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no longer assume that there is a default tag: give the machine the chance to tag all allocations

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This commit is contained in:
Ralf Jung 2019-05-28 10:44:46 +02:00
parent 2726a91cca
commit 77be06b7ed
12 changed files with 198 additions and 229 deletions
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15
src/librustc/mir/interpret/allocation.rs
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@ -111,9 +111,10 @@ pub trait AllocationExtra<Tag>: ::std::fmt::Debug + Clone {
// For Tag=() and no extra state, we have is a trivial implementation.
impl AllocationExtra<()> for () { }
impl<Tag, Extra> Allocation<Tag, Extra> {
// The constructors are all without extra; the extra gets added by a machine hook later.
impl<Tag> Allocation<Tag> {
/// Creates a read-only allocation initialized by the given bytes
pub fn from_bytes<'a>(slice: impl Into<Cow<'a, [u8]>>, align: Align, extra: Extra) -> Self {
pub fn from_bytes<'a>(slice: impl Into<Cow<'a, [u8]>>, align: Align) -> Self {
let bytes = slice.into().into_owned();
let undef_mask = UndefMask::new(Size::from_bytes(bytes.len() as u64), true);
Self {
@ -122,15 +123,15 @@ impl<Tag, Extra> Allocation<Tag, Extra> {
undef_mask,
align,
mutability: Mutability::Immutable,
extra,
extra: (),
}
}
pub fn from_byte_aligned_bytes<'a>(slice: impl Into<Cow<'a, [u8]>>, extra: Extra) -> Self {
Allocation::from_bytes(slice, Align::from_bytes(1).unwrap(), extra)
pub fn from_byte_aligned_bytes<'a>(slice: impl Into<Cow<'a, [u8]>>) -> Self {
Allocation::from_bytes(slice, Align::from_bytes(1).unwrap())
}
pub fn undef(size: Size, align: Align, extra: Extra) -> Self {
pub fn undef(size: Size, align: Align) -> Self {
assert_eq!(size.bytes() as usize as u64, size.bytes());
Allocation {
bytes: vec![0; size.bytes() as usize],
@ -138,7 +139,7 @@ impl<Tag, Extra> Allocation<Tag, Extra> {
undef_mask: UndefMask::new(size, false),
align,
mutability: Mutability::Mutable,
extra,
extra: (),
}
}
}

7
src/librustc/mir/interpret/pointer.rs
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@ -116,13 +116,6 @@ impl<'tcx> Pointer<()> {
{
Pointer::new_with_tag(self.alloc_id, self.offset, tag)
}
#[inline(always)]
pub fn with_default_tag<Tag>(self) -> Pointer<Tag>
where Tag: Default
{
self.with_tag(Tag::default())
}
}
impl<'tcx, Tag> Pointer<Tag> {

27
src/librustc/mir/interpret/value.rs
View File

@ -140,23 +140,18 @@ impl<'tcx> Scalar<()> {
#[inline]
pub fn with_tag<Tag>(self, new_tag: Tag) -> Scalar<Tag> {
// Used by `MemPlace::replace_tag`
match self {
Scalar::Ptr(ptr) => Scalar::Ptr(ptr.with_tag(new_tag)),
Scalar::Raw { data, size } => Scalar::Raw { data, size },
}
}
#[inline(always)]
pub fn with_default_tag<Tag>(self) -> Scalar<Tag>
where Tag: Default
{
self.with_tag(Tag::default())
}
}
impl<'tcx, Tag> Scalar<Tag> {
#[inline]
pub fn erase_tag(self) -> Scalar {
// Used by error reporting code to avoid having the error type depend on `Tag`
match self {
Scalar::Ptr(ptr) => Scalar::Ptr(ptr.erase_tag()),
Scalar::Raw { data, size } => Scalar::Raw { data, size },
@ -476,27 +471,11 @@ impl<Tag> fmt::Display for ScalarMaybeUndef<Tag> {
}
}
impl<'tcx> ScalarMaybeUndef<()> {
#[inline]
pub fn with_tag<Tag>(self, new_tag: Tag) -> ScalarMaybeUndef<Tag> {
match self {
ScalarMaybeUndef::Scalar(s) => ScalarMaybeUndef::Scalar(s.with_tag(new_tag)),
ScalarMaybeUndef::Undef => ScalarMaybeUndef::Undef,
}
}
#[inline(always)]
pub fn with_default_tag<Tag>(self) -> ScalarMaybeUndef<Tag>
where Tag: Default
{
self.with_tag(Tag::default())
}
}
impl<'tcx, Tag> ScalarMaybeUndef<Tag> {
#[inline]
pub fn erase_tag(self) -> ScalarMaybeUndef
{
// Used by error reporting code to avoid having the error type depend on `Tag`
match self {
ScalarMaybeUndef::Scalar(s) => ScalarMaybeUndef::Scalar(s.erase_tag()),
ScalarMaybeUndef::Undef => ScalarMaybeUndef::Undef,

