| use std::convert::TryFrom; |
| |
| use rustc_apfloat::Float; |
| use rustc_middle::mir; |
| use rustc_middle::mir::interpret::{InterpResult, Scalar}; |
| use rustc_middle::ty::layout::{LayoutOf, TyAndLayout}; |
| use rustc_middle::ty::{self, FloatTy, Ty}; |
| use rustc_target::abi::Abi; |
| |
| use super::{ImmTy, Immediate, InterpCx, Machine, PlaceTy}; |
| |
| impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { |
| /// Applies the binary operation `op` to the two operands and writes a tuple of the result |
| /// and a boolean signifying the potential overflow to the destination. |
| /// |
| /// `force_overflow_checks` indicates whether overflow checks should be done even when |
| /// `tcx.sess.overflow_checks()` is `false`. |
| pub fn binop_with_overflow( |
| &mut self, |
| op: mir::BinOp, |
| force_overflow_checks: bool, |
| left: &ImmTy<'tcx, M::Provenance>, |
| right: &ImmTy<'tcx, M::Provenance>, |
| dest: &PlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx> { |
| let (val, overflowed, ty) = self.overflowing_binary_op(op, &left, &right)?; |
| debug_assert_eq!( |
| self.tcx.intern_tup(&[ty, self.tcx.types.bool]), |
| dest.layout.ty, |
| "type mismatch for result of {:?}", |
| op, |
| ); |
| // As per https://github.com/rust-lang/rust/pull/98738, we always return `false` in the 2nd |
| // component when overflow checking is disabled. |
| let overflowed = |
| overflowed && (force_overflow_checks || M::checked_binop_checks_overflow(self)); |
| // Write the result to `dest`. |
| if let Abi::ScalarPair(..) = dest.layout.abi { |
| // We can use the optimized path and avoid `place_field` (which might do |
| // `force_allocation`). |
| let pair = Immediate::ScalarPair(val.into(), Scalar::from_bool(overflowed).into()); |
| self.write_immediate(pair, dest)?; |
| } else { |
| assert!(self.tcx.sess.opts.unstable_opts.randomize_layout); |
| // With randomized layout, `(int, bool)` might cease to be a `ScalarPair`, so we have to |
| // do a component-wise write here. This code path is slower than the above because |
| // `place_field` will have to `force_allocate` locals here. |
| let val_field = self.place_field(&dest, 0)?; |
| self.write_scalar(val, &val_field)?; |
| let overflowed_field = self.place_field(&dest, 1)?; |
| self.write_scalar(Scalar::from_bool(overflowed), &overflowed_field)?; |
| } |
| Ok(()) |
| } |
| |
| /// Applies the binary operation `op` to the arguments and writes the result to the |
| /// destination. |
| pub fn binop_ignore_overflow( |
| &mut self, |
| op: mir::BinOp, |
| left: &ImmTy<'tcx, M::Provenance>, |
| right: &ImmTy<'tcx, M::Provenance>, |
| dest: &PlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx> { |
| let (val, _overflowed, ty) = self.overflowing_binary_op(op, left, right)?; |
| assert_eq!(ty, dest.layout.ty, "type mismatch for result of {:?}", op); |
| self.write_scalar(val, dest) |
| } |
| } |
| |
| impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { |
| fn binary_char_op( |
| &self, |
| bin_op: mir::BinOp, |
| l: char, |
| r: char, |
| ) -> (Scalar<M::Provenance>, bool, Ty<'tcx>) { |
| use rustc_middle::mir::BinOp::*; |
| |
| let res = match bin_op { |
| Eq => l == r, |
| Ne => l != r, |
| Lt => l < r, |
