src/shims/intrinsics.rs

   1 use std::iter;
   2
   3 use log::trace;
   4
   5 use rustc_apfloat::{Float, Round};
   6 use rustc_middle::ty::layout::{HasParamEnv, IntegerExt, LayoutOf};
   7 use rustc_middle::{mir, mir::BinOp, ty, ty::FloatTy};
   8 use rustc_target::abi::{Align, Integer};
   9
  10 use crate::*;
  11 use helpers::{bool_to_simd_element, check_arg_count, simd_element_to_bool};
  12
  13 pub enum AtomicOp {
  14     MirOp(mir::BinOp, bool),
  15     Max,
  16     Min,
  17 }
  18
  19 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
  20 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
  21     fn call_intrinsic(
  22         &mut self,
  23         instance: ty::Instance<'tcx>,
  24         args: &[OpTy<'tcx, Tag>],
  25         ret: Option<(&PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
  26         _unwind: StackPopUnwind,
  27     ) -> InterpResult<'tcx> {
  28         let this = self.eval_context_mut();
  29
  30         if this.emulate_intrinsic(instance, args, ret)? {
  31             return Ok(());
  32         }
  33
  34         // All supported intrinsics have a return place.
  35         let intrinsic_name = this.tcx.item_name(instance.def_id());
  36         let intrinsic_name = intrinsic_name.as_str();
  37         let (dest, ret) = match ret {
  38             None => throw_unsup_format!("unimplemented (diverging) intrinsic: {}", intrinsic_name),
  39             Some(p) => p,
  40         };
  41
  42         // Then handle terminating intrinsics.
  43         match intrinsic_name {
  44             // Miri overwriting CTFE intrinsics.
  45             "ptr_guaranteed_eq" => {
  46                 let &[ref left, ref right] = check_arg_count(args)?;
  47                 let left = this.read_immediate(left)?;
  48                 let right = this.read_immediate(right)?;
  49                 this.binop_ignore_overflow(mir::BinOp::Eq, &left, &right, dest)?;
  50             }
  51             "ptr_guaranteed_ne" => {
  52                 let &[ref left, ref right] = check_arg_count(args)?;
  53                 let left = this.read_immediate(left)?;
  54                 let right = this.read_immediate(right)?;
  55                 this.binop_ignore_overflow(mir::BinOp::Ne, &left, &right, dest)?;
  56             }
  57             "const_allocate" => {
  58                 // For now, for compatibility with the run-time implementation of this, we just return null.
  59                 // See <https://github.com/rust-lang/rust/issues/93935>.
  60                 this.write_null(dest)?;
  61             }
  62             "const_deallocate" => {
  63                 // complete NOP
  64             }
  65
  66             // Raw memory accesses
  67             "volatile_load" => {
  68                 let &[ref place] = check_arg_count(args)?;
  69                 let place = this.deref_operand(place)?;
  70                 this.copy_op(&place.into(), dest)?;
  71             }
  72             "volatile_store" => {
  73                 let &[ref place, ref dest] = check_arg_count(args)?;
  74                 let place = this.deref_operand(place)?;
  75                 this.copy_op(dest, &place.into())?;
  76             }
  77
  78             "write_bytes" | "volatile_set_memory" => {
  79                 let &[ref ptr, ref val_byte, ref count] = check_arg_count(args)?;
  80                 let ty = instance.substs.type_at(0);
  81                 let ty_layout = this.layout_of(ty)?;
  82                 let val_byte = this.read_scalar(val_byte)?.to_u8()?;
  83                 let ptr = this.read_pointer(ptr)?;
  84                 let count = this.read_scalar(count)?.to_machine_usize(this)?;
  85                 let byte_count = ty_layout.size.checked_mul(count, this).ok_or_else(|| {
  86                     err_ub_format!("overflow computing total size of `{}`", intrinsic_name)
  87                 })?;
  88                 this.memory
  89                     .write_bytes(ptr, iter::repeat(val_byte).take(byte_count.bytes() as usize))?;
  90             }
  91
  92             // Floating-point operations
  93             "fabsf32" => {
  94                 let &[ref f] = check_arg_count(args)?;
  95                 let f = this.read_scalar(f)?.to_f32()?;
  96                 // Can be implemented in soft-floats.
  97                 this.write_scalar(Scalar::from_f32(f.abs()), dest)?;
  98             }
  99             "fabsf64" => {
 100                 let &[ref f] = check_arg_count(args)?;
 101                 let f = this.read_scalar(f)?.to_f64()?;
 102                 // Can be implemented in soft-floats.
 103                 this.write_scalar(Scalar::from_f64(f.abs()), dest)?;
 104             }
 105             #[rustfmt::skip]
 106             | "sinf32"
 107             | "cosf32"
 108             | "sqrtf32"
 109             | "expf32"
 110             | "exp2f32"
 111             | "logf32"
 112             | "log10f32"
 113             | "log2f32"
 114             | "floorf32"
 115             | "ceilf32"
 116             | "truncf32"
 117             | "roundf32"
 118             => {
 119                 let &[ref f] = check_arg_count(args)?;
 120                 // FIXME: Using host floats.
 121                 let f = f32::from_bits(this.read_scalar(f)?.to_u32()?);
 122                 let f = match intrinsic_name {
 123                     "sinf32" => f.sin(),
 124                     "cosf32" => f.cos(),
 125                     "sqrtf32" => f.sqrt(),
 126                     "expf32" => f.exp(),
 127                     "exp2f32" => f.exp2(),
 128                     "logf32" => f.ln(),
 129                     "log10f32" => f.log10(),
 130                     "log2f32" => f.log2(),
 131                     "floorf32" => f.floor(),
 132                     "ceilf32" => f.ceil(),
 133                     "truncf32" => f.trunc(),
 134                     "roundf32" => f.round(),
 135                     _ => bug!(),
 136                 };
 137                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 138             }
 139
 140             #[rustfmt::skip]
 141             | "sinf64"
 142             | "cosf64"
 143             | "sqrtf64"
 144             | "expf64"
 145             | "exp2f64"
 146             | "logf64"
 147             | "log10f64"
 148             | "log2f64"
 149             | "floorf64"
 150             | "ceilf64"
 151             | "truncf64"
 152             | "roundf64"
 153             => {
 154                 let &[ref f] = check_arg_count(args)?;
 155                 // FIXME: Using host floats.
