compiler/rustc_middle/src/mir/interpret/value.rs

   1 use std::convert::TryFrom;
   2 use std::fmt;
   3
   4 use rustc_apfloat::{
   5     ieee::{Double, Single},
   6     Float,
   7 };
   8 use rustc_macros::HashStable;
   9 use rustc_target::abi::{HasDataLayout, Size, TargetDataLayout};
  10
  11 use crate::ty::{ParamEnv, ScalarInt, Ty, TyCtxt};
  12
  13 use super::{AllocId, Allocation, InterpResult, Pointer, PointerArithmetic};
  14
  15 /// Represents the result of const evaluation via the `eval_to_allocation` query.
  16 #[derive(Clone, HashStable, TyEncodable, TyDecodable)]
  17 pub struct ConstAlloc<'tcx> {
  18     // the value lives here, at offset 0, and that allocation definitely is a `AllocKind::Memory`
  19     // (so you can use `AllocMap::unwrap_memory`).
  20     pub alloc_id: AllocId,
  21     pub ty: Ty<'tcx>,
  22 }
  23
  24 /// Represents a constant value in Rust. `Scalar` and `Slice` are optimizations for
  25 /// array length computations, enum discriminants and the pattern matching logic.
  26 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Hash)]
  27 #[derive(HashStable)]
  28 pub enum ConstValue<'tcx> {
  29     /// Used only for types with `layout::abi::Scalar` ABI and ZSTs.
  30     ///
  31     /// Not using the enum `Value` to encode that this must not be `Uninit`.
  32     Scalar(Scalar),
  33
  34     /// Used only for `&[u8]` and `&str`
  35     Slice { data: &'tcx Allocation, start: usize, end: usize },
  36
  37     /// A value not represented/representable by `Scalar` or `Slice`
  38     ByRef {
  39         /// The backing memory of the value, may contain more memory than needed for just the value
  40         /// in order to share `Allocation`s between values
  41         alloc: &'tcx Allocation,
  42         /// Offset into `alloc`
  43         offset: Size,
  44     },
  45 }
  46
  47 #[cfg(target_arch = "x86_64")]
  48 static_assert_size!(ConstValue<'_>, 32);
  49
  50 impl<'tcx> ConstValue<'tcx> {
  51     #[inline]
  52     pub fn try_to_scalar(&self) -> Option<Scalar> {
  53         match *self {
  54             ConstValue::ByRef { .. } | ConstValue::Slice { .. } => None,
  55             ConstValue::Scalar(val) => Some(val),
  56         }
  57     }
  58
  59     pub fn try_to_bits(&self, size: Size) -> Option<u128> {
  60         self.try_to_scalar()?.to_bits(size).ok()
  61     }
  62
  63     pub fn try_to_bool(&self) -> Option<bool> {
  64         match self.try_to_bits(Size::from_bytes(1))? {
  65             0 => Some(false),
  66             1 => Some(true),
  67             _ => None,
  68         }
  69     }
  70
  71     pub fn try_to_machine_usize(&self, tcx: TyCtxt<'tcx>) -> Option<u64> {
  72         Some(self.try_to_bits(tcx.data_layout.pointer_size)? as u64)
  73     }
  74
  75     pub fn try_to_bits_for_ty(
  76         &self,
  77         tcx: TyCtxt<'tcx>,
  78         param_env: ParamEnv<'tcx>,
  79         ty: Ty<'tcx>,
  80     ) -> Option<u128> {
  81         let size = tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size;
  82         self.try_to_bits(size)
  83     }
  84
  85     pub fn from_bool(b: bool) -> Self {
  86         ConstValue::Scalar(Scalar::from_bool(b))
  87     }
  88
  89     pub fn from_u64(i: u64) -> Self {
  90         ConstValue::Scalar(Scalar::from_u64(i))
  91     }
  92
  93     pub fn from_machine_usize(i: u64, cx: &impl HasDataLayout) -> Self {
  94         ConstValue::Scalar(Scalar::from_machine_usize(i, cx))
  95     }
  96 }
  97
  98 /// A `Scalar` represents an immediate, primitive value existing outside of a
  99 /// `memory::Allocation`. It is in many ways like a small chunk of a `Allocation`, up to 8 bytes in
 100 /// size. Like a range of bytes in an `Allocation`, a `Scalar` can either represent the raw bytes
 101 /// of a simple value or a pointer into another `Allocation`
 102 #[derive(Clone, Copy, Eq, PartialEq, Ord, PartialOrd, TyEncodable, TyDecodable, Hash)]
 103 #[derive(HashStable)]
 104 pub enum Scalar<Tag = ()> {
 105     /// The raw bytes of a simple value.
