695 lines
26 KiB
Rust
695 lines
26 KiB
Rust
// 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 std::fmt;
|
|
use rustc::hir;
|
|
use rustc::mir::*;
|
|
use rustc::middle::const_val::ConstInt;
|
|
use rustc::middle::lang_items;
|
|
use rustc::ty::{self, Ty};
|
|
use rustc::ty::subst::{Kind, Substs};
|
|
use rustc::ty::util::IntTypeExt;
|
|
use rustc_data_structures::indexed_vec::Idx;
|
|
use util::patch::MirPatch;
|
|
|
|
use std::iter;
|
|
|
|
#[derive(Debug, PartialEq, Eq, Copy, Clone)]
|
|
pub enum DropFlagState {
|
|
Present, // i.e. initialized
|
|
Absent, // i.e. deinitialized or "moved"
|
|
}
|
|
|
|
impl DropFlagState {
|
|
pub fn value(self) -> bool {
|
|
match self {
|
|
DropFlagState::Present => true,
|
|
DropFlagState::Absent => false
|
|
}
|
|
}
|
|
}
|
|
|
|
#[derive(Debug)]
|
|
pub enum DropStyle {
|
|
Dead,
|
|
Static,
|
|
Conditional,
|
|
Open,
|
|
}
|
|
|
|
#[derive(Debug)]
|
|
pub enum DropFlagMode {
|
|
Shallow,
|
|
Deep
|
|
}
|
|
|
|
pub trait DropElaborator<'a, 'tcx: 'a> : fmt::Debug {
|
|
type Path : Copy + fmt::Debug;
|
|
|
|
fn patch(&mut self) -> &mut MirPatch<'tcx>;
|
|
fn mir(&self) -> &'a Mir<'tcx>;
|
|
fn tcx(&self) -> ty::TyCtxt<'a, 'tcx, 'tcx>;
|
|
fn param_env(&self) -> ty::ParamEnv<'tcx>;
|
|
|
|
fn drop_style(&self, path: Self::Path, mode: DropFlagMode) -> DropStyle;
|
|
fn get_drop_flag(&mut self, path: Self::Path) -> Option<Operand<'tcx>>;
|
|
fn clear_drop_flag(&mut self, location: Location, path: Self::Path, mode: DropFlagMode);
|
|
|
|
|
|
fn field_subpath(&self, path: Self::Path, field: Field) -> Option<Self::Path>;
|
|
fn deref_subpath(&self, path: Self::Path) -> Option<Self::Path>;
|
|
fn downcast_subpath(&self, path: Self::Path, variant: usize) -> Option<Self::Path>;
|
|
}
|
|
|
|
#[derive(Debug)]
|
|
struct DropCtxt<'l, 'b: 'l, 'tcx: 'b, D>
|
|
where D : DropElaborator<'b, 'tcx> + 'l
|
|
{
|
|
elaborator: &'l mut D,
|
|
|
|
source_info: SourceInfo,
|
|
is_cleanup: bool,
|
|
|
|
lvalue: &'l Lvalue<'tcx>,
|
|
path: D::Path,
|
|
succ: BasicBlock,
|
|
unwind: Option<BasicBlock>,
|
|
}
|
|
|
|
pub fn elaborate_drop<'b, 'tcx, D>(
|
|
elaborator: &mut D,
|
|
source_info: SourceInfo,
|
|
is_cleanup: bool,
|
|
lvalue: &Lvalue<'tcx>,
|
|
path: D::Path,
|
|
succ: BasicBlock,
|
|
unwind: Option<BasicBlock>,
|
|
bb: BasicBlock)
|
|
where D: DropElaborator<'b, 'tcx>
|
|
{
|
|
assert_eq!(unwind.is_none(), is_cleanup);
|
|
DropCtxt {
|
|
elaborator, source_info, is_cleanup, lvalue, path, succ, unwind
|
|
}.elaborate_drop(bb)
|
|
}
|
|
|
|
impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
|
|
where D: DropElaborator<'b, 'tcx>
|
|
{
|
|
fn lvalue_ty(&self, lvalue: &Lvalue<'tcx>) -> Ty<'tcx> {
|
|
lvalue.ty(self.elaborator.mir(), self.tcx()).to_ty(self.tcx())
|
|
}
|
|
|
|
fn tcx(&self) -> ty::TyCtxt<'b, 'tcx, 'tcx> {
|
|
self.elaborator.tcx()
|
|
}
|
|
|
|
/// This elaborates a single drop instruction, located at `bb`, and
|
|
/// patches over it.