 156                 let f = f64::from_bits(this.read_scalar(f)?.to_u64()?);
 157                 let f = match intrinsic_name {
 158                     "sinf64" => f.sin(),
 159                     "cosf64" => f.cos(),
 160                     "sqrtf64" => f.sqrt(),
 161                     "expf64" => f.exp(),
 162                     "exp2f64" => f.exp2(),
 163                     "logf64" => f.ln(),
 164                     "log10f64" => f.log10(),
 165                     "log2f64" => f.log2(),
 166                     "floorf64" => f.floor(),
 167                     "ceilf64" => f.ceil(),
 168                     "truncf64" => f.trunc(),
 169                     "roundf64" => f.round(),
 170                     _ => bug!(),
 171                 };
 172                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 173             }
 174
 175             #[rustfmt::skip]
 176             | "fadd_fast"
 177             | "fsub_fast"
 178             | "fmul_fast"
 179             | "fdiv_fast"
 180             | "frem_fast"
 181             => {
 182                 let &[ref a, ref b] = check_arg_count(args)?;
 183                 let a = this.read_immediate(a)?;
 184                 let b = this.read_immediate(b)?;
 185                 let op = match intrinsic_name {
 186                     "fadd_fast" => mir::BinOp::Add,
 187                     "fsub_fast" => mir::BinOp::Sub,
 188                     "fmul_fast" => mir::BinOp::Mul,
 189                     "fdiv_fast" => mir::BinOp::Div,
 190                     "frem_fast" => mir::BinOp::Rem,
 191                     _ => bug!(),
 192                 };
 193                 let float_finite = |x: ImmTy<'tcx, _>| -> InterpResult<'tcx, bool> {
 194                     Ok(match x.layout.ty.kind() {
 195                         ty::Float(FloatTy::F32) => x.to_scalar()?.to_f32()?.is_finite(),
 196                         ty::Float(FloatTy::F64) => x.to_scalar()?.to_f64()?.is_finite(),
 197                         _ => bug!(
 198                             "`{}` called with non-float input type {:?}",
 199                             intrinsic_name,
 200                             x.layout.ty
 201                         ),
 202                     })
 203                 };
 204                 match (float_finite(a)?, float_finite(b)?) {
 205                     (false, false) => throw_ub_format!(
 206                         "`{}` intrinsic called with non-finite value as both parameters",
 207                         intrinsic_name,
 208                     ),
 209                     (false, _) => throw_ub_format!(
 210                         "`{}` intrinsic called with non-finite value as first parameter",
 211                         intrinsic_name,
 212                     ),
 213                     (_, false) => throw_ub_format!(
 214                         "`{}` intrinsic called with non-finite value as second parameter",
 215                         intrinsic_name,
 216                     ),
 217                     _ => {}
 218                 }
 219                 this.binop_ignore_overflow(op, &a, &b, dest)?;
 220             }
 221
 222             #[rustfmt::skip]
 223             | "minnumf32"
 224             | "maxnumf32"
 225             | "copysignf32"
 226             => {
 227                 let &[ref a, ref b] = check_arg_count(args)?;
 228                 let a = this.read_scalar(a)?.to_f32()?;
 229                 let b = this.read_scalar(b)?.to_f32()?;
 230                 let res = match intrinsic_name {
 231                     "minnumf32" => a.min(b),
 232                     "maxnumf32" => a.max(b),
 233                     "copysignf32" => a.copy_sign(b),
 234                     _ => bug!(),
 235                 };
 236                 this.write_scalar(Scalar::from_f32(res), dest)?;
 237             }
 238
 239             #[rustfmt::skip]
 240             | "minnumf64"
 241             | "maxnumf64"
 242             | "copysignf64"
 243             => {
 244                 let &[ref a, ref b] = check_arg_count(args)?;
 245                 let a = this.read_scalar(a)?.to_f64()?;
 246                 let b = this.read_scalar(b)?.to_f64()?;
 247                 let res = match intrinsic_name {
 248                     "minnumf64" => a.min(b),
 249                     "maxnumf64" => a.max(b),
 250                     "copysignf64" => a.copy_sign(b),
 251                     _ => bug!(),
 252                 };
 253                 this.write_scalar(Scalar::from_f64(res), dest)?;
 254             }
 255
 256             "powf32" => {
 257                 let &[ref f, ref f2] = check_arg_count(args)?;
 258                 // FIXME: Using host floats.
 259                 let f = f32::from_bits(this.read_scalar(f)?.to_u32()?);
 260                 let f2 = f32::from_bits(this.read_scalar(f2)?.to_u32()?);
 261                 this.write_scalar(Scalar::from_u32(f.powf(f2).to_bits()), dest)?;
 262             }
 263
 264             "powf64" => {
 265                 let &[ref f, ref f2] = check_arg_count(args)?;
 266                 // FIXME: Using host floats.
 267                 let f = f64::from_bits(this.read_scalar(f)?.to_u64()?);
 268                 let f2 = f64::from_bits(this.read_scalar(f2)?.to_u64()?);
 269                 this.write_scalar(Scalar::from_u64(f.powf(f2).to_bits()), dest)?;
 270             }
 271
 272             "fmaf32" => {
 273                 let &[ref a, ref b, ref c] = check_arg_count(args)?;
 274                 let a = this.read_scalar(a)?.to_f32()?;
 275                 let b = this.read_scalar(b)?.to_f32()?;
 276                 let c = this.read_scalar(c)?.to_f32()?;
 277                 let res = a.mul_add(b, c).value;
 278                 this.write_scalar(Scalar::from_f32(res), dest)?;
 279             }
 280
 281             "fmaf64" => {
 282                 let &[ref a, ref b, ref c] = check_arg_count(args)?;
 283                 let a = this.read_scalar(a)?.to_f64()?;
 284                 let b = this.read_scalar(b)?.to_f64()?;
 285                 let c = this.read_scalar(c)?.to_f64()?;
 286                 let res = a.mul_add(b, c).value;
 287                 this.write_scalar(Scalar::from_f64(res), dest)?;
 288             }
 289
 290             "powif32" => {
 291                 let &[ref f, ref i] = check_arg_count(args)?;
 292                 // FIXME: Using host floats.
 293                 let f = f32::from_bits(this.read_scalar(f)?.to_u32()?);
 294                 let i = this.read_scalar(i)?.to_i32()?;
 295                 this.write_scalar(Scalar::from_u32(f.powi(i).to_bits()), dest)?;
 296             }
 297
 298             "powif64" => {
 299                 let &[ref f, ref i] = check_arg_count(args)?;
 300                 // FIXME: Using host floats.
 301                 let f = f64::from_bits(this.read_scalar(f)?.to_u64()?);
 302                 let i = this.read_scalar(i)?.to_i32()?;
 303                 this.write_scalar(Scalar::from_u64(f.powi(i).to_bits()), dest)?;
 304             }
 305
 306             "float_to_int_unchecked" => {
 307                 let &[ref val] = check_arg_count(args)?;
 308                 let val = this.read_immediate(val)?;
 309
 310                 let res = match val.layout.ty.kind() {
 311                     ty::Float(FloatTy::F32) =>
 312                         this.float_to_int_unchecked(val.to_scalar()?.to_f32()?, dest.layout.ty)?,
 313                     ty::Float(FloatTy::F64) =>
 314                         this.float_to_int_unchecked(val.to_scalar()?.to_f64()?, dest.layout.ty)?,
 315                     _ =>
 316                         bug!(
 317                             "`float_to_int_unchecked` called with non-float input type {:?}",
 318                             val.layout.ty
 319                         ),
 320                 };
 321
 322                 this.write_scalar(res, dest)?;
 323             }
 324
 325             // SIMD operations
 326             #[rustfmt::skip]
 327             | "simd_neg"
 328             | "simd_fabs" => {
 329                 let &[ref op] = check_arg_count(args)?;
 330                 let (op, op_len) = this.operand_to_simd(op)?;
 331                 let (dest, dest_len) = this.place_to_simd(dest)?;
 332
 333                 assert_eq!(dest_len, op_len);
 334
 335                 enum Op {
 336                     MirOp(mir::UnOp),
 337                     Abs,
 338                 }
 339                 let which = match intrinsic_name {
 340                     "simd_neg" => Op::MirOp(mir::UnOp::Neg),
 341                     "simd_fabs" => Op::Abs,
 342                     _ => unreachable!(),
 343                 };
 344
 345                 for i in 0..dest_len {
 346                     let op = this.read_immediate(&this.mplace_index(&op, i)?.into())?;
 347                     let dest = this.mplace_index(&dest, i)?;
 348                     let val = match which {
 349                         Op::MirOp(mir_op) => this.unary_op(mir_op, &op)?.to_scalar()?,
 350                         Op::Abs => {
 351                             // Works for f32 and f64.
