rustc_const_eval/interpret/
intrinsics.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
//! Intrinsics and other functions that the interpreter executes without
//! looking at their MIR. Intrinsics/functions supported here are shared by CTFE
//! and miri.

use std::assert_matches::assert_matches;

use rustc_abi::Size;
use rustc_apfloat::ieee::{Double, Half, Quad, Single};
use rustc_hir::def_id::DefId;
use rustc_middle::mir::{self, BinOp, ConstValue, NonDivergingIntrinsic};
use rustc_middle::ty::layout::{LayoutOf as _, TyAndLayout, ValidityRequirement};
use rustc_middle::ty::{GenericArgsRef, Ty, TyCtxt};
use rustc_middle::{bug, ty};
use rustc_span::symbol::{Symbol, sym};
use tracing::trace;

use super::memory::MemoryKind;
use super::util::ensure_monomorphic_enough;
use super::{
    Allocation, CheckInAllocMsg, ConstAllocation, GlobalId, ImmTy, InterpCx, InterpResult,
    MPlaceTy, Machine, OpTy, Pointer, PointerArithmetic, Provenance, Scalar, err_inval,
    err_ub_custom, err_unsup_format, interp_ok, throw_inval, throw_ub_custom, throw_ub_format,
};
use crate::fluent_generated as fluent;

/// Directly returns an `Allocation` containing an absolute path representation of the given type.
pub(crate) fn alloc_type_name<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> ConstAllocation<'tcx> {
    let path = crate::util::type_name(tcx, ty);
    let alloc = Allocation::from_bytes_byte_aligned_immutable(path.into_bytes());
    tcx.mk_const_alloc(alloc)
}

/// The logic for all nullary intrinsics is implemented here. These intrinsics don't get evaluated
/// inside an `InterpCx` and instead have their value computed directly from rustc internal info.
pub(crate) fn eval_nullary_intrinsic<'tcx>(
    tcx: TyCtxt<'tcx>,
    typing_env: ty::TypingEnv<'tcx>,
    def_id: DefId,
    args: GenericArgsRef<'tcx>,
) -> InterpResult<'tcx, ConstValue<'tcx>> {
    let tp_ty = args.type_at(0);
    let name = tcx.item_name(def_id);
    interp_ok(match name {
        sym::type_name => {
            ensure_monomorphic_enough(tcx, tp_ty)?;
            let alloc = alloc_type_name(tcx, tp_ty);
            ConstValue::Slice { data: alloc, meta: alloc.inner().size().bytes() }
        }
        sym::needs_drop => {
            ensure_monomorphic_enough(tcx, tp_ty)?;
            ConstValue::from_bool(tp_ty.needs_drop(tcx, typing_env))
        }
        sym::pref_align_of => {
            // Correctly handles non-monomorphic calls, so there is no need for ensure_monomorphic_enough.
            let layout = tcx
                .layout_of(typing_env.as_query_input(tp_ty))
                .map_err(|e| err_inval!(Layout(*e)))?;
            ConstValue::from_target_usize(layout.align.pref.bytes(), &tcx)
        }
        sym::type_id => {
            ensure_monomorphic_enough(tcx, tp_ty)?;
            ConstValue::from_u128(tcx.type_id_hash(tp_ty).as_u128())
        }
        sym::variant_count => match tp_ty.kind() {
            // Correctly handles non-monomorphic calls, so there is no need for ensure_monomorphic_enough.
            ty::Adt(adt, _) => ConstValue::from_target_usize(adt.variants().len() as u64, &tcx),
            ty::Alias(..) | ty::Param(_) | ty::Placeholder(_) | ty::Infer(_) => {
                throw_inval!(TooGeneric)
            }
            ty::Pat(_, pat) => match **pat {
                ty::PatternKind::Range { .. } => ConstValue::from_target_usize(0u64, &tcx),
                // Future pattern kinds may have more variants
            },
            ty::Bound(_, _) => bug!("bound ty during ctfe"),
            ty::Bool
            | ty::Char
            | ty::Int(_)
            | ty::Uint(_)
            | ty::Float(_)
            | ty::Foreign(_)
            | ty::Str
            | ty::Array(_, _)
            | ty::Slice(_)
            | ty::RawPtr(_, _)
            | ty::Ref(_, _, _)
            | ty::FnDef(_, _)
            | ty::FnPtr(..)
            | ty::Dynamic(_, _, _)
            | ty::Closure(_, _)
            | ty::CoroutineClosure(_, _)
            | ty::Coroutine(_, _)
            | ty::CoroutineWitness(..)
            | ty::Never
            | ty::Tuple(_)
            | ty::Error(_) => ConstValue::from_target_usize(0u64, &tcx),
        },
        other => bug!("`{}` is not a zero arg intrinsic", other),
    })
}

impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
    /// Returns `true` if emulation happened.
    /// Here we implement the intrinsics that are common to all Miri instances; individual machines can add their own
    /// intrinsic handling.
    pub fn eval_intrinsic(
        &mut self,
        instance: ty::Instance<'tcx>,
        args: &[OpTy<'tcx, M::Provenance>],
        dest: &MPlaceTy<'tcx, M::Provenance>,
        ret: Option<mir::BasicBlock>,
    ) -> InterpResult<'tcx, bool> {
        let instance_args = instance.args;
        let intrinsic_name = self.tcx.item_name(instance.def_id());

        match intrinsic_name {
            sym::caller_location => {
                let span = self.find_closest_untracked_caller_location();
                let val = self.tcx.span_as_caller_location(span);
                let val =
                    self.const_val_to_op(val, self.tcx.caller_location_ty(), Some(dest.layout))?;
                self.copy_op(&val, dest)?;
            }

            sym::min_align_of_val | sym::size_of_val => {
                // Avoid `deref_pointer` -- this is not a deref, the ptr does not have to be
                // dereferenceable!
                let place = self.ref_to_mplace(&self.read_immediate(&args[0])?)?;
                let (size, align) = self
                    .size_and_align_of_mplace(&place)?
                    .ok_or_else(|| err_unsup_format!("`extern type` does not have known layout"))?;

                let result = match intrinsic_name {
                    sym::min_align_of_val => align.bytes(),
                    sym::size_of_val => size.bytes(),
                    _ => bug!(),
                };

                self.write_scalar(Scalar::from_target_usize(result, self), dest)?;
            }

            sym::pref_align_of
            | sym::needs_drop
            | sym::type_id
            | sym::type_name
            | sym::variant_count => {
                let gid = GlobalId { instance, promoted: None };
                let ty = match intrinsic_name {
                    sym::pref_align_of | sym::variant_count => self.tcx.types.usize,
                    sym::needs_drop => self.tcx.types.bool,
                    sym::type_id => self.tcx.types.u128,
                    sym::type_name => Ty::new_static_str(self.tcx.tcx),
                    _ => bug!(),
                };
                let val = self
                    .ctfe_query(|tcx| tcx.const_eval_global_id(self.typing_env, gid, tcx.span))?;
                let val = self.const_val_to_op(val, ty, Some(dest.layout))?;
                self.copy_op(&val, dest)?;
            }

            sym::ctpop
            | sym::cttz
            | sym::cttz_nonzero
            | sym::ctlz
            | sym::ctlz_nonzero
            | sym::bswap
            | sym::bitreverse => {
                let ty = instance_args.type_at(0);
                let layout = self.layout_of(ty)?;
                let val = self.read_scalar(&args[0])?;

                let out_val = self.numeric_intrinsic(intrinsic_name, val, layout, dest.layout)?;
                self.write_scalar(out_val, dest)?;
            }
            sym::saturating_add | sym::saturating_sub => {
                let l = self.read_immediate(&args[0])?;
                let r = self.read_immediate(&args[1])?;
                let val = self.saturating_arith(
                    if intrinsic_name == sym::saturating_add { BinOp::Add } else { BinOp::Sub },
                    &l,
                    &r,
                )?;
                self.write_scalar(val, dest)?;
            }
            sym::discriminant_value => {
                let place = self.deref_pointer(&args[0])?;
                let variant = self.read_discriminant(&place)?;
                let discr = self.discriminant_for_variant(place.layout.ty, variant)?;
                self.write_immediate(*discr, dest)?;
            }
            sym::exact_div => {
                let l = self.read_immediate(&args[0])?;
                let r = self.read_immediate(&args[1])?;
                self.exact_div(&l, &r, dest)?;
            }
            sym::rotate_left | sym::rotate_right => {
                // rotate_left: (X << (S % BW)) | (X >> ((BW - S) % BW))
                // rotate_right: (X << ((BW - S) % BW)) | (X >> (S % BW))
                let layout_val = self.layout_of(instance_args.type_at(0))?;
                let val = self.read_scalar(&args[0])?;
                let val_bits = val.to_bits(layout_val.size)?; // sign is ignored here

