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use std::hash::{Hash, Hasher};
use std::convert::TryInto;
use rustc::{mir, ty};
use rustc::ty::layout::{self, Size, LayoutOf, TyLayout, HasDataLayout, IntegerExt};
use rustc::mir::interpret::{
GlobalId, AllocId,
ConstValue, Pointer, Scalar, ScalarMaybeUndef,
EvalResult, EvalErrorKind
};
use super::{EvalContext, Machine, MemPlace, MPlaceTy, MemoryKind};
#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
pub enum Value<Id=AllocId> {
Scalar(ScalarMaybeUndef<Id>),
ScalarPair(ScalarMaybeUndef<Id>, ScalarMaybeUndef<Id>),
}
impl<'tcx> Value {
pub fn new_slice(
val: Scalar,
len: u64,
cx: impl HasDataLayout
) -> Self {
Value::ScalarPair(val.into(), Scalar::from_uint(len, cx.data_layout().pointer_size).into())
}
pub fn new_dyn_trait(val: Scalar, vtable: Pointer) -> Self {
Value::ScalarPair(val.into(), Scalar::Ptr(vtable).into())
}
#[inline]
pub fn to_scalar_or_undef(self) -> ScalarMaybeUndef {
match self {
Value::Scalar(val) => val,
Value::ScalarPair(..) => bug!("Got a fat pointer where a scalar was expected"),
}
}
#[inline]
pub fn to_scalar(self) -> EvalResult<'tcx, Scalar> {
self.to_scalar_or_undef().not_undef()
}
#[inline]
pub fn to_scalar_pair(self) -> EvalResult<'tcx, (Scalar, Scalar)> {
match self {
Value::Scalar(..) => bug!("Got a thin pointer where a scalar pair was expected"),
Value::ScalarPair(a, b) => Ok((a.not_undef()?, b.not_undef()?))
}
}
#[inline]
pub fn to_scalar_ptr(self) -> EvalResult<'tcx, Scalar> {
match self {
Value::Scalar(ptr) |
Value::ScalarPair(ptr, _) => ptr.not_undef(),
}
}
}
impl_stable_hash_for!(enum ::interpret::Value {
Scalar(x),
ScalarPair(x, y),
});
#[derive(Copy, Clone, Debug)]
pub struct ValTy<'tcx> {
value: Value,
pub layout: TyLayout<'tcx>,
}
impl<'tcx> ::std::ops::Deref for ValTy<'tcx> {
type Target = Value;
#[inline(always)]
fn deref(&self) -> &Value {
&self.value
}
}
#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
pub enum Operand<Id=AllocId> {
Immediate(Value<Id>),
Indirect(MemPlace<Id>),
}
impl Operand {
#[inline]
pub fn to_mem_place(self) -> MemPlace {
match self {
Operand::Indirect(mplace) => mplace,
_ => bug!("to_mem_place: expected Operand::Indirect, got {:?}", self),
}
}
#[inline]
pub fn to_immediate(self) -> Value {
match self {
Operand::Immediate(val) => val,
_ => bug!("to_immediate: expected Operand::Immediate, got {:?}", self),
}
}
}
impl_stable_hash_for!(enum ::interpret::Operand {
Immediate(x),
Indirect(x),
});
#[derive(Copy, Clone, Debug)]
pub struct OpTy<'tcx> {
crate op: Operand,
pub layout: TyLayout<'tcx>,
}
impl<'tcx> ::std::ops::Deref for OpTy<'tcx> {
type Target = Operand;
#[inline(always)]
fn deref(&self) -> &Operand {
&self.op
}
}
impl<'tcx> From<MPlaceTy<'tcx>> for OpTy<'tcx> {
#[inline(always)]
fn from(mplace: MPlaceTy<'tcx>) -> Self {
OpTy {
op: Operand::Indirect(*mplace),
layout: mplace.layout
}
}
}
impl<'tcx> From<ValTy<'tcx>> for OpTy<'tcx> {
#[inline(always)]
fn from(val: ValTy<'tcx>) -> Self {
OpTy {
op: Operand::Immediate(val.value),
layout: val.layout
}
}
}
impl<'tcx> Hash for OpTy<'tcx> {
fn hash<H: Hasher>(&self, state: &mut H) {
self.op.hash(state);
self.layout.ty.hash(state);
}
}
impl<'tcx> PartialEq for OpTy<'tcx> {