 352                             let ty::Float(float_ty) = op.layout.ty.kind() else {
 353                                 bug!("simd_fabs operand is not a float")
 354                             };
 355                             let op = op.to_scalar()?;
 356                             match float_ty {
 357                                 FloatTy::F32 => Scalar::from_f32(op.to_f32()?.abs()),
 358                                 FloatTy::F64 => Scalar::from_f64(op.to_f64()?.abs()),
 359                             }
 360                         }
 361                     };
 362                     this.write_scalar(val, &dest.into())?;
 363                 }
 364             }
 365             #[rustfmt::skip]
 366             | "simd_add"
 367             | "simd_sub"
 368             | "simd_mul"
 369             | "simd_div"
 370             | "simd_rem"
 371             | "simd_shl"
 372             | "simd_shr"
 373             | "simd_and"
 374             | "simd_or"
 375             | "simd_xor"
 376             | "simd_eq"
 377             | "simd_ne"
 378             | "simd_lt"
 379             | "simd_le"
 380             | "simd_gt"
 381             | "simd_ge"
 382             | "simd_fmax"
 383             | "simd_fmin"
 384             | "simd_saturating_add"
 385             | "simd_saturating_sub" => {
 386                 use mir::BinOp;
 387
 388                 let &[ref left, ref right] = check_arg_count(args)?;
 389                 let (left, left_len) = this.operand_to_simd(left)?;
 390                 let (right, right_len) = this.operand_to_simd(right)?;
 391                 let (dest, dest_len) = this.place_to_simd(dest)?;
 392
 393                 assert_eq!(dest_len, left_len);
 394                 assert_eq!(dest_len, right_len);
 395
 396                 enum Op {
 397                     MirOp(BinOp),
 398                     SaturatingOp(BinOp),
 399                     FMax,
 400                     FMin,
 401                 }
 402                 let which = match intrinsic_name {
 403                     "simd_add" => Op::MirOp(BinOp::Add),
 404                     "simd_sub" => Op::MirOp(BinOp::Sub),
 405                     "simd_mul" => Op::MirOp(BinOp::Mul),
 406                     "simd_div" => Op::MirOp(BinOp::Div),
 407                     "simd_rem" => Op::MirOp(BinOp::Rem),
 408                     "simd_shl" => Op::MirOp(BinOp::Shl),
 409                     "simd_shr" => Op::MirOp(BinOp::Shr),
 410                     "simd_and" => Op::MirOp(BinOp::BitAnd),
 411                     "simd_or" => Op::MirOp(BinOp::BitOr),
 412                     "simd_xor" => Op::MirOp(BinOp::BitXor),
 413                     "simd_eq" => Op::MirOp(BinOp::Eq),
 414                     "simd_ne" => Op::MirOp(BinOp::Ne),
 415                     "simd_lt" => Op::MirOp(BinOp::Lt),
 416                     "simd_le" => Op::MirOp(BinOp::Le),
 417                     "simd_gt" => Op::MirOp(BinOp::Gt),
 418                     "simd_ge" => Op::MirOp(BinOp::Ge),
 419                     "simd_fmax" => Op::FMax,
 420                     "simd_fmin" => Op::FMin,
 421                     "simd_saturating_add" => Op::SaturatingOp(BinOp::Add),
 422                     "simd_saturating_sub" => Op::SaturatingOp(BinOp::Sub),
 423                     _ => unreachable!(),
 424                 };
 425
 426                 for i in 0..dest_len {
 427                     let left = this.read_immediate(&this.mplace_index(&left, i)?.into())?;
 428                     let right = this.read_immediate(&this.mplace_index(&right, i)?.into())?;
 429                     let dest = this.mplace_index(&dest, i)?;
 430                     let val = match which {
 431                         Op::MirOp(mir_op) => {
 432                             let (val, overflowed, ty) = this.overflowing_binary_op(mir_op, &left, &right)?;
 433                             if matches!(mir_op, BinOp::Shl | BinOp::Shr) {
 434                                 // Shifts have extra UB as SIMD operations that the MIR binop does not have.
 435                                 // See <https://github.com/rust-lang/rust/issues/91237>.
 436                                 if overflowed {
 437                                     let r_val = right.to_scalar()?.to_bits(right.layout.size)?;
 438                                     throw_ub_format!("overflowing shift by {} in `{}` in SIMD lane {}", r_val, intrinsic_name, i);
 439                                 }
 440                             }
 441                             if matches!(mir_op, BinOp::Eq | BinOp::Ne | BinOp::Lt | BinOp::Le | BinOp::Gt | BinOp::Ge) {
 442                                 // Special handling for boolean-returning operations
 443                                 assert_eq!(ty, this.tcx.types.bool);
 444                                 let val = val.to_bool().unwrap();
 445                                 bool_to_simd_element(val, dest.layout.size)
 446                             } else {
 447                                 assert_ne!(ty, this.tcx.types.bool);
 448                                 assert_eq!(ty, dest.layout.ty);
 449                                 val
 450                             }
 451                         }
 452                         Op::FMax => {
 453                             fmax_op(&left, &right)?
 454                         }
 455                         Op::FMin => {
 456                             fmin_op(&left, &right)?
 457                         }
 458                         Op::SaturatingOp(mir_op) => {
 459                             this.saturating_arith(mir_op, &left, &right)?
 460                         }
 461                     };
 462                     this.write_scalar(val, &dest.into())?;
 463                 }
 464             }
 465             #[rustfmt::skip]
 466             | "simd_reduce_and"
 467             | "simd_reduce_or"
 468             | "simd_reduce_xor"
 469             | "simd_reduce_any"
 470             | "simd_reduce_all"
 471             | "simd_reduce_max"
 472             | "simd_reduce_min" => {
 473                 use mir::BinOp;
 474
 475                 let &[ref op] = check_arg_count(args)?;
 476                 let (op, op_len) = this.operand_to_simd(op)?;
 477
 478                 let imm_from_bool =
 479                     |b| ImmTy::from_scalar(Scalar::from_bool(b), this.machine.layouts.bool);
 480
 481                 enum Op {
 482                     MirOp(BinOp),
 483                     MirOpBool(BinOp),
 484                     Max,
 485                     Min,
 486                 }
 487                 let which = match intrinsic_name {
 488                     "simd_reduce_and" => Op::MirOp(BinOp::BitAnd),
 489                     "simd_reduce_or" => Op::MirOp(BinOp::BitOr),
 490                     "simd_reduce_xor" => Op::MirOp(BinOp::BitXor),
 491                     "simd_reduce_any" => Op::MirOpBool(BinOp::BitOr),
 492                     "simd_reduce_all" => Op::MirOpBool(BinOp::BitAnd),
 493                     "simd_reduce_max" => Op::Max,
 494                     "simd_reduce_min" => Op::Min,
 495                     _ => unreachable!(),
 496                 };
 497
 498                 // Initialize with first lane, then proceed with the rest.
 499                 let mut res = this.read_immediate(&this.mplace_index(&op, 0)?.into())?;
 500                 if matches!(which, Op::MirOpBool(_)) {
 501                     // Convert to `bool` scalar.