                let layout_raw_shift = self.layout_of(self.tcx.types.u32)?;
                let raw_shift = self.read_scalar(&args[1])?;
                let raw_shift_bits = raw_shift.to_bits(layout_raw_shift.size)?;

                let width_bits = u128::from(layout_val.size.bits());
                let shift_bits = raw_shift_bits % width_bits;
                let inv_shift_bits = (width_bits - shift_bits) % width_bits;
                let result_bits = if intrinsic_name == sym::rotate_left {
                    (val_bits << shift_bits) | (val_bits >> inv_shift_bits)
                } else {
                    (val_bits >> shift_bits) | (val_bits << inv_shift_bits)
                };
                let truncated_bits = layout_val.size.truncate(result_bits);
                let result = Scalar::from_uint(truncated_bits, layout_val.size);
                self.write_scalar(result, dest)?;
            }
            sym::copy => {
                self.copy_intrinsic(&args[0], &args[1], &args[2], /*nonoverlapping*/ false)?;
            }
            sym::write_bytes => {
                self.write_bytes_intrinsic(&args[0], &args[1], &args[2], "write_bytes")?;
            }
            sym::compare_bytes => {
                let result = self.compare_bytes_intrinsic(&args[0], &args[1], &args[2])?;
                self.write_scalar(result, dest)?;
            }
            sym::arith_offset => {
                let ptr = self.read_pointer(&args[0])?;
                let offset_count = self.read_target_isize(&args[1])?;
                let pointee_ty = instance_args.type_at(0);

                let pointee_size = i64::try_from(self.layout_of(pointee_ty)?.size.bytes()).unwrap();
                let offset_bytes = offset_count.wrapping_mul(pointee_size);
                let offset_ptr = ptr.wrapping_signed_offset(offset_bytes, self);
                self.write_pointer(offset_ptr, dest)?;
            }
            sym::ptr_offset_from | sym::ptr_offset_from_unsigned => {
                let a = self.read_pointer(&args[0])?;
                let b = self.read_pointer(&args[1])?;

                let usize_layout = self.layout_of(self.tcx.types.usize)?;
                let isize_layout = self.layout_of(self.tcx.types.isize)?;

                // Get offsets for both that are at least relative to the same base.
                // With `OFFSET_IS_ADDR` this is trivial; without it we need either
                // two integers or two pointers into the same allocation.
                let (a_offset, b_offset, is_addr) = if M::Provenance::OFFSET_IS_ADDR {
                    (a.addr().bytes(), b.addr().bytes(), /*is_addr*/ true)
                } else {
                    match (self.ptr_try_get_alloc_id(a, 0), self.ptr_try_get_alloc_id(b, 0)) {
                        (Err(a), Err(b)) => {
                            // Neither pointer points to an allocation, so they are both absolute.
                            (a, b, /*is_addr*/ true)
                        }
                        (Ok((a_alloc_id, a_offset, _)), Ok((b_alloc_id, b_offset, _)))
                            if a_alloc_id == b_alloc_id =>
                        {
                            // Found allocation for both, and it's the same.
                            // Use these offsets for distance calculation.
                            (a_offset.bytes(), b_offset.bytes(), /*is_addr*/ false)
                        }
                        _ => {
                            // Not into the same allocation -- this is UB.
                            throw_ub_custom!(
                                fluent::const_eval_offset_from_different_allocations,
                                name = intrinsic_name,
                            );
                        }
                    }
                };