| Le => l <= r, |
| Gt => l > r, |
| Ge => l >= r, |
| _ => span_bug!(self.cur_span(), "Invalid operation on char: {:?}", bin_op), |
| }; |
| (Scalar::from_bool(res), false, self.tcx.types.bool) |
| } |
| |
| fn binary_bool_op( |
| &self, |
| bin_op: mir::BinOp, |
| l: bool, |
| r: bool, |
| ) -> (Scalar<M::Provenance>, bool, Ty<'tcx>) { |
| use rustc_middle::mir::BinOp::*; |
| |
| let res = match bin_op { |
| Eq => l == r, |
| Ne => l != r, |
| Lt => l < r, |
| Le => l <= r, |
| Gt => l > r, |
| Ge => l >= r, |
| BitAnd => l & r, |
| BitOr => l | r, |
| BitXor => l ^ r, |
| _ => span_bug!(self.cur_span(), "Invalid operation on bool: {:?}", bin_op), |
| }; |
| (Scalar::from_bool(res), false, self.tcx.types.bool) |
| } |
| |
| fn binary_float_op<F: Float + Into<Scalar<M::Provenance>>>( |
| &self, |
| bin_op: mir::BinOp, |
| ty: Ty<'tcx>, |
| l: F, |
| r: F, |
| ) -> (Scalar<M::Provenance>, bool, Ty<'tcx>) { |
| use rustc_middle::mir::BinOp::*; |
| |
| let (val, ty) = match bin_op { |
| Eq => (Scalar::from_bool(l == r), self.tcx.types.bool), |
| Ne => (Scalar::from_bool(l != r), self.tcx.types.bool), |
| Lt => (Scalar::from_bool(l < r), self.tcx.types.bool), |
| Le => (Scalar::from_bool(l <= r), self.tcx.types.bool), |
| Gt => (Scalar::from_bool(l > r), self.tcx.types.bool), |
| Ge => (Scalar::from_bool(l >= r), self.tcx.types.bool), |
| Add => ((l + r).value.into(), ty), |
| Sub => ((l - r).value.into(), ty), |
| Mul => ((l * r).value.into(), ty), |
| Div => ((l / r).value.into(), ty), |
| Rem => ((l % r).value.into(), ty), |
| _ => span_bug!(self.cur_span(), "invalid float op: `{:?}`", bin_op), |
| }; |
| (val, false, ty) |
| } |
| |
| fn binary_int_op( |
| &self, |
| bin_op: mir::BinOp, |
| // passing in raw bits |
| l: u128, |
| left_layout: TyAndLayout<'tcx>, |
| r: u128, |
| right_layout: TyAndLayout<'tcx>, |
| ) -> InterpResult<'tcx, (Scalar<M::Provenance>, bool, Ty<'tcx>)> { |
| use rustc_middle::mir::BinOp::*; |
| |
| // Shift ops can have an RHS with a different numeric type. |
| if bin_op == Shl || bin_op == Shr { |
| let size = u128::from(left_layout.size.bits()); |
| // Even if `r` is signed, we treat it as if it was unsigned (i.e., we use its |
| // zero-extended form). This matches the codegen backend: |
| // <https://github.com/rust-lang/rust/blob/c274e4969f058b1c644243181ece9f829efa7594/compiler/rustc_codegen_ssa/src/base.rs#L315-L317>. |
| // The overflow check is also ignorant to the sign: |
| // <https://github.com/rust-lang/rust/blob/c274e4969f058b1c644243181ece9f829efa7594/compiler/rustc_codegen_ssa/src/mir/rvalue.rs#L728>. |
| // This would behave rather strangely if we had integer types of size 256: a shift by |
| // -1i8 would actually shift by 255, but that would *not* be considered overflowing. A |
| // shift by -1i16 though would be considered overflowing. If we had integers of size |
| // 512, then a shift by -1i8 would even produce a different result than one by -1i16: |
| // the first shifts by 255, the latter by u16::MAX % 512 = 511. Lucky enough, our |
| // integers are maximally 128bits wide, so negative shifts *always* overflow and we have |
| // consistent results for the same value represented at different bit widths. |
| assert!(size <= 128); |