|
|
///
|
|
/// The elaborated drop checks the drop flags to only drop what
|
|
/// is initialized.
|
|
///
|
|
/// In addition, the relevant drop flags also need to be cleared
|
|
/// to avoid double-drops. However, in the middle of a complex
|
|
/// drop, one must avoid clearing some of the flags before they
|
|
/// are read, as that would cause a memory leak.
|
|
///
|
|
/// In particular, when dropping an ADT, multiple fields may be
|
|
/// joined together under the `rest` subpath. They are all controlled
|
|
/// by the primary drop flag, but only the last rest-field dropped
|
|
/// should clear it (and it must also not clear anything else).
|
|
///
|
|
/// FIXME: I think we should just control the flags externally
|
|
/// and then we do not need this machinery.
|
|
pub fn elaborate_drop<'a>(&mut self, bb: BasicBlock) {
|
|
debug!("elaborate_drop({:?})", self);
|
|
let style = self.elaborator.drop_style(self.path, DropFlagMode::Deep);
|
|
debug!("elaborate_drop({:?}): live - {:?}", self, style);
|
|
match style {
|
|
DropStyle::Dead => {
|
|
self.elaborator.patch().patch_terminator(bb, TerminatorKind::Goto {
|
|
target: self.succ
|
|
});
|
|
}
|
|
DropStyle::Static => {
|
|
let loc = self.terminator_loc(bb);
|
|
self.elaborator.clear_drop_flag(loc, self.path, DropFlagMode::Deep);
|
|
self.elaborator.patch().patch_terminator(bb, TerminatorKind::Drop {
|
|
location: self.lvalue.clone(),
|
|
target: self.succ,
|
|
unwind: self.unwind
|
|
});
|
|
}
|
|
DropStyle::Conditional => {
|
|
let is_cleanup = self.is_cleanup; // FIXME(#6393)
|
|
let succ = self.succ;
|
|
let drop_bb = self.complete_drop(
|
|
is_cleanup, Some(DropFlagMode::Deep), succ);
|
|
self.elaborator.patch().patch_terminator(bb, TerminatorKind::Goto {
|
|
target: drop_bb
|
|
});
|
|
}
|
|
DropStyle::Open => {
|
|
let drop_bb = self.open_drop();
|
|
self.elaborator.patch().patch_terminator(bb, TerminatorKind::Goto {
|
|
target: drop_bb
|
|
});
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Return the lvalue and move path for each field of `variant`,
|
|
/// (the move path is `None` if the field is a rest field).
|
|
fn move_paths_for_fields(&self,
|
|
base_lv: &Lvalue<'tcx>,
|
|
variant_path: D::Path,
|
|
variant: &'tcx ty::VariantDef,
|
|
substs: &'tcx Substs<'tcx>)
|
|
-> Vec<(Lvalue<'tcx>, Option<D::Path>)>
|
|
{
|
|
variant.fields.iter().enumerate().map(|(i, f)| {
|
|
let field = Field::new(i);
|
|
let subpath = self.elaborator.field_subpath(variant_path, field);
|
|
|
|
let field_ty =
|
|
self.tcx().normalize_associated_type_in_env(
|
|
&f.ty(self.tcx(), substs),
|
|
self.elaborator.param_env()
|
|
);
|
|
(base_lv.clone().field(field, field_ty), subpath)
|
|
}).collect()
|
|
}
|
|
|
|
fn drop_subpath(&mut self,
|
|
is_cleanup: bool,
|
|
lvalue: &Lvalue<'tcx>,
|
|
path: Option<D::Path>,
|
|
succ: BasicBlock,
|
|
unwind: Option<BasicBlock>)
|
|
-> BasicBlock
|
|
{
|
|
if let Some(path) = path {
|
|
debug!("drop_subpath: for std field {:?}", lvalue);
|
|
|
|
DropCtxt {
|
|
elaborator: self.elaborator,
|
|
source_info: self.source_info,
|
|
path, lvalue, succ, unwind, is_cleanup
|
|
}.elaborated_drop_block()
|
|
} else {
|
|
debug!("drop_subpath: for rest field {:?}", lvalue);
|
|
|
|
DropCtxt {
|
|
elaborator: self.elaborator,
|
|
source_info: self.source_info,
|
|
lvalue, succ, unwind, is_cleanup,
|
|
// Using `self.path` here to condition the drop on
|
|
// our own drop flag.