2
src/librustc/ty/context.rs
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@ -1154,7 +1154,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
/// Allocates a byte or string literal for `mir::interpret`, read-only
pub fn allocate_bytes(self, bytes: &[u8]) -> interpret::AllocId {
// create an allocation that just contains these bytes
let alloc = interpret::Allocation::from_byte_aligned_bytes(bytes, ());
let alloc = interpret::Allocation::from_byte_aligned_bytes(bytes);
let alloc = self.intern_const_alloc(alloc);
self.alloc_map.lock().create_memory_alloc(alloc)
}

28
src/librustc_mir/const_eval.rs
View File

@ -12,7 +12,7 @@ use rustc::hir::def_id::DefId;
use rustc::mir::interpret::{ConstEvalErr, ErrorHandled};
use rustc::mir;
use rustc::ty::{self, TyCtxt, query::TyCtxtAt};
use rustc::ty::layout::{self, LayoutOf, VariantIdx, Size};
use rustc::ty::layout::{self, LayoutOf, VariantIdx};
use rustc::ty::subst::Subst;
use rustc::traits::Reveal;
use rustc::util::common::ErrorReported;
@ -117,7 +117,7 @@ fn op_to_const<'tcx>(
),
Scalar::Raw { .. } => (
ecx.tcx.intern_const_alloc(Allocation::from_byte_aligned_bytes(
b"" as &[u8], (),
b"" as &[u8],
)),
0,
),
@ -397,27 +397,27 @@ impl<'a, 'mir, 'tcx> interpret::Machine<'a, 'mir, 'tcx>
fn find_foreign_static(
_def_id: DefId,
_tcx: TyCtxtAt<'a, 'tcx, 'tcx>,
_memory_extra: &(),
) -> EvalResult<'tcx, Cow<'tcx, Allocation<Self::PointerTag>>> {
err!(ReadForeignStatic)
}
#[inline(always)]
fn adjust_static_allocation<'b>(
alloc: &'b Allocation,
fn tag_allocation<'b>(
_id: AllocId,
alloc: Cow<'b, Allocation>,
_kind: Option<MemoryKind<!>>,
_memory_extra: &(),
) -> Cow<'b, Allocation<Self::PointerTag>> {
// We do not use a tag so we can just cheaply forward the reference
Cow::Borrowed(alloc)
) -> (Cow<'b, Allocation<Self::PointerTag>>, Self::PointerTag) {
// We do not use a tag so we can just cheaply forward the allocation
(alloc, ())
}
#[inline(always)]
fn new_allocation(
_size: Size,
_extra: &Self::MemoryExtra,
_kind: MemoryKind<!>,
) -> (Self::AllocExtra, Self::PointerTag) {
((), ())
fn tag_static_base_pointer(
_id: AllocId,
_memory_extra: &(),
) -> Self::PointerTag {
()
}
fn box_alloc(

