compiler/rustc_middle/src/ty/consts/int.rs

   1 use rustc_apfloat::ieee::{Double, Single};
   2 use rustc_apfloat::Float;
   3 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
   4 use rustc_target::abi::Size;
   5 use std::convert::{TryFrom, TryInto};
   6 use std::fmt;
   7
   8 use crate::ty::TyCtxt;
   9
  10 #[derive(Copy, Clone)]
  11 /// A type for representing any integer. Only used for printing.
  12 pub struct ConstInt {
  13     /// The "untyped" variant of `ConstInt`.
  14     int: ScalarInt,
  15     /// Whether the value is of a signed integer type.
  16     signed: bool,
  17     /// Whether the value is a `usize` or `isize` type.
  18     is_ptr_sized_integral: bool,
  19 }
  20
  21 impl ConstInt {
  22     pub fn new(int: ScalarInt, signed: bool, is_ptr_sized_integral: bool) -> Self {
  23         Self { int, signed, is_ptr_sized_integral }
  24     }
  25 }
  26
  27 impl std::fmt::Debug for ConstInt {
  28     fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
  29         let Self { int, signed, is_ptr_sized_integral } = *self;
  30         let size = int.size().bytes();
  31         let raw = int.data;
  32         if signed {
  33             let bit_size = size * 8;
  34             let min = 1u128 << (bit_size - 1);
  35             let max = min - 1;
  36             if raw == min {
  37                 match (size, is_ptr_sized_integral) {
  38                     (_, true) => write!(fmt, "isize::MIN"),
  39                     (1, _) => write!(fmt, "i8::MIN"),
  40                     (2, _) => write!(fmt, "i16::MIN"),
  41                     (4, _) => write!(fmt, "i32::MIN"),
  42                     (8, _) => write!(fmt, "i64::MIN"),
  43                     (16, _) => write!(fmt, "i128::MIN"),
  44                     _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
  45                 }
  46             } else if raw == max {
  47                 match (size, is_ptr_sized_integral) {
  48                     (_, true) => write!(fmt, "isize::MAX"),
  49                     (1, _) => write!(fmt, "i8::MAX"),
  50                     (2, _) => write!(fmt, "i16::MAX"),
  51                     (4, _) => write!(fmt, "i32::MAX"),
  52                     (8, _) => write!(fmt, "i64::MAX"),
  53                     (16, _) => write!(fmt, "i128::MAX"),
  54                     _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
  55                 }
  56             } else {
  57                 match size {
  58                     1 => write!(fmt, "{}", raw as i8)?,
  59                     2 => write!(fmt, "{}", raw as i16)?,
  60                     4 => write!(fmt, "{}", raw as i32)?,
  61                     8 => write!(fmt, "{}", raw as i64)?,
  62                     16 => write!(fmt, "{}", raw as i128)?,
  63                     _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
  64                 }
  65                 if fmt.alternate() {
  66                     match (size, is_ptr_sized_integral) {
  67                         (_, true) => write!(fmt, "_isize")?,
  68                         (1, _) => write!(fmt, "_i8")?,
  69                         (2, _) => write!(fmt, "_i16")?,
  70                         (4, _) => write!(fmt, "_i32")?,
  71                         (8, _) => write!(fmt, "_i64")?,
  72                         (16, _) => write!(fmt, "_i128")?,
  73                         _ => bug!(),
  74                     }
  75                 }
  76                 Ok(())
  77             }
  78         } else {
  79             let max = Size::from_bytes(size).truncate(u128::MAX);
  80             if raw == max {
  81                 match (size, is_ptr_sized_integral) {
  82                     (_, true) => write!(fmt, "usize::MAX"),
  83                     (1, _) => write!(fmt, "u8::MAX"),
  84                     (2, _) => write!(fmt, "u16::MAX"),
  85                     (4, _) => write!(fmt, "u32::MAX"),
  86                     (8, _) => write!(fmt, "u64::MAX"),
