1 use std::convert::{TryFrom, TryInto};
5 ieee::{Double, Single},
8 use rustc_macros::HashStable;
9 use rustc_target::abi::{HasDataLayout, Size};
11 use crate::ty::{Lift, ParamEnv, ScalarInt, Ty, TyCtxt};
14 AllocId, AllocRange, Allocation, InterpResult, Pointer, PointerArithmetic, Provenance,
17 /// Represents the result of const evaluation via the `eval_to_allocation` query.
18 #[derive(Copy, Clone, HashStable, TyEncodable, TyDecodable, Debug, Hash, Eq, PartialEq)]
19 pub struct ConstAlloc<'tcx> {
20 // the value lives here, at offset 0, and that allocation definitely is an `AllocKind::Memory`
21 // (so you can use `AllocMap::unwrap_memory`).
22 pub alloc_id: AllocId,
26 /// Represents a constant value in Rust. `Scalar` and `Slice` are optimizations for
27 /// array length computations, enum discriminants and the pattern matching logic.
28 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Hash)]
30 pub enum ConstValue<'tcx> {
31 /// Used only for types with `layout::abi::Scalar` ABI and ZSTs.
33 /// Not using the enum `Value` to encode that this must not be `Uninit`.
36 /// Used only for `&[u8]` and `&str`
37 Slice { data: &'tcx Allocation, start: usize, end: usize },
39 /// A value not represented/representable by `Scalar` or `Slice`
41 /// The backing memory of the value, may contain more memory than needed for just the value
42 /// in order to share `Allocation`s between values
43 alloc: &'tcx Allocation,
44 /// Offset into `alloc`
49 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
50 static_assert_size!(ConstValue<'_>, 32);
52 impl<'a, 'tcx> Lift<'tcx> for ConstValue<'a> {
53 type Lifted = ConstValue<'tcx>;
54 fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ConstValue<'tcx>> {
56 ConstValue::Scalar(s) => ConstValue::Scalar(s),
57 ConstValue::Slice { data, start, end } => {
58 ConstValue::Slice { data: tcx.lift(data)?, start, end }
60 ConstValue::ByRef { alloc, offset } => {
61 ConstValue::ByRef { alloc: tcx.lift(alloc)?, offset }
67 impl<'tcx> ConstValue<'tcx> {
69 pub fn try_to_scalar(&self) -> Option<Scalar<AllocId>> {
71 ConstValue::ByRef { .. } | ConstValue::Slice { .. } => None,
72 ConstValue::Scalar(val) => Some(val),
76 pub fn try_to_scalar_int(&self) -> Option<ScalarInt> {
77 Some(self.try_to_scalar()?.assert_int())
80 pub fn try_to_bits(&self, size: Size) -> Option<u128> {
81 self.try_to_scalar_int()?.to_bits(size).ok()
84 pub fn try_to_bool(&self) -> Option<bool> {
85 self.try_to_scalar_int()?.try_into().ok()
88 pub fn try_to_machine_usize(&self, tcx: TyCtxt<'tcx>) -> Option<u64> {
89 self.try_to_scalar_int()?.try_to_machine_usize(tcx).ok()
92 pub fn try_to_bits_for_ty(
95 param_env: ParamEnv<'tcx>,
98 let size = tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size;
99 self.try_to_bits(size)
102 pub fn from_bool(b: bool) -> Self {
103 ConstValue::Scalar(Scalar::from_bool(b))
106 pub fn from_u64(i: u64) -> Self {
107 ConstValue::Scalar(Scalar::from_u64(i))
110 pub fn from_machine_usize(i: u64, cx: &impl HasDataLayout) -> Self {
111 ConstValue::Scalar(Scalar::from_machine_usize(i, cx))
115 /// A `Scalar` represents an immediate, primitive value existing outside of a
116 /// `memory::Allocation`. It is in many ways like a small chunk of an `Allocation`, up to 16 bytes in
117 /// size. Like a range of bytes in an `Allocation`, a `Scalar` can either represent the raw bytes
118 /// of a simple value or a pointer into another `Allocation`
120 /// These variants would be private if there was a convenient way to achieve that in Rust.
