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Diffstat (limited to 'compiler/rustc_const_eval/src/interpret/intrinsics.rs')
| -rw-r--r-- | compiler/rustc_const_eval/src/interpret/intrinsics.rs | 696 |
1 files changed, 696 insertions, 0 deletions
diff --git a/compiler/rustc_const_eval/src/interpret/intrinsics.rs b/compiler/rustc_const_eval/src/interpret/intrinsics.rs new file mode 100644 index 000000000..08209eb79 --- /dev/null +++ b/compiler/rustc_const_eval/src/interpret/intrinsics.rs @@ -0,0 +1,696 @@ +//! Intrinsics and other functions that the miri engine executes without +//! looking at their MIR. Intrinsics/functions supported here are shared by CTFE +//! and miri. + +use std::convert::TryFrom; + +use rustc_hir::def_id::DefId; +use rustc_middle::mir::{ + self, + interpret::{ConstValue, GlobalId, InterpResult, PointerArithmetic, Scalar}, + BinOp, +}; +use rustc_middle::ty; +use rustc_middle::ty::layout::LayoutOf as _; +use rustc_middle::ty::subst::SubstsRef; +use rustc_middle::ty::{Ty, TyCtxt}; +use rustc_span::symbol::{sym, Symbol}; +use rustc_target::abi::{Abi, Align, Primitive, Size}; + +use super::{ + util::ensure_monomorphic_enough, CheckInAllocMsg, ImmTy, InterpCx, Machine, OpTy, PlaceTy, + Pointer, +}; + +mod caller_location; +mod type_name; + +fn numeric_intrinsic<Prov>(name: Symbol, bits: u128, kind: Primitive) -> Scalar<Prov> { + let size = match kind { + Primitive::Int(integer, _) => integer.size(), + _ => bug!("invalid `{}` argument: {:?}", name, bits), + }; + let extra = 128 - u128::from(size.bits()); + let bits_out = match name { + sym::ctpop => u128::from(bits.count_ones()), + sym::ctlz => u128::from(bits.leading_zeros()) - extra, + sym::cttz => u128::from((bits << extra).trailing_zeros()) - extra, + sym::bswap => (bits << extra).swap_bytes(), + sym::bitreverse => (bits << extra).reverse_bits(), + _ => bug!("not a numeric intrinsic: {}", name), + }; + Scalar::from_uint(bits_out, size) +} + +/// 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>, + param_env: ty::ParamEnv<'tcx>, + def_id: DefId, + substs: SubstsRef<'tcx>, +) -> InterpResult<'tcx, ConstValue<'tcx>> { + let tp_ty = substs.type_at(0); + let name = tcx.item_name(def_id); + Ok(match name { + sym::type_name => { + ensure_monomorphic_enough(tcx, tp_ty)?; + let alloc = type_name::alloc_type_name(tcx, tp_ty); + ConstValue::Slice { data: alloc, start: 0, end: alloc.inner().len() } + } + sym::needs_drop => { + ensure_monomorphic_enough(tcx, tp_ty)?; + ConstValue::from_bool(tp_ty.needs_drop(tcx, param_env)) + } + sym::pref_align_of => { + // Correctly handles non-monomorphic calls, so there is no need for ensure_monomorphic_enough. + let layout = tcx.layout_of(param_env.and(tp_ty)).map_err(|e| err_inval!(Layout(e)))?; + ConstValue::from_machine_usize(layout.align.pref.bytes(), &tcx) + } + sym::type_id => { + ensure_monomorphic_enough(tcx, tp_ty)?; + ConstValue::from_u64(tcx.type_id_hash(tp_ty)) + } + sym::variant_count => match tp_ty.kind() { + // Correctly handles non-monomorphic calls, so there is no need for ensure_monomorphic_enough. + ty::Adt(ref adt, _) => { + ConstValue::from_machine_usize(adt.variants().len() as u64, &tcx) + } + ty::Projection(_) + | ty::Opaque(_, _) + | ty::Param(_) + | ty::Bound(_, _) + | ty::Placeholder(_) + | ty::Infer(_) => throw_inval!(TooGeneric), + 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::Generator(_, _, _) + | ty::GeneratorWitness(_) + | ty::Never + | ty::Tuple(_) + | ty::Error(_) => ConstValue::from_machine_usize(0u64, &tcx), + }, + other => bug!("`{}` is not a zero arg intrinsic", other), + }) +} + +impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, '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 emulate_intrinsic( + &mut self, + instance: ty::Instance<'tcx>, + args: &[OpTy<'tcx, M::Provenance>], + dest: &PlaceTy<'tcx, M::Provenance>, + ret: Option<mir::BasicBlock>, + ) -> InterpResult<'tcx, bool> { + let substs = instance.substs; + let intrinsic_name = self.tcx.item_name(instance.def_id()); + + // First handle intrinsics without return place. + let ret = match ret { + None => match intrinsic_name { + sym::transmute => throw_ub_format!