4
src/librustc_mir/hair/constant.rs
View File

@ -30,13 +30,13 @@ crate fn lit_to_const<'a, 'gcx, 'tcx>(
let lit = match *lit {
LitKind::Str(ref s, _) => {
let s = s.as_str();
let allocation = Allocation::from_byte_aligned_bytes(s.as_bytes(), ());
let allocation = Allocation::from_byte_aligned_bytes(s.as_bytes());
let allocation = tcx.intern_const_alloc(allocation);
ConstValue::Slice { data: allocation, start: 0, end: s.len() }
},
LitKind::Err(ref s) => {
let s = s.as_str();
let allocation = Allocation::from_byte_aligned_bytes(s.as_bytes(), ());
let allocation = Allocation::from_byte_aligned_bytes(s.as_bytes());
let allocation = tcx.intern_const_alloc(allocation);
return Ok(tcx.mk_const(ty::Const {
val: ConstValue::Slice{ data: allocation, start: 0, end: s.len() },

10
src/librustc_mir/interpret/eval_context.rs
View File

@ -225,6 +225,11 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> InterpretCx<'a, 'mir, 'tc
&mut self.memory
}
#[inline(always)]
pub fn tag_static_base_pointer(&self, ptr: Pointer) -> Pointer<M::PointerTag> {
self.memory.tag_static_base_pointer(ptr)
}
#[inline(always)]
pub fn stack(&self) -> &[Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>] {
&self.stack
@ -363,11 +368,6 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> InterpretCx<'a, 'mir, 'tc
}
}
pub fn str_to_immediate(&mut self, s: &str) -> EvalResult<'tcx, Immediate<M::PointerTag>> {
let ptr = self.memory.allocate_static_bytes(s.as_bytes()).with_default_tag();
Ok(Immediate::new_slice(Scalar::Ptr(ptr), s.len() as u64, self))
}
/// Returns the actual dynamic size and alignment of the place at the given type.
/// Only the "meta" (metadata) part of the place matters.
/// This can fail to provide an answer for extern types.

2
src/librustc_mir/interpret/intrinsics/type_name.rs
View File

@ -215,7 +215,7 @@ impl Write for AbsolutePathPrinter<'_, '_> {
pub fn type_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, ty: Ty<'tcx>) -> &'tcx ty::Const<'tcx> {
let path = AbsolutePathPrinter { tcx, path: String::new() }.print_type(ty).unwrap().path;
let len = path.len();
let alloc = Allocation::from_byte_aligned_bytes(path.into_bytes(), ());
let alloc = Allocation::from_byte_aligned_bytes(path.into_bytes());
let alloc = tcx.intern_const_alloc(alloc);
tcx.mk_const(ty::Const {
val: ConstValue::Slice {

