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Diffstat (limited to 'compiler/rustc_mir/src/interpret/operator.rs')
| -rw-r--r-- | compiler/rustc_mir/src/interpret/operator.rs | 418 |
1 files changed, 418 insertions, 0 deletions
diff --git a/compiler/rustc_mir/src/interpret/operator.rs b/compiler/rustc_mir/src/interpret/operator.rs new file mode 100644 index 00000000000..30c40b8fde9 --- /dev/null +++ b/compiler/rustc_mir/src/interpret/operator.rs @@ -0,0 +1,418 @@ +use std::convert::TryFrom; + +use rustc_apfloat::Float; +use rustc_ast::FloatTy; +use rustc_middle::mir; +use rustc_middle::mir::interpret::{InterpResult, Scalar}; +use rustc_middle::ty::{self, layout::TyAndLayout, Ty}; +use rustc_target::abi::LayoutOf; + +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. + pub fn binop_with_overflow( + &mut self, + op: mir::BinOp, + left: ImmTy<'tcx, M::PointerTag>, + right: ImmTy<'tcx, M::PointerTag>, + dest: PlaceTy<'tcx, M::PointerTag>, + ) -> 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, + ); + let val = Immediate::ScalarPair(val.into(), Scalar::from_bool(overflowed).into()); + self.write_immediate(val, dest) + } + + /// 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::PointerTag>, + right: ImmTy<'tcx, M::PointerTag>, + dest: PlaceTy<'tcx, M::PointerTag>, + ) -> 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::PointerTag>, 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::PointerTag>, 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::PointerTag>>>( + &self, + bin_op: mir::BinOp, + ty: Ty<'tcx>, + l: F, + r: F, + ) -> (Scalar<M::PointerTag>, 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::PointerTag>, 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 signed = left_layout.abi.is_signed(); + let size = u128::from(left_layout.size.bits()); + let overflow = r >= size; + let r = r % size; // mask to type size + let r = u32::try_from(r).unwrap(); // we masked so this will always fit + let result = if 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!("it has already been checked that this is a shift op"), + }; + result as u128 + } else { + match bin_op { + Shl => l.checked_shl(r).unwrap(), + Shr => l.checked_shr(r).unwrap(), + _ => bug!("it has already been checked that this is a shift op"), + } + }; + 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 r = self.sign_extend(r, right_layout) as i128; + // We need a special check for overflowing remainder: + // "int_min % -1" overflows and returns 0, but after casting things to a larger int + // type it does *not* overflow nor give an unrepresentable result! + if bin_op == Rem { + if r == -1 && l == (1 << (size.bits() - 1)) { + return Ok((Scalar::from_int(0, size), true, left_layout.ty)); + } + } + let l = self.sign_extend(l, left_layout) as i128; + + 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::PointerTag>, + right: ImmTy<'tcx, M::PointerTag>, + ) -> InterpResult<'tcx, (Scalar<M::PointerTag>, 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 = self.force_bits(left.to_scalar()?, left.layout.size)?; + let r = self.force_bits(right.to_scalar()?, 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 the same *or an integer type* (for `Offset`). + assert!( + right.layout.ty == left.layout.ty || 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::PointerTag>, + right: ImmTy<'tcx, M::PointerTag>, + ) -> InterpResult<'tcx, ImmTy<'tcx, M::PointerTag>> { + 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::PointerTag>, + ) -> InterpResult<'tcx, (Scalar<M::PointerTag>, 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 = self.force_bits(val, 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::PointerTag>, + ) -> InterpResult<'tcx, ImmTy<'tcx, M::PointerTag>> { + let (val, _overflow, ty) = self.overflowing_unary_op(un_op, val)?; + Ok(ImmTy::from_scalar(val, self.layout_of(ty)?)) + } +} |