("transmuting to uninhabited type"), + sym::abort => M::abort(self, "the program aborted execution".to_owned())?, + // Unsupported diverging intrinsic. + _ => return Ok(false), + }, + Some(p) => p, + }; + + match intrinsic_name { + sym::caller_location => { + let span = self.find_closest_untracked_caller_location(); + let location = self.alloc_caller_location_for_span(span); + self.write_immediate(location.to_ref(self), dest)?; + } + + sym::min_align_of_val | sym::size_of_val => { + // Avoid `deref_operand` -- 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_machine_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.u64, + sym::type_name => self.tcx.mk_static_str(), + _ => bug!(), + }; + let val = + self.tcx.const_eval_global_id(self.param_env, gid, Some(self.tcx.span))?; + let val = self.const_val_to_op(val, ty, Some(dest.layout))?; + self.copy_op(&val, dest, /*allow_transmute*/ false)?; + } + + sym::ctpop + | sym::cttz + | sym::cttz_nonzero + | sym::ctlz + | sym::ctlz_nonzero + | sym::bswap + | sym::bitreverse => { + let ty = substs.type_at(0); + let layout_of = self.layout_of(ty)?; + let val = self.read_scalar(&args[0])?.check_init()?; + let bits = val.to_bits(layout_of.size)?; + let kind = match layout_of.abi { + Abi::Scalar(scalar) => scalar.primitive(), + _ => span_bug!( + self.cur_span(), + "{} called on invalid type {:?}", + intrinsic_name, + ty + ), + }; + let (nonzero, intrinsic_name) = match intrinsic_name { + sym::cttz_nonzero => (true, sym::cttz), + sym::ctlz_nonzero => (true, sym::ctlz), + other => (false, other), + }; + if nonzero && bits == 0 { + throw_ub_format!("`{}_nonzero` called on 0", intrinsic_name); + } + let out_val = numeric_intrinsic(intrinsic_name, bits, kind); + self.write_scalar(out_val, dest)?; + } + sym::add_with_overflow | sym::sub_with_overflow | sym::mul_with_overflow => { + let lhs = self.read_immediate(&args[0])?; + let rhs = self.read_immediate(&args[1])?; + let bin_op = match intrinsic_name { + sym::add_with_overflow => BinOp::Add, + sym::sub_with_overflow => BinOp::Sub, + sym::mul_with_overflow => BinOp::Mul, + _ => bug!(), + }; + self.binop_with_overflow( + bin_op, /*force_overflow_checks*/ true, &lhs, &rhs, 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_operand(&args[0])?; + let discr_val = self.read_discriminant(&place.into())?.0; + self.write_scalar(discr_val, dest)?; + } + sym::unchecked_shl + | sym::unchecked_shr + | sym::unchecked_add + | sym::unchecked_sub + | sym::unchecked_mul + | sym::unchecked_div + | sym::unchecked_rem => { + let l = self.read_immediate(&args[0])?; + let r = self.read_immediate(&args[1])?; + let bin_op = match intrinsic_name { + sym::unchecked_shl => BinOp::Shl, + sym::unchecked_shr => BinOp::Shr, + sym::unchecked_add => BinOp::Add, + sym::unchecked_sub => BinOp::Sub, + sym::unchecked_mul => BinOp::Mul, + sym::unchecked_div => BinOp::Div, + sym::unchecked_rem => BinOp::Rem, + _ => bug!(), + }; + let (val, overflowed, _ty) = self.overflowing_binary_op(bin_op, &l, &r)?; + if overflowed { + let layout = self.layout_of(substs.type_at(0))?; + let r_val = r.to_scalar()?.to_bits(layout.size)?; + if let sym::unchecked_shl | sym::unchecked_shr = intrinsic_name { + throw_ub_format!("overflowing shift by {} in `{}`", r_val, intrinsic_name); + } else { + throw_ub_format!("overflow executing `{}`", intrinsic_name); + } + } + self.write_scalar(val, 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 = self.layout_of(substs.type_at(0))?; + let val = self.read_scalar(&args[0])?.check_init()?; + let val_bits = val.to_bits(layout.size)?; + let raw_shift = self.read_scalar(&args[1])?.check_init()?; + let raw_shift_bits = raw_shift.to_bits(layout.size)?; + let width_bits = u128::from(layout.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 = self.truncate(result_bits, layout); + let result = Scalar::from_uint(truncated_bits, layout.