 106     Int(ScalarInt),
 107
 108     /// A pointer into an `Allocation`. An `Allocation` in the `memory` module has a list of
 109     /// relocations, but a `Scalar` is only large enough to contain one, so we just represent the
 110     /// relocation and its associated offset together as a `Pointer` here.
 111     Ptr(Pointer<Tag>),
 112 }
 113
 114 #[cfg(target_arch = "x86_64")]
 115 static_assert_size!(Scalar, 24);
 116
 117 // We want the `Debug` output to be readable as it is used by `derive(Debug)` for
 118 // all the Miri types.
 119 impl<Tag: fmt::Debug> fmt::Debug for Scalar<Tag> {
 120     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 121         match self {
 122             Scalar::Ptr(ptr) => write!(f, "{:?}", ptr),
 123             Scalar::Int(int) => write!(f, "{:?}", int),
 124         }
 125     }
 126 }
 127
 128 impl<Tag: fmt::Debug> fmt::Display for Scalar<Tag> {
 129     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 130         match self {
 131             Scalar::Ptr(ptr) => write!(f, "pointer to {}", ptr),
 132             Scalar::Int { .. } => fmt::Debug::fmt(self, f),
 133         }
 134     }
 135 }
 136
 137 impl<Tag> From<Single> for Scalar<Tag> {
 138     #[inline(always)]
 139     fn from(f: Single) -> Self {
 140         Scalar::from_f32(f)
 141     }
 142 }
 143
 144 impl<Tag> From<Double> for Scalar<Tag> {
 145     #[inline(always)]
 146     fn from(f: Double) -> Self {
 147         Scalar::from_f64(f)
 148     }
 149 }
 150
 151 impl Scalar<()> {
 152     /// Tag this scalar with `new_tag` if it is a pointer, leave it unchanged otherwise.
 153     ///
 154     /// Used by `MemPlace::replace_tag`.
 155     #[inline]
 156     pub fn with_tag<Tag>(self, new_tag: Tag) -> Scalar<Tag> {
 157         match self {
 158             Scalar::Ptr(ptr) => Scalar::Ptr(ptr.with_tag(new_tag)),
 159             Scalar::Int(int) => Scalar::Int(int),
 160         }
 161     }
 162 }
 163
 164 impl<'tcx, Tag> Scalar<Tag> {
 165     pub const ZST: Self = Scalar::Int(ScalarInt::ZST);
 166
 167     /// Erase the tag from the scalar, if any.
 168     ///
 169     /// Used by error reporting code to avoid having the error type depend on `Tag`.