| let overflow = r >= size; |
| // The shift offset is implicitly masked to the type size, to make sure this operation |
| // is always defined. This is the one MIR operator that does *not* directly map to a |
| // single LLVM operation. See |
| // <https://github.com/rust-lang/rust/blob/c274e4969f058b1c644243181ece9f829efa7594/compiler/rustc_codegen_ssa/src/common.rs#L131-L158> |
| // for the corresponding truncation in our codegen backends. |
| let r = r % size; |
| let r = u32::try_from(r).unwrap(); // we masked so this will always fit |
| let result = if left_layout.abi.is_signed() { |
| let l = self.sign_extend(l, left_layout) as i128; |
| let result = match bin_op { |
| Shl => l.checked_shl(r).unwrap(), |
| Shr => l.checked_shr(r).unwrap(), |
| _ => bug!(), |
| }; |
| result as u128 |
| } else { |
| match bin_op { |
| Shl => l.checked_shl(r).unwrap(), |
| Shr => l.checked_shr(r).unwrap(), |
| _ => bug!(), |
| } |
| }; |
| let truncated = self.truncate(result, left_layout); |
| return Ok((Scalar::from_uint(truncated, left_layout.size), overflow, left_layout.ty)); |
| } |
| |
| // For the remaining ops, the types must be the same on both sides |
| if left_layout.ty != right_layout.ty { |
| span_bug!( |
| self.cur_span(), |
| "invalid asymmetric binary op {:?}: {:?} ({:?}), {:?} ({:?})", |
| bin_op, |
| l, |
| left_layout.ty, |
| r, |
| right_layout.ty, |
| ) |
| } |
| |
| let size = left_layout.size; |
| |
| // Operations that need special treatment for signed integers |
| if left_layout.abi.is_signed() { |
| let op: Option<fn(&i128, &i128) -> bool> = match bin_op { |
| Lt => Some(i128::lt), |
| Le => Some(i128::le), |
| Gt => Some(i128::gt), |
| Ge => Some(i128::ge), |
| _ => None, |
| }; |
| if let Some(op) = op { |
| let l = self.sign_extend(l, left_layout) as i128; |
| let r = self.sign_extend(r, right_layout) as i128; |
| return Ok((Scalar::from_bool(op(&l, &r)), false, self.tcx.types.bool)); |
| } |
| let op: Option<fn(i128, i128) -> (i128, bool)> = match bin_op { |
| Div if r == 0 => throw_ub!(DivisionByZero), |
| Rem if r == 0 => throw_ub!(RemainderByZero), |
| Div => Some(i128::overflowing_div), |
| Rem => Some(i128::overflowing_rem), |
| Add => Some(i128::overflowing_add), |
| Sub => Some(i128::overflowing_sub), |
| Mul => Some(i128::overflowing_mul), |
| _ => None, |
| }; |
| if let Some(op) = op { |
| let l = self.sign_extend(l, left_layout) as i128; |
| let r = self.sign_extend(r, right_layout) as i128; |
| |
| // We need a special check for overflowing Rem and Div since they are *UB* |
| // on overflow, which can happen with "int_min $OP -1". |
| if matches!(bin_op, Rem | Div) { |
| if l == size.signed_int_min() && r == -1 { |
| if bin_op == Rem { |
| throw_ub!(RemainderOverflow) |
| } else { |
| throw_ub!(DivisionOverflow) |
| } |
| } |
| } |
| |
| let (result, oflo) = op(l, r); |
| // This may be out-of-bounds for the result type, so we have to truncate ourselves. |
| // If that truncation loses any information, we have an overflow. |
| let result = result as u128; |
| let truncated = self.truncate(result, left_layout); |
| return Ok(( |
| Scalar::from_uint(truncated, size), |
| oflo || self.sign_extend(truncated, left_layout) != result, |
