/
value.rs
616 lines (535 loc) · 18.6 KB
/
value.rs
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use std::fmt;
use rustc_macros::HashStable;
use rustc_apfloat::{Float, ieee::{Double, Single}};
use crate::ty::{Ty, InferConst, ParamConst, layout::{HasDataLayout, Size, Align}, subst::SubstsRef};
use crate::ty::PlaceholderConst;
use crate::hir::def_id::DefId;
use super::{InterpResult, Pointer, PointerArithmetic, Allocation, AllocId, sign_extend, truncate};
/// Represents the result of a raw const operation, pre-validation.
#[derive(Copy, Clone, Debug, Eq, PartialEq, RustcEncodable, RustcDecodable, Hash, HashStable)]
pub struct RawConst<'tcx> {
// the value lives here, at offset 0, and that allocation definitely is a `AllocKind::Memory`
// (so you can use `AllocMap::unwrap_memory`).
pub alloc_id: AllocId,
pub ty: Ty<'tcx>,
}
/// Represents a constant value in Rust. `Scalar` and `ScalarPair` are optimizations that
/// match the `LocalState` optimizations for easy conversions between `Value` and `ConstValue`.
#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord,
RustcEncodable, RustcDecodable, Hash, HashStable)]
pub enum ConstValue<'tcx> {
/// A const generic parameter.
Param(ParamConst),
/// Infer the value of the const.
Infer(InferConst<'tcx>),
/// A placeholder const - universally quantified higher-ranked const.
Placeholder(PlaceholderConst),
/// Used only for types with `layout::abi::Scalar` ABI and ZSTs.
///
/// Not using the enum `Value` to encode that this must not be `Undef`.
Scalar(Scalar),
/// Used only for `&[u8]` and `&str`
Slice {
data: &'tcx Allocation,
start: usize,
end: usize,
},
/// An allocation together with an offset into the allocation.
/// The alignment exists to allow `const_field` to have `ByRef` access to nonprimitive fields
/// of `repr(packed)` structs. The alignment may be lower than the type of this constant.
/// This permits reads with lower alignment than what the type would normally require.
/// FIXME(RalfJ,oli-obk): The alignment checks are part of miri, but const eval doesn't really
/// need them. Disabling them may be too hard though.
ByRef(Size, Align, &'tcx Allocation),
/// Used in the HIR by using `Unevaluated` everywhere and later normalizing to one of the other
/// variants when the code is monomorphic enough for that.
Unevaluated(DefId, SubstsRef<'tcx>),
}
#[cfg(target_arch = "x86_64")]
static_assert_size!(ConstValue<'_>, 32);
impl<'tcx> ConstValue<'tcx> {
#[inline]
pub fn try_to_scalar(&self) -> Option<Scalar> {
match *self {
ConstValue::Param(_) |
ConstValue::Infer(_) |
ConstValue::Placeholder(_) |
ConstValue::ByRef(..) |
ConstValue::Unevaluated(..) |
ConstValue::Slice { .. } => None,
ConstValue::Scalar(val) => Some(val),
}
}
#[inline]
pub fn try_to_bits(&self, size: Size) -> Option<u128> {
self.try_to_scalar()?.to_bits(size).ok()
}
#[inline]
pub fn try_to_ptr(&self) -> Option<Pointer> {
self.try_to_scalar()?.to_ptr().ok()
}
}
/// A `Scalar` represents an immediate, primitive value existing outside of a
/// `memory::Allocation`. It is in many ways like a small chunk of a `Allocation`, up to 8 bytes in
/// size. Like a range of bytes in an `Allocation`, a `Scalar` can either represent the raw bytes
/// of a simple value or a pointer into another `Allocation`
#[derive(Clone, Copy, Eq, PartialEq, Ord, PartialOrd,
RustcEncodable, RustcDecodable, Hash, HashStable)]
pub enum Scalar<Tag=(), Id=AllocId> {
/// The raw bytes of a simple value.
Raw {
/// The first `size` bytes of `data` are the value.