 170     #[inline]
 171     pub fn erase_tag(self) -> Scalar {
 172         match self {
 173             Scalar::Ptr(ptr) => Scalar::Ptr(ptr.erase_tag()),
 174             Scalar::Int(int) => Scalar::Int(int),
 175         }
 176     }
 177
 178     #[inline]
 179     pub fn null_ptr(cx: &impl HasDataLayout) -> Self {
 180         Scalar::Int(ScalarInt::null(cx.data_layout().pointer_size))
 181     }
 182
 183     #[inline(always)]
 184     fn ptr_op(
 185         self,
 186         dl: &TargetDataLayout,
 187         f_int: impl FnOnce(u64) -> InterpResult<'tcx, u64>,
 188         f_ptr: impl FnOnce(Pointer<Tag>) -> InterpResult<'tcx, Pointer<Tag>>,
 189     ) -> InterpResult<'tcx, Self> {
 190         match self {
 191             Scalar::Int(int) => Ok(Scalar::Int(int.ptr_sized_op(dl, f_int)?)),
 192             Scalar::Ptr(ptr) => Ok(Scalar::Ptr(f_ptr(ptr)?)),
 193         }
 194     }
 195
 196     #[inline]
 197     pub fn ptr_offset(self, i: Size, cx: &impl HasDataLayout) -> InterpResult<'tcx, Self> {
 198         let dl = cx.data_layout();
 199         self.ptr_op(dl, |int| dl.offset(int, i.bytes()), |ptr| ptr.offset(i, dl))
 200     }
 201
 202     #[inline]
 203     pub fn ptr_wrapping_offset(self, i: Size, cx: &impl HasDataLayout) -> Self {
 204         let dl = cx.data_layout();
 205         self.ptr_op(
 206             dl,
 207             |int| Ok(dl.overflowing_offset(int, i.bytes()).0),
 208             |ptr| Ok(ptr.wrapping_offset(i, dl)),
 209         )
 210         .unwrap()
 211     }
 212
 213     #[inline]
 214     pub fn ptr_signed_offset(self, i: i64, cx: &impl HasDataLayout) -> InterpResult<'tcx, Self> {
 215         let dl = cx.data_layout();
 216         self.ptr_op(dl, |int| dl.signed_offset(int, i), |ptr| ptr.signed_offset(i, dl))
 217     }
 218
 219     #[inline]
 220     pub fn ptr_wrapping_signed_offset(self, i: i64, cx: &impl HasDataLayout) -> Self {
 221         let dl = cx.data_layout();
 222         self.ptr_op(
 223             dl,
 224             |int| Ok(dl.overflowing_signed_offset(int, i).0),
 225             |ptr| Ok(ptr.wrapping_signed_offset(i, dl)),
 226         )
 227         .unwrap()
 228     }
 229
 230     #[inline]
 231     pub fn from_bool(b: bool) -> Self {
 232         Scalar::Int(b.into())
 233     }
 234
 235     #[inline]
 236     pub fn from_char(c: char) -> Self {
 237         Scalar::Int(c.into())
 238     }
 239
 240     #[inline]
 241     pub fn try_from_uint(i: impl Into<u128>, size: Size) -> Option<Self> {
 242         ScalarInt::try_from_uint(i, size).map(Scalar::Int)
 243     }
 244
 245     #[inline]
 246     pub fn from_uint(i: impl Into<u128>, size: Size) -> Self {
 247         let i = i.into();
 248         Self::try_from_uint(i, size)
 249             .unwrap_or_else(|| bug!("Unsigned value {:#x} does not fit in {} bits", i, size.bits()))
 250     }
 251
 252     #[inline]
 253     pub fn from_u8(i: u8) -> Self {
 254         Scalar::Int(i.into())
 255     }
 256
 257     #[inline]
 258     pub fn from_u16(i: u16) -> Self {
 259         Scalar::Int(i.into())
 260     }
 261
 262     #[inline]
 263     pub fn from_u32(i: u32) -> Self {
 264         Scalar::Int(i.into())
 265     }
 266
 267     #[inline]
 268     pub fn from_u64(i: u64) -> Self {
 269         Scalar::Int(i.into())
 270     }
 271
 272     #[inline]
 273     pub fn from_machine_usize(i: u64, cx: &impl HasDataLayout) -> Self {
 274         Self::from_uint(i, cx.data_layout().pointer_size)
 275     }
 276
 277     #[inline]
 278     pub fn try_from_int(i: impl Into<i128>, size: Size) -> Option<Self> {
 279         ScalarInt::try_from_int(i, size).map(Scalar::Int)