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])?; + } + sym::offset => { + let ptr = self.read_pointer(&args[0])?; + let offset_count = self.read_scalar(&args[1])?.to_machine_isize(self)?; + let pointee_ty = substs.type_at(0); + + let offset_ptr = self.ptr_offset_inbounds(ptr, pointee_ty, offset_count)?; + self.write_pointer(offset_ptr, dest)?; + } + sym::arith_offset => { + let ptr = self.read_pointer(&args[0])?; + let offset_count = self.read_scalar(&args[1])?.to_machine_isize(self)?; + let pointee_ty = substs.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. + let (a_offset, b_offset) = + match (self.ptr_try_get_alloc_id(a), self.ptr_try_get_alloc_id(b)) { + (Err(a), Err(b)) => { + // Neither poiner points to an allocation. + // If these are inequal or null, this *will* fail the deref check below. + (a, b) + } + (Err(_), _) | (_, Err(_)) => { + // We managed to find a valid allocation for one pointer, but not the other. + // That means they are definitely not pointing to the same allocation. + throw_ub_format!( + "`{}` called on pointers into different allocations", + intrinsic_name + ); + } + (Ok((a_alloc_id, a_offset, _)), Ok((b_alloc_id, b_offset, _))) => { + // Found allocation for both. They must be into the same allocation. + if a_alloc_id != b_alloc_id { + throw_ub_format!( + "`{}` called on pointers into different allocations", + intrinsic_name + ); + } + // Use these offsets for distance calculation. + (a_offset.bytes(), b_offset.bytes()) + } + }; + + // Compute distance. + let dist = { + // Addresses are unsigned, so this is a `usize` computation. We have to do the + // overflow check separately anyway. + let (val, overflowed, _ty) = { + let a_offset = ImmTy::from_uint(a_offset, usize_layout); + let b_offset = ImmTy::from_uint(b_offset, usize_layout); + self.overflowing_binary_op(BinOp::Sub, &a_offset, &b_offset)? + }; + if overflowed { + // a < b + if intrinsic_name == sym::ptr_offset_from_unsigned { + throw_ub_format!( + "`{}` called when first pointer has smaller offset than second: {} < {}", + intrinsic_name, + a_offset, + b_offset, + ); + } + // 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*, they were more than isize::MAX apart. + let dist = val.to_machine_isize(self)?; + if dist >= 0 { + throw_ub_format!( + "`{}` called when first pointer is too far before second", + intrinsic_name + ); + } + dist + } else { + // b >= a + let dist = val.to_machine_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_format!( + "`{}` called when first pointer is too far ahead of second", + intrinsic_name + ); + } + dist + } + }; + + // Check that the range between them is dereferenceable ("in-bounds or one past the + // end of the same allocation"). This is like the check in ptr_offset_inbounds. + let min_ptr = if dist >= 0 { b } else { a }; + self.check_ptr_access_align( + min_ptr, + Size::from_bytes(dist.unsigned_abs()), + Align::ONE, + CheckInAllocMsg::OffsetFromTest, + )?; + + // Perform division by size to compute return value. + let ret_layout = if intrinsic_name == sym::ptr_offset_from_unsigned { + assert!(0 <= dist && dist <= self.machine_isize_max()); + usize_layout + } else { + assert!(self.machine_isize_min() <= dist && dist <= self.machine_isize_max()); + isize_layout + }; + let pointee_layout = self.layout_of(substs.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::transmute => { + self.copy_op(&args[0], dest, /*allow_transmute*/ true)?; + } + sym::assert_inhabited | sym::assert_zero_valid | sym::assert_uninit_valid => { + let ty = instance.substs.type_at(0); + let layout = self.layout_of(ty)?; + + // For *all* intrinsics we first check `is_uninhabited` to give a more specific + // error message. + if layout.abi.is_uninhabited() { + // The run-time intrinsic panics just to get a good backtrace; here we abort + // since there is no problem showing a backtrace even for aborts. + M::abort( + self, + format!