  87                     (16, _) => write!(fmt, "u128::MAX"),
  88                     _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
  89                 }
  90             } else {
  91                 match size {
  92                     1 => write!(fmt, "{}", raw as u8)?,
  93                     2 => write!(fmt, "{}", raw as u16)?,
  94                     4 => write!(fmt, "{}", raw as u32)?,
  95                     8 => write!(fmt, "{}", raw as u64)?,
  96                     16 => write!(fmt, "{}", raw as u128)?,
  97                     _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
  98                 }
  99                 if fmt.alternate() {
 100                     match (size, is_ptr_sized_integral) {
 101                         (_, true) => write!(fmt, "_usize")?,
 102                         (1, _) => write!(fmt, "_u8")?,
 103                         (2, _) => write!(fmt, "_u16")?,
 104                         (4, _) => write!(fmt, "_u32")?,
 105                         (8, _) => write!(fmt, "_u64")?,
 106                         (16, _) => write!(fmt, "_u128")?,
 107                         _ => bug!(),
 108                     }
 109                 }
 110                 Ok(())
 111             }
 112         }
 113     }
 114 }
 115
 116 /// The raw bytes of a simple value.
 117 ///
 118 /// This is a packed struct in order to allow this type to be optimally embedded in enums
 119 /// (like Scalar).
 120 #[derive(Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
 121 #[repr(packed)]
 122 pub struct ScalarInt {
 123     /// The first `size` bytes of `data` are the value.
 124     /// Do not try to read less or more bytes than that. The remaining bytes must be 0.
 125     data: u128,
 126     size: u8,
 127 }
 128
 129 // Cannot derive these, as the derives take references to the fields, and we
 130 // can't take references to fields of packed structs.
 131 impl<CTX> crate::ty::HashStable<CTX> for ScalarInt {
 132     fn hash_stable(&self, hcx: &mut CTX, hasher: &mut crate::ty::StableHasher) {
 133         // Using a block `{self.data}` here to force a copy instead of using `self.data`
 134         // directly, because `hash_stable` takes `&self` and would thus borrow `self.data`.
 135         // Since `Self` is a packed struct, that would create a possibly unaligned reference,
 136         // which is UB.
 137         { self.data }.hash_stable(hcx, hasher);
 138         self.size.hash_stable(hcx, hasher);
 139     }
 140 }
 141
 142 impl<S: Encoder> Encodable<S> for ScalarInt {
 143     fn encode(&self, s: &mut S) -> Result<(), S::Error> {
 144         s.emit_u128(self.data)?;
 145         s.emit_u8(self.size)
 146     }
 147 }
 148
 149 impl<D: Decoder> Decodable<D> for ScalarInt {
 150     fn decode(d: &mut D) -> ScalarInt {
 151         ScalarInt { data: d.read_u128(), size: d.read_u8() }
 152     }
 153 }
 154
 155 impl ScalarInt {
 156     pub const TRUE: ScalarInt = ScalarInt { data: 1_u128, size: 1 };
 157
 158     pub const FALSE: ScalarInt = ScalarInt { data: 0_u128, size: 1 };
 159
 160     pub const ZST: ScalarInt = ScalarInt { data: 0_u128, size: 0 };
 161
 162     #[inline]
 163     pub fn size(self) -> Size {
 164         Size::from_bytes(self.size)
 165     }
 166
 167     /// Make sure the `data` fits in `size`.
 168     /// This is guaranteed by all constructors here, but having had this check saved us from
 169     /// bugs many times in the past, so keeping it around is definitely worth it.
 170     #[inline(always)]
 171     fn check_data(self) {
 172         // Using a block `{self.data}` here to force a copy instead of using `self.data`
 173         // directly, because `debug_assert_eq` takes references to its arguments and formatting
 174         // arguments and would thus borrow `self.data`. Since `Self`
 175         // is a packed struct, that would create a possibly unaligned reference, which
 176         // is UB.