/// Do not try to read less or more bytes than that. The remaining bytes must be 0.
data: u128,
size: u8,
},
/// A pointer into an `Allocation`. An `Allocation` in the `memory` module has a list of
/// relocations, but a `Scalar` is only large enough to contain one, so we just represent the
/// relocation and its associated offset together as a `Pointer` here.
Ptr(Pointer<Tag, Id>),
}
#[cfg(target_arch = "x86_64")]
static_assert_size!(Scalar, 24);
impl<Tag: fmt::Debug, Id: fmt::Debug> fmt::Debug for Scalar<Tag, Id> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Scalar::Ptr(ptr) =>
write!(f, "{:?}", ptr),
&Scalar::Raw { data, size } => {
Scalar::check_data(data, size);
if size == 0 {
write!(f, "<ZST>")
} else {
// Format as hex number wide enough to fit any value of the given `size`.
// So data=20, size=1 will be "0x14", but with size=4 it'll be "0x00000014".
write!(f, "0x{:>0width$x}", data, width=(size*2) as usize)
}
}
}
}
}
impl<Tag> fmt::Display for Scalar<Tag> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Scalar::Ptr(_) => write!(f, "a pointer"),
Scalar::Raw { data, .. } => write!(f, "{}", data),
}
}
}
impl<Tag> From<Single> for Scalar<Tag> {
#[inline(always)]
fn from(f: Single) -> Self {
Scalar::from_f32(f)
}
}
impl<Tag> From<Double> for Scalar<Tag> {
#[inline(always)]
fn from(f: Double) -> Self {
Scalar::from_f64(f)
}
}
impl Scalar<()> {
#[inline(always)]
fn check_data(data: u128, size: u8) {
debug_assert_eq!(truncate(data, Size::from_bytes(size as u64)), data,
"Scalar value {:#x} exceeds size of {} bytes", data, size);
}
/// Tag this scalar with `new_tag` if it is a pointer, leave it unchanged otherwise.
///
/// Used by `MemPlace::replace_tag`.
#[inline]
pub fn with_tag<Tag>(self, new_tag: Tag) -> Scalar<Tag> {
match self {
Scalar::Ptr(ptr) => Scalar::Ptr(ptr.with_tag(new_tag)),
Scalar::Raw { data, size } => Scalar::Raw { data, size },
}
}
}
impl<'tcx, Tag> Scalar<Tag> {
/// Erase the tag from the scalar, if any.
///
/// Used by error reporting code to avoid having the error type depend on `Tag`.
#[inline]
pub fn erase_tag(self) -> Scalar {
match self {
Scalar::Ptr(ptr) => Scalar::Ptr(ptr.erase_tag()),
Scalar::Raw { data, size } => Scalar::Raw { data, size },
}
}
#[inline]
pub fn ptr_null(cx: &impl HasDataLayout) -> Self {
Scalar::Raw {
data: 0,
size: cx.data_layout().pointer_size.bytes() as u8,
}
}
#[inline]
pub fn zst() -> Self {
Scalar::Raw { data: 0, size: 0 }
}
#[inline]
pub fn ptr_offset(self, i: Size, cx: &impl HasDataLayout) -> InterpResult<'tcx, Self> {
let dl = cx.data_layout();
match self {
Scalar::Raw { data, size } => {
assert_eq!(size as u64, dl.pointer_size.bytes());
Ok(Scalar::Raw {
data: dl.offset(data as u64, i.bytes())? as u128,
size,
})
}
Scalar::Ptr(ptr) => ptr.offset(i, dl).map(Scalar::Ptr),
}
}
#[inline]
pub fn ptr_wrapping_offset(self, i: Size, cx: &impl HasDataLayout) -> Self {
let dl = cx.data_layout();
match self {
Scalar::Raw { data, size } => {
assert_eq!(size as u64, dl.pointer_size.bytes());
Scalar::Raw {
data: dl.overflowing_offset(data as u64, i.bytes()).0 as u128,
size,
}
}
Scalar::Ptr(ptr) => Scalar::Ptr(ptr.wrapping_offset(i, dl)),
}
}
#[inline]
pub fn ptr_signed_offset(self, i: i64, cx: &impl HasDataLayout) -> InterpResult<'tcx, Self> {
let dl = cx.data_layout();
match self {
Scalar::Raw { data, size } => {
assert_eq!(size as u64, dl.pointer_size().bytes());
Ok(Scalar::Raw {
data: dl.signed_offset(data as u64, i)? as u128,
size,
})
}
Scalar::Ptr(ptr) => ptr.signed_offset(i, dl).map(Scalar::Ptr),
}
}
#[inline]
pub fn ptr_wrapping_signed_offset(self, i: i64, cx: &impl HasDataLayout) -> Self {
let dl = cx.data_layout();
match self {
Scalar::Raw { data, size } => {
assert_eq!(size as u64, dl.pointer_size.bytes());
Scalar::Raw {
data: dl.overflowing_signed_offset(data as u64, i128::from(i)).0 as u128,
size,
}
}
Scalar::Ptr(ptr) => Scalar::Ptr(ptr.wrapping_signed_offset(i, dl)),
}
}
/// Returns this pointer's offset from the allocation base, or from NULL (for
/// integer pointers).