 502                     res = imm_from_bool(simd_element_to_bool(res)?);
 503                 }
 504                 for i in 1..op_len {
 505                     let op = this.read_immediate(&this.mplace_index(&op, i)?.into())?;
 506                     res = match which {
 507                         Op::MirOp(mir_op) => {
 508                             this.binary_op(mir_op, &res, &op)?
 509                         }
 510                         Op::MirOpBool(mir_op) => {
 511                             let op = imm_from_bool(simd_element_to_bool(op)?);
 512                             this.binary_op(mir_op, &res, &op)?
 513                         }
 514                         Op::Max => {
 515                             if matches!(res.layout.ty.kind(), ty::Float(_)) {
 516                                 ImmTy::from_scalar(fmax_op(&res, &op)?, res.layout)
 517                             } else {
 518                                 // Just boring integers, so NaNs to worry about
 519                                 if this.binary_op(BinOp::Ge, &res, &op)?.to_scalar()?.to_bool()? {
 520                                     res
 521                                 } else {
 522                                     op
 523                                 }
 524                             }
 525                         }
 526                         Op::Min => {
 527                             if matches!(res.layout.ty.kind(), ty::Float(_)) {
 528                                 ImmTy::from_scalar(fmin_op(&res, &op)?, res.layout)
 529                             } else {
 530                                 // Just boring integers, so NaNs to worry about
 531                                 if this.binary_op(BinOp::Le, &res, &op)?.to_scalar()?.to_bool()? {
 532                                     res
 533                                 } else {
 534                                     op
 535                                 }
 536                             }
 537                         }
 538                     };
 539                 }
 540                 this.write_immediate(*res, dest)?;
 541             }
 542             #[rustfmt::skip]
 543             | "simd_reduce_add_ordered"
 544             | "simd_reduce_mul_ordered" => {
 545                 use mir::BinOp;
 546
 547                 let &[ref op, ref init] = check_arg_count(args)?;
 548                 let (op, op_len) = this.operand_to_simd(op)?;
 549                 let init = this.read_immediate(init)?;
 550
 551                 let mir_op = match intrinsic_name {
 552                     "simd_reduce_add_ordered" => BinOp::Add,
 553                     "simd_reduce_mul_ordered" => BinOp::Mul,
 554                     _ => unreachable!(),
 555                 };
 556
 557                 let mut res = init;
 558                 for i in 0..op_len {
 559                     let op = this.read_immediate(&this.mplace_index(&op, i)?.into())?;
 560                     res = this.binary_op(mir_op, &res, &op)?;
 561                 }
 562                 this.write_immediate(*res, dest)?;
 563             }
 564             "simd_select" => {
 565                 let &[ref mask, ref yes, ref no] = check_arg_count(args)?;
 566                 let (mask, mask_len) = this.operand_to_simd(mask)?;
 567                 let (yes, yes_len) = this.operand_to_simd(yes)?;
 568                 let (no, no_len) = this.operand_to_simd(no)?;
 569                 let (dest, dest_len) = this.place_to_simd(dest)?;
 570
 571                 assert_eq!(dest_len, mask_len);
 572                 assert_eq!(dest_len, yes_len);
 573                 assert_eq!(dest_len, no_len);
 574
 575                 for i in 0..dest_len {
 576                     let mask = this.read_immediate(&this.mplace_index(&mask, i)?.into())?;
 577                     let yes = this.read_immediate(&this.mplace_index(&yes, i)?.into())?;
 578                     let no = this.read_immediate(&this.mplace_index(&no, i)?.into())?;
 579                     let dest = this.mplace_index(&dest, i)?;
 580
 581                     let val = if simd_element_to_bool(mask)? { yes } else { no };
 582                     this.write_immediate(*val, &dest.into())?;
 583                 }
 584             }
 585             #[rustfmt::skip]
 586             "simd_cast" | "simd_as" => {
 587                 let &[ref op] = check_arg_count(args)?;
 588                 let (op, op_len) = this.operand_to_simd(op)?;
 589                 let (dest, dest_len) = this.place_to_simd(dest)?;
 590
 591                 assert_eq!(dest_len, op_len);
 592
 593                 let safe_cast = intrinsic_name == "simd_as";
 594
 595                 for i in 0..dest_len {
 596                     let op = this.read_immediate(&this.mplace_index(&op, i)?.into())?;
 597                     let dest = this.mplace_index(&dest, i)?;
 598
 599                     let val = match (op.layout.ty.kind(), dest.layout.ty.kind()) {
 600                         // Int-to-(int|float): always safe
 601                         (ty::Int(_) | ty::Uint(_), ty::Int(_) | ty::Uint(_) | ty::Float(_)) =>
 602                             this.misc_cast(&op, dest.layout.ty)?,
 603                         // Float-to-float: always safe
 604                         (ty::Float(_), ty::Float(_)) =>
 605                             this.misc_cast(&op, dest.layout.ty)?,
 606                         // Float-to-int in safe mode
 607                         (ty::Float(_), ty::Int(_) | ty::Uint(_)) if safe_cast =>
 608                             this.misc_cast(&op, dest.layout.ty)?,
 609                         // Float-to-int in unchecked mode
 610                         (ty::Float(FloatTy::F32), ty::Int(_) | ty::Uint(_)) if !safe_cast =>
 611                             this.float_to_int_unchecked(op.to_scalar()?.to_f32()?, dest.layout.ty)?.into(),
 612                         (ty::Float(FloatTy::F64), ty::Int(_) | ty::Uint(_)) if !safe_cast =>
 613                             this.float_to_int_unchecked(op.to_scalar()?.to_f64()?, dest.layout.ty)?.into(),
 614                         _ =>
 615                             throw_unsup_format!(
 616                                 "Unsupported SIMD cast from element type {} to {}",
 617                                 op.layout.ty,
 618                                 dest.layout.ty
 619                             ),
 620                     };
 621                     this.write_immediate(val, &dest.into())?;
 622                 }
 623             }
 624             "simd_shuffle" => {
 625                 let &[ref left, ref right, ref index] = check_arg_count(args)?;
 626                 let (left, left_len) = this.operand_to_simd(left)?;
 627                 let (right, right_len) = this.operand_to_simd(right)?;
 628                 let (dest, dest_len) = this.place_to_simd(dest)?;
 629
 630                 // `index` is an array, not a SIMD type
 631                 let ty::Array(_, index_len) = index.layout.ty.kind() else {
 632                     bug!("simd_shuffle index argument has non-array type {}", index.layout.ty)
 633                 };
 634                 let index_len = index_len.eval_usize(*this.tcx, this.param_env());
 635
 636                 assert_eq!(left_len, right_len);
 637                 assert_eq!(index_len, dest_len);
 638
 639                 for i in 0..dest_len {
 640                     let src_index: u64 = this
 641                         .read_immediate(&this.operand_index(&index, i)?.into())?
 642                         .to_scalar()?
 643                         .to_u32()?
 644                         .into();
 645                     let dest = this.mplace_index(&dest, i)?;
 646
 647                     let val = if src_index < left_len {
 648                         this.read_immediate(&this.mplace_index(&left, src_index)?.into())?
 649                     } else if src_index < left_len.checked_add(right_len).unwrap() {
 650                         this.read_immediate(
 651                             &this.mplace_index(&right, src_index - left_len)?.into(),
 652                         )?