62
src/librustc_mir/interpret/machine.rs
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@ -5,13 +5,13 @@
use std::borrow::{Borrow, Cow};
use std::hash::Hash;
use rustc::hir::{self, def_id::DefId};
use rustc::hir::def_id::DefId;
use rustc::mir;
use rustc::ty::{self, query::TyCtxtAt, layout::Size};
use rustc::ty::{self, query::TyCtxtAt};
use super::{
Allocation, AllocId, EvalResult, Scalar, AllocationExtra,
InterpretCx, PlaceTy, MPlaceTy, OpTy, ImmTy, MemoryKind,
InterpretCx, PlaceTy, OpTy, ImmTy, MemoryKind,
};
/// Whether this kind of memory is allowed to leak
@ -65,7 +65,7 @@ pub trait Machine<'a, 'mir, 'tcx>: Sized {
/// Tag tracked alongside every pointer. This is used to implement "Stacked Borrows"
/// <https://www.ralfj.de/blog/2018/08/07/stacked-borrows.html>.
/// The `default()` is used for pointers to consts, statics, vtables and functions.
type PointerTag: ::std::fmt::Debug + Default + Copy + Eq + Hash + 'static;
type PointerTag: ::std::fmt::Debug + Copy + Eq + Hash + 'static;
/// Extra data stored in every call frame.
type FrameExtra;
@ -90,7 +90,7 @@ pub trait Machine<'a, 'mir, 'tcx>: Sized {
/// The memory kind to use for copied statics -- or None if statics should not be mutated
/// and thus any such attempt will cause a `ModifiedStatic` error to be raised.
/// Statics are copied under two circumstances: When they are mutated, and when
/// `static_with_default_tag` or `find_foreign_static` (see below) returns an owned allocation
/// `tag_allocation` or `find_foreign_static` (see below) returns an owned allocation
/// that is added to the memory so that the work is not done twice.
const STATIC_KIND: Option<Self::MemoryKinds>;
@ -133,11 +133,12 @@ pub trait Machine<'a, 'mir, 'tcx>: Sized {
/// This will only be called once per static and machine; the result is cached in
/// the machine memory. (This relies on `AllocMap::get_or` being able to add the
/// owned allocation to the map even when the map is shared.)
///
/// This allocation will then be fed to `tag_allocation` to initialize the "extra" state.
fn find_foreign_static(
def_id: DefId,
tcx: TyCtxtAt<'a, 'tcx, 'tcx>,
memory_extra: &Self::MemoryExtra,
) -> EvalResult<'tcx, Cow<'tcx, Allocation<Self::PointerTag, Self::AllocExtra>>>;
) -> EvalResult<'tcx, Cow<'tcx, Allocation>>;
/// Called for all binary operations on integer(-like) types when one operand is a pointer
/// value, and for the `Offset` operation that is inherently about pointers.
@ -156,36 +157,37 @@ pub trait Machine<'a, 'mir, 'tcx>: Sized {
dest: PlaceTy<'tcx, Self::PointerTag>,
) -> EvalResult<'tcx>;
/// Called to turn an allocation obtained from the `tcx` into one that has
/// the right type for this machine.
/// Called to initialize the "extra" state of an allocation and make the pointers
/// it contains (in relocations) tagged. The way we construct allocations is
/// to always first construct it without extra and then add the extra.
/// This keeps uniform code paths for handling both allocations created by CTFE
/// for statics, and allocations ceated by Miri during evaluation.
///
/// `kind` is the kind of the allocation being tagged; it can be `None` when
/// it's a static and `STATIC_KIND` is `None`.
///
/// This should avoid copying if no work has to be done! If this returns an owned
/// allocation (because a copy had to be done to add tags or metadata), machine memory will
/// cache the result. (This relies on `AllocMap::get_or` being able to add the
/// owned allocation to the map even when the map is shared.)
fn adjust_static_allocation<'b>(
alloc: &'b Allocation,
///
/// The tag returned must be the same as the one returned by `tag_base_pointer`.
fn tag_allocation<'b>(
id: AllocId,
alloc: Cow<'b, Allocation>,
kind: Option<MemoryKind<Self::MemoryKinds>>,
memory_extra: &Self::MemoryExtra,
) -> Cow<'b, Allocation<Self::PointerTag, Self::AllocExtra>>;
) -> (Cow<'b, Allocation<Self::PointerTag, Self::AllocExtra>>, Self::PointerTag);
/// Computes the extra state and the tag for a new allocation.
fn new_allocation(
size: Size,
extra: &Self::MemoryExtra,
kind: MemoryKind<Self::MemoryKinds>,
) -> (Self::AllocExtra, Self::PointerTag);
/// Executed when evaluating the `*` operator: Following a reference.
/// This has the chance to adjust the tag. It should not change anything else!
/// `mutability` can be `None` in case a raw ptr is being dereferenced.
#[inline]
fn tag_dereference(
_ecx: &InterpretCx<'a, 'mir, 'tcx, Self>,
place: MPlaceTy<'tcx, Self::PointerTag>,
_mutability: Option<hir::Mutability>,
) -> EvalResult<'tcx, Scalar<Self::PointerTag>> {
Ok(place.ptr)
}
/// Return the "base" tag for the given static allocation: the one that is used for direct
/// accesses to this static/const/fn allocation.
///
/// Be aware that requesting the `Allocation` for that `id` will lead to cycles
/// for cyclic statics!
fn tag_static_base_pointer(
id: AllocId,
memory_extra: &Self::MemoryExtra,
) -> Self::PointerTag;
/// Executes a retagging operation
#[inline]