#[inline]
pub fn get_ptr_offset(self, cx: &impl HasDataLayout) -> Size {
match self {
Scalar::Raw { data, size } => {
assert_eq!(size as u64, cx.pointer_size().bytes());
Size::from_bytes(data as u64)
}
Scalar::Ptr(ptr) => ptr.offset,
}
}
#[inline]
pub fn is_null_ptr(self, cx: &impl HasDataLayout) -> bool {
match self {
Scalar::Raw { data, size } => {
assert_eq!(size as u64, cx.data_layout().pointer_size.bytes());
data == 0
},
Scalar::Ptr(_) => false,
}
}
#[inline]
pub fn from_bool(b: bool) -> Self {
Scalar::Raw { data: b as u128, size: 1 }
}
#[inline]
pub fn from_char(c: char) -> Self {
Scalar::Raw { data: c as u128, size: 4 }
}
#[inline]
pub fn from_uint(i: impl Into<u128>, size: Size) -> Self {
let i = i.into();
assert_eq!(
truncate(i, size), i,
"Unsigned value {:#x} does not fit in {} bits", i, size.bits()
);
Scalar::Raw { data: i, size: size.bytes() as u8 }
}
#[inline]
pub fn from_u8(i: u8) -> Self {
Scalar::Raw { data: i as u128, size: 1 }
}
#[inline]
pub fn from_u16(i: u16) -> Self {
Scalar::Raw { data: i as u128, size: 2 }
}
#[inline]
pub fn from_u32(i: u32) -> Self {
Scalar::Raw { data: i as u128, size: 4 }
}
#[inline]
pub fn from_u64(i: u64) -> Self {
Scalar::Raw { data: i as u128, size: 8 }
}
#[inline]
pub fn from_int(i: impl Into<i128>, size: Size) -> Self {
let i = i.into();
// `into` performed sign extension, we have to truncate
let truncated = truncate(i as u128, size);
assert_eq!(
sign_extend(truncated, size) as i128, i,
"Signed value {:#x} does not fit in {} bits", i, size.bits()
);
Scalar::Raw { data: truncated, size: size.bytes() as u8 }
}
#[inline]
pub fn from_f32(f: Single) -> Self {
// We trust apfloat to give us properly truncated data.
Scalar::Raw { data: f.to_bits(), size: 4 }
}
#[inline]
pub fn from_f64(f: Double) -> Self {
// We trust apfloat to give us properly truncated data.