                // Compute distance: a - b.
                let dist = {
                    // Addresses are unsigned, so this is a `usize` computation. We have to do the
                    // overflow check separately anyway.
                    let (val, overflowed) = {
                        let a_offset = ImmTy::from_uint(a_offset, usize_layout);
                        let b_offset = ImmTy::from_uint(b_offset, usize_layout);
                        self.binary_op(BinOp::SubWithOverflow, &a_offset, &b_offset)?
                            .to_scalar_pair()
                    };
                    if overflowed.to_bool()? {
                        // a < b
                        if intrinsic_name == sym::ptr_offset_from_unsigned {
                            throw_ub_custom!(
                                fluent::const_eval_offset_from_unsigned_overflow,
                                a_offset = a_offset,
                                b_offset = b_offset,
                                is_addr = is_addr,
                            );
                        }
                        // The signed form of the intrinsic allows this. If we interpret the
                        // difference as isize, we'll get the proper signed difference. If that
                        // seems *positive* or equal to isize::MIN, they were more than isize::MAX apart.
                        let dist = val.to_target_isize(self)?;
                        if dist >= 0 || i128::from(dist) == self.pointer_size().signed_int_min() {
                            throw_ub_custom!(
                                fluent::const_eval_offset_from_underflow,
                                name = intrinsic_name,
                            );
                        }
                        dist
                    } else {
                        // b >= a
                        let dist = val.to_target_isize(self)?;
                        // If converting to isize produced a *negative* result, we had an overflow
                        // because they were more than isize::MAX apart.
                        if dist < 0 {
                            throw_ub_custom!(
                                fluent::const_eval_offset_from_overflow,
                                name = intrinsic_name,
                            );
                        }
                        dist
                    }
                };

                // Check that the memory between them is dereferenceable at all, starting from the
                // origin pointer: `dist` is `a - b`, so it is based on `b`.
                self.check_ptr_access_signed(b, dist, CheckInAllocMsg::OffsetFromTest)?;
                // Then check that this is also dereferenceable from `a`. This ensures that they are
                // derived from the same allocation.
                self.check_ptr_access_signed(
                    a,
                    dist.checked_neg().unwrap(), // i64::MIN is impossible as no allocation can be that large
                    CheckInAllocMsg::OffsetFromTest,
                )
                .map_err_kind(|_| {
                    // Make the error more specific.
                    err_ub_custom!(
                        fluent::const_eval_offset_from_different_allocations,
                        name = intrinsic_name,
                    )
                })?;

                // Perform division by size to compute return value.
                let ret_layout = if intrinsic_name == sym::ptr_offset_from_unsigned {
                    assert!(0 <= dist && dist <= self.target_isize_max());
                    usize_layout
                } else {
                    assert!(self.target_isize_min() <= dist && dist <= self.target_isize_max());
                    isize_layout
                };
                let pointee_layout = self.layout_of(instance_args.type_at(0))?;
                // If ret_layout is unsigned, we checked that so is the distance, so we are good.
                let val = ImmTy::from_int(dist, ret_layout);
                let size = ImmTy::from_int(pointee_layout.size.bytes(), ret_layout);
                self.exact_div(&val, &size, dest)?;
            }

            sym::assert_inhabited
            | sym::assert_zero_valid
            | sym::assert_mem_uninitialized_valid => {
                let ty = instance.args.type_at(0);
                let requirement = ValidityRequirement::from_intrinsic(intrinsic_name).unwrap();

                let should_panic = !self
                    .tcx
                    .check_validity_requirement((requirement, self.typing_env.as_query_input(ty)))
                    .map_err(|_| err_inval!(TooGeneric))?;

                if should_panic {
                    let layout = self.layout_of(ty)?;

                    let msg = match requirement {
                        // For *all* intrinsics we first check `is_uninhabited` to give a more specific
                        // error message.
                        _ if layout.is_uninhabited() => format!(
                            "aborted execution: attempted to instantiate uninhabited type `{ty}`"
                        ),
                        ValidityRequirement::Inhabited => bug!("handled earlier"),
                        ValidityRequirement::Zero => format!(
                            "aborted execution: attempted to zero-initialize type `{ty}`, which is invalid"
                        ),
                        ValidityRequirement::UninitMitigated0x01Fill => format!(
                            "aborted execution: attempted to leave type `{ty}` uninitialized, which is invalid"
                        ),
                        ValidityRequirement::Uninit => bug!("assert_uninit_valid doesn't exist"),
                    };