|
|
path: self.path
|
|
}.complete_drop(is_cleanup, None, succ)
|
|
}
|
|
}
|
|
|
|
/// Create one-half of the drop ladder for a list of fields, and return
|
|
/// the list of steps in it in reverse order.
|
|
///
|
|
/// `unwind_ladder` is such a list of steps in reverse order,
|
|
/// which is called instead of the next step if the drop unwinds
|
|
/// (the first field is never reached). If it is `None`, all
|
|
/// unwind targets are left blank.
|
|
fn drop_halfladder<'a>(&mut self,
|
|
unwind_ladder: Option<&[BasicBlock]>,
|
|
succ: BasicBlock,
|
|
fields: &[(Lvalue<'tcx>, Option<D::Path>)],
|
|
is_cleanup: bool)
|
|
-> Vec<BasicBlock>
|
|
{
|
|
let mut unwind_succ = if is_cleanup {
|
|
None
|
|
} else {
|
|
self.unwind
|
|
};
|
|
|
|
let goto = TerminatorKind::Goto { target: succ };
|
|
let mut succ = self.new_block(is_cleanup, goto);
|
|
|
|
// Always clear the "master" drop flag at the bottom of the
|
|
// ladder. This is needed because the "master" drop flag
|
|
// protects the ADT's discriminant, which is invalidated
|
|
// after the ADT is dropped.
|
|
let succ_loc = Location { block: succ, statement_index: 0 };
|
|
self.elaborator.clear_drop_flag(succ_loc, self.path, DropFlagMode::Shallow);
|
|
|
|
fields.iter().rev().enumerate().map(|(i, &(ref lv, path))| {
|
|
succ = self.drop_subpath(is_cleanup, lv, path, succ, unwind_succ);
|
|
unwind_succ = unwind_ladder.as_ref().map(|p| p[i]);
|
|
succ
|
|
}).collect()
|
|
}
|
|
|
|
/// Create a full drop ladder, consisting of 2 connected half-drop-ladders
|
|
///
|
|
/// For example, with 3 fields, the drop ladder is
|
|
///
|
|
/// .d0:
|
|
/// ELAB(drop location.0 [target=.d1, unwind=.c1])
|
|
/// .d1:
|
|
/// ELAB(drop location.1 [target=.d2, unwind=.c2])
|
|
/// .d2:
|
|
/// ELAB(drop location.2 [target=`self.succ`, unwind=`self.unwind`])
|
|
/// .c1:
|
|
/// ELAB(drop location.1 [target=.c2])
|
|
/// .c2:
|
|
/// ELAB(drop location.2 [target=`self.unwind`])
|
|
fn drop_ladder<'a>(&mut self,
|
|
fields: Vec<(Lvalue<'tcx>, Option<D::Path>)>)
|
|
-> (BasicBlock, Option<BasicBlock>)
|
|
{
|
|
debug!("drop_ladder({:?}, {:?})", self, fields);
|
|
|
|
let mut fields = fields;
|
|
fields.retain(|&(ref lvalue, _)| {
|
|
self.lvalue_ty(lvalue).needs_drop(self.tcx(), self.elaborator.param_env())
|
|
});
|
|
|
|
debug!("drop_ladder - fields needing drop: {:?}", fields);
|
|
|
|
let unwind_ladder = if self.is_cleanup {
|
|
None
|
|
} else {
|
|
let unwind = self.unwind.unwrap(); // FIXME(#6393)
|
|
Some(self.drop_halfladder(None, unwind, &fields, true))
|
|
};
|
|
|
|
let succ = self.succ; // FIXME(#6393)
|
|
let is_cleanup = self.is_cleanup;
|
|
let normal_ladder =
|
|
self.drop_halfladder(unwind_ladder.as_ref().map(|x| &**x),
|
|
succ, &fields, is_cleanup);
|
|
|
|
(normal_ladder.last().cloned().unwrap_or(succ),
|
|
unwind_ladder.and_then(|l| l.last().cloned()).or(self.unwind))
|
|
}
|
|
|
|
fn open_drop_for_tuple<'a>(&mut self, tys: &[Ty<'tcx>])
|
|
-> BasicBlock
|
|
{
|
|
debug!("open_drop_for_tuple({:?}, {:?})", self, tys);
|
|
|
|
let fields = tys.iter().enumerate().map(|(i, &ty)| {
|
|
(self.lvalue.clone().field(Field::new(i), ty),
|
|
self.elaborator.field_subpath(self.path, Field::new(i)))
|
|
}).collect();