Scalar::Raw { data: f.to_bits(), size: 8 }
}
#[inline]
pub fn to_bits_or_ptr(
self,
target_size: Size,
cx: &impl HasDataLayout,
) -> Result<u128, Pointer<Tag>> {
match self {
Scalar::Raw { data, size } => {
assert_eq!(target_size.bytes(), size as u64);
assert_ne!(size, 0, "you should never look at the bits of a ZST");
Scalar::check_data(data, size);
Ok(data)
}
Scalar::Ptr(ptr) => {
assert_eq!(target_size, cx.data_layout().pointer_size);
Err(ptr)
}
}
}
#[inline]
pub fn to_bits(self, target_size: Size) -> InterpResult<'tcx, u128> {
match self {
Scalar::Raw { data, size } => {
assert_eq!(target_size.bytes(), size as u64);
assert_ne!(size, 0, "you should never look at the bits of a ZST");
Scalar::check_data(data, size);
Ok(data)
}
Scalar::Ptr(_) => err!(ReadPointerAsBytes),
}
}
#[inline]
pub fn to_ptr(self) -> InterpResult<'tcx, Pointer<Tag>> {
match self {
Scalar::Raw { data: 0, .. } => err!(InvalidNullPointerUsage),
Scalar::Raw { .. } => err!(ReadBytesAsPointer),
Scalar::Ptr(p) => Ok(p),
}
}
#[inline]
pub fn is_bits(self) -> bool {
match self {
Scalar::Raw { .. } => true,
_ => false,
}
}
#[inline]
pub fn is_ptr(self) -> bool {
match self {
Scalar::Ptr(_) => true,
_ => false,
}
}
pub fn to_bool(self) -> InterpResult<'tcx, bool> {
match self {
Scalar::Raw { data: 0, size: 1 } => Ok(false),
Scalar::Raw { data: 1, size: 1 } => Ok(true),
_ => err!(InvalidBool),
}
}
pub fn to_char(self) -> InterpResult<'tcx, char> {
let val = self.to_u32()?;
match ::std::char::from_u32(val) {
Some(c) => Ok(c),
None => err!(InvalidChar(val as u128)),
}
}
pub fn to_u8(self) -> InterpResult<'static, u8> {
let sz = Size::from_bits(8);
let b = self.to_bits(sz)?;
Ok(b as u8)
}
pub fn to_u32(self) -> InterpResult<'static, u32> {
let sz = Size::from_bits(32);
let b = self.to_bits(sz)?;
Ok(b as u32)
}
pub fn to_u64(self) -> InterpResult<'static, u64> {
let sz = Size::from_bits(64);
let b = self.to_bits(sz)?;
Ok(b as u64)
}
pub fn to_usize(self, cx: &impl HasDataLayout) -> InterpResult<'static, u64> {
let b = self.to_bits(cx.data_layout().pointer_size)?;
Ok(b as u64)
}
pub fn to_i8(self) -> InterpResult<'static, i8> {
let sz = Size::from_bits(8);
let b = self.to_bits(sz)?;
let b = sign_extend(b, sz) as i128;
Ok(b as i8)
}
pub fn to_i32(self) -> InterpResult<'static, i32> {
let sz = Size::from_bits(32);
let b = self.to_bits(sz)?;
let b = sign_extend(b, sz) as i128;
Ok(b as i32)
}
pub fn to_i64(self) -> InterpResult<'static, i64> {
let sz = Size::from_bits(64);
let b = self.to_bits(sz)?;
let b = sign_extend(b, sz) as i128;
Ok(b as i64)
}
pub fn to_isize(self, cx: &impl HasDataLayout) -> InterpResult<'static, i64> {
let sz = cx.data_layout().pointer_size;
let b = self.to_bits(sz)?;
let b = sign_extend(b, sz) as i128;
Ok(b as i64)
}
#[inline]
pub fn to_f32(self) -> InterpResult<'static, Single> {
// Going through `u32` to check size and truncation.
Ok(Single::from_bits(self.to_u32()? as u128))
}
#[inline]
pub fn to_f64(self) -> InterpResult<'static, Double> {
// Going through `u64` to check size and truncation.