                    M::panic_nounwind(self, &msg)?;
                    // Skip the `return_to_block` at the end (we panicked, we do not return).
                    return interp_ok(true);
                }
            }
            sym::simd_insert => {
                let index = u64::from(self.read_scalar(&args[1])?.to_u32()?);
                let elem = &args[2];
                let (input, input_len) = self.project_to_simd(&args[0])?;
                let (dest, dest_len) = self.project_to_simd(dest)?;
                assert_eq!(input_len, dest_len, "Return vector length must match input length");
                // Bounds are not checked by typeck so we have to do it ourselves.
                if index >= input_len {
                    throw_ub_format!(
                        "`simd_insert` index {index} is out-of-bounds of vector with length {input_len}"
                    );
                }

                for i in 0..dest_len {
                    let place = self.project_index(&dest, i)?;
                    let value =
                        if i == index { elem.clone() } else { self.project_index(&input, i)? };
                    self.copy_op(&value, &place)?;
                }
            }
            sym::simd_extract => {
                let index = u64::from(self.read_scalar(&args[1])?.to_u32()?);
                let (input, input_len) = self.project_to_simd(&args[0])?;
                // Bounds are not checked by typeck so we have to do it ourselves.
                if index >= input_len {
                    throw_ub_format!(
                        "`simd_extract` index {index} is out-of-bounds of vector with length {input_len}"
                    );
                }
                self.copy_op(&self.project_index(&input, index)?, dest)?;
            }
            sym::black_box => {
                // These just return their argument
                self.copy_op(&args[0], dest)?;
            }
            sym::raw_eq => {
                let result = self.raw_eq_intrinsic(&args[0], &args[1])?;
                self.write_scalar(result, dest)?;
            }
            sym::typed_swap => {
                self.typed_swap_intrinsic(&args[0], &args[1])?;
            }

            sym::vtable_size => {
                let ptr = self.read_pointer(&args[0])?;
                // `None` because we don't know which trait to expect here; any vtable is okay.
                let (size, _align) = self.get_vtable_size_and_align(ptr, None)?;
                self.write_scalar(Scalar::from_target_usize(size.bytes(), self), dest)?;
            }
            sym::vtable_align => {
                let ptr = self.read_pointer(&args[0])?;
                // `None` because we don't know which trait to expect here; any vtable is okay.
                let (_size, align) = self.get_vtable_size_and_align(ptr, None)?;
                self.write_scalar(Scalar::from_target_usize(align.bytes(), self), dest)?;
            }

            sym::minnumf16 => self.float_min_intrinsic::<Half>(args, dest)?,
            sym::minnumf32 => self.float_min_intrinsic::<Single>(args, dest)?,
            sym::minnumf64 => self.float_min_intrinsic::<Double>(args, dest)?,
            sym::minnumf128 => self.float_min_intrinsic::<Quad>(args, dest)?,

            sym::maxnumf16 => self.float_max_intrinsic::<Half>(args, dest)?,
            sym::maxnumf32 => self.float_max_intrinsic::<Single>(args, dest)?,
            sym::maxnumf64 => self.float_max_intrinsic::<Double>(args, dest)?,
            sym::maxnumf128 => self.float_max_intrinsic::<Quad>(args, dest)?,

            sym::copysignf16 => self.float_copysign_intrinsic::<Half>(args, dest)?,
            sym::copysignf32 => self.float_copysign_intrinsic::<Single>(args, dest)?,
            sym::copysignf64 => self.float_copysign_intrinsic::<Double>(args, dest)?,
            sym::copysignf128 => self.float_copysign_intrinsic::<Quad>(args, dest)?,

            sym::fabsf16 => self.float_abs_intrinsic::<Half>(args, dest)?,
            sym::fabsf32 => self.float_abs_intrinsic::<Single>(args, dest)?,
            sym::fabsf64 => self.float_abs_intrinsic::<Double>(args, dest)?,
            sym::fabsf128 => self.float_abs_intrinsic::<Quad>(args, dest)?,