138
src/librustc_mir/interpret/memory.rs
View File

@ -108,23 +108,14 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> Memory<'a, 'mir, 'tcx, M> {
}
}
#[inline]
pub fn tag_static_base_pointer(&self, ptr: Pointer) -> Pointer<M::PointerTag> {
ptr.with_tag(M::tag_static_base_pointer(ptr.alloc_id, &self.extra))
}
pub fn create_fn_alloc(&mut self, instance: Instance<'tcx>) -> Pointer<M::PointerTag> {
// Default tag is okay because anyway you cannot access memory with this.
Pointer::from(self.tcx.alloc_map.lock().create_fn_alloc(instance)).with_default_tag()
}
pub fn allocate_static_bytes(&mut self, bytes: &[u8]) -> Pointer {
Pointer::from(self.tcx.allocate_bytes(bytes))
}
pub fn allocate_with(
&mut self,
alloc: Allocation<M::PointerTag, M::AllocExtra>,
kind: MemoryKind<M::MemoryKinds>,
) -> AllocId {
let id = self.tcx.alloc_map.lock().reserve();
self.alloc_map.insert(id, (kind, alloc));
id
let id = self.tcx.alloc_map.lock().create_fn_alloc(instance);
self.tag_static_base_pointer(Pointer::from(id))
}
pub fn allocate(
@ -133,8 +124,28 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> Memory<'a, 'mir, 'tcx, M> {
align: Align,
kind: MemoryKind<M::MemoryKinds>,
) -> Pointer<M::PointerTag> {
let (extra, tag) = M::new_allocation(size, &self.extra, kind);
Pointer::from(self.allocate_with(Allocation::undef(size, align, extra), kind)).with_tag(tag)
let alloc = Allocation::undef(size, align);
self.allocate_with(alloc, kind)
}
pub fn allocate_static_bytes(
&mut self,
bytes: &[u8],
kind: MemoryKind<M::MemoryKinds>,
) -> Pointer<M::PointerTag> {
let alloc = Allocation::from_byte_aligned_bytes(bytes);
self.allocate_with(alloc, kind)
}
pub fn allocate_with(
&mut self,
alloc: Allocation,
kind: MemoryKind<M::MemoryKinds>,
) -> Pointer<M::PointerTag> {
let id = self.tcx.alloc_map.lock().reserve();
let (alloc, tag) = M::tag_allocation(id, Cow::Owned(alloc), Some(kind), &self.extra);
self.alloc_map.insert(id, (kind, alloc.into_owned()));
Pointer::from(id).with_tag(tag)
}
pub fn reallocate(
@ -306,53 +317,68 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> Memory<'a, 'mir, 'tcx, M> {
/// This attempts to return a reference to an existing allocation if
/// one can be found in `tcx`. That, however, is only possible if `tcx` and
/// this machine use the same pointer tag, so it is indirected through
/// `M::static_with_default_tag`.
/// `M::tag_allocation`.
///
/// Notice that every static has two `AllocId` that will resolve to the same
/// thing here: one maps to `GlobalAlloc::Static`, this is the "lazy" ID,
/// and the other one is maps to `GlobalAlloc::Memory`, this is returned by
/// `const_eval_raw` and it is the "resolved" ID.
/// The resolved ID is never used by the interpreted progrma, it is hidden.
/// The `GlobalAlloc::Memory` branch here is still reachable though; when a static
/// contains a reference to memory that was created during its evaluation (i.e., not to
/// another static), those inner references only exist in "resolved" from.
fn get_static_alloc(
id: AllocId,
tcx: TyCtxtAt<'a, 'tcx, 'tcx>,
memory_extra: &M::MemoryExtra,
