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// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use rustc::ty::{self, TyCtxt};
use rustc::mir::*;
use rustc::mir::tcx::RvalueInitializationState;
use rustc::util::nodemap::FxHashMap;
use rustc_data_structures::indexed_vec::{IndexVec};
use std::collections::hash_map::Entry;
use std::mem;
use super::abs_domain::Lift;
use super::{LocationMap, MoveData, MovePath, MovePathLookup, MovePathIndex, MoveOut, MoveOutIndex};
use super::{MoveError, InitIndex, Init, LookupResult, InitKind};
use super::IllegalMoveOriginKind::*;
struct MoveDataBuilder<'a, 'gcx: 'tcx, 'tcx: 'a> {
mir: &'a Mir<'tcx>,
tcx: TyCtxt<'a, 'gcx, 'tcx>,
data: MoveData<'tcx>,
errors: Vec<MoveError<'tcx>>,
}
impl<'a, 'gcx, 'tcx> MoveDataBuilder<'a, 'gcx, 'tcx> {
fn new(mir: &'a Mir<'tcx>, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Self {
let mut move_paths = IndexVec::new();
let mut path_map = IndexVec::new();
let mut init_path_map = IndexVec::new();
MoveDataBuilder {
mir,
tcx,
errors: Vec::new(),
data: MoveData {
moves: IndexVec::new(),
loc_map: LocationMap::new(mir),
rev_lookup: MovePathLookup {
locals: mir.local_decls.indices().map(Place::Local).map(|v| {
Self::new_move_path(
&mut move_paths,
&mut path_map,
&mut init_path_map,
None,
v,
)
}).collect(),
projections: FxHashMap(),
},
move_paths,
path_map,
inits: IndexVec::new(),
init_loc_map: LocationMap::new(mir),
init_path_map,
}
}
}
fn new_move_path(move_paths: &mut IndexVec<MovePathIndex, MovePath<'tcx>>,
path_map: &mut IndexVec<MovePathIndex, Vec<MoveOutIndex>>,
init_path_map: &mut IndexVec<MovePathIndex, Vec<InitIndex>>,
parent: Option<MovePathIndex>,
place: Place<'tcx>)
-> MovePathIndex
{
let move_path = move_paths.push(MovePath {
next_sibling: None,
first_child: None,
parent,
place,
});
if let Some(parent) = parent {
let next_sibling =
mem::replace(&mut move_paths[parent].first_child, Some(move_path));
move_paths[move_path].next_sibling = next_sibling;
}
let path_map_ent = path_map.push(vec![]);
assert_eq!(path_map_ent, move_path);
let init_path_map_ent = init_path_map.push(vec![]);
assert_eq!(init_path_map_ent, move_path);
move_path
}
}
impl<'b, 'a, 'gcx, 'tcx> Gatherer<'b, 'a, 'gcx, 'tcx> {
/// This creates a MovePath for a given place, returning an `MovePathError`
/// if that place can't be moved from.
///
/// NOTE: places behind references *do not* get a move path, which is
/// problematic for borrowck.
///
/// Maybe we should have separate "borrowck" and "moveck" modes.
fn move_path_for(&mut self, place: &Place<'tcx>)
-> Result<MovePathIndex, MoveError<'tcx>>
{
debug!("lookup({:?})", place);
match *place {
Place::Local(local) => Ok(self.builder.data.rev_lookup.locals[local]),
Place::Promoted(..) |
Place::Static(..) => {
Err(MoveError::cannot_move_out_of(self.loc, Static))
}
Place::Projection(ref proj) => {
self.move_path_for_projection(place, proj)
}
}
}
fn create_move_path(&mut self, place: &Place<'tcx>) {
// This is an non-moving access (such as an overwrite or
// drop), so this not being a valid move path is OK.