            // Unsupported intrinsic: skip the return_to_block below.
            _ => return interp_ok(false),
        }

        trace!("{:?}", self.dump_place(&dest.clone().into()));
        self.return_to_block(ret)?;
        interp_ok(true)
    }

    pub(super) fn eval_nondiverging_intrinsic(
        &mut self,
        intrinsic: &NonDivergingIntrinsic<'tcx>,
    ) -> InterpResult<'tcx> {
        match intrinsic {
            NonDivergingIntrinsic::Assume(op) => {
                let op = self.eval_operand(op, None)?;
                let cond = self.read_scalar(&op)?.to_bool()?;
                if !cond {
                    throw_ub_custom!(fluent::const_eval_assume_false);
                }
                interp_ok(())
            }
            NonDivergingIntrinsic::CopyNonOverlapping(mir::CopyNonOverlapping {
                count,
                src,
                dst,
            }) => {
                let src = self.eval_operand(src, None)?;
                let dst = self.eval_operand(dst, None)?;
                let count = self.eval_operand(count, None)?;
                self.copy_intrinsic(&src, &dst, &count, /* nonoverlapping */ true)
            }
        }
    }

    pub fn numeric_intrinsic(
        &self,
        name: Symbol,
        val: Scalar<M::Provenance>,
        layout: TyAndLayout<'tcx>,
        ret_layout: TyAndLayout<'tcx>,
    ) -> InterpResult<'tcx, Scalar<M::Provenance>> {
        assert!(layout.ty.is_integral(), "invalid type for numeric intrinsic: {}", layout.ty);
        let bits = val.to_bits(layout.size)?; // these operations all ignore the sign
        let extra = 128 - u128::from(layout.size.bits());
        let bits_out = match name {
            sym::ctpop => u128::from(bits.count_ones()),
            sym::ctlz_nonzero | sym::cttz_nonzero if bits == 0 => {
                throw_ub_custom!(fluent::const_eval_call_nonzero_intrinsic, name = name,);
            }
            sym::ctlz | sym::ctlz_nonzero => u128::from(bits.leading_zeros()) - extra,
            sym::cttz | sym::cttz_nonzero => u128::from((bits << extra).trailing_zeros()) - extra,
            sym::bswap => {
                assert_eq!(layout, ret_layout);
                (bits << extra).swap_bytes()
            }
            sym::bitreverse => {
                assert_eq!(layout, ret_layout);
                (bits << extra).reverse_bits()
            }
            _ => bug!("not a numeric intrinsic: {}", name),
        };
        interp_ok(Scalar::from_uint(bits_out, ret_layout.size))
    }

    pub fn exact_div(
        &mut self,
        a: &ImmTy<'tcx, M::Provenance>,
        b: &ImmTy<'tcx, M::Provenance>,
        dest: &MPlaceTy<'tcx, M::Provenance>,
    ) -> InterpResult<'tcx> {
        assert_eq!(a.layout.ty, b.layout.ty);
        assert_matches!(a.layout.ty.kind(), ty::Int(..) | ty::Uint(..));

        // Performs an exact division, resulting in undefined behavior where
        // `x % y != 0` or `y == 0` or `x == T::MIN && y == -1`.
        // First, check x % y != 0 (or if that computation overflows).
        let rem = self.binary_op(BinOp::Rem, a, b)?;
        // sign does not matter for 0 test, so `to_bits` is fine
        if rem.to_scalar().to_bits(a.layout.size)? != 0 {
            throw_ub_custom!(
                fluent::const_eval_exact_div_has_remainder,
                a = format!("{a}"),
                b = format!("{b}")
            )
        }
        // `Rem` says this is all right, so we can let `Div` do its job.
        let res = self.binary_op(BinOp::Div, a, b)?;
        self.write_immediate(*res, dest)
    }

    pub fn saturating_arith(
        &self,
        mir_op: BinOp,
        l: &ImmTy<'tcx, M::Provenance>,
        r: &ImmTy<'tcx, M::Provenance>,
    ) -> InterpResult<'tcx, Scalar<M::Provenance>> {
        assert_eq!(l.layout.ty, r.layout.ty);
        assert_matches!(l.layout.ty.kind(), ty::Int(..) | ty::Uint(..));
        assert_matches!(mir_op, BinOp::Add | BinOp::Sub);