 653                     } else {
 654                         bug!(
 655                             "simd_shuffle index {} is out of bounds for 2 vectors of size {}",
 656                             src_index,
 657                             left_len
 658                         );
 659                     };
 660                     this.write_immediate(*val, &dest.into())?;
 661                 }
 662             }
 663             "simd_gather" => {
 664                 let &[ref passthru, ref ptrs, ref mask] = check_arg_count(args)?;
 665                 let (passthru, passthru_len) = this.operand_to_simd(passthru)?;
 666                 let (ptrs, ptrs_len) = this.operand_to_simd(ptrs)?;
 667                 let (mask, mask_len) = this.operand_to_simd(mask)?;
 668                 let (dest, dest_len) = this.place_to_simd(dest)?;
 669
 670                 assert_eq!(dest_len, passthru_len);
 671                 assert_eq!(dest_len, ptrs_len);
 672                 assert_eq!(dest_len, mask_len);
 673
 674                 for i in 0..dest_len {
 675                     let passthru = this.read_immediate(&this.mplace_index(&passthru, i)?.into())?;
 676                     let ptr = this.read_immediate(&this.mplace_index(&ptrs, i)?.into())?;
 677                     let mask = this.read_immediate(&this.mplace_index(&mask, i)?.into())?;
 678                     let dest = this.mplace_index(&dest, i)?;
 679
 680                     let val = if simd_element_to_bool(mask)? {
 681                         let place = this.deref_operand(&ptr.into())?;
 682                         this.read_immediate(&place.into())?
 683                     } else {
 684                         passthru
 685                     };
 686                     this.write_immediate(*val, &dest.into())?;
 687                 }
 688             }
 689             "simd_scatter" => {
 690                 let &[ref value, ref ptrs, ref mask] = check_arg_count(args)?;
 691                 let (value, value_len) = this.operand_to_simd(value)?;
 692                 let (ptrs, ptrs_len) = this.operand_to_simd(ptrs)?;
 693                 let (mask, mask_len) = this.operand_to_simd(mask)?;
 694
 695                 assert_eq!(ptrs_len, value_len);
 696                 assert_eq!(ptrs_len, mask_len);
 697
 698                 for i in 0..ptrs_len {
 699                     let value = this.read_immediate(&this.mplace_index(&value, i)?.into())?;
 700                     let ptr = this.read_immediate(&this.mplace_index(&ptrs, i)?.into())?;
 701                     let mask = this.read_immediate(&this.mplace_index(&mask, i)?.into())?;
 702
 703                     if simd_element_to_bool(mask)? {
 704                         let place = this.deref_operand(&ptr.into())?;
 705                         this.write_immediate(*value, &place.into())?;
 706                     }
 707                 }
 708             }
 709
 710             // Atomic operations
 711             "atomic_load" => this.atomic_load(args, dest, AtomicReadOp::SeqCst)?,
 712             "atomic_load_relaxed" => this.atomic_load(args, dest, AtomicReadOp::Relaxed)?,
 713             "atomic_load_acq" => this.atomic_load(args, dest, AtomicReadOp::Acquire)?,
 714
 715             "atomic_store" => this.atomic_store(args, AtomicWriteOp::SeqCst)?,
 716             "atomic_store_relaxed" => this.atomic_store(args, AtomicWriteOp::Relaxed)?,
 717             "atomic_store_rel" => this.atomic_store(args, AtomicWriteOp::Release)?,
 718
 719             "atomic_fence_acq" => this.atomic_fence(args, AtomicFenceOp::Acquire)?,
 720             "atomic_fence_rel" => this.atomic_fence(args, AtomicFenceOp::Release)?,
 721             "atomic_fence_acqrel" => this.atomic_fence(args, AtomicFenceOp::AcqRel)?,
 722             "atomic_fence" => this.atomic_fence(args, AtomicFenceOp::SeqCst)?,
 723
 724             "atomic_singlethreadfence_acq" => this.compiler_fence(args, AtomicFenceOp::Acquire)?,
 725             "atomic_singlethreadfence_rel" => this.compiler_fence(args, AtomicFenceOp::Release)?,
 726             "atomic_singlethreadfence_acqrel" =>
 727                 this.compiler_fence(args, AtomicFenceOp::AcqRel)?,
 728             "atomic_singlethreadfence" => this.compiler_fence(args, AtomicFenceOp::SeqCst)?,
 729
 730             "atomic_xchg" => this.atomic_exchange(args, dest, AtomicRwOp::SeqCst)?,
 731             "atomic_xchg_acq" => this.atomic_exchange(args, dest, AtomicRwOp::Acquire)?,
 732             "atomic_xchg_rel" => this.atomic_exchange(args, dest, AtomicRwOp::Release)?,
 733             "atomic_xchg_acqrel" => this.atomic_exchange(args, dest, AtomicRwOp::AcqRel)?,
 734             "atomic_xchg_relaxed" => this.atomic_exchange(args, dest, AtomicRwOp::Relaxed)?,
 735
 736             #[rustfmt::skip]
 737             "atomic_cxchg" =>
 738                 this.atomic_compare_exchange(args, dest, AtomicRwOp::SeqCst, AtomicReadOp::SeqCst)?,
 739             #[rustfmt::skip]
 740             "atomic_cxchg_acq" =>
 741                 this.atomic_compare_exchange(args, dest, AtomicRwOp::Acquire, AtomicReadOp::Acquire)?,
 742             #[rustfmt::skip]
 743             "atomic_cxchg_rel" =>
 744                 this.atomic_compare_exchange(args, dest, AtomicRwOp::Release, AtomicReadOp::Relaxed)?,
 745             #[rustfmt::skip]
 746             "atomic_cxchg_acqrel" =>
 747                 this.atomic_compare_exchange(args, dest, AtomicRwOp::AcqRel, AtomicReadOp::Acquire)?,
 748             #[rustfmt::skip]
 749             "atomic_cxchg_relaxed" =>
 750                 this.atomic_compare_exchange(args, dest, AtomicRwOp::Relaxed, AtomicReadOp::Relaxed)?,
 751             #[rustfmt::skip]
 752             "atomic_cxchg_acq_failrelaxed" =>
 753                 this.atomic_compare_exchange(args, dest, AtomicRwOp::Acquire, AtomicReadOp::Relaxed)?,
 754             #[rustfmt::skip]
 755             "atomic_cxchg_acqrel_failrelaxed" =>
 756                 this.atomic_compare_exchange(args, dest, AtomicRwOp::AcqRel, AtomicReadOp::Relaxed)?,
 757             #[rustfmt::skip]
 758             "atomic_cxchg_failrelaxed" =>
 759                 this.atomic_compare_exchange(args, dest, AtomicRwOp::SeqCst, AtomicReadOp::Relaxed)?,
 760             #[rustfmt::skip]
 761             "atomic_cxchg_failacq" =>
 762                 this.atomic_compare_exchange(args, dest, AtomicRwOp::SeqCst, AtomicReadOp::Acquire)?,
 763
 764             #[rustfmt::skip]
 765             "atomic_cxchgweak" =>
 766                 this.atomic_compare_exchange_weak(args, dest, AtomicRwOp::SeqCst, AtomicReadOp::SeqCst)?,
 767             #[rustfmt::skip]
 768             "atomic_cxchgweak_acq" =>
 769                 this.atomic_compare_exchange_weak(args, dest, AtomicRwOp::Acquire, AtomicReadOp::Acquire)?,
 770             #[rustfmt::skip]
 771             "atomic_cxchgweak_rel" =>
 772                 this.atomic_compare_exchange_weak(args, dest, AtomicRwOp::Release, AtomicReadOp::Relaxed)?,
 773             #[rustfmt::skip]
 774             "atomic_cxchgweak_acqrel" =>
 775                 this.atomic_compare_exchange_weak(args, dest, AtomicRwOp::AcqRel, AtomicReadOp::Acquire)?,
 776             #[rustfmt::skip]
 777             "atomic_cxchgweak_relaxed" =>
 778                 this.atomic_compare_exchange_weak(args, dest, AtomicRwOp::Relaxed, AtomicReadOp::Relaxed)?,