 280     }
 281
 282     #[inline]
 283     pub fn from_int(i: impl Into<i128>, size: Size) -> Self {
 284         let i = i.into();
 285         Self::try_from_int(i, size)
 286             .unwrap_or_else(|| bug!("Signed value {:#x} does not fit in {} bits", i, size.bits()))
 287     }
 288
 289     #[inline]
 290     pub fn from_i8(i: i8) -> Self {
 291         Self::from_int(i, Size::from_bits(8))
 292     }
 293
 294     #[inline]
 295     pub fn from_i16(i: i16) -> Self {
 296         Self::from_int(i, Size::from_bits(16))
 297     }
 298
 299     #[inline]
 300     pub fn from_i32(i: i32) -> Self {
 301         Self::from_int(i, Size::from_bits(32))
 302     }
 303
 304     #[inline]
 305     pub fn from_i64(i: i64) -> Self {
 306         Self::from_int(i, Size::from_bits(64))
 307     }
 308
 309     #[inline]
 310     pub fn from_machine_isize(i: i64, cx: &impl HasDataLayout) -> Self {
 311         Self::from_int(i, cx.data_layout().pointer_size)
 312     }
 313
 314     #[inline]
 315     pub fn from_f32(f: Single) -> Self {
 316         Scalar::Int(f.into())
 317     }
 318
 319     #[inline]
 320     pub fn from_f64(f: Double) -> Self {
 321         Scalar::Int(f.into())
 322     }
 323
 324     /// This is very rarely the method you want!  You should dispatch on the type
 325     /// and use `force_bits`/`assert_bits`/`force_ptr`/`assert_ptr`.
 326     /// This method only exists for the benefit of low-level memory operations
 327     /// as well as the implementation of the `force_*` methods.
 328     #[inline]
 329     pub fn to_bits_or_ptr(
 330         self,
 331         target_size: Size,
 332         cx: &impl HasDataLayout,
 333     ) -> Result<u128, Pointer<Tag>> {
 334         assert_ne!(target_size.bytes(), 0, "you should never look at the bits of a ZST");
 335         match self {
 336             Scalar::Int(int) => Ok(int.assert_bits(target_size)),
 337             Scalar::Ptr(ptr) => {
 338                 assert_eq!(target_size, cx.data_layout().pointer_size);
 339                 Err(ptr)
 340             }
 341         }
 342     }
 343
 344     /// This method is intentionally private!
 345     /// It is just a helper for other methods in this file.
 346     #[inline]
 347     fn to_bits(self, target_size: Size) -> InterpResult<'tcx, u128> {
 348         assert_ne!(target_size.bytes(), 0, "you should never look at the bits of a ZST");
 349         match self {
 350             Scalar::Int(int) => int.to_bits(target_size).map_err(|size| {
 351                 err_ub!(ScalarSizeMismatch {
 352                     target_size: target_size.bytes(),
 353                     data_size: size.bytes(),
 354                 })
 355                 .into()
 356             }),
 357             Scalar::Ptr(_) => throw_unsup!(ReadPointerAsBytes),
 358         }
 359     }
 360
 361     #[inline(always)]
 362     pub fn assert_bits(self, target_size: Size) -> u128 {
 363         self.to_bits(target_size).expect("expected Raw bits but got a Pointer")
 364     }
 365
 366     #[inline]
 367     pub fn assert_int(self) -> ScalarInt {
 368         match self {
 369             Scalar::Ptr(_) => bug!("expected an int but got an abstract pointer"),
 370             Scalar::Int(int) => int,
 371         }
 372     }
 373
 374     #[inline]
 375     pub fn assert_ptr(self) -> Pointer<Tag> {
 376         match self {
 377             Scalar::Ptr(p) => p,
 378             Scalar::Int { .. } => bug!("expected a Pointer but got Raw bits"),
 379         }
 380     }
 381
 382     /// Do not call this method!  Dispatch based on the type instead.
