupResult::Exact(path) => elaborate_drop(
@ -372,9 +393,12 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
}
}
}
TerminatorKind::DropAndReplace { place, ref value, target, unwind } => {
TerminatorKind::DropAndReplace { mut place, ref value, target, unwind } => {
assert!(!data.is_cleanup);
if let Some(new_place) = self.un_derefer.derefer(place.as_ref(), self.body) {
place = new_place;
}
self.elaborate_replace(loc, place, value, target, unwind);
}
_ => continue,

2
compiler/rustc_mir_transform/src/lib.rs
View file

@ -420,6 +420,7 @@ fn run_post_borrowck_cleanup_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tc
&remove_noop_landing_pads::RemoveNoopLandingPads,
&cleanup_post_borrowck::CleanupNonCodegenStatements,
&simplify::SimplifyCfg::new("early-opt"),
&deref_separator::Derefer,
// These next passes must be executed together
&add_call_guards::CriticalCallEdges,
&elaborate_drops::ElaborateDrops,
@ -432,7 +433,6 @@ fn run_post_borrowck_cleanup_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tc
&add_moves_for_packed_drops::AddMovesForPackedDrops,
// `AddRetag` needs to run after `ElaborateDrops`. Otherwise it should run fairly late,
// but before optimizations begin.
&deref_separator::Derefer,
&elaborate_box_derefs::ElaborateBoxDerefs,
&add_retag::AddRetag,
&lower_intrinsics::LowerIntrinsics,

2
compiler/rustc_mir_transform/src/separate_const_switch.rs
View file

@ -218,6 +218,7 @@ fn is_likely_const<'tcx>(mut tracked_place: Place<'tcx>, block: &BasicBlockData<
// These rvalues move the place to track
Rvalue::Cast(_, Operand::Copy(place) | Operand::Move(place), _)
| Rvalue::Use(Operand::Copy(place) | Operand::Move(place))
| Rvalue::CopyForDeref(place)
| Rvalue::UnaryOp(_, Operand::Copy(place) | Operand::Move(place))
| Rvalue::Discriminant(place) => tracked_place = place,
}
@ -279,6 +280,7 @@ fn find_determining_place<'tcx>(
// that may be const in the predecessor
Rvalue::Use(Operand::Move(new) | Operand::Copy(new))
| Rvalue::UnaryOp(_, Operand::Copy(new) | Operand::Move(new))
| Rvalue::CopyForDeref(new)
| Rvalue::Cast(_, Operand::Move(new) | Operand::Copy(new), _)
| Rvalue::Repeat(Operand::Move(new) | Operand::Copy(new), _)
| Rvalue::Discriminant(new)