|
|
|
|
self.drop_ladder(fields).0
|
|
}
|
|
|
|
fn open_drop_for_box<'a>(&mut self, ty: Ty<'tcx>) -> BasicBlock
|
|
{
|
|
debug!("open_drop_for_box({:?}, {:?})", self, ty);
|
|
|
|
let interior = self.lvalue.clone().deref();
|
|
let interior_path = self.elaborator.deref_subpath(self.path);
|
|
|
|
let succ = self.succ; // FIXME(#6393)
|
|
let is_cleanup = self.is_cleanup;
|
|
let succ = self.box_free_block(ty, succ, is_cleanup);
|
|
let unwind_succ = self.unwind.map(|u| {
|
|
self.box_free_block(ty, u, true)
|
|
});
|
|
|
|
self.drop_subpath(is_cleanup, &interior, interior_path, succ, unwind_succ)
|
|
}
|
|
|
|
fn open_drop_for_adt<'a>(&mut self, adt: &'tcx ty::AdtDef, substs: &'tcx Substs<'tcx>)
|
|
-> BasicBlock {
|
|
debug!("open_drop_for_adt({:?}, {:?}, {:?})", self, adt, substs);
|
|
if adt.variants.len() == 0 {
|
|
return self.elaborator.patch().new_block(BasicBlockData {
|
|
statements: vec![],
|
|
terminator: Some(Terminator {
|
|
source_info: self.source_info,
|
|
kind: TerminatorKind::Unreachable
|
|
}),
|
|
is_cleanup: self.is_cleanup
|
|
});
|
|
}
|
|
|
|
let contents_drop = if adt.is_union() {
|
|
(self.succ, self.unwind)
|
|
} else {
|
|
self.open_drop_for_adt_contents(adt, substs)
|
|
};
|
|
|
|
if adt.has_dtor(self.tcx()) {
|
|
self.destructor_call_block(contents_drop)
|
|
} else {
|
|
contents_drop.0
|
|
}
|
|
}
|
|
|
|
fn open_drop_for_adt_contents<'a>(&mut self, adt: &'tcx ty::AdtDef,
|
|
substs: &'tcx Substs<'tcx>)
|
|
-> (BasicBlock, Option<BasicBlock>) {
|
|
match adt.variants.len() {
|
|
1 => {
|
|
let fields = self.move_paths_for_fields(
|
|
self.lvalue,
|
|
self.path,
|
|
&adt.variants[0],
|
|
substs
|
|
);
|
|
self.drop_ladder(fields)
|
|
}
|
|
_ => {
|
|
let is_cleanup = self.is_cleanup;
|
|
let succ = self.succ;
|
|
let unwind = self.unwind; // FIXME(#6393)
|
|
|
|
let mut values = Vec::with_capacity(adt.variants.len());
|
|
let mut normal_blocks = Vec::with_capacity(adt.variants.len());
|
|
let mut unwind_blocks = if is_cleanup {
|
|
None
|
|
} else {
|
|
Some(Vec::with_capacity(adt.variants.len()))
|
|
};
|
|
let mut otherwise = None;
|
|
let mut unwind_otherwise = None;
|
|
for (variant_index, discr) in adt.discriminants(self.tcx()).enumerate() {
|
|
let subpath = self.elaborator.downcast_subpath(
|
|
self.path, variant_index);
|
|
if let Some(variant_path) = subpath {
|
|
let base_lv = self.lvalue.clone().elem(
|
|
ProjectionElem::Downcast(adt, variant_index)
|
|
);
|
|
let fields = self.move_paths_for_fields(
|
|
&base_lv,
|
|
variant_path,
|
|
&adt.variants[variant_index],
|
|
substs);
|
|
values.push(discr);
|
|
if let Some(ref mut unwind_blocks) = unwind_blocks {
|
|
// We can't use the half-ladder from the original
|
|
// drop ladder, because this breaks the
|
|
// "funclet can't have 2 successor funclets"
|
|
// requirement from MSVC:
|
|
//
|
|
// switch unwind-switch
|
|
// / \ / \
|
|
// v1.0 v2.0 v2.0-unwind v1.0-unwind
|
|
// | | / |
|
|
// v1.1-unwind v2.1-unwind |
|
|
// ^ |
|
|
// \-------------------------------/
|
|
//
|
|
// Create a duplicate half-ladder to avoid that. We
|
|
// could technically only do this on MSVC, but I
|
|
// I want to minimize the divergence between MSVC
|
|
// and non-MSVC.