121 /// Do *not* match on a `Scalar`! Use the various `to_*` methods instead.
122 #[derive(Clone, Copy, Eq, PartialEq, Ord, PartialOrd, TyEncodable, TyDecodable, Hash)]
123 #[derive(HashStable)]
124 pub enum Scalar<Tag = AllocId> {
125 /// The raw bytes of a simple value.
128 /// A pointer into an `Allocation`. An `Allocation` in the `memory` module has a list of
129 /// relocations, but a `Scalar` is only large enough to contain one, so we just represent the
130 /// relocation and its associated offset together as a `Pointer` here.
132 /// We also store the size of the pointer, such that a `Scalar` always knows how big it is.
133 /// The size is always the pointer size of the current target, but this is not information
134 /// that we always have readily available.
135 Ptr(Pointer<Tag>, u8),
138 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
139 static_assert_size!(Scalar, 24);
141 // We want the `Debug` output to be readable as it is used by `derive(Debug)` for
142 // all the Miri types.
143 impl<Tag: Provenance> fmt::Debug for Scalar<Tag> {
144 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
146 Scalar::Ptr(ptr, _size) => write!(f, "{:?}", ptr),
147 Scalar::Int(int) => write!(f, "{:?}", int),
152 impl<Tag: Provenance> fmt::Display for Scalar<Tag> {
153 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
155 Scalar::Ptr(ptr, _size) => write!(f, "pointer to {:?}", ptr),
156 Scalar::Int(int) => write!(f, "{:?}", int),
161 impl<Tag> From<Single> for Scalar<Tag> {
163 fn from(f: Single) -> Self {
168 impl<Tag> From<Double> for Scalar<Tag> {
170 fn from(f: Double) -> Self {
175 impl<Tag> From<ScalarInt> for Scalar<Tag> {
177 fn from(ptr: ScalarInt) -> Self {
182 impl<Tag> Scalar<Tag> {
183 pub const ZST: Self = Scalar::Int(ScalarInt::ZST);
186 pub fn from_pointer(ptr: Pointer<Tag>, cx: &impl HasDataLayout) -> Self {
187 Scalar::Ptr(ptr, u8::try_from(cx.pointer_size().bytes()).unwrap())
190 /// Create a Scalar from a pointer with an `Option<_>` tag (where `None` represents a plain integer).
191 pub fn from_maybe_pointer(ptr: Pointer<Option<Tag>>, cx: &impl HasDataLayout) -> Self {
192 match ptr.into_parts() {
193 (Some(tag), offset) => Scalar::from_pointer(Pointer::new(tag, offset), cx),
195 Scalar::Int(ScalarInt::try_from_uint(offset.bytes(), cx.pointer_size()).unwrap())
201 pub fn null_ptr(cx: &impl HasDataLayout) -> Self {
202 Scalar::Int(ScalarInt::null(cx.pointer_size()))
206 pub fn from_bool(b: bool) -> Self {
207 Scalar::Int(b.into())
211 pub fn from_char(c: char) -> Self {
212 Scalar::Int(c.into())
216 pub fn try_from_uint(i: impl Into<u128>, size: Size) -> Option<Self> {
217 ScalarInt::try_from_uint(i, size).map(Scalar::Int)
221 pub fn from_uint(i: impl Into<u128>, size: Size) -> Self {
223 Self::try_from_uint(i, size)
224 .unwrap_or_else(|| bug!("Unsigned value {:#x} does not fit in {} bits", i, size.bits()))
228 pub fn from_u8(i: u8) -> Self {
229 Scalar::Int(i.into())
233 pub fn from_u16(i: u16) -> Self {
234 Scalar::Int(i.into())
238 pub fn from_u32(i: u32) -> Self {
239 Scalar::Int(i.into())
243 pub fn from_u64(i: u64) -> Self {
244 Scalar::Int(i.into())
248 pub fn from_machine_usize(i: u64, cx: &impl HasDataLayout) -> Self {
249 Self::from_uint(i, cx.data_layout().pointer_size)
253 pub fn try_from_int(i: impl Into<i128>, size: Size) -> Option<Self> {
254 ScalarInt::try_from_int(i, size).map(Scalar::Int)
258 pub fn from_int(i: impl Into<i128>, size: Size) -> Self {
260 Self::try_from_int(i, size)
261 .unwrap_or_else(|| bug!("Signed value {:#x} does not fit in {} bits", i, size.bits()))
265 pub fn from_i32(i: i32) -> Self {
266 Self::from_int(i, Size::from_bits(32))
270 pub fn from_i64(i: i64) -> Self {
271 Self::from_int(i, Size::from_bits(64))
275 pub fn from_machine_isize(i: i64, cx: &impl HasDataLayout) -> Self {
276 Self::from_int(i, cx.data_layout().pointer_size)
280 pub fn from_f32(f: Single) -> Self {
281 Scalar::Int(f.into())
285 pub fn from_f64(f: Double) -> Self {
286 Scalar::Int(f.into())
289 /// This is almost certainly not the method you want! You should dispatch on the type
290 /// and use `to_{u8,u16,...}`/`scalar_to_ptr` to perform ptr-to-int / int-to-ptr casts as needed.