( + "aborted execution: attempted to instantiate uninhabited type `{}`", + ty + ), + )?; + } + + if intrinsic_name == sym::assert_zero_valid { + let should_panic = !self.tcx.permits_zero_init(layout); + + if should_panic { + M::abort( + self, + format!( + "aborted execution: attempted to zero-initialize type `{}`, which is invalid", + ty + ), + )?; + } + } + + if intrinsic_name == sym::assert_uninit_valid { + let should_panic = !self.tcx.permits_uninit_init(layout); + + if should_panic { + M::abort( + self, + format!( + "aborted execution: attempted to leave type `{}` uninitialized, which is invalid", + ty + ), + )?; + } + } + } + sym::simd_insert => { + let index = u64::from(self.read_scalar(&args[1])?.to_u32()?); + let elem = &args[2]; + let (input, input_len) = self.operand_to_simd(&args[0])?; + let (dest, dest_len) = self.place_to_simd(dest)?; + assert_eq!(input_len, dest_len, "Return vector length must match input length"); + assert!( + index < dest_len, + "Index `{}` must be in bounds of vector with length {}`", + index, + dest_len + ); + + for i in 0..dest_len { + let place = self.mplace_index(&dest, i)?; + let value = if i == index { + elem.clone() + } else { + self.mplace_index(&input, i)?.into() + }; + self.copy_op(&value, &place.into(), /*allow_transmute*/ false)?; + } + } + sym::simd_extract => { + let index = u64::from(self.read_scalar(&args[1])?.to_u32()?); + let (input, input_len) = self.operand_to_simd(&args[0])?; + assert!( + index < input_len, + "index `{}` must be in bounds of vector with length `{}`", + index, + input_len + ); + self.copy_op( + &self.mplace_index(&input, index)?.into(), + dest, + /*allow_transmute*/ false, + )?; + } + sym::likely | sym::unlikely | sym::black_box => { + // These just return their argument + self.copy_op(&args[0], dest, /*allow_transmute*/ false)?; + } + sym::assume => { + let cond = self.read_scalar(&args[0])?.check_init()?.to_bool()?; + if !cond { + throw_ub_format!("`assume` intrinsic called with `false`"); + } + } + sym::raw_eq => { + let result = self.raw_eq_intrinsic(&args[0], &args[1])?; + self.write_scalar(result, dest)?; + } + + sym::vtable_size => { + let ptr = self.read_pointer(&args[0])?; + let (size, _align) = self.get_vtable_size_and_align(ptr)?; + self.write_scalar(Scalar::from_machine_usize(size.bytes(), self), dest)?; + } + sym::vtable_align => { + let ptr = self.read_pointer(&args[0])?; + let (_size, align) = self.get_vtable_size_and_align(ptr)?; + self.write_scalar(Scalar::from_machine_usize(align.bytes(), self), dest)?; + } + + _ => return Ok(false), + } + + trace!("{:?}", self.dump_place(**dest)); + self.go_to_block(ret); + Ok(true) + } + + pub fn exact_div( + &mut self, + a: &ImmTy<'tcx, M::Provenance>, + b: &ImmTy<'tcx, M::Provenance>, + dest: &PlaceTy<'tcx, M::Provenance>, + ) -> InterpResult<'tcx> { + // 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 (res, overflow, _ty) = self.overflowing_binary_op(BinOp::Rem, &a, &b)?; + assert!(!overflow); // All overflow is UB, so this should never return on overflow. + if res.assert_bits(a.layout.size) != 0 { + throw_ub_format!("exact_div: {} cannot be divided by {} without remainder", a, b) + } + // `Rem` says this is all right, so we can let `Div` do its job. + self.binop_ignore_overflow(BinOp::Div, &a, &b, 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!(matches!(mir_op, BinOp::Add | BinOp::Sub)); + let (val, overflowed, _ty) = self.overflowing_binary_op(mir_op, l, r)?; + Ok(if overflowed { + let size = l.layout.size; + let num_bits = size.bits(); + if l.layout.abi.