fn eq(&self, other: &Self) -> bool {
self.op == other.op && self.layout.ty == other.layout.ty
}
}
impl<'tcx> Eq for OpTy<'tcx> {}
#[inline(always)]
fn from_known_layout<'tcx>(
layout: Option<TyLayout<'tcx>>,
compute: impl FnOnce() -> EvalResult<'tcx, TyLayout<'tcx>>
) -> EvalResult<'tcx, TyLayout<'tcx>> {
match layout {
None => compute(),
Some(layout) => {
if cfg!(debug_assertions) {
let layout2 = compute()?;
assert_eq!(layout.details, layout2.details,
"Mismatch in layout of supposedly equal-layout types {:?} and {:?}",
layout.ty, layout2.ty);
}
Ok(layout)
}
}
}
impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M> {
pub(super) fn try_read_value_from_mplace(
&self,
mplace: MPlaceTy<'tcx>,
) -> EvalResult<'tcx, Option<Value>> {
if mplace.layout.is_unsized() {
return Ok(None);
}
let (ptr, ptr_align) = mplace.to_scalar_ptr_align();
if mplace.layout.is_zst() {
self.memory.check_align(ptr, ptr_align)?;
return Ok(Some(Value::Scalar(Scalar::zst().into())));
}
let ptr = ptr.to_ptr()?;
match mplace.layout.abi {
layout::Abi::Scalar(..) => {
let scalar = self.memory.read_scalar(ptr, ptr_align, mplace.layout.size)?;
Ok(Some(Value::Scalar(scalar)))
}
layout::Abi::ScalarPair(ref a, ref b) => {
let (a, b) = (&a.value, &b.value);
let (a_size, b_size) = (a.size(self), b.size(self));
let a_ptr = ptr;
let b_offset = a_size.abi_align(b.align(self));
assert!(b_offset.bytes() > 0);
let b_ptr = ptr.offset(b_offset, self)?.into();
let a_val = self.memory.read_scalar(a_ptr, ptr_align, a_size)?;
let b_val = self.memory.read_scalar(b_ptr, ptr_align, b_size)?;
Ok(Some(Value::ScalarPair(a_val, b_val)))
}
_ => Ok(None),
}
}
pub(crate) fn try_read_value(
&self,
src: OpTy<'tcx>,
) -> EvalResult<'tcx, Result<Value, MemPlace>> {
Ok(match src.try_as_mplace() {
Ok(mplace) => {
if let Some(val) = self.try_read_value_from_mplace(mplace)? {
Ok(val)
} else {
Err(*mplace)
}
},
Err(val) => Ok(val),
})
}
#[inline(always)]
pub fn read_value(&self, op: OpTy<'tcx>) -> EvalResult<'tcx, ValTy<'tcx>> {
if let Ok(value) = self.try_read_value(op)? {
Ok(ValTy { value, layout: op.layout })
} else {
bug!("primitive read failed for type: {:?}", op.layout.ty);
}
}
pub fn read_scalar(&self, op: OpTy<'tcx>) -> EvalResult<'tcx, ScalarMaybeUndef> {
match *self.read_value(op)? {
Value::ScalarPair(..) => bug!("got ScalarPair for type: {:?}", op.layout.ty),
Value::Scalar(val) => Ok(val),
}
}
pub fn read_str(
&self,
mplace: MPlaceTy<'tcx>,
) -> EvalResult<'tcx, &str> {
let len = mplace.len(self)?;
let bytes = self.memory.read_bytes(mplace.ptr, Size::from_bytes(len as u64))?;
let str = ::std::str::from_utf8(bytes)
.map_err(|err| EvalErrorKind::ValidationFailure(err.to_string()))?;
Ok(str)
}
pub fn uninit_operand(&mut self, layout: TyLayout<'tcx>) -> EvalResult<'tcx, Operand> {
if layout.is_zst() {
return Ok(Operand::Immediate(Value::Scalar(Scalar::zst().into())));
}
Ok(match layout.abi {
layout::Abi::Scalar(..) =>
Operand::Immediate(Value::Scalar(ScalarMaybeUndef::Undef)),
layout::Abi::ScalarPair(..) =>
Operand::Immediate(Value::ScalarPair(
ScalarMaybeUndef::Undef,
ScalarMaybeUndef::Undef,
)),
_ => {
trace!("Forcing allocation for local of type {:?}", layout.ty);
Operand::Indirect(
*self.allocate(layout, MemoryKind::Stack)?