Ok(Double::from_bits(self.to_u64()? as u128))
}
}
impl<Tag> From<Pointer<Tag>> for Scalar<Tag> {
#[inline(always)]
fn from(ptr: Pointer<Tag>) -> Self {
Scalar::Ptr(ptr)
}
}
#[derive(Clone, Copy, Eq, PartialEq, Ord, PartialOrd, RustcEncodable, RustcDecodable, Hash)]
pub enum ScalarMaybeUndef<Tag=(), Id=AllocId> {
Scalar(Scalar<Tag, Id>),
Undef,
}
impl<Tag> From<Scalar<Tag>> for ScalarMaybeUndef<Tag> {
#[inline(always)]
fn from(s: Scalar<Tag>) -> Self {
ScalarMaybeUndef::Scalar(s)
}
}
impl<Tag: fmt::Debug, Id: fmt::Debug> fmt::Debug for ScalarMaybeUndef<Tag, Id> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
ScalarMaybeUndef::Undef => write!(f, "Undef"),
ScalarMaybeUndef::Scalar(s) => write!(f, "{:?}", s),
}
}
}
impl<Tag> fmt::Display for ScalarMaybeUndef<Tag> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
ScalarMaybeUndef::Undef => write!(f, "uninitialized bytes"),
ScalarMaybeUndef::Scalar(s) => write!(f, "{}", s),
}
}
}
impl<'tcx, Tag> ScalarMaybeUndef<Tag> {
/// Erase the tag from the scalar, if any.
///
/// Used by error reporting code to avoid having the error type depend on `Tag`.
#[inline]
pub fn erase_tag(self) -> ScalarMaybeUndef
{
match self {
ScalarMaybeUndef::Scalar(s) => ScalarMaybeUndef::Scalar(s.erase_tag()),
ScalarMaybeUndef::Undef => ScalarMaybeUndef::Undef,
}
}
#[inline]
pub fn not_undef(self) -> InterpResult<'static, Scalar<Tag>> {
match self {
ScalarMaybeUndef::Scalar(scalar) => Ok(scalar),
ScalarMaybeUndef::Undef => err!(ReadUndefBytes(Size::from_bytes(0))),
}
}
#[inline(always)]
pub fn to_ptr(self) -> InterpResult<'tcx, Pointer<Tag>> {
self.not_undef()?.to_ptr()
}
#[inline(always)]
pub fn to_bits(self, target_size: Size) -> InterpResult<'tcx, u128> {
self.not_undef()?.to_bits(target_size)
}
#[inline(always)]
pub fn to_bool(self) -> InterpResult<'tcx, bool> {
self.not_undef()?.to_bool()
}
#[inline(always)]
pub fn to_char(self) -> InterpResult<'tcx, char> {
self.not_undef()?.to_char()
}
#[inline(always)]
pub fn to_f32(self) -> InterpResult<'tcx, Single> {
self.not_undef()?.to_f32()
}
#[inline(always)]
pub fn to_f64(self) -> InterpResult<'tcx, Double> {
self.not_undef()?.to_f64()
}
#[inline(always)]
pub fn to_u8(self) -> InterpResult<'tcx, u8> {
self.not_undef()?.to_u8()
}
#[inline(always)]
pub fn to_u32(self) -> InterpResult<'tcx, u32> {
self.not_undef()?.to_u32()
}
#[inline(always)]
pub fn to_u64(self) -> InterpResult<'tcx, u64> {
self.not_undef()?.to_u64()
}
#[inline(always)]
pub fn to_usize(self, cx: &impl HasDataLayout) -> InterpResult<'tcx, u64> {
self.not_undef()?.to_usize(cx)
}
#[inline(always)]
pub fn to_i8(self) -> InterpResult<'tcx, i8> {
self.not_undef()?.to_i8()
}
#[inline(always)]
pub fn to_i32(self) -> InterpResult<'tcx, i32> {
self.not_undef()?.to_i32()
}
#[inline(always)]
pub fn to_i64(self) -> InterpResult<'tcx, i64> {
self.not_undef()?.to_i64()
}
#[inline(always)]
pub fn to_isize(self, cx: &impl HasDataLayout) -> InterpResult<'tcx, i64> {
self.not_undef()?.to_isize(cx)
}
}
impl_stable_hash_for!(enum crate::mir::interpret::ScalarMaybeUndef {
Scalar(v),
Undef
});