 177         debug_assert_eq!(
 178             self.size().truncate(self.data),
 179             { self.data },
 180             "Scalar value {:#x} exceeds size of {} bytes",
 181             { self.data },
 182             self.size
 183         );
 184     }
 185
 186     #[inline]
 187     pub fn null(size: Size) -> Self {
 188         Self { data: 0, size: size.bytes() as u8 }
 189     }
 190
 191     #[inline]
 192     pub fn is_null(self) -> bool {
 193         self.data == 0
 194     }
 195
 196     #[inline]
 197     pub fn try_from_uint(i: impl Into<u128>, size: Size) -> Option<Self> {
 198         let data = i.into();
 199         if size.truncate(data) == data {
 200             Some(Self { data, size: size.bytes() as u8 })
 201         } else {
 202             None
 203         }
 204     }
 205
 206     #[inline]
 207     pub fn try_from_int(i: impl Into<i128>, size: Size) -> Option<Self> {
 208         let i = i.into();
 209         // `into` performed sign extension, we have to truncate
 210         let truncated = size.truncate(i as u128);
 211         if size.sign_extend(truncated) as i128 == i {
 212             Some(Self { data: truncated, size: size.bytes() as u8 })
 213         } else {
 214             None
 215         }
 216     }
 217
 218     #[inline]
 219     pub fn assert_bits(self, target_size: Size) -> u128 {
 220         self.to_bits(target_size).unwrap_or_else(|size| {
 221             bug!("expected int of size {}, but got size {}", target_size.bytes(), size.bytes())
 222         })
 223     }
 224
 225     #[inline]
 226     pub fn to_bits(self, target_size: Size) -> Result<u128, Size> {
 227         assert_ne!(target_size.bytes(), 0, "you should never look at the bits of a ZST");
 228         if target_size.bytes() == u64::from(self.size) {
 229             self.check_data();
 230             Ok(self.data)
 231         } else {
 232             Err(self.size())
 233         }
 234     }
 235
 236     #[inline]
 237     pub fn try_to_machine_usize<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Result<u64, Size> {
 238         Ok(self.to_bits(tcx.data_layout.pointer_size)? as u64)
 239     }
 240 }
 241
 242 macro_rules! from {
 243     ($($ty:ty),*) => {
 244         $(
 245             impl From<$ty> for ScalarInt {
 246                 #[inline]
 247                 fn from(u: $ty) -> Self {
 248                     Self {
 249                         data: u128::from(u),
 250                         size: std::mem::size_of::<$ty>() as u8,
 251                     }
 252                 }
 253             }
 254         )*
 255     }
 256 }
 257
 258 macro_rules! try_from {
 259     ($($ty:ty),*) => {
 260         $(
 261             impl TryFrom<ScalarInt> for $ty {
 262                 type Error = Size;
 263                 #[inline]
 264                 fn try_from(int: ScalarInt) -> Result<Self, Size> {
 265                     // The `unwrap` cannot fail because to_bits (if it succeeds)
 266                     // is guaranteed to return a value that fits into the size.
 267                     int.to_bits(Size::from_bytes(std::mem::size_of::<$ty>()))
 268                        .map(|u| u.try_into().unwrap())
 269                 }
 270             }
 271         )*
 272     }
 273 }
 274
 275 from!(u8, u16, u32, u64, u128, bool);
 276 try_from!(u8, u16, u32, u64, u128);
 277
 278 impl TryFrom<ScalarInt> for bool {
 279     type Error = Size;
 280     #[inline]
 281     fn try_from(int: ScalarInt) -> Result<Self, Size> {
 282         int.to_bits(Size::from_bytes(1)).and_then(|u| match u {
 283             0 => Ok(false),
 284             1 => Ok(true),
 285             _ => Err(Size::from_bytes(1)),
 286         })
 287     }
 288 }
 289
 290 impl From<char> for ScalarInt {
 291     #[inline]
 292     fn from(c: char) -> Self {
 293         Self { data: c as u128, size: std::mem::size_of::<char>() as u8 }
 294     }
 295 }
 296
 297 /// Error returned when a conversion from ScalarInt to char fails.