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: u128 = l.to_scalar()?.to_bits(l.layout.size)?; + let first_term_positive = first_term & (1 << (num_bits - 1)) == 0; + if first_term_positive { + // 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 + // max negative + 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. For integer pointers, we consider each of them their own tiny allocation of size + /// 0, so offset-by-0 (and only 0) is okay -- except that null cannot be offset by _any_ value. + pub fn ptr_offset_inbounds( + &self, + ptr: Pointer<Option<M::Provenance>>, + pointee_ty: Ty<'tcx>, + offset_count: i64, + ) -> InterpResult<'tcx, Pointer<Option<M::Provenance>>> { + // We cannot overflow i64 as a type's size must be <= isize::MAX. + let pointee_size = i64::try_from(self.layout_of(pointee_ty)?.size.bytes()).unwrap(); + // The computed offset, in bytes, must not overflow an isize. + // `checked_mul` enforces a too small bound, but no actual allocation can be big enough for + // the difference to be noticeable. + let offset_bytes = + offset_count.checked_mul(pointee_size).ok_or(err_ub!(PointerArithOverflow))?; + // The offset being in bounds cannot rely on "wrapping around" the address space. + // So, first rule out overflows in the pointer arithmetic. + let offset_ptr = ptr.signed_offset(offset_bytes, self)?; + // ptr and offset_ptr must be in bounds of the same allocated object. This means all of the + // memory between these pointers must be accessible. Note that we do not require the + // pointers to be properly aligned (unlike a read/write operation). + let min_ptr = if offset_bytes >= 0 { ptr } else { offset_ptr }; + // This call handles checking for integer/null pointers. + self.check_ptr_access_align( + min_ptr, + Size::from_bytes(offset_bytes.unsigned_abs()), + Align::ONE, + CheckInAllocMsg::PointerArithmeticTest, + )?; + Ok(offset_ptr) + } + + /// Copy `count*size_of::<T>()` many bytes from `*src` to `*dst`. + pub(crate) fn copy_intrinsic( + &mut self, + src: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>, + dst: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>, + count: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>, + nonoverlapping: bool, + ) -> InterpResult<'tcx> { + let count = self.read_scalar(&count)?.to_machine_usize(self)?; + let layout = self.layout_of(src.layout.ty.builtin_deref(true).unwrap().ty)?; + let (size, align) = (layout.size, layout.align.abi); + // `checked_mul` enforces a too small bound (the correct one would probably be machine_isize_max), + // but no actual allocation can be big enough for the difference to be noticeable. + let size = size.checked_mul(count, self).ok_or_else(|| { + err_ub_format!( + "overflow computing total size of `{}`", + if nonoverlapping { "copy_nonoverlapping" } else { "copy" } + ) + })?; + + let src = self.read_pointer(&src)?; + let dst = self.read_pointer(&dst)?; + + self.mem_copy(src, align, dst, align, size, nonoverlapping) + } + + pub(crate) fn write_bytes_intrinsic( + &mut self, + dst: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>, + byte: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>, + count: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>, + ) -> InterpResult<'tcx> { + let layout = self.layout_of(dst.layout.ty.builtin_deref(true).unwrap().ty)?; + + let dst = self.read_pointer(&dst)?; + let byte = self.read_scalar(&byte)?.to_u8()?; + let count = self.read_scalar(&count)?.to_machine_usize(self)?; + + // `checked_mul` enforces a too small bound (the correct one would probably be machine_isize_max), + // but no actual allocation can be big enough for the difference to be noticeable. + let len = layout + .size + .checked_mul(count, self) + .ok_or_else(|| err_ub_format!("overflow computing total size of `write_bytes`"))?; + + let bytes = std::iter::repeat(byte).take(len.bytes_usize()); + self.write_bytes_ptr(dst, bytes) + } + + pub(crate) fn raw_eq_intrinsic( + &mut self, + lhs: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>, + rhs: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>, + ) -> InterpResult<'tcx, Scalar<M::Provenance>> { + let layout = self.layout_of(lhs.layout.ty.builtin_deref(true).unwrap().ty)?; + assert!(!layout.is_unsized()); + + let lhs = self.read_pointer(lhs)?; + let rhs = self.read_pointer(rhs)?; + let lhs_bytes = self.read_bytes_ptr(lhs, layout.size)?; + let rhs_bytes = self.read_bytes_ptr(rhs, layout.size)?; + Ok(Scalar::from_bool(lhs_bytes == rhs_bytes)) + } +} |