|
|
|
|
let unwind = unwind.unwrap();
|
|
let halfladder = self.drop_halfladder(
|
|
None, unwind, &fields, true);
|
|
unwind_blocks.push(
|
|
halfladder.last().cloned().unwrap_or(unwind)
|
|
);
|
|
}
|
|
let (normal, _) = self.drop_ladder(fields);
|
|
normal_blocks.push(normal);
|
|
} else {
|
|
// variant not found - drop the entire enum
|
|
if let None = otherwise {
|
|
otherwise = Some(self.complete_drop(
|
|
is_cleanup,
|
|
Some(DropFlagMode::Shallow),
|
|
succ));
|
|
unwind_otherwise = unwind.map(|unwind| self.complete_drop(
|
|
true,
|
|
Some(DropFlagMode::Shallow),
|
|
unwind
|
|
));
|
|
}
|
|
}
|
|
}
|
|
if let Some(block) = otherwise {
|
|
normal_blocks.push(block);
|
|
if let Some(ref mut unwind_blocks) = unwind_blocks {
|
|
unwind_blocks.push(unwind_otherwise.unwrap());
|
|
}
|
|
} else {
|
|
values.pop();
|
|
}
|
|
|
|
(self.adt_switch_block(is_cleanup, adt, normal_blocks, &values, succ),
|
|
unwind_blocks.map(|unwind_blocks| {
|
|
self.adt_switch_block(
|
|
is_cleanup, adt, unwind_blocks, &values, unwind.unwrap()
|
|
)
|
|
}))
|
|
}
|
|
}
|
|
}
|
|
|
|
fn adt_switch_block(&mut self,
|
|
is_cleanup: bool,
|
|
adt: &'tcx ty::AdtDef,
|
|
blocks: Vec<BasicBlock>,
|
|
values: &[ConstInt],
|
|
succ: BasicBlock)
|
|
-> BasicBlock {
|
|
// If there are multiple variants, then if something
|
|
// is present within the enum the discriminant, tracked
|
|
// by the rest path, must be initialized.
|
|
//
|
|
// Additionally, we do not want to switch on the
|
|
// discriminant after it is free-ed, because that
|
|
// way lies only trouble.
|
|
let discr_ty = adt.repr.discr_type().to_ty(self.tcx());
|
|
let discr = Lvalue::Local(self.new_temp(discr_ty));
|
|
let discr_rv = Rvalue::Discriminant(self.lvalue.clone());
|
|
let switch_block = self.elaborator.patch().new_block(BasicBlockData {
|
|
statements: vec![
|
|
Statement {
|
|
source_info: self.source_info,
|
|
kind: StatementKind::Assign(discr.clone(), discr_rv),
|
|
}
|
|
],
|
|
terminator: Some(Terminator {
|
|
source_info: self.source_info,
|
|
kind: TerminatorKind::SwitchInt {
|
|
discr: Operand::Consume(discr),
|
|
switch_ty: discr_ty,
|
|
values: From::from(values.to_owned()),
|
|
targets: blocks,
|
|
}
|
|
}),
|
|
is_cleanup: is_cleanup,
|
|
});
|
|
self.drop_flag_test_block(is_cleanup, switch_block, succ)
|
|
}
|
|
|
|
fn destructor_call_block<'a>(&mut self, (succ, unwind): (BasicBlock, Option<BasicBlock>))
|
|
-> BasicBlock
|
|
{
|
|
debug!("destructor_call_block({:?}, {:?})", self, succ);
|
|
let tcx = self.tcx();
|
|
let drop_trait = tcx.lang_items.drop_trait().unwrap();
|
|