 383     #[inline]
 384     pub fn is_bits(self) -> bool {
 385         matches!(self, Scalar::Int { .. })
 386     }
 387
 388     /// Do not call this method!  Dispatch based on the type instead.
 389     #[inline]
 390     pub fn is_ptr(self) -> bool {
 391         matches!(self, Scalar::Ptr(_))
 392     }
 393
 394     pub fn to_bool(self) -> InterpResult<'tcx, bool> {
 395         let val = self.to_u8()?;
 396         match val {
 397             0 => Ok(false),
 398             1 => Ok(true),
 399             _ => throw_ub!(InvalidBool(val)),
 400         }
 401     }
 402
 403     pub fn to_char(self) -> InterpResult<'tcx, char> {
 404         let val = self.to_u32()?;
 405         match std::char::from_u32(val) {
 406             Some(c) => Ok(c),
 407             None => throw_ub!(InvalidChar(val)),
 408         }
 409     }
 410
 411     #[inline]
 412     fn to_unsigned_with_bit_width(self, bits: u64) -> InterpResult<'static, u128> {
 413         let sz = Size::from_bits(bits);
 414         self.to_bits(sz)
 415     }
 416
 417     /// Converts the scalar to produce an `u8`. Fails if the scalar is a pointer.
 418     pub fn to_u8(self) -> InterpResult<'static, u8> {
 419         self.to_unsigned_with_bit_width(8).map(|v| u8::try_from(v).unwrap())
 420     }
 421
 422     /// Converts the scalar to produce an `u16`. Fails if the scalar is a pointer.
 423     pub fn to_u16(self) -> InterpResult<'static, u16> {
 424         self.to_unsigned_with_bit_width(16).map(|v| u16::try_from(v).unwrap())
 425     }
 426
 427     /// Converts the scalar to produce an `u32`. Fails if the scalar is a pointer.
 428     pub fn to_u32(self) -> InterpResult<'static, u32> {
 429         self.to_unsigned_with_bit_width(32).map(|v| u32::try_from(v).unwrap())
 430     }
 431
 432     /// Converts the scalar to produce an `u64`. Fails if the scalar is a pointer.
 433     pub fn to_u64(self) -> InterpResult<'static, u64> {
 434         self.to_unsigned_with_bit_width(64).map(|v| u64::try_from(v).unwrap())
 435     }
 436
 437     /// Converts the scalar to produce an `u128`. Fails if the scalar is a pointer.
 438     pub fn to_u128(self) -> InterpResult<'static, u128> {
 439         self.to_unsigned_with_bit_width(128)
 440     }
 441
 442     pub fn to_machine_usize(self, cx: &impl HasDataLayout) -> InterpResult<'static, u64> {
 443         let b = self.to_bits(cx.data_layout().pointer_size)?;
 444         Ok(u64::try_from(b).unwrap())
 445     }
 446
 447     #[inline]
 448     fn to_signed_with_bit_width(self, bits: u64) -> InterpResult<'static, i128> {
 449         let sz = Size::from_bits(bits);
 450         let b = self.to_bits(sz)?;
 451         Ok(sz.sign_extend(b) as i128)
 452     }
 453
 454     /// Converts the scalar to produce an `i8`. Fails if the scalar is a pointer.
 455     pub fn to_i8(self) -> InterpResult<'static, i8> {
 456         self.to_signed_with_bit_width(8).map(|v| i8::try_from(v).unwrap())
 457     }
 458
 459     /// Converts the scalar to produce an `i16`. Fails if the scalar is a pointer.
 460     pub fn to_i16(self) -> InterpResult<'static, i16> {
 461         self.to_signed_with_bit_width(16).map(|v| i16::try_from(v).unwrap())
 462     }
 463
 464     /// Converts the scalar to produce an `i32`. Fails if the scalar is a pointer.