 779             #[rustfmt::skip]
 780             "atomic_cxchgweak_acq_failrelaxed" =>
 781                 this.atomic_compare_exchange_weak(args, dest, AtomicRwOp::Acquire, AtomicReadOp::Relaxed)?,
 782             #[rustfmt::skip]
 783             "atomic_cxchgweak_acqrel_failrelaxed" =>
 784                 this.atomic_compare_exchange_weak(args, dest, AtomicRwOp::AcqRel, AtomicReadOp::Relaxed)?,
 785             #[rustfmt::skip]
 786             "atomic_cxchgweak_failrelaxed" =>
 787                 this.atomic_compare_exchange_weak(args, dest, AtomicRwOp::SeqCst, AtomicReadOp::Relaxed)?,
 788             #[rustfmt::skip]
 789             "atomic_cxchgweak_failacq" =>
 790                 this.atomic_compare_exchange_weak(args, dest, AtomicRwOp::SeqCst, AtomicReadOp::Acquire)?,
 791
 792             #[rustfmt::skip]
 793             "atomic_or" =>
 794                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitOr, false), AtomicRwOp::SeqCst)?,
 795             #[rustfmt::skip]
 796             "atomic_or_acq" =>
 797                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitOr, false), AtomicRwOp::Acquire)?,
 798             #[rustfmt::skip]
 799             "atomic_or_rel" =>
 800                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitOr, false), AtomicRwOp::Release)?,
 801             #[rustfmt::skip]
 802             "atomic_or_acqrel" =>
 803                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitOr, false), AtomicRwOp::AcqRel)?,
 804             #[rustfmt::skip]
 805             "atomic_or_relaxed" =>
 806                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitOr, false), AtomicRwOp::Relaxed)?,
 807             #[rustfmt::skip]
 808             "atomic_xor" =>
 809                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitXor, false), AtomicRwOp::SeqCst)?,
 810             #[rustfmt::skip]
 811             "atomic_xor_acq" =>
 812                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitXor, false), AtomicRwOp::Acquire)?,
 813             #[rustfmt::skip]
 814             "atomic_xor_rel" =>
 815                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitXor, false), AtomicRwOp::Release)?,
 816             #[rustfmt::skip]
 817             "atomic_xor_acqrel" =>
 818                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitXor, false), AtomicRwOp::AcqRel)?,
 819             #[rustfmt::skip]
 820             "atomic_xor_relaxed" =>
 821                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitXor, false), AtomicRwOp::Relaxed)?,
 822             #[rustfmt::skip]
 823             "atomic_and" =>
 824                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitAnd, false), AtomicRwOp::SeqCst)?,
 825             #[rustfmt::skip]
 826             "atomic_and_acq" =>
 827                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitAnd, false), AtomicRwOp::Acquire)?,
 828             #[rustfmt::skip]
 829             "atomic_and_rel" =>
 830                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitAnd, false), AtomicRwOp::Release)?,
 831             #[rustfmt::skip]
 832             "atomic_and_acqrel" =>
 833                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitAnd, false), AtomicRwOp::AcqRel)?,
 834             #[rustfmt::skip]
 835             "atomic_and_relaxed" =>
 836                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitAnd, false), AtomicRwOp::Relaxed)?,
 837             #[rustfmt::skip]
 838             "atomic_nand" =>
 839                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitAnd, true), AtomicRwOp::SeqCst)?,
 840             #[rustfmt::skip]
 841             "atomic_nand_acq" =>
 842                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitAnd, true), AtomicRwOp::Acquire)?,
 843             #[rustfmt::skip]
 844             "atomic_nand_rel" =>
 845                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitAnd, true), AtomicRwOp::Release)?,
 846             #[rustfmt::skip]
 847             "atomic_nand_acqrel" =>
 848                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitAnd, true), AtomicRwOp::AcqRel)?,
 849             #[rustfmt::skip]
 850             "atomic_nand_relaxed" =>
 851                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::BitAnd, true), AtomicRwOp::Relaxed)?,
 852             #[rustfmt::skip]
 853             "atomic_xadd" =>
 854                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::Add, false), AtomicRwOp::SeqCst)?,
 855             #[rustfmt::skip]
 856             "atomic_xadd_acq" =>
 857                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::Add, false), AtomicRwOp::Acquire)?,
 858             #[rustfmt::skip]
 859             "atomic_xadd_rel" =>
 860                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::Add, false), AtomicRwOp::Release)?,
 861             #[rustfmt::skip]
 862             "atomic_xadd_acqrel" =>
 863                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::Add, false), AtomicRwOp::AcqRel)?,
 864             #[rustfmt::skip]
 865             "atomic_xadd_relaxed" =>
 866                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::Add, false), AtomicRwOp::Relaxed)?,
 867             #[rustfmt::skip]
 868             "atomic_xsub" =>
 869                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::Sub, false), AtomicRwOp::SeqCst)?,
 870             #[rustfmt::skip]
 871             "atomic_xsub_acq" =>
 872                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::Sub, false), AtomicRwOp::Acquire)?,
 873             #[rustfmt::skip]
 874             "atomic_xsub_rel" =>
 875                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::Sub, false), AtomicRwOp::Release)?,
 876             #[rustfmt::skip]
 877             "atomic_xsub_acqrel" =>
 878                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::Sub, false), AtomicRwOp::AcqRel)?,
 879             #[rustfmt::skip]
 880             "atomic_xsub_relaxed" =>
 881                 this.atomic_op(args, dest, AtomicOp::MirOp(BinOp::Sub, false), AtomicRwOp::Relaxed)?,
 882             "atomic_min" => this.atomic_op(args, dest, AtomicOp::Min, AtomicRwOp::SeqCst)?,
 883             "atomic_min_acq" => this.atomic_op(args, dest, AtomicOp::Min, AtomicRwOp::Acquire)?,
 884             "atomic_min_rel" => this.atomic_op(args, dest, AtomicOp::Min, AtomicRwOp::Release)?,
 885             "atomic_min_acqrel" => this.atomic_op(args, dest, AtomicOp::Min, AtomicRwOp::AcqRel)?,
 886             "atomic_min_relaxed" =>
 887                 this.atomic_op(args, dest, AtomicOp::Min, AtomicRwOp::Relaxed)?,
 888             "atomic_max" => this.atomic_op(args, dest, AtomicOp::Max, AtomicRwOp::SeqCst)?,
 889             "atomic_max_acq" => this.atomic_op(args, dest, AtomicOp::Max, AtomicRwOp::Acquire)?,
 890             "atomic_max_rel" => this.atomic_op(args, dest, AtomicOp::Max, AtomicRwOp::Release)?,
 891             "atomic_max_acqrel" => this.atomic_op(args, dest, AtomicOp::Max, AtomicRwOp::AcqRel)?,
 892             "atomic_max_relaxed" =>
 893                 this.atomic_op(args, dest, AtomicOp::Max, AtomicRwOp::Relaxed)?,
 894             "atomic_umin" => this.atomic_op(args, dest, AtomicOp::Min, AtomicRwOp::SeqCst)?,