let _ = self.move_path_for(place);
}
fn move_path_for_projection(&mut self,
place: &Place<'tcx>,
proj: &PlaceProjection<'tcx>)
-> Result<MovePathIndex, MoveError<'tcx>>
{
let base = try!(self.move_path_for(&proj.base));
let mir = self.builder.mir;
let tcx = self.builder.tcx;
let place_ty = proj.base.ty(mir, tcx).to_ty(tcx);
match place_ty.sty {
ty::TyRef(..) | ty::TyRawPtr(..) =>
return Err(MoveError::cannot_move_out_of(
self.loc,
BorrowedContent { target_place: place.clone() })),
ty::TyAdt(adt, _) if adt.has_dtor(tcx) && !adt.is_box() =>
return Err(MoveError::cannot_move_out_of(self.loc,
InteriorOfTypeWithDestructor {
container_ty: place_ty
})),
// move out of union - always move the entire union
ty::TyAdt(adt, _) if adt.is_union() =>
return Err(MoveError::UnionMove { path: base }),
ty::TySlice(_) =>
return Err(MoveError::cannot_move_out_of(
self.loc,
InteriorOfSliceOrArray {
ty: place_ty, is_index: match proj.elem {
ProjectionElem::Index(..) => true,
_ => false
},
})),
ty::TyArray(..) => match proj.elem {
ProjectionElem::Index(..) =>
return Err(MoveError::cannot_move_out_of(
self.loc,
InteriorOfSliceOrArray {
ty: place_ty, is_index: true
})),
_ => {
// FIXME: still badly broken
}
},
_ => {}
};
match self.builder.data.rev_lookup.projections.entry((base, proj.elem.lift())) {
Entry::Occupied(ent) => Ok(*ent.get()),
Entry::Vacant(ent) => {
let path = MoveDataBuilder::new_move_path(
&mut self.builder.data.move_paths,
&mut self.builder.data.path_map,
&mut self.builder.data.init_path_map,
Some(base),
place.clone()
);
ent.insert(path);
Ok(path)
}
}
}
}
impl<'a, 'gcx, 'tcx> MoveDataBuilder<'a, 'gcx, 'tcx> {
fn finalize(self) -> Result<MoveData<'tcx>, (MoveData<'tcx>, Vec<MoveError<'tcx>>)> {
debug!("{}", {
debug!("moves for {:?}:", self.mir.span);
for (j, mo) in self.data.moves.iter_enumerated() {
debug!(" {:?} = {:?}", j, mo);
}
debug!("move paths for {:?}:", self.mir.span);
for (j, path) in self.data.move_paths.iter_enumerated() {
debug!(" {:?} = {:?}", j, path);
}
"done dumping moves"
});
if self.errors.len() > 0 {
Err((self.data, self.errors))
} else {
Ok(self.data)
}
}
}
pub(super) fn gather_moves<'a, 'gcx, 'tcx>(mir: &Mir<'tcx>, tcx: TyCtxt<'a, 'gcx, 'tcx>)
-> Result<MoveData<'tcx>,
(MoveData<'tcx>, Vec<MoveError<'tcx>>)> {
let mut builder = MoveDataBuilder::new(mir, tcx);
builder.gather_args();
for (bb, block) in mir.basic_blocks().iter_enumerated() {
for (i, stmt) in block.statements.iter().enumerate() {
let source = Location { block: bb, statement_index: i };
builder.gather_statement(source, stmt);
}
let terminator_loc = Location {
block: bb,
statement_index: block.statements.len()
};
builder.gather_terminator(terminator_loc, block.terminator());
}
builder.finalize()
}
impl<'a, 'gcx, 'tcx> MoveDataBuilder<'a, 'gcx, 'tcx> {
fn gather_args(&mut self) {
for arg in self.mir.args_iter() {
let path = self.data.rev_lookup.locals[arg];
let span = self.mir.local_decls[arg].source_info.span;
let init = self.data.inits.push(Init {
path, span, kind: InitKind::Deep
});
debug!("gather_args: adding init {:?} of {:?} for argument {:?}",
init, path, arg);
self.data.init_path_map[path].push(init);
}
}
fn gather_statement(&mut self, loc: Location, stmt: &Statement<'tcx>) {
debug!("gather_statement({:?}, {:?})", loc, stmt);
(Gatherer { builder: self, loc }).gather_statement(stmt);
}
fn gather_terminator(&mut self, loc: Location, term: &Terminator<'tcx>) {
debug!("gather_terminator({:?}, {:?})", loc, term);
(Gatherer { builder: self, loc }).gather_terminator(term);
}
}
struct Gatherer<'b, 'a: 'b, 'gcx: 'tcx, 'tcx: 'a> {
builder: &'b mut MoveDataBuilder<'a, 'gcx, 'tcx>,
loc: Location,
}
impl<'b, 'a, 'gcx, 'tcx> Gatherer<'b, 'a, 'gcx, 'tcx> {
fn gather_statement(&mut self, stmt: &Statement<'tcx>) {
match stmt.kind {
StatementKind::Assign(ref place, ref rval) => {
self.create_move_path(place);
if let RvalueInitializationState::Shallow = rval.initialization_state() {
// Box starts out uninitialized - need to create a separate
// move-path for the interior so it will be separate from
// the exterior.