        let (val, overflowed) =
            self.binary_op(mir_op.wrapping_to_overflowing().unwrap(), l, r)?.to_scalar_pair();
        interp_ok(if overflowed.to_bool()? {
            let size = l.layout.size;
            if l.layout.backend_repr.is_signed() {
                // For signed ints the saturated value depends on the sign of the first
                // term since the sign of the second term can be inferred from this and
                // the fact that the operation has overflowed (if either is 0 no
                // overflow can occur)
                let first_term: i128 = l.to_scalar().to_int(l.layout.size)?;
                if first_term >= 0 {
                    // Negative overflow not possible since the positive first term
                    // can only increase an (in range) negative term for addition
                    // or corresponding negated positive term for subtraction.
                    Scalar::from_int(size.signed_int_max(), size)
                } else {
                    // Positive overflow not possible for similar reason.
                    Scalar::from_int(size.signed_int_min(), size)
                }
            } else {
                // unsigned
                if matches!(mir_op, BinOp::Add) {
                    // max unsigned
                    Scalar::from_uint(size.unsigned_int_max(), size)
                } else {
                    // underflow to 0
                    Scalar::from_uint(0u128, size)
                }
            }
        } else {
            val
        })
    }

    /// Offsets a pointer by some multiple of its type, returning an error if the pointer leaves its
    /// allocation.
    pub fn ptr_offset_inbounds(
        &self,
        ptr: Pointer<Option<M::Provenance>>,
        offset_bytes: i64,
    ) -> InterpResult<'tcx, Pointer<Option<M::Provenance>>> {
        // The offset must be in bounds starting from `ptr`.
        self.check_ptr_access_signed(ptr, offset_bytes, CheckInAllocMsg::PointerArithmeticTest)?;
        // This also implies that there is no overflow, so we are done.
        interp_ok(ptr.wrapping_signed_offset(offset_bytes, self))
    }

    /// Copy `count*size_of::<T>()` many bytes from `*src` to `*dst`.
    pub(crate) fn copy_intrinsic(
        &mut self,
        src: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
        dst: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
        count: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
        nonoverlapping: bool,
    ) -> InterpResult<'tcx> {
        let count = self.read_target_usize(count)?;
        let layout = self.layout_of(src.layout.ty.builtin_deref(true).unwrap())?;
        let (size, align) = (layout.size, layout.align.abi);

        let size = self.compute_size_in_bytes(size, count).ok_or_else(|| {
            err_ub_custom!(
                fluent::const_eval_size_overflow,
                name = if nonoverlapping { "copy_nonoverlapping" } else { "copy" }
            )
        })?;

        let src = self.read_pointer(src)?;
        let dst = self.read_pointer(dst)?;

        self.check_ptr_align(src, align)?;
        self.check_ptr_align(dst, align)?;

        self.mem_copy(src, dst, size, nonoverlapping)
    }

    /// Does a *typed* swap of `*left` and `*right`.
    fn typed_swap_intrinsic(
        &mut self,
        left: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
        right: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
    ) -> InterpResult<'tcx> {
        let left = self.deref_pointer(left)?;
        let right = self.deref_pointer(right)?;
        debug_assert_eq!(left.layout, right.layout);
        let kind = MemoryKind::Stack;
        let temp = self.allocate(left.layout, kind)?;
        self.copy_op(&left, &temp)?;
        self.copy_op(&right, &left)?;
        self.copy_op(&temp, &right)?;
        self.deallocate_ptr(temp.ptr(), None, kind)?;
        interp_ok(())
    }

    pub fn write_bytes_intrinsic(
        &mut self,
        dst: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
        byte: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
        count: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
        name: &'static str,
    ) -> InterpResult<'tcx> {
        let layout = self.layout_of(dst.layout.ty.builtin_deref(true).unwrap())?;

        let dst = self.read_pointer(dst)?;
        let byte = self.read_scalar(byte)?.to_u8()?;
        let count = self.read_target_usize(count)?;

        // `checked_mul` enforces a too small bound (the correct one would probably be target_isize_max),
        // but no actual allocation can be big enough for the difference to be noticeable.
        let len = self
            .compute_size_in_bytes(layout.size, count)
            .ok_or_else(|| err_ub_custom!(fluent::const_eval_size_overflow, name = name))?;

        let bytes = std::iter::repeat(byte).take(len.bytes_usize());
        self.write_bytes_ptr(dst, bytes)
    }

    pub(crate) fn compare_bytes_intrinsic(
        &mut self,
        left: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
        right: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
        byte_count: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
    ) -> InterpResult<'tcx, Scalar<M::Provenance>> {
        let left = self.read_pointer(left)?;
        let right = self.read_pointer(right)?;
        let n = Size::from_bytes(self.read_target_usize(byte_count)?);

        let left_bytes = self.read_bytes_ptr_strip_provenance(left, n)?;
        let right_bytes = self.read_bytes_ptr_strip_provenance(right, n)?;