let drop_fn = tcx.associated_items(drop_trait).next().unwrap();
|
|
let ty = self.lvalue_ty(self.lvalue);
|
|
let substs = tcx.mk_substs(iter::once(Kind::from(ty)));
|
|
|
|
let ref_ty = tcx.mk_ref(tcx.types.re_erased, ty::TypeAndMut {
|
|
ty: ty,
|
|
mutbl: hir::Mutability::MutMutable
|
|
});
|
|
let ref_lvalue = self.new_temp(ref_ty);
|
|
let unit_temp = Lvalue::Local(self.new_temp(tcx.mk_nil()));
|
|
|
|
self.elaborator.patch().new_block(BasicBlockData {
|
|
statements: vec![Statement {
|
|
source_info: self.source_info,
|
|
kind: StatementKind::Assign(
|
|
Lvalue::Local(ref_lvalue),
|
|
Rvalue::Ref(tcx.types.re_erased, BorrowKind::Mut, self.lvalue.clone())
|
|
)
|
|
}],
|
|
terminator: Some(Terminator {
|
|
kind: TerminatorKind::Call {
|
|
func: Operand::function_handle(tcx, drop_fn.def_id, substs,
|
|
self.source_info.span),
|
|
args: vec![Operand::Consume(Lvalue::Local(ref_lvalue))],
|
|
destination: Some((unit_temp, succ)),
|
|
cleanup: unwind,
|
|
},
|
|
source_info: self.source_info
|
|
}),
|
|
is_cleanup: self.is_cleanup,
|
|
})
|
|
}
|
|
|
|
/// The slow-path - create an "open", elaborated drop for a type
|
|
/// which is moved-out-of only partially, and patch `bb` to a jump
|
|
/// to it. This must not be called on ADTs with a destructor,
|
|
/// as these can't be moved-out-of, except for `Box<T>`, which is
|
|
/// special-cased.
|
|
///
|
|
/// This creates a "drop ladder" that drops the needed fields of the
|
|
/// ADT, both in the success case or if one of the destructors fail.
|
|
fn open_drop<'a>(&mut self) -> BasicBlock {
|
|
let ty = self.lvalue_ty(self.lvalue);
|
|
let is_cleanup = self.is_cleanup; // FIXME(#6393)
|
|
let succ = self.succ;
|
|
match ty.sty {
|
|
ty::TyClosure(def_id, substs) => {
|
|
let tys : Vec<_> = substs.upvar_tys(def_id, self.tcx()).collect();
|
|
self.open_drop_for_tuple(&tys)
|
|
}
|
|
ty::TyTuple(tys, _) => {
|
|
self.open_drop_for_tuple(tys)
|
|
}
|
|
ty::TyAdt(def, _) if def.is_box() => {
|
|
self.open_drop_for_box(ty.boxed_ty())
|
|
}
|
|
ty::TyAdt(def, substs) => {
|
|
self.open_drop_for_adt(def, substs)
|
|
}
|
|
ty::TyDynamic(..) => {
|
|
self.complete_drop(is_cleanup, Some(DropFlagMode::Deep), succ)
|
|
}
|
|
ty::TyArray(..) | ty::TySlice(..) => {
|
|
// FIXME(#34708): handle partially-dropped
|
|
// array/slice elements.
|
|
self.complete_drop(is_cleanup, Some(DropFlagMode::Deep), succ)
|
|
}
|
|
_ => bug!("open drop from non-ADT `{:?}`", ty)
|
|
}
|
|
}
|
|
|
|
/// Return a basic block that drop an lvalue using the context
|
|
/// and path in `c`. If `mode` is something, also clear `c`
|
|
/// according to it.