| left_layout.ty, |
| )); |
| } |
| } |
| |
| let (val, ty) = match bin_op { |
| Eq => (Scalar::from_bool(l == r), self.tcx.types.bool), |
| Ne => (Scalar::from_bool(l != r), self.tcx.types.bool), |
| |
| Lt => (Scalar::from_bool(l < r), self.tcx.types.bool), |
| Le => (Scalar::from_bool(l <= r), self.tcx.types.bool), |
| Gt => (Scalar::from_bool(l > r), self.tcx.types.bool), |
| Ge => (Scalar::from_bool(l >= r), self.tcx.types.bool), |
| |
| BitOr => (Scalar::from_uint(l | r, size), left_layout.ty), |
| BitAnd => (Scalar::from_uint(l & r, size), left_layout.ty), |
| BitXor => (Scalar::from_uint(l ^ r, size), left_layout.ty), |
| |
| Add | Sub | Mul | Rem | Div => { |
| assert!(!left_layout.abi.is_signed()); |
| let op: fn(u128, u128) -> (u128, bool) = match bin_op { |
| Add => u128::overflowing_add, |
| Sub => u128::overflowing_sub, |
| Mul => u128::overflowing_mul, |
| Div if r == 0 => throw_ub!(DivisionByZero), |
| Rem if r == 0 => throw_ub!(RemainderByZero), |
| Div => u128::overflowing_div, |
| Rem => u128::overflowing_rem, |
| _ => bug!(), |
| }; |
| let (result, oflo) = op(l, r); |
| // Truncate to target type. |
| // If that truncation loses any information, we have an overflow. |
| let truncated = self.truncate(result, left_layout); |
| return Ok(( |
| Scalar::from_uint(truncated, size), |
| oflo || truncated != result, |
| left_layout.ty, |
| )); |
| } |
| |
| _ => span_bug!( |
| self.cur_span(), |
| "invalid binary op {:?}: {:?}, {:?} (both {:?})", |
| bin_op, |
| l, |
| r, |
| right_layout.ty, |
| ), |
| }; |
| |
| Ok((val, false, ty)) |
| } |
| |
| /// Returns the result of the specified operation, whether it overflowed, and |
| /// the result type. |
| pub fn overflowing_binary_op( |
| &self, |
| bin_op: mir::BinOp, |
| left: &ImmTy<'tcx, M::Provenance>, |
| right: &ImmTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, (Scalar<M::Provenance>, bool, Ty<'tcx>)> { |
| trace!( |
| "Running binary op {:?}: {:?} ({:?}), {:?} ({:?})", |
| bin_op, |
| *left, |
| left.layout.ty, |
| *right, |
| right.layout.ty |
| ); |
| |
| match left.layout.ty.kind() { |
| ty::Char => { |
| assert_eq!(left.layout.ty, right.layout.ty); |
| let left = left.to_scalar()?; |
| let right = right.to_scalar()?; |
| Ok(self.binary_char_op(bin_op, left.to_char()?, right.to_char()?)) |
| } |
| ty::Bool => { |
| assert_eq!(left.layout.ty, right.layout.ty); |
| let left = left.to_scalar()?; |
| let right = right.to_scalar()?; |
| Ok(self.binary_bool_op(bin_op, left.to_bool()?, right.to_bool()?)) |
| } |
| ty::Float(fty) => { |
| assert_eq!(left.layout.ty, right.layout.ty); |
| let ty = left.layout.ty; |
| let left = left.to_scalar()?; |
| let right = right.to_scalar()?; |
| Ok(match fty { |
| FloatTy::F32 => { |
| self.binary_float_op(bin_op, ty, left.to_f32()?, right.to_f32()?) |
| } |
| FloatTy::F64 => { |
| self.binary_float_op(bin_op, ty, left.to_f64()?, right.to_f64()?) |
| } |
| }) |
| } |
| _ if left.layout.ty.is_integral() => { |
| // the RHS type can be different, e.g. for shifts -- but it has to be integral, too |
| assert!( |
| right.layout.ty.is_integral(), |
| "Unexpected types for BinOp: {:?} {:?} {:?}", |
| left.layout.ty, |
| bin_op, |
| right.layout.ty |
| ); |
| |