 895             "atomic_umin_acq" => this.atomic_op(args, dest, AtomicOp::Min, AtomicRwOp::Acquire)?,
 896             "atomic_umin_rel" => this.atomic_op(args, dest, AtomicOp::Min, AtomicRwOp::Release)?,
 897             "atomic_umin_acqrel" =>
 898                 this.atomic_op(args, dest, AtomicOp::Min, AtomicRwOp::AcqRel)?,
 899             "atomic_umin_relaxed" =>
 900                 this.atomic_op(args, dest, AtomicOp::Min, AtomicRwOp::Relaxed)?,
 901             "atomic_umax" => this.atomic_op(args, dest, AtomicOp::Max, AtomicRwOp::SeqCst)?,
 902             "atomic_umax_acq" => this.atomic_op(args, dest, AtomicOp::Max, AtomicRwOp::Acquire)?,
 903             "atomic_umax_rel" => this.atomic_op(args, dest, AtomicOp::Max, AtomicRwOp::Release)?,
 904             "atomic_umax_acqrel" =>
 905                 this.atomic_op(args, dest, AtomicOp::Max, AtomicRwOp::AcqRel)?,
 906             "atomic_umax_relaxed" =>
 907                 this.atomic_op(args, dest, AtomicOp::Max, AtomicRwOp::Relaxed)?,
 908
 909             // Other
 910             "exact_div" => {
 911                 let &[ref num, ref denom] = check_arg_count(args)?;
 912                 this.exact_div(&this.read_immediate(num)?, &this.read_immediate(denom)?, dest)?;
 913             }
 914
 915             "try" => return this.handle_try(args, dest, ret),
 916
 917             "breakpoint" => {
 918                 let &[] = check_arg_count(args)?;
 919                 // normally this would raise a SIGTRAP, which aborts if no debugger is connected
 920                 throw_machine_stop!(TerminationInfo::Abort("Trace/breakpoint trap".to_string()))
 921             }
 922
 923             name => throw_unsup_format!("unimplemented intrinsic: {}", name),
 924         }
 925
 926         trace!("{:?}", this.dump_place(**dest));
 927         this.go_to_block(ret);
 928         Ok(())
 929     }
 930
 931     fn atomic_load(
 932         &mut self,
 933         args: &[OpTy<'tcx, Tag>],
 934         dest: &PlaceTy<'tcx, Tag>,
 935         atomic: AtomicReadOp,
 936     ) -> InterpResult<'tcx> {
 937         let this = self.eval_context_mut();
 938
 939         let &[ref place] = check_arg_count(args)?;
 940         let place = this.deref_operand(place)?;
 941
 942         // make sure it fits into a scalar; otherwise it cannot be atomic
 943         let val = this.read_scalar_atomic(&place, atomic)?;
 944
 945         // Check alignment requirements. Atomics must always be aligned to their size,
 946         // even if the type they wrap would be less aligned (e.g. AtomicU64 on 32bit must
 947         // be 8-aligned).
 948         let align = Align::from_bytes(place.layout.size.bytes()).unwrap();
 949         this.memory.check_ptr_access_align(
 950             place.ptr,
 951             place.layout.size,
 952             align,
 953             CheckInAllocMsg::MemoryAccessTest,
 954         )?;
 955         // Perform regular access.
 956         this.write_scalar(val, dest)?;
 957         Ok(())
 958     }
 959
 960     fn atomic_store(
 961         &mut self,
 962         args: &[OpTy<'tcx, Tag>],
 963         atomic: AtomicWriteOp,
 964     ) -> InterpResult<'tcx> {
 965         let this = self.eval_context_mut();
 966
 967         let &[ref place, ref val] = check_arg_count(args)?;
 968         let place = this.deref_operand(place)?;
 969         let val = this.read_scalar(val)?; // make sure it fits into a scalar; otherwise it cannot be atomic
 970
 971         // Check alignment requirements. Atomics must always be aligned to their size,
 972         // even if the type they wrap would be less aligned (e.g. AtomicU64 on 32bit must
 973         // be 8-aligned).
 974         let align = Align::from_bytes(place.layout.size.bytes()).unwrap();
 975         this.memory.check_ptr_access_align(
 976             place.ptr,
 977             place.layout.size,
 978             align,
 979             CheckInAllocMsg::MemoryAccessTest,
 980         )?;
 981
 982         // Perform atomic store
 983         this.write_scalar_atomic(val, &place, atomic)?;
 984         Ok(())
 985     }
 986
 987     fn compiler_fence(
 988         &mut self,
 989         args: &[OpTy<'tcx, Tag>],
 990         atomic: AtomicFenceOp,
 991     ) -> InterpResult<'tcx> {
 992         let &[] = check_arg_count(args)?;
 993         let _ = atomic;
 994         //FIXME: compiler fences are currently ignored
 995         Ok(())
 996     }
 997
 998     fn atomic_fence(
 999         &mut self,
1000         args: &[OpTy<'tcx, Tag>],
1001         atomic: AtomicFenceOp,
1002     ) -> InterpResult<'tcx> {
1003         let this = self.eval_context_mut();
1004         let &[] = check_arg_count(args)?;
1005         this.validate_atomic_fence(atomic)?;
1006         Ok(())
1007     }
1008
1009     fn atomic_op(
1010         &mut self,
1011         args: &[OpTy<'tcx, Tag>],
1012         dest: &PlaceTy<'tcx, Tag>,
1013         atomic_op: AtomicOp,
1014         atomic: AtomicRwOp,
1015     ) -> InterpResult<'tcx> {
1016         let this = self.eval_context_mut();
1017
1018         let &[ref place, ref rhs] = check_arg_count(args)?;
1019         let place = this.deref_operand(place)?;
1020
1021         if !place.layout.ty.is_integral() {
1022             bug!("Atomic arithmetic operations only work on integer types");
1023         }
1024         let rhs = this.read_immediate(rhs)?;
1025
1026         // Check alignment requirements. Atomics must always be aligned to their size,
1027         // even if the type they wrap would be less aligned (e.g. AtomicU64 on 32bit must
1028         // be 8-aligned).
1029         let align = Align::from_bytes(place.layout.size.bytes()).unwrap();
1030         this.memory.check_ptr_access_align(
1031             place.ptr,
1032             place.layout.size,
1033             align,
1034             CheckInAllocMsg::MemoryAccessTest,
1035         )?;
1036
1037         match atomic_op {
1038             AtomicOp::Min => {
1039                 let old = this.atomic_min_max_scalar(&place, rhs, true, atomic)?;
1040                 this.write_immediate(*old, &dest)?; // old value is returned
1041                 Ok(())
1042             }
1043             AtomicOp::Max => {
1044                 let old = this.atomic_min_max_scalar(&place, rhs, false, atomic)?;
1045                 this.write_immediate(*old, &dest)?; // old value is returned
1046                 Ok(())
1047             }
1048             AtomicOp::MirOp(op, neg) => {
1049                 let old = this.atomic_op_immediate(&place, &rhs, op, neg, atomic)?;
1050                 this.write_immediate(*old, dest)?; // old value is returned
1051                 Ok(())
1052             }
1053         }
1054     }
1055
1056     fn atomic_exchange(
1057         &mut self,
1058         args: &[OpTy<'tcx, Tag>],
1059         dest: &PlaceTy<'tcx, Tag>,
1060         atomic: AtomicRwOp,
1061     ) -> InterpResult<'tcx> {
1062         let this = self.eval_context_mut();
1063
1064         let &[ref place, ref new] = check_arg_count(args)?;
1065         let place = this.deref_operand(place)?;
1066         let new = this.read_scalar(new)?;
1067
1068         // Check alignment requirements. Atomics must always be aligned to their size,
1069         // even if the type they wrap would be less aligned (e.g. AtomicU64 on 32bit must
1070         // be 8-aligned).