292 /// This method only exists for the benefit of low-level operations that truly need to treat the
293 /// scalar in whatever form it is.
295 pub fn to_bits_or_ptr_internal(self, target_size: Size) -> Result<u128, Pointer<Tag>> {
296 assert_ne!(target_size.bytes(), 0, "you should never look at the bits of a ZST");
298 Scalar::Int(int) => Ok(int.assert_bits(target_size)),
299 Scalar::Ptr(ptr, sz) => {
300 assert_eq!(target_size.bytes(), u64::from(sz));
307 impl<'tcx, Tag: Provenance> Scalar<Tag> {
308 /// Fundamental scalar-to-int (cast) operation. Many convenience wrappers exist below, that you
309 /// likely want to use instead.
311 /// Will perform ptr-to-int casts if needed and possible.
312 /// If that fails, we know the offset is relative, so we return an "erased" Scalar
313 /// (which is useful for error messages but not much else).
315 pub fn try_to_int(self) -> Result<ScalarInt, Scalar<AllocId>> {
317 Scalar::Int(int) => Ok(int),
318 Scalar::Ptr(ptr, sz) => {
319 if Tag::OFFSET_IS_ADDR {
320 Ok(ScalarInt::try_from_uint(ptr.offset.bytes(), Size::from_bytes(sz)).unwrap())
322 // We know `offset` is relative, since `OFFSET_IS_ADDR == false`.
323 let (tag, offset) = ptr.into_parts();
324 Err(Scalar::Ptr(Pointer::new(tag.get_alloc_id(), offset), sz))
331 pub fn assert_int(self) -> ScalarInt {
332 self.try_to_int().unwrap()
335 /// This throws UB (instead of ICEing) on a size mismatch since size mismatches can arise in
336 /// Miri when someone declares a function that we shim (such as `malloc`) with a wrong type.
338 pub fn to_bits(self, target_size: Size) -> InterpResult<'tcx, u128> {
339 assert_ne!(target_size.bytes(), 0, "you should never look at the bits of a ZST");
340 self.try_to_int().map_err(|_| err_unsup!(ReadPointerAsBytes))?.to_bits(target_size).map_err(
342 err_ub!(ScalarSizeMismatch {
343 target_size: target_size.bytes(),
344 data_size: size.bytes(),
352 pub fn assert_bits(self, target_size: Size) -> u128 {
353 self.to_bits(target_size).unwrap()
356 pub fn to_bool(self) -> InterpResult<'tcx, bool> {
357 let val = self.to_u8()?;
361 _ => throw_ub!(InvalidBool(val)),
365 pub fn to_char(self) -> InterpResult<'tcx, char> {
366 let val = self.to_u32()?;
367 match std::char::from_u32(val) {
369 None => throw_ub!(InvalidChar(val)),
374 fn to_unsigned_with_bit_width(self, bits: u64) -> InterpResult<'static, u128> {
375 let sz = Size::from_bits(bits);
379 /// Converts the scalar to produce a `u8`. Fails if the scalar is a pointer.