 465     pub fn to_i32(self) -> InterpResult<'static, i32> {
 466         self.to_signed_with_bit_width(32).map(|v| i32::try_from(v).unwrap())
 467     }
 468
 469     /// Converts the scalar to produce an `i64`. Fails if the scalar is a pointer.
 470     pub fn to_i64(self) -> InterpResult<'static, i64> {
 471         self.to_signed_with_bit_width(64).map(|v| i64::try_from(v).unwrap())
 472     }
 473
 474     /// Converts the scalar to produce an `i128`. Fails if the scalar is a pointer.
 475     pub fn to_i128(self) -> InterpResult<'static, i128> {
 476         self.to_signed_with_bit_width(128)
 477     }
 478
 479     pub fn to_machine_isize(self, cx: &impl HasDataLayout) -> InterpResult<'static, i64> {
 480         let sz = cx.data_layout().pointer_size;
 481         let b = self.to_bits(sz)?;
 482         let b = sz.sign_extend(b) as i128;
 483         Ok(i64::try_from(b).unwrap())
 484     }
 485
 486     #[inline]
 487     pub fn to_f32(self) -> InterpResult<'static, Single> {
 488         // Going through `u32` to check size and truncation.
 489         Ok(Single::from_bits(self.to_u32()?.into()))
 490     }
 491
 492     #[inline]
 493     pub fn to_f64(self) -> InterpResult<'static, Double> {
 494         // Going through `u64` to check size and truncation.
 495         Ok(Double::from_bits(self.to_u64()?.into()))
 496     }
 497 }
 498
 499 impl<Tag> From<Pointer<Tag>> for Scalar<Tag> {
 500     #[inline(always)]
 501     fn from(ptr: Pointer<Tag>) -> Self {
 502         Scalar::Ptr(ptr)
 503     }
 504 }
 505
 506 #[derive(Clone, Copy, Eq, PartialEq, TyEncodable, TyDecodable, HashStable, Hash)]
 507 pub enum ScalarMaybeUninit<Tag = ()> {
 508     Scalar(Scalar<Tag>),
 509     Uninit,
 510 }
 511
 512 #[cfg(target_arch = "x86_64")]
 513 static_assert_size!(ScalarMaybeUninit, 24);
 514
 515 impl<Tag> From<Scalar<Tag>> for ScalarMaybeUninit<Tag> {
 516     #[inline(always)]
 517     fn from(s: Scalar<Tag>) -> Self {
 518         ScalarMaybeUninit::Scalar(s)
 519     }
 520 }
 521
 522 impl<Tag> From<Pointer<Tag>> for ScalarMaybeUninit<Tag> {
 523     #[inline(always)]
 524     fn from(s: Pointer<Tag>) -> Self {
 525         ScalarMaybeUninit::Scalar(s.into())
 526     }
 527 }
 528
 529 // We want the `Debug` output to be readable as it is used by `derive(Debug)` for
 530 // all the Miri types.
 531 impl<Tag: fmt::Debug> fmt::Debug for ScalarMaybeUninit<Tag> {
 532     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 533         match self {
 534             ScalarMaybeUninit::Uninit => write!(f, "<uninitialized>"),
 535             ScalarMaybeUninit::Scalar(s) => write!(f, "{:?}", s),
 536         }
 537     }
 538 }
 539
 540 impl<Tag: fmt::Debug> fmt::Display for ScalarMaybeUninit<Tag> {
 541     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 542         match self {
 543             ScalarMaybeUninit::Uninit => write!(f, "uninitialized bytes"),
 544             ScalarMaybeUninit::Scalar(s) => write!(f, "{}", s),
 545         }
 546     }
 547 }
 548
 549 impl<'tcx, Tag> ScalarMaybeUninit<Tag> {
 550     /// Erase the tag from the scalar, if any.
 551     ///
 552     /// Used by error reporting code to avoid having the error type depend on `Tag`.