 298 #[derive(Debug)]
 299 pub struct CharTryFromScalarInt;
 300
 301 impl TryFrom<ScalarInt> for char {
 302     type Error = CharTryFromScalarInt;
 303
 304     #[inline]
 305     fn try_from(int: ScalarInt) -> Result<Self, Self::Error> {
 306         let Ok(bits) = int.to_bits(Size::from_bytes(std::mem::size_of::<char>())) else  {
 307             return Err(CharTryFromScalarInt);
 308         };
 309         match char::from_u32(bits.try_into().unwrap()) {
 310             Some(c) => Ok(c),
 311             None => Err(CharTryFromScalarInt),
 312         }
 313     }
 314 }
 315
 316 impl From<Single> for ScalarInt {
 317     #[inline]
 318     fn from(f: Single) -> Self {
 319         // We trust apfloat to give us properly truncated data.
 320         Self { data: f.to_bits(), size: 4 }
 321     }
 322 }
 323
 324 impl TryFrom<ScalarInt> for Single {
 325     type Error = Size;
 326     #[inline]
 327     fn try_from(int: ScalarInt) -> Result<Self, Size> {
 328         int.to_bits(Size::from_bytes(4)).map(Self::from_bits)
 329     }
 330 }
 331
 332 impl From<Double> for ScalarInt {
 333     #[inline]
 334     fn from(f: Double) -> Self {
 335         // We trust apfloat to give us properly truncated data.
 336         Self { data: f.to_bits(), size: 8 }
 337     }
 338 }
 339
 340 impl TryFrom<ScalarInt> for Double {
 341     type Error = Size;
 342     #[inline]
 343     fn try_from(int: ScalarInt) -> Result<Self, Size> {
 344         int.to_bits(Size::from_bytes(8)).map(Self::from_bits)
 345     }
 346 }
 347
 348 impl fmt::Debug for ScalarInt {
 349     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 350         if self.size == 0 {
 351             self.check_data();
 352             write!(f, "<ZST>")
 353         } else {
 354             // Dispatch to LowerHex below.
 355             write!(f, "0x{:x}", self)
 356         }
 357     }
 358 }
 359
 360 impl fmt::LowerHex for ScalarInt {
 361     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 362         self.check_data();
 363         // Format as hex number wide enough to fit any value of the given `size`.
 364         // So data=20, size=1 will be "0x14", but with size=4 it'll be "0x00000014".
 365         // Using a block `{self.data}` here to force a copy instead of using `self.data`
 366         // directly, because `write!` takes references to its formatting arguments and
 367         // would thus borrow `self.data`. Since `Self`
 368         // is a packed struct, that would create a possibly unaligned reference, which
 369         // is UB.
 370         write!(f, "{:01$x}", { self.data }, self.size as usize * 2)
 371     }
 372 }
 373
 374 impl fmt::UpperHex for ScalarInt {
 375     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 376         self.check_data();
 377         // Format as hex number wide enough to fit any value of the given `size`.
 378         // So data=20, size=1 will be "0x14", but with size=4 it'll be "0x00000014".
 379         // Using a block `{self.data}` here to force a copy instead of using `self.data`
 380         // directly, because `write!` takes references to its formatting arguments and
 381         // would thus borrow `self.data`. Since `Self`
 382         // is a packed struct, that would create a possibly unaligned reference, which
 383         // is UB.
 384         write!(f, "{:01$X}", { self.data }, self.size as usize * 2)
 385     }
 386 }
 387
 388 impl fmt::Display for ScalarInt {
 389     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 390         self.check_data();
 391         write!(f, "{}", { self.data })
 392     }
 393 }