| let l = left.to_scalar()?.to_bits(left.layout.size)?; |
| let r = right.to_scalar()?.to_bits(right.layout.size)?; |
| self.binary_int_op(bin_op, l, left.layout, r, right.layout) |
| } |
| _ if left.layout.ty.is_any_ptr() => { |
| // The RHS type must be a `pointer` *or an integer type* (for `Offset`). |
| // (Even when both sides are pointers, their type might differ, see issue #91636) |
| assert!( |
| right.layout.ty.is_any_ptr() || right.layout.ty.is_integral(), |
| "Unexpected types for BinOp: {:?} {:?} {:?}", |
| left.layout.ty, |
| bin_op, |
| right.layout.ty |
| ); |
| |
| M::binary_ptr_op(self, bin_op, left, right) |
| } |
| _ => span_bug!( |
| self.cur_span(), |
| "Invalid MIR: bad LHS type for binop: {:?}", |
| left.layout.ty |
| ), |
| } |
| } |
| |
| /// Typed version of `overflowing_binary_op`, returning an `ImmTy`. Also ignores overflows. |
| #[inline] |
| pub fn binary_op( |
| &self, |
| bin_op: mir::BinOp, |
| left: &ImmTy<'tcx, M::Provenance>, |
| right: &ImmTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> { |
| let (val, _overflow, ty) = self.overflowing_binary_op(bin_op, left, right)?; |
| Ok(ImmTy::from_scalar(val, self.layout_of(ty)?)) |
| } |
| |
| /// Returns the result of the specified operation, whether it overflowed, and |
| /// the result type. |
| pub fn overflowing_unary_op( |
| &self, |
| un_op: mir::UnOp, |
| val: &ImmTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, (Scalar<M::Provenance>, bool, Ty<'tcx>)> { |
| use rustc_middle::mir::UnOp::*; |
| |
| let layout = val.layout; |
| let val = val.to_scalar()?; |
| trace!("Running unary op {:?}: {:?} ({:?})", un_op, val, layout.ty); |
| |
| match layout.ty.kind() { |
| ty::Bool => { |
| let val = val.to_bool()?; |
| let res = match un_op { |
| Not => !val, |
| _ => span_bug!(self.cur_span(), "Invalid bool op {:?}", un_op), |
| }; |
| Ok((Scalar::from_bool(res), false, self.tcx.types.bool)) |
| } |
| ty::Float(fty) => { |
| let res = match (un_op, fty) { |
| (Neg, FloatTy::F32) => Scalar::from_f32(-val.to_f32()?), |
| (Neg, FloatTy::F64) => Scalar::from_f64(-val.to_f64()?), |
| _ => span_bug!(self.cur_span(), "Invalid float op {:?}", un_op), |
| }; |
| Ok((res, false, layout.ty)) |
| } |
| _ => { |
| assert!(layout.ty.is_integral()); |
| let val = val.to_bits(layout.size)?; |
| let (res, overflow) = match un_op { |
| Not => (self.truncate(!val, layout), false), // bitwise negation, then truncate |
| Neg => { |
| // arithmetic negation |
| assert!(layout.abi.is_signed()); |
| let val = self.sign_extend(val, layout) as i128; |
| let (res, overflow) = val.overflowing_neg(); |
| let res = res as u128; |
| // Truncate to target type. |
| // If that truncation loses any information, we have an overflow. |
| let truncated = self.truncate(res, layout); |
| (truncated, overflow || self.sign_extend(truncated, layout) != res) |
| } |
| }; |
| Ok((Scalar::from_uint(res, layout.size), overflow, layout.ty)) |
| } |
| } |
| } |
| |
| pub fn unary_op( |
| &self, |
| un_op: mir::UnOp, |
| val: &ImmTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> { |
| let (val, _overflow, ty) = self.overflowing_unary_op(un_op, val)?; |
| Ok(ImmTy::from_scalar(val, self.layout_of(ty)?)) |
| } |
| } |