1071         let align = Align::from_bytes(place.layout.size.bytes()).unwrap();
1072         this.memory.check_ptr_access_align(
1073             place.ptr,
1074             place.layout.size,
1075             align,
1076             CheckInAllocMsg::MemoryAccessTest,
1077         )?;
1078
1079         let old = this.atomic_exchange_scalar(&place, new, atomic)?;
1080         this.write_scalar(old, dest)?; // old value is returned
1081         Ok(())
1082     }
1083
1084     fn atomic_compare_exchange_impl(
1085         &mut self,
1086         args: &[OpTy<'tcx, Tag>],
1087         dest: &PlaceTy<'tcx, Tag>,
1088         success: AtomicRwOp,
1089         fail: AtomicReadOp,
1090         can_fail_spuriously: bool,
1091     ) -> InterpResult<'tcx> {
1092         let this = self.eval_context_mut();
1093
1094         let &[ref place, ref expect_old, ref new] = check_arg_count(args)?;
1095         let place = this.deref_operand(place)?;
1096         let expect_old = this.read_immediate(expect_old)?; // read as immediate for the sake of `binary_op()`
1097         let new = this.read_scalar(new)?;
1098
1099         // Check alignment requirements. Atomics must always be aligned to their size,
1100         // even if the type they wrap would be less aligned (e.g. AtomicU64 on 32bit must
1101         // be 8-aligned).
1102         let align = Align::from_bytes(place.layout.size.bytes()).unwrap();
1103         this.memory.check_ptr_access_align(
1104             place.ptr,
1105             place.layout.size,
1106             align,
1107             CheckInAllocMsg::MemoryAccessTest,
1108         )?;
1109
1110         let old = this.atomic_compare_exchange_scalar(
1111             &place,
1112             &expect_old,
1113             new,
1114             success,
1115             fail,
1116             can_fail_spuriously,
1117         )?;
1118
1119         // Return old value.
1120         this.write_immediate(old, dest)?;
1121         Ok(())
1122     }
1123
1124     fn atomic_compare_exchange(
1125         &mut self,
1126         args: &[OpTy<'tcx, Tag>],
1127         dest: &PlaceTy<'tcx, Tag>,
1128         success: AtomicRwOp,
1129         fail: AtomicReadOp,
1130     ) -> InterpResult<'tcx> {
1131         self.atomic_compare_exchange_impl(args, dest, success, fail, false)
1132     }
1133
1134     fn atomic_compare_exchange_weak(
1135         &mut self,
1136         args: &[OpTy<'tcx, Tag>],
1137         dest: &PlaceTy<'tcx, Tag>,
1138         success: AtomicRwOp,
1139         fail: AtomicReadOp,
1140     ) -> InterpResult<'tcx> {
1141         self.atomic_compare_exchange_impl(args, dest, success, fail, true)
1142     }
1143
1144     fn float_to_int_unchecked<F>(
1145         &self,
1146         f: F,
1147         dest_ty: ty::Ty<'tcx>,
1148     ) -> InterpResult<'tcx, Scalar<Tag>>
1149     where
1150         F: Float + Into<Scalar<Tag>>,
1151     {
1152         let this = self.eval_context_ref();
1153
1154         // Step 1: cut off the fractional part of `f`. The result of this is
1155         // guaranteed to be precisely representable in IEEE floats.
1156         let f = f.round_to_integral(Round::TowardZero).value;
1157
1158         // Step 2: Cast the truncated float to the target integer type and see if we lose any information in this step.
1159         Ok(match dest_ty.kind() {
1160             // Unsigned
1161             ty::Uint(t) => {
1162                 let size = Integer::from_uint_ty(this, *t).size();
1163                 let res = f.to_u128(size.bits_usize());
1164                 if res.status.is_empty() {
1165                     // No status flags means there was no further rounding or other loss of precision.
1166                     Scalar::from_uint(res.value, size)
1167                 } else {
1168                     // `f` was not representable in this integer type.
1169                     throw_ub_format!(
1170                         "`float_to_int_unchecked` intrinsic called on {} which cannot be represented in target type `{:?}`",
1171                         f,
1172                         dest_ty,
1173                     );
1174                 }
1175             }
1176             // Signed
1177             ty::Int(t) => {
1178                 let size = Integer::from_int_ty(this, *t).size();
1179                 let res = f.to_i128(size.bits_usize());
1180                 if res.status.is_empty() {
1181                     // No status flags means there was no further rounding or other loss of precision.
1182                     Scalar::from_int(res.value, size)
1183                 } else {
1184                     // `f` was not representable in this integer type.
1185                     throw_ub_format!(
1186                         "`float_to_int_unchecked` intrinsic called on {} which cannot be represented in target type `{:?}`",
1187                         f,
1188                         dest_ty,
1189                     );
1190                 }
1191             }
1192             // Nothing else
1193             _ => bug!("`float_to_int_unchecked` called with non-int output type {:?}", dest_ty),
1194         })
1195     }
1196 }
1197
1198 fn fmax_op<'tcx>(
1199     left: &ImmTy<'tcx, Tag>,
1200     right: &ImmTy<'tcx, Tag>,
1201 ) -> InterpResult<'tcx, Scalar<Tag>> {
1202     assert_eq!(left.layout.ty, right.layout.ty);
1203     let ty::Float(float_ty) = left.layout.ty.kind() else {
1204         bug!("fmax operand is not a float")
1205     };
1206     let left = left.to_scalar()?;
1207     let right = right.to_scalar()?;
1208     Ok(match float_ty {
1209         FloatTy::F32 => Scalar::from_f32(left.to_f32()?.max(right.to_f32()?)),
1210         FloatTy::F64 => Scalar::from_f64(left.to_f64()?.max(right.to_f64()?)),
1211     })
1212 }
1213
1214 fn fmin_op<'tcx>(
1215     left: &ImmTy<'tcx, Tag>,
1216     right: &ImmTy<'tcx, Tag>,
1217 ) -> InterpResult<'tcx, Scalar<Tag>> {
1218     assert_eq!(left.layout.ty, right.layout.ty);
1219     let ty::Float(float_ty) = left.layout.ty.kind() else {
1220         bug!("fmin operand is not a float")
1221     };
1222     let left = left.to_scalar()?;
1223     let right = right.to_scalar()?;
1224     Ok(match float_ty {
1225         FloatTy::F32 => Scalar::from_f32(left.to_f32()?.min(right.to_f32()?)),
1226         FloatTy::F64 => Scalar::from_f64(left.to_f64()?.min(right.to_f64()?)),
1227     })
1228 }