) -> EvalResult<'tcx, Cow<'tcx, Allocation<M::PointerTag, M::AllocExtra>>> {
let alloc = tcx.alloc_map.lock().get(id);
let def_id = match alloc {
Some(GlobalAlloc::Memory(mem)) => {
// We got tcx memory. Let the machine figure out whether and how to
// turn that into memory with the right pointer tag.
return Ok(M::adjust_static_allocation(mem, memory_extra))
}
Some(GlobalAlloc::Function(..)) => {
return err!(DerefFunctionPointer)
}
Some(GlobalAlloc::Static(did)) => {
did
}
let alloc = match alloc {
Some(GlobalAlloc::Memory(mem)) =>
Cow::Borrowed(mem),
Some(GlobalAlloc::Function(..)) =>
return err!(DerefFunctionPointer),
None =>
return err!(DanglingPointerDeref),
};
// We got a "lazy" static that has not been computed yet, do some work
trace!("static_alloc: Need to compute {:?}", def_id);
if tcx.is_foreign_item(def_id) {
return M::find_foreign_static(def_id, tcx, memory_extra);
}
let instance = Instance::mono(tcx.tcx, def_id);
let gid = GlobalId {
instance,
promoted: None,
};
// use the raw query here to break validation cycles. Later uses of the static will call the
// full query anyway
tcx.const_eval_raw(ty::ParamEnv::reveal_all().and(gid)).map_err(|err| {
// no need to report anything, the const_eval call takes care of that for statics
assert!(tcx.is_static(def_id));
match err {
ErrorHandled::Reported => InterpError::ReferencedConstant.into(),
ErrorHandled::TooGeneric => InterpError::TooGeneric.into(),
Some(GlobalAlloc::Static(def_id)) => {
// We got a "lazy" static that has not been computed yet.
if tcx.is_foreign_item(def_id) {
trace!("static_alloc: foreign item {:?}", def_id);
M::find_foreign_static(def_id, tcx)?
} else {
trace!("static_alloc: Need to compute {:?}", def_id);
let instance = Instance::mono(tcx.tcx, def_id);
let gid = GlobalId {
instance,
promoted: None,
};
// use the raw query here to break validation cycles. Later uses of the static
// will call the full query anyway
let raw_const = tcx.const_eval_raw(ty::ParamEnv::reveal_all().and(gid))
.map_err(|err| {
// no need to report anything, the const_eval call takes care of that
// for statics
assert!(tcx.is_static(def_id));
match err {
ErrorHandled::Reported => InterpError::ReferencedConstant,
ErrorHandled::TooGeneric => InterpError::TooGeneric,
}
})?;
// Make sure we use the ID of the resolved memory, not the lazy one!
let id = raw_const.alloc_id;
let allocation = tcx.alloc_map.lock().unwrap_memory(id);
Cow::Borrowed(allocation)
}
}
}).map(|raw_const| {
let allocation = tcx.alloc_map.lock().unwrap_memory(raw_const.alloc_id);
// We got tcx memory. Let the machine figure out whether and how to
// turn that into memory with the right pointer tag.
M::adjust_static_allocation(allocation, memory_extra)
})
};
// We got tcx memory. Let the machine figure out whether and how to
// turn that into memory with the right pointer tag.
Ok(M::tag_allocation(
id, // always use the ID we got as input, not the "hidden" one.
alloc,
M::STATIC_KIND.map(MemoryKind::Machine),
memory_extra
).0)
}
pub fn get(&self, id: AllocId) -> EvalResult<'tcx, &Allocation<M::PointerTag, M::AllocExtra>> {