380 pub fn to_u8(self) -> InterpResult<'static, u8> {
381 self.to_unsigned_with_bit_width(8).map(|v| u8::try_from(v).unwrap())
384 /// Converts the scalar to produce a `u16`. Fails if the scalar is a pointer.
385 pub fn to_u16(self) -> InterpResult<'static, u16> {
386 self.to_unsigned_with_bit_width(16).map(|v| u16::try_from(v).unwrap())
389 /// Converts the scalar to produce a `u32`. Fails if the scalar is a pointer.
390 pub fn to_u32(self) -> InterpResult<'static, u32> {
391 self.to_unsigned_with_bit_width(32).map(|v| u32::try_from(v).unwrap())
394 /// Converts the scalar to produce a `u64`. Fails if the scalar is a pointer.
395 pub fn to_u64(self) -> InterpResult<'static, u64> {
396 self.to_unsigned_with_bit_width(64).map(|v| u64::try_from(v).unwrap())
399 /// Converts the scalar to produce a `u128`. Fails if the scalar is a pointer.
400 pub fn to_u128(self) -> InterpResult<'static, u128> {
401 self.to_unsigned_with_bit_width(128)
404 pub fn to_machine_usize(self, cx: &impl HasDataLayout) -> InterpResult<'static, u64> {
405 let b = self.to_bits(cx.data_layout().pointer_size)?;
406 Ok(u64::try_from(b).unwrap())
410 fn to_signed_with_bit_width(self, bits: u64) -> InterpResult<'static, i128> {
411 let sz = Size::from_bits(bits);
412 let b = self.to_bits(sz)?;
413 Ok(sz.sign_extend(b) as i128)
416 /// Converts the scalar to produce an `i8`. Fails if the scalar is a pointer.
417 pub fn to_i8(self) -> InterpResult<'static, i8> {
418 self.to_signed_with_bit_width(8).map(|v| i8::try_from(v).unwrap())
421 /// Converts the scalar to produce an `i16`. Fails if the scalar is a pointer.
422 pub fn to_i16(self) -> InterpResult<'static, i16> {
423 self.to_signed_with_bit_width(16).map(|v| i16::try_from(v).unwrap())
426 /// Converts the scalar to produce an `i32`. Fails if the scalar is a pointer.
427 pub fn to_i32(self) -> InterpResult<'static, i32> {
428 self.to_signed_with_bit_width(32).map(|v| i32::try_from(v).unwrap())
431 /// Converts the scalar to produce an `i64`. Fails if the scalar is a pointer.
432 pub fn to_i64(self) -> InterpResult<'static, i64> {
433 self.to_signed_with_bit_width(64).map(|v| i64::try_from(v).unwrap())
436 /// Converts the scalar to produce an `i128`. Fails if the scalar is a pointer.
437 pub fn to_i128(self) -> InterpResult<'static, i128> {
438 self.to_signed_with_bit_width(128)
441 pub fn to_machine_isize(self, cx: &impl HasDataLayout) -> InterpResult<'static, i64> {
442 let sz = cx.data_layout().pointer_size;
443 let b = self.to_bits(sz)?;
444 let b = sz.sign_extend(b) as i128;
445 Ok(i64::try_from(b).unwrap())
449 pub fn to_f32(self) -> InterpResult<'static, Single> {
450 // Going through `u32` to check size and truncation.
451 Ok(Single::from_bits(self.to_u32()?.into()))
455 pub fn to_f64(self) -> InterpResult<'static, Double> {
456 // Going through `u64` to check size and truncation.
457 Ok(Double::from_bits(self.to_u64()?.into()))
461 #[derive(Clone, Copy, Eq, PartialEq, TyEncodable, TyDecodable, HashStable, Hash)]
462 pub enum ScalarMaybeUninit<Tag = AllocId> {
467 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
468 static_assert_size!(ScalarMaybeUninit, 24);
470 impl<Tag> From<Scalar<Tag>> for ScalarMaybeUninit<Tag> {
472 fn from(s: Scalar<Tag>) -> Self {
473 ScalarMaybeUninit::Scalar(s)
477 // We want the `Debug` output to be readable as it is used by `derive(Debug)` for
478 // all the Miri types.