)
}
})
}
pub fn operand_field(
&self,
op: OpTy<'tcx>,
field: u64,
) -> EvalResult<'tcx, OpTy<'tcx>> {
let base = match op.try_as_mplace() {
Ok(mplace) => {
let field = self.mplace_field(mplace, field)?;
return Ok(field.into());
},
Err(value) => value
};
let field = field.try_into().unwrap();
let field_layout = op.layout.field(self, field)?;
if field_layout.is_zst() {
let val = Value::Scalar(Scalar::zst().into());
return Ok(OpTy { op: Operand::Immediate(val), layout: field_layout });
}
let offset = op.layout.fields.offset(field);
let value = match base {
_ if offset.bytes() == 0 && field_layout.size == op.layout.size => base,
Value::ScalarPair(a, b) => {
let val = if offset.bytes() == 0 { a } else { b };
Value::Scalar(val)
},
Value::Scalar(val) =>
bug!("field access on non aggregate {:#?}, {:#?}", val, op.layout),
};
Ok(OpTy { op: Operand::Immediate(value), layout: field_layout })
}
pub fn operand_downcast(
&self,
op: OpTy<'tcx>,
variant: usize,
) -> EvalResult<'tcx, OpTy<'tcx>> {
Ok(match op.try_as_mplace() {
Ok(mplace) => {
self.mplace_downcast(mplace, variant)?.into()
},
Err(..) => {
let layout = op.layout.for_variant(self, variant);
OpTy { layout, ..op }
}
})
}
pub(super) fn deref_operand(
&self,
src: OpTy<'tcx>,
) -> EvalResult<'tcx, MPlaceTy<'tcx>> {
let val = self.read_value(src)?;
trace!("deref to {} on {:?}", val.layout.ty, *val);
Ok(self.ref_to_mplace(val)?)
}
pub fn operand_projection(
&self,
base: OpTy<'tcx>,
proj_elem: &mir::PlaceElem<'tcx>,
) -> EvalResult<'tcx, OpTy<'tcx>> {
use rustc::mir::ProjectionElem::*;
Ok(match *proj_elem {
Field(field, _) => self.operand_field(base, field.index() as u64)?,
Downcast(_, variant) => self.operand_downcast(base, variant)?,
Deref => self.deref_operand(base)?.into(),
Subslice { .. } | ConstantIndex { .. } | Index(_) => if base.layout.is_zst() {
OpTy {
op: Operand::Immediate(Value::Scalar(Scalar::zst().into())),
layout: base.layout.field(self, 0)?,
}
} else {
let mplace = base.to_mem_place();
self.mplace_projection(mplace, proj_elem)?.into()
}
})
}
fn eval_place_to_op(
&self,
mir_place: &mir::Place<'tcx>,
layout: Option<TyLayout<'tcx>>,
) -> EvalResult<'tcx, OpTy<'tcx>> {
use rustc::mir::Place::*;
let op = match *mir_place {
Local(mir::RETURN_PLACE) => return err!(ReadFromReturnPointer),
Local(local) => {
let op = *self.frame().locals[local].access()?;
let layout = from_known_layout(layout,
|| self.layout_of_local(self.cur_frame(), local))?;
OpTy { op, layout }
},
Projection(ref proj) => {
let op = self.eval_place_to_op(&proj.base, None)?;
self.operand_projection(op, &proj.elem)?