96
src/librustc_mir/interpret/operand.rs
View File

@ -37,16 +37,6 @@ impl<'tcx, Tag> Immediate<Tag> {
Immediate::Scalar(ScalarMaybeUndef::Scalar(val))
}
#[inline]
pub fn erase_tag(self) -> Immediate
{
match self {
Immediate::Scalar(x) => Immediate::Scalar(x.erase_tag()),
Immediate::ScalarPair(x, y) =>
Immediate::ScalarPair(x.erase_tag(), y.erase_tag()),
}
}
pub fn new_slice(
val: Scalar<Tag>,
len: u64,
@ -130,15 +120,6 @@ pub enum Operand<Tag=(), Id=AllocId> {
}
impl<Tag> Operand<Tag> {
#[inline]
pub fn erase_tag(self) -> Operand
{
match self {
Operand::Immediate(x) => Operand::Immediate(x.erase_tag()),
Operand::Indirect(x) => Operand::Indirect(x.erase_tag()),
}
}
#[inline]
pub fn to_mem_place(self) -> MemPlace<Tag>
where Tag: ::std::fmt::Debug
@ -209,18 +190,6 @@ impl<'tcx, Tag: Copy> ImmTy<'tcx, Tag>
}
}
impl<'tcx, Tag> OpTy<'tcx, Tag>
{
#[inline]
pub fn erase_tag(self) -> OpTy<'tcx>
{
OpTy {
op: self.op.erase_tag(),
layout: self.layout,
}
}
}
// Use the existing layout if given (but sanity check in debug mode),
// or compute the layout.
#[inline(always)]
@ -537,44 +506,53 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> InterpretCx<'a, 'mir, 'tcx, M>
val: &'tcx ty::Const<'tcx>,
layout: Option<TyLayout<'tcx>>,
) -> EvalResult<'tcx, OpTy<'tcx, M::PointerTag>> {
let op = match val.val {
let tag_scalar = |scalar| match scalar {
Scalar::Ptr(ptr) => Scalar::Ptr(self.tag_static_base_pointer(ptr)),
Scalar::Raw { data, size } => Scalar::Raw { data, size },
};
// Early-return cases.
match val.val {
ConstValue::Param(_) => return err!(TooGeneric),
ConstValue::Infer(_) | ConstValue::Placeholder(_) => bug!(),
ConstValue::ByRef(ptr, alloc) => {
// We rely on mutability being set correctly in that allocation to prevent writes
// where none should happen -- and for `static mut`, we copy on demand anyway.
Operand::Indirect(
MemPlace::from_ptr(ptr.with_default_tag(), alloc.align)
)
},
ConstValue::Slice { data, start, end } =>
Operand::Immediate(Immediate::ScalarPair(
Scalar::from(Pointer::new(
self.tcx.alloc_map.lock().create_memory_alloc(data),
Size::from_bytes(start as u64),
)).with_default_tag().into(),
Scalar::from_uint(
(end - start) as u64,
self.tcx.data_layout.pointer_size,
).with_default_tag().into(),
)),
ConstValue::Scalar(x) =>
Operand::Immediate(Immediate::Scalar(x.with_default_tag().into())),
ConstValue::Unevaluated(def_id, substs) => {
let instance = self.resolve(def_id, substs)?;
return Ok(OpTy::from(self.const_eval_raw(GlobalId {
instance,
promoted: None,
})?));
},
};
}
_ => {}
}
// Other cases need layout.
let layout = from_known_layout(layout, || {
self.layout_of(self.monomorphize(val.ty)?)
})?;
Ok(OpTy {
op,
layout,
})
let op = match val.val {
ConstValue::ByRef(ptr, _alloc) => {
// We rely on mutability being set correctly in that allocation to prevent writes
// where none should happen -- and for `static mut`, we copy on demand anyway.
let ptr = self.tag_static_base_pointer(ptr);
Operand::Indirect(MemPlace::from_ptr(ptr, layout.align.abi))
},
ConstValue::Scalar(x) =>
Operand::Immediate(Immediate::Scalar(tag_scalar(x).into())),
ConstValue::Slice { data, start, end } => {
let ptr = Pointer::new(
self.tcx.alloc_map.lock().create_memory_alloc(data),
Size::from_bytes(start as u64), // offset: `start`
);
Operand::Immediate(Immediate::new_slice(
self.tag_static_base_pointer(ptr).into(),
(end - start) as u64, // len: `end - start`
self,
))
}
ConstValue::Param(..) |
ConstValue::Infer(..) |
ConstValue::Placeholder(..) |
ConstValue::Unevaluated(..) =>
bug!("eval_const_to_op: Unexpected ConstValue {:?}", val),
};
Ok(OpTy { op, layout })
}
/// Read discriminant, return the runtime value as well as the variant index.