 553     #[inline]
 554     pub fn erase_tag(self) -> ScalarMaybeUninit {
 555         match self {
 556             ScalarMaybeUninit::Scalar(s) => ScalarMaybeUninit::Scalar(s.erase_tag()),
 557             ScalarMaybeUninit::Uninit => ScalarMaybeUninit::Uninit,
 558         }
 559     }
 560
 561     #[inline]
 562     pub fn check_init(self) -> InterpResult<'static, Scalar<Tag>> {
 563         match self {
 564             ScalarMaybeUninit::Scalar(scalar) => Ok(scalar),
 565             ScalarMaybeUninit::Uninit => throw_ub!(InvalidUninitBytes(None)),
 566         }
 567     }
 568
 569     #[inline(always)]
 570     pub fn to_bool(self) -> InterpResult<'tcx, bool> {
 571         self.check_init()?.to_bool()
 572     }
 573
 574     #[inline(always)]
 575     pub fn to_char(self) -> InterpResult<'tcx, char> {
 576         self.check_init()?.to_char()
 577     }
 578
 579     #[inline(always)]
 580     pub fn to_f32(self) -> InterpResult<'tcx, Single> {
 581         self.check_init()?.to_f32()
 582     }
 583
 584     #[inline(always)]
 585     pub fn to_f64(self) -> InterpResult<'tcx, Double> {
 586         self.check_init()?.to_f64()
 587     }
 588
 589     #[inline(always)]
 590     pub fn to_u8(self) -> InterpResult<'tcx, u8> {
 591         self.check_init()?.to_u8()
 592     }
 593
 594     #[inline(always)]
 595     pub fn to_u16(self) -> InterpResult<'tcx, u16> {
 596         self.check_init()?.to_u16()
 597     }
 598
 599     #[inline(always)]
 600     pub fn to_u32(self) -> InterpResult<'tcx, u32> {
 601         self.check_init()?.to_u32()
 602     }
 603
 604     #[inline(always)]
 605     pub fn to_u64(self) -> InterpResult<'tcx, u64> {
 606         self.check_init()?.to_u64()
 607     }
 608
 609     #[inline(always)]
 610     pub fn to_machine_usize(self, cx: &impl HasDataLayout) -> InterpResult<'tcx, u64> {
 611         self.check_init()?.to_machine_usize(cx)
 612     }
 613
 614     #[inline(always)]
 615     pub fn to_i8(self) -> InterpResult<'tcx, i8> {
 616         self.check_init()?.to_i8()
 617     }
 618
 619     #[inline(always)]
 620     pub fn to_i16(self) -> InterpResult<'tcx, i16> {
 621         self.check_init()?.to_i16()
 622     }
 623
 624     #[inline(always)]
 625     pub fn to_i32(self) -> InterpResult<'tcx, i32> {
 626         self.check_init()?.to_i32()
 627     }
 628
 629     #[inline(always)]
 630     pub fn to_i64(self) -> InterpResult<'tcx, i64> {
 631         self.check_init()?.to_i64()
 632     }
 633
 634     #[inline(always)]
 635     pub fn to_machine_isize(self, cx: &impl HasDataLayout) -> InterpResult<'tcx, i64> {
 636         self.check_init()?.to_machine_isize(cx)
 637     }
 638 }
 639
 640 /// Gets the bytes of a constant slice value.
 641 pub fn get_slice_bytes<'tcx>(cx: &impl HasDataLayout, val: ConstValue<'tcx>) -> &'tcx [u8] {
 642     if let ConstValue::Slice { data, start, end } = val {
 643         let len = end - start;
 644         data.get_bytes(
 645             cx,
 646             // invent a pointer, only the offset is relevant anyway
 647             Pointer::new(AllocId(0), Size::from_bytes(start)),
 648             Size::from_bytes(len),
 649         )
 650         .unwrap_or_else(|err| bug!("const slice is invalid: {:?}", err))
 651     } else {
 652         bug!("expected const slice, but found another const value");
 653     }
 654 }