}
_ => self.eval_place_to_mplace(mir_place)?.into(),
};
trace!("eval_place_to_op: got {:?}", *op);
Ok(op)
}
pub fn eval_operand(
&self,
mir_op: &mir::Operand<'tcx>,
layout: Option<TyLayout<'tcx>>,
) -> EvalResult<'tcx, OpTy<'tcx>> {
use rustc::mir::Operand::*;
let op = match *mir_op {
Copy(ref place) |
Move(ref place) =>
self.eval_place_to_op(place, layout)?,
Constant(ref constant) => {
let layout = from_known_layout(layout, || {
let ty = self.monomorphize(mir_op.ty(self.mir(), *self.tcx), self.substs());
self.layout_of(ty)
})?;
let op = self.const_value_to_op(constant.literal.val)?;
OpTy { op, layout }
}
};
trace!("{:?}: {:?}", mir_op, *op);
Ok(op)
}
pub(super) fn eval_operands(
&self,
ops: &[mir::Operand<'tcx>],
) -> EvalResult<'tcx, Vec<OpTy<'tcx>>> {
ops.into_iter()
.map(|op| self.eval_operand(op, None))
.collect()
}
pub(super) fn const_value_to_op(
&self,
val: ConstValue<'tcx>,
) -> EvalResult<'tcx, Operand> {
trace!("const_value_to_op: {:?}", val);
match val {
ConstValue::Unevaluated(def_id, substs) => {
let instance = self.resolve(def_id, substs)?;
self.global_to_op(GlobalId {
instance,
promoted: None,
})
}
ConstValue::ByRef(id, alloc, offset) => {
Ok(Operand::Indirect(MemPlace::from_ptr(Pointer::new(id, offset), alloc.align)))
},
ConstValue::ScalarPair(a, b) =>
Ok(Operand::Immediate(Value::ScalarPair(a.into(), b))),
ConstValue::Scalar(x) =>
Ok(Operand::Immediate(Value::Scalar(x.into()))),
}
}
pub fn const_to_op(
&self,
cnst: &ty::Const<'tcx>,
) -> EvalResult<'tcx, OpTy<'tcx>> {
let op = self.const_value_to_op(cnst.val)?;
Ok(OpTy { op, layout: self.layout_of(cnst.ty)? })
}
pub(super) fn global_to_op(&self, gid: GlobalId<'tcx>) -> EvalResult<'tcx, Operand> {
let cv = self.const_eval(gid)?;
self.const_value_to_op(cv.val)
}
pub fn read_discriminant(
&self,
rval: OpTy<'tcx>,
) -> EvalResult<'tcx, (u128, usize)> {
trace!("read_discriminant_value {:#?}", rval.layout);
if rval.layout.abi == layout::Abi::Uninhabited {
return err!(Unreachable);
}
match rval.layout.variants {
layout::Variants::Single { index } => {
let discr_val = rval.layout.ty.ty_adt_def().map_or(
index as u128,
|def| def.discriminant_for_variant(*self.tcx, index).val);
return Ok((discr_val, index));
}
layout::Variants::Tagged { .. } |
layout::Variants::NicheFilling { .. } => {},
}
let discr_op = self.operand_field(rval, 0)?;
let discr_val = self.read_value(discr_op)?;
let raw_discr = discr_val.to_scalar()?;
trace!("discr value: {:?}", raw_discr);
Ok(match rval.layout.variants {
layout::Variants::Single { .. } => bug!(),
layout::Variants::Tagged { .. } => {
let real_discr = if discr_val.layout.ty.is_signed() {
let i = raw_discr.to_bits(discr_val.layout.size)? as i128;
let shift = 128 - discr_val.layout.size.bits();
let sexted = (i << shift) >> shift;
let discr_ty = rval.layout.ty
.ty_adt_def().expect("tagged layout corresponds to adt")
.repr
.discr_type();
let discr_ty = layout::Integer::from_attr(self.tcx.tcx, discr_ty);
let shift = 128 - discr_ty.size().bits();
let truncatee = sexted as u128;
(truncatee << shift) >> shift
} else {
raw_discr.to_bits(discr_val.layout.size)?
};
let index = rval.layout.ty
.ty_adt_def()
.expect("tagged layout for non adt")
.discriminants(self.tcx.tcx)
.position(|var| var.val == real_discr)
.ok_or_else(|| EvalErrorKind::InvalidDiscriminant(real_discr))?;
(real_discr, index)
},
layout::Variants::NicheFilling {
dataful_variant,
ref niche_variants,
niche_start,
..
} => {
let variants_start = *niche_variants.start() as u128;
let variants_end = *niche_variants.end() as u128;
let real_discr = match raw_discr {
Scalar::Ptr(_) => {
assert!(niche_start == 0);
assert!(variants_start == variants_end);
dataful_variant as u128
},
Scalar::Bits { bits: raw_discr, size } => {
assert_eq!(size as u64, discr_val.layout.size.bytes());
let discr = raw_discr.wrapping_sub(niche_start)
.wrapping_add(variants_start);
if variants_start <= discr && discr <= variants_end {
discr
} else {
dataful_variant as u128
}
},
};
let index = real_discr as usize;
assert_eq!(index as u128, real_discr);
assert!(index < rval.layout.ty
.ty_adt_def()
.expect("tagged layout for non adt")
.variants.len());
(real_discr, index)
}
})
}
}