self.create_move_path(&place.clone().deref());
self.gather_init(place, InitKind::Shallow);
} else {
self.gather_init(place, InitKind::Deep);
}
self.gather_rvalue(rval);
}
StatementKind::ReadForMatch(ref place) => {
self.create_move_path(place);
}
StatementKind::InlineAsm { ref outputs, ref inputs, ref asm } => {
for (output, kind) in outputs.iter().zip(&asm.outputs) {
if !kind.is_indirect {
self.gather_init(output, InitKind::Deep);
}
}
for input in inputs {
self.gather_operand(input);
}
}
StatementKind::StorageLive(_) => {}
StatementKind::StorageDead(local) => {
self.gather_move(&Place::Local(local));
}
StatementKind::SetDiscriminant{ .. } => {
span_bug!(stmt.source_info.span,
"SetDiscriminant should not exist during borrowck");
}
StatementKind::EndRegion(_) |
StatementKind::Validate(..) |
StatementKind::UserAssertTy(..) |
StatementKind::Nop => {}
}
}
fn gather_rvalue(&mut self, rvalue: &Rvalue<'tcx>) {
match *rvalue {
Rvalue::Use(ref operand) |
Rvalue::Repeat(ref operand, _) |
Rvalue::Cast(_, ref operand, _) |
Rvalue::UnaryOp(_, ref operand) => {
self.gather_operand(operand)
}
Rvalue::BinaryOp(ref _binop, ref lhs, ref rhs) |
Rvalue::CheckedBinaryOp(ref _binop, ref lhs, ref rhs) => {
self.gather_operand(lhs);
self.gather_operand(rhs);
}
Rvalue::Aggregate(ref _kind, ref operands) => {
for operand in operands {
self.gather_operand(operand);
}
}
Rvalue::Ref(..) |
Rvalue::Discriminant(..) |
Rvalue::Len(..) |
Rvalue::NullaryOp(NullOp::SizeOf, _) |
Rvalue::NullaryOp(NullOp::Box, _) => {
// This returns an rvalue with uninitialized contents. We can't
// move out of it here because it is an rvalue - assignments always
// completely initialize their place.
//
// However, this does not matter - MIR building is careful to
// only emit a shallow free for the partially-initialized
// temporary.
//
// In any case, if we want to fix this, we have to register a
// special move and change the `statement_effect` functions.
}
}
}
fn gather_terminator(&mut self, term: &Terminator<'tcx>) {
match term.kind {
TerminatorKind::Goto { target: _ } |
TerminatorKind::Resume |
TerminatorKind::Abort |
TerminatorKind::GeneratorDrop |
TerminatorKind::FalseEdges { .. } |
TerminatorKind::FalseUnwind { .. } |
TerminatorKind::Unreachable => { }
TerminatorKind::Return => {
self.gather_move(&Place::Local(RETURN_PLACE));
}
TerminatorKind::Assert { ref cond, .. } => {
self.gather_operand(cond);
}
TerminatorKind::SwitchInt { ref discr, .. } => {
self.gather_operand(discr);
}
TerminatorKind::Yield { ref value, .. } => {
self.gather_operand(value);
}
TerminatorKind::Drop { ref location, target: _, unwind: _ } => {
self.gather_move(location);
}
TerminatorKind::DropAndReplace { ref location, ref value, .. } => {
self.create_move_path(location);
self.gather_operand(value);
self.gather_init(location, InitKind::Deep);
}
TerminatorKind::Call { ref func, ref args, ref destination, cleanup: _ } => {
self.gather_operand(func);
for arg in args {
self.gather_operand(arg);
}
if let Some((ref destination, _bb)) = *destination {
self.create_move_path(destination);
self.gather_init(destination, InitKind::NonPanicPathOnly);
}
}
}
}
fn gather_operand(&mut self, operand: &Operand<'tcx>) {
match *operand {
Operand::Constant(..) |
Operand::Copy(..) => {} // not-a-move
Operand::Move(ref place) => { // a move
self.gather_move(place);
}
}
}
fn gather_move(&mut self, place: &Place<'tcx>) {
debug!("gather_move({:?}, {:?})", self.loc, place);
let path = match self.move_path_for(place) {
Ok(path) | Err(MoveError::UnionMove { path }) => path,
Err(error @ MoveError::IllegalMove { .. }) => {
self.builder.errors.push(error);
return;
}
};
let move_out = self.builder.data.moves.push(MoveOut { path: path, source: self.loc });
debug!("gather_move({:?}, {:?}): adding move {:?} of {:?}",
self.loc, place, move_out, path);
self.builder.data.path_map[path].push(move_out);
self.builder.data.loc_map[self.loc].push(move_out);
}
fn gather_init(&mut self, place: &Place<'tcx>, kind: InitKind) {
debug!("gather_init({:?}, {:?})", self.loc, place);
if let LookupResult::Exact(path) = self.builder.data.rev_lookup.find(place) {
let init = self.builder.data.inits.push(Init {
span: self.builder.mir.source_info(self.loc).span,
path,
kind,
});
debug!("gather_init({:?}, {:?}): adding init {:?} of {:?}",
self.loc, place, init, path);
self.builder.data.init_path_map[path].push(init);
self.builder.data.init_loc_map[self.loc].push(init);
}
}
}