        // `Ordering`'s discriminants are -1/0/+1, so casting does the right thing.
        let result = Ord::cmp(left_bytes, right_bytes) as i32;
        interp_ok(Scalar::from_i32(result))
    }

    pub(crate) fn raw_eq_intrinsic(
        &mut self,
        lhs: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
        rhs: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
    ) -> InterpResult<'tcx, Scalar<M::Provenance>> {
        let layout = self.layout_of(lhs.layout.ty.builtin_deref(true).unwrap())?;
        assert!(layout.is_sized());

        let get_bytes = |this: &InterpCx<'tcx, M>,
                         op: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>|
         -> InterpResult<'tcx, &[u8]> {
            let ptr = this.read_pointer(op)?;
            this.check_ptr_align(ptr, layout.align.abi)?;
            let Some(alloc_ref) = self.get_ptr_alloc(ptr, layout.size)? else {
                // zero-sized access
                return interp_ok(&[]);
            };
            alloc_ref.get_bytes_strip_provenance()
        };

        let lhs_bytes = get_bytes(self, lhs)?;
        let rhs_bytes = get_bytes(self, rhs)?;
        interp_ok(Scalar::from_bool(lhs_bytes == rhs_bytes))
    }

    fn float_min_intrinsic<F>(
        &mut self,
        args: &[OpTy<'tcx, M::Provenance>],
        dest: &MPlaceTy<'tcx, M::Provenance>,
    ) -> InterpResult<'tcx, ()>
    where
        F: rustc_apfloat::Float + rustc_apfloat::FloatConvert<F> + Into<Scalar<M::Provenance>>,
    {
        let a: F = self.read_scalar(&args[0])?.to_float()?;
        let b: F = self.read_scalar(&args[1])?.to_float()?;
        let res = self.adjust_nan(a.min(b), &[a, b]);
        self.write_scalar(res, dest)?;
        interp_ok(())
    }

    fn float_max_intrinsic<F>(
        &mut self,
        args: &[OpTy<'tcx, M::Provenance>],
        dest: &MPlaceTy<'tcx, M::Provenance>,
    ) -> InterpResult<'tcx, ()>
    where
        F: rustc_apfloat::Float + rustc_apfloat::FloatConvert<F> + Into<Scalar<M::Provenance>>,
    {
        let a: F = self.read_scalar(&args[0])?.to_float()?;
        let b: F = self.read_scalar(&args[1])?.to_float()?;
        let res = self.adjust_nan(a.max(b), &[a, b]);
        self.write_scalar(res, dest)?;
        interp_ok(())
    }

    fn float_copysign_intrinsic<F>(
        &mut self,
        args: &[OpTy<'tcx, M::Provenance>],
        dest: &MPlaceTy<'tcx, M::Provenance>,
    ) -> InterpResult<'tcx, ()>
    where
        F: rustc_apfloat::Float + rustc_apfloat::FloatConvert<F> + Into<Scalar<M::Provenance>>,
    {
        let a: F = self.read_scalar(&args[0])?.to_float()?;
        let b: F = self.read_scalar(&args[1])?.to_float()?;
        // bitwise, no NaN adjustments
        self.write_scalar(a.copy_sign(b), dest)?;
        interp_ok(())
    }

    fn float_abs_intrinsic<F>(
        &mut self,
        args: &[OpTy<'tcx, M::Provenance>],
        dest: &MPlaceTy<'tcx, M::Provenance>,
    ) -> InterpResult<'tcx, ()>
    where
        F: rustc_apfloat::Float + rustc_apfloat::FloatConvert<F> + Into<Scalar<M::Provenance>>,
    {
        let x: F = self.read_scalar(&args[0])?.to_float()?;
        // bitwise, no NaN adjustments
        self.write_scalar(x.abs(), dest)?;
        interp_ok(())
    }
}