| //! 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 rustc_hir::def_id::DefId; |
| use rustc_middle::mir::{ |
| self, |
| interpret::{ |
| Allocation, ConstAllocation, ConstValue, GlobalId, InterpResult, PointerArithmetic, Scalar, |
| }, |
| BinOp, NonDivergingIntrinsic, |
| }; |
| use rustc_middle::ty; |
| use rustc_middle::ty::layout::{LayoutOf as _, ValidityRequirement}; |
| 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; |
| |
| 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) |
| } |
| |
| /// 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>, |
| 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 = 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_target_usize(layout.align.pref.bytes(), &tcx) |
| } |
| sym::type_id => { |
| ensure_monomorphic_enough(tcx, tp_ty)?; |
| ConstValue::from_u64(tcx.type_id_hash(tp_ty).as_u64()) |
| } |
| 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::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::Generator(_, _, _) |
| | ty::GeneratorWitness(_) |
| | ty::GeneratorWitnessMIR(_, _) |
| | ty::Never |
| | ty::Tuple(_) |
| | ty::Error(_) => ConstValue::from_target_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::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_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.u64, |
| sym::type_name => self.tcx.mk_static_str(), |
| _ => bug!(), |
| }; |
| let val = self.ctfe_query(None, |tcx| { |
| tcx.const_eval_global_id(self.param_env, gid, Some(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])?; |
| 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::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::exact_div => { |
| let l = self.read_immediate(&args[0])?; |
| let r = self.read_immediate(&args[1])?; |
| self.exact_div(&l, &r, 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])?; |
| let val_bits = val.to_bits(layout.size)?; |
| let raw_shift = self.read_scalar(&args[1])?; |
| 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::arith_offset => { |
| let ptr = self.read_pointer(&args[0])?; |
| let offset_count = self.read_target_isize(&args[1])?; |
| 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 pointer 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_target_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_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_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.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(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::assert_inhabited |
| | sym::assert_zero_valid |
| | sym::assert_mem_uninitialized_valid => { |
| let ty = instance.substs.type_at(0); |
| let requirement = ValidityRequirement::from_intrinsic(intrinsic_name).unwrap(); |
| |
| let should_panic = !self |
| .tcx |
| .check_validity_requirement((requirement, self.param_env.and(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.abi.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 `{}`, which is invalid", |
| ty |
| ), |
| ValidityRequirement::UninitMitigated0x01Fill => format!( |
| "aborted execution: attempted to leave type `{}` uninitialized, which is invalid", |
| ty |
| ), |
| ValidityRequirement::Uninit => bug!("assert_uninit_valid doesn't exist"), |
| }; |
| |
| M::abort(self, msg)?; |
| } |
| } |
| 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::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_target_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_target_usize(align.bytes(), self), dest)?; |
| } |
| |
| _ => return Ok(false), |
| } |
| |
| trace!("{:?}", self.dump_place(**dest)); |
| self.go_to_block(ret); |
| Ok(true) |
| } |
| |
| pub(super) fn emulate_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_format!("`assume` called with `false`"); |
| } |
| 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 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_target_usize(&count)?; |
| 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 target_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_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 = 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_sized()); |
| |
| let get_bytes = |this: &InterpCx<'mir, 'tcx, M>, |
| op: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>, |
| size| |
| -> InterpResult<'tcx, &[u8]> { |
| let ptr = this.read_pointer(op)?; |
| let Some(alloc_ref) = self.get_ptr_alloc(ptr, size, Align::ONE)? else { |
| // zero-sized access |
| return Ok(&[]); |
| }; |
| if alloc_ref.has_provenance() { |
| throw_ub_format!("`raw_eq` on bytes with provenance"); |
| } |
| alloc_ref.get_bytes_strip_provenance() |
| }; |
| |
| let lhs_bytes = get_bytes(self, lhs, layout.size)?; |
| let rhs_bytes = get_bytes(self, rhs, layout.size)?; |
| Ok(Scalar::from_bool(lhs_bytes == rhs_bytes)) |
| } |
| } |