479 impl<Tag: Provenance> fmt::Debug for ScalarMaybeUninit<Tag> {
480 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
482 ScalarMaybeUninit::Uninit => write!(f, "<uninitialized>"),
483 ScalarMaybeUninit::Scalar(s) => write!(f, "{:?}", s),
488 impl<Tag: Provenance> fmt::Display for ScalarMaybeUninit<Tag> {
489 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
491 ScalarMaybeUninit::Uninit => write!(f, "uninitialized bytes"),
492 ScalarMaybeUninit::Scalar(s) => write!(f, "{}", s),
497 impl<Tag> ScalarMaybeUninit<Tag> {
499 pub fn from_pointer(ptr: Pointer<Tag>, cx: &impl HasDataLayout) -> Self {
500 ScalarMaybeUninit::Scalar(Scalar::from_pointer(ptr, cx))
504 pub fn from_maybe_pointer(ptr: Pointer<Option<Tag>>, cx: &impl HasDataLayout) -> Self {
505 ScalarMaybeUninit::Scalar(Scalar::from_maybe_pointer(ptr, cx))
509 pub fn check_init(self) -> InterpResult<'static, Scalar<Tag>> {
511 ScalarMaybeUninit::Scalar(scalar) => Ok(scalar),
512 ScalarMaybeUninit::Uninit => throw_ub!(InvalidUninitBytes(None)),
517 impl<'tcx, Tag: Provenance> ScalarMaybeUninit<Tag> {
519 pub fn to_bool(self) -> InterpResult<'tcx, bool> {
520 self.check_init()?.to_bool()
524 pub fn to_char(self) -> InterpResult<'tcx, char> {
525 self.check_init()?.to_char()
529 pub fn to_f32(self) -> InterpResult<'tcx, Single> {
530 self.check_init()?.to_f32()
534 pub fn to_f64(self) -> InterpResult<'tcx, Double> {
535 self.check_init()?.to_f64()
539 pub fn to_u8(self) -> InterpResult<'tcx, u8> {
540 self.check_init()?.to_u8()
544 pub fn to_u16(self) -> InterpResult<'tcx, u16> {
545 self.check_init()?.to_u16()
549 pub fn to_u32(self) -> InterpResult<'tcx, u32> {
550 self.check_init()?.to_u32()
554 pub fn to_u64(self) -> InterpResult<'tcx, u64> {
555 self.check_init()?.to_u64()
559 pub fn to_machine_usize(self, cx: &impl HasDataLayout) -> InterpResult<'tcx, u64> {
560 self.check_init()?.to_machine_usize(cx)
564 pub fn to_i8(self) -> InterpResult<'tcx, i8> {
565 self.check_init()?.to_i8()
569 pub fn to_i16(self) -> InterpResult<'tcx, i16> {
570 self.check_init()?.to_i16()
574 pub fn to_i32(self) -> InterpResult<'tcx, i32> {
575 self.check_init()?.to_i32()
579 pub fn to_i64(self) -> InterpResult<'tcx, i64> {
580 self.check_init()?.to_i64()
584 pub fn to_machine_isize(self, cx: &impl HasDataLayout) -> InterpResult<'tcx, i64> {
585 self.check_init()?.to_machine_isize(cx)
589 /// Gets the bytes of a constant slice value.
590 pub fn get_slice_bytes<'tcx>(cx: &impl HasDataLayout, val: ConstValue<'tcx>) -> &'tcx [u8] {
591 if let ConstValue::Slice { data, start, end } = val {
592 let len = end - start;
595 AllocRange { start: Size::from_bytes(start), size: Size::from_bytes(len) },
597 .unwrap_or_else(|err| bug!("const slice is invalid: {:?}", err))
599 bug!("expected const slice, but found another const value");