|
|
///
|
|
/// if FLAG(self.path)
|
|
/// if let Some(mode) = mode: FLAG(self.path)[mode] = false
|
|
/// drop(self.lv)
|
|
fn complete_drop<'a>(&mut self,
|
|
is_cleanup: bool,
|
|
drop_mode: Option<DropFlagMode>,
|
|
succ: BasicBlock) -> BasicBlock
|
|
{
|
|
debug!("complete_drop({:?},{:?})", self, drop_mode);
|
|
|
|
let drop_block = self.drop_block(is_cleanup, succ);
|
|
if let Some(mode) = drop_mode {
|
|
let block_start = Location { block: drop_block, statement_index: 0 };
|
|
self.elaborator.clear_drop_flag(block_start, self.path, mode);
|
|
}
|
|
|
|
self.drop_flag_test_block(is_cleanup, drop_block, succ)
|
|
}
|
|
|
|
fn elaborated_drop_block<'a>(&mut self) -> BasicBlock {
|
|
debug!("elaborated_drop_block({:?})", self);
|
|
let is_cleanup = self.is_cleanup; // FIXME(#6393)
|
|
let succ = self.succ;
|
|
let blk = self.drop_block(is_cleanup, succ);
|
|
self.elaborate_drop(blk);
|
|
blk
|
|
}
|
|
|
|
fn box_free_block<'a>(
|
|
&mut self,
|
|
ty: Ty<'tcx>,
|
|
target: BasicBlock,
|
|
is_cleanup: bool
|
|
) -> BasicBlock {
|
|
let block = self.unelaborated_free_block(ty, target, is_cleanup);
|
|
self.drop_flag_test_block(is_cleanup, block, target)
|
|
}
|
|
|
|
fn unelaborated_free_block<'a>(
|
|
&mut self,
|
|
ty: Ty<'tcx>,
|
|
target: BasicBlock,
|
|
is_cleanup: bool
|
|
) -> BasicBlock {
|
|
let tcx = self.tcx();
|
|
let unit_temp = Lvalue::Local(self.new_temp(tcx.mk_nil()));
|
|
let free_func = tcx.require_lang_item(lang_items::BoxFreeFnLangItem);
|
|
let substs = tcx.mk_substs(iter::once(Kind::from(ty)));
|
|
|
|
let call = TerminatorKind::Call {
|
|
func: Operand::function_handle(tcx, free_func, substs, self.source_info.span),
|
|
args: vec![Operand::Consume(self.lvalue.clone())],
|
|
destination: Some((unit_temp, target)),
|
|
cleanup: None
|
|
}; // FIXME(#6393)
|
|
let free_block = self.new_block(is_cleanup, call);
|
|
|
|
let block_start = Location { block: free_block, statement_index: 0 };
|
|
self.elaborator.clear_drop_flag(block_start, self.path, DropFlagMode::Shallow);
|
|
free_block
|
|
}
|
|
|
|
fn drop_block<'a>(&mut self, is_cleanup: bool, succ: BasicBlock) -> BasicBlock {
|
|
let block = TerminatorKind::Drop {
|
|
location: self.lvalue.clone(),
|
|
target: succ,
|
|
unwind: if is_cleanup { None } else { self.unwind }
|
|
};
|
|
self.new_block(is_cleanup, block)
|
|
}
|
|
|
|
fn drop_flag_test_block(&mut self,
|
|
is_cleanup: bool,
|
|
on_set: BasicBlock,
|
|
on_unset: BasicBlock)
|
|
-> BasicBlock
|
|
{
|
|
let style = self.elaborator.drop_style(self.path, DropFlagMode::Shallow);
|
|
debug!("drop_flag_test_block({:?},{:?},{:?}) - {:?}",
|
|
self, is_cleanup, on_set, style);
|
|
|
|
match style {
|
|
DropStyle::Dead => on_unset,
|
|
DropStyle::Static => on_set,
|
|
DropStyle::Conditional | DropStyle::Open => {
|
|
let flag = self.elaborator.get_drop_flag(self.path).unwrap();
|
|
let term = TerminatorKind::if_(self.tcx(), flag, on_set, on_unset);
|
|
self.new_block(is_cleanup, term)
|
|
}
|
|
}
|
|
}
|
|
|
|
fn new_block<'a>(&mut self,
|
|
is_cleanup: bool,
|
|
k: TerminatorKind<'tcx>)
|
|
-> BasicBlock
|
|
{
|
|
self.elaborator.patch().new_block(BasicBlockData {
|
|
statements: vec![],
|
|
terminator: Some(Terminator {
|
|
source_info: self.source_info, kind: k
|
|
}),
|
|
is_cleanup: is_cleanup
|
|
})
|
|
}
|
|
|
|
fn new_temp(&mut self, ty: Ty<'tcx>) -> Local {
|
|
self.elaborator.patch().new_temp(ty, self.source_info.span)
|
|
}
|
|
|
|
fn terminator_loc(&mut self, bb: BasicBlock) -> Location {
|
|
let mir = self.elaborator.mir();
|
|
self.elaborator.patch().terminator_loc(mir, bb)
|
|
}
|
|
}
|