36
src/librustc_mir/interpret/place.rs
View File

@ -5,7 +5,6 @@
use std::convert::TryFrom;
use std::hash::Hash;
use rustc::hir;
use rustc::mir;
use rustc::mir::interpret::truncate;
use rustc::ty::{self, Ty};
@ -294,7 +293,7 @@ impl<'tcx, Tag: ::std::fmt::Debug> PlaceTy<'tcx, Tag> {
impl<'a, 'mir, 'tcx, Tag, M> InterpretCx<'a, 'mir, 'tcx, M>
where
// FIXME: Working around https://github.com/rust-lang/rust/issues/54385
Tag: ::std::fmt::Debug+Default+Copy+Eq+Hash+'static,
Tag: ::std::fmt::Debug + Copy + Eq + Hash + 'static,
M: Machine<'a, 'mir, 'tcx, PointerTag=Tag>,
// FIXME: Working around https://github.com/rust-lang/rust/issues/24159
M::MemoryMap: AllocMap<AllocId, (MemoryKind<M::MemoryKinds>, Allocation<Tag, M::AllocExtra>)>,
@ -325,25 +324,13 @@ where
// Take an operand, representing a pointer, and dereference it to a place -- that
// will always be a MemPlace. Lives in `place.rs` because it creates a place.
// This calls the "deref" machine hook, and counts as a deref as far as
// Stacked Borrows is concerned.
pub fn deref_operand(
&self,
src: OpTy<'tcx, M::PointerTag>,
) -> EvalResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
let val = self.read_immediate(src)?;
trace!("deref to {} on {:?}", val.layout.ty, *val);
let mut place = self.ref_to_mplace(val)?;
// Pointer tag tracking might want to adjust the tag.
let mutbl = match val.layout.ty.sty {
// `builtin_deref` considers boxes immutable, that's useless for our purposes
ty::Ref(_, _, mutbl) => Some(mutbl),
ty::Adt(def, _) if def.is_box() => Some(hir::MutMutable),
ty::RawPtr(_) => None,
_ => bug!("Unexpected pointer type {}", val.layout.ty),
};
place.mplace.ptr = M::tag_dereference(self, place, mutbl)?;
Ok(place)
self.ref_to_mplace(val)
}
/// Offset a pointer to project to a field. Unlike `place_field`, this is always
@ -587,18 +574,23 @@ where
promoted: None
};
// Just create a lazy reference, so we can support recursive statics.
// tcx takes are of assigning every static one and only one unique AllocId.
// tcx takes care of assigning every static one and only one unique AllocId.
// When the data here is ever actually used, memory will notice,
// and it knows how to deal with alloc_id that are present in the
// global table but not in its local memory: It calls back into tcx through
// a query, triggering the CTFE machinery to actually turn this lazy reference
// into a bunch of bytes. IOW, statics are evaluated with CTFE even when
// this InterpretCx uses another Machine (e.g., in miri). This is what we
// want! This way, computing statics works concistently between codegen
// want! This way, computing statics works consistently between codegen
// and miri: They use the same query to eventually obtain a `ty::Const`
// and use that for further computation.
let alloc = self.tcx.alloc_map.lock().create_static_alloc(cid.instance.def_id());
MPlaceTy::from_aligned_ptr(Pointer::from(alloc).with_default_tag(), layout)
//
// Notice that statics have *two* AllocIds: the lazy one, and the resolved
// one. Here we make sure that the interpreted program never sees the
// resolved ID. Also see the doc comment of `Memory::get_static_alloc`.
let alloc_id = self.tcx.alloc_map.lock().create_static_alloc(cid.instance.def_id());
let ptr = self.tag_static_base_pointer(Pointer::from(alloc_id));
MPlaceTy::from_aligned_ptr(ptr, layout)
}
})
}
@ -1032,11 +1024,9 @@ where
) -> EvalResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
// This must be an allocation in `tcx`
assert!(self.tcx.alloc_map.lock().get(raw.alloc_id).is_some());
let ptr = self.tag_static_base_pointer(Pointer::from(raw.alloc_id));
let layout = self.layout_of(raw.ty)?;
Ok(MPlaceTy::from_aligned_ptr(
Pointer::new(raw.alloc_id, Size::ZERO).with_default_tag(),
layout,
))
Ok(MPlaceTy::from_aligned_ptr(ptr, layout))
}
/// Turn a place with a `dyn Trait` type into a place with the actual dynamic type.