| use rustc::ty::{self, Ty, TypeAndMut, TypeFoldable}; |
| use rustc::ty::layout::{self, TyLayout, Size}; |
| use rustc::ty::adjustment::{PointerCast}; |
| use syntax::ast::FloatTy; |
| use syntax::symbol::sym; |
| |
| use rustc_apfloat::ieee::{Single, Double}; |
| use rustc_apfloat::{Float, FloatConvert}; |
| use rustc::mir::interpret::{ |
| Scalar, InterpResult, PointerArithmetic, |
| }; |
| use rustc::mir::CastKind; |
| |
| use super::{InterpCx, Machine, PlaceTy, OpTy, ImmTy, Immediate, FnVal}; |
| |
| impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { |
| pub fn cast( |
| &mut self, |
| src: OpTy<'tcx, M::PointerTag>, |
| kind: CastKind, |
| dest: PlaceTy<'tcx, M::PointerTag>, |
| ) -> InterpResult<'tcx> { |
| use rustc::mir::CastKind::*; |
| match kind { |
| Pointer(PointerCast::Unsize) => { |
| self.unsize_into(src, dest)?; |
| } |
| |
| Misc |
| | Pointer(PointerCast::MutToConstPointer) |
| | Pointer(PointerCast::ArrayToPointer) => { |
| let src = self.read_immediate(src)?; |
| let res = self.cast_immediate(src, dest.layout)?; |
| self.write_immediate(res, dest)?; |
| } |
| |
| Pointer(PointerCast::ReifyFnPointer) => { |
| // The src operand does not matter, just its type |
| match src.layout.ty.kind { |
| ty::FnDef(def_id, substs) => { |
| // All reifications must be monomorphic, bail out otherwise. |
| if src.layout.ty.needs_subst() { |
| throw_inval!(TooGeneric); |
| } |
| |
| if self.tcx.has_attr(def_id, sym::rustc_args_required_const) { |
| bug!("reifying a fn ptr that requires const arguments"); |
| } |
| |
| let instance = ty::Instance::resolve_for_fn_ptr( |
| *self.tcx, |
| self.param_env, |
| def_id, |
| substs, |
| ).ok_or_else(|| err_inval!(TooGeneric))?; |
| |
| let fn_ptr = self.memory.create_fn_alloc(FnVal::Instance(instance)); |
| self.write_scalar(Scalar::Ptr(fn_ptr.into()), dest)?; |
| } |
| _ => bug!("reify fn pointer on {:?}", src.layout.ty), |
| } |
| } |
| |
| Pointer(PointerCast::UnsafeFnPointer) => { |
| let src = self.read_immediate(src)?; |
| match dest.layout.ty.kind { |
| ty::FnPtr(_) => { |
| // No change to value |
| self.write_immediate(*src, dest)?; |
| } |
| _ => bug!("fn to unsafe fn cast on {:?}", dest.layout.ty), |
| } |
| } |
| |
| Pointer(PointerCast::ClosureFnPointer(_)) => { |
| // The src operand does not matter, just its type |
| match src.layout.ty.kind { |
| ty::Closure(def_id, substs) => { |
| // All reifications must be monomorphic, bail out otherwise. |
| if src.layout.ty.needs_subst() { |
| throw_inval!(TooGeneric); |
| } |
| |
| let instance = ty::Instance::resolve_closure( |
| *self.tcx, |
| def_id, |
| substs, |
| ty::ClosureKind::FnOnce, |
| ); |
| let fn_ptr = self.memory.create_fn_alloc(FnVal::Instance(instance)); |
| let val = Immediate::Scalar(Scalar::Ptr(fn_ptr.into()).into()); |
| self.write_immediate(val, dest)?; |
| } |
| _ => bug!("closure fn pointer on {:?}", src.layout.ty), |
| } |
| } |
| } |
| Ok(()) |
| } |
| |
| fn cast_immediate( |
| &self, |
| src: ImmTy<'tcx, M::PointerTag>, |
| dest_layout: TyLayout<'tcx>, |
| ) -> InterpResult<'tcx, Immediate<M::PointerTag>> { |
| use rustc::ty::TyKind::*; |
| trace!("Casting {:?}: {:?} to {:?}", *src, src.layout.ty, dest_layout.ty); |
| |
| match src.layout.ty.kind { |
| // Floating point |
| Float(FloatTy::F32) => |
| return Ok(self.cast_from_float(src.to_scalar()?.to_f32()?, dest_layout.ty)?.into()), |
| Float(FloatTy::F64) => |
| return Ok(self.cast_from_float(src.to_scalar()?.to_f64()?, dest_layout.ty)?.into()), |
| // The rest is integer/pointer-"like", including fn ptr casts and casts from enums that |
| // are represented as integers. |
| _ => |
| assert!( |
| src.layout.ty.is_bool() || src.layout.ty.is_char() || |
| src.layout.ty.is_enum() || src.layout.ty.is_integral() || |
| src.layout.ty.is_any_ptr(), |
| "Unexpected cast from type {:?}", src.layout.ty |
| ) |
| } |
| |
| // Handle cast from a univariant (ZST) enum. |
| match src.layout.variants { |
| layout::Variants::Single { index } => { |
| if let Some(discr) = |
| src.layout.ty.discriminant_for_variant(*self.tcx, index) |
| { |
| assert!(src.layout.is_zst()); |
| return Ok(Scalar::from_uint(discr.val, dest_layout.size).into()); |
| } |
| } |
| layout::Variants::Multiple { .. } => {}, |
| } |
| |
| // Handle casting the metadata away from a fat pointer. |
| if src.layout.ty.is_unsafe_ptr() && dest_layout.ty.is_unsafe_ptr() && |
| dest_layout.size != src.layout.size |
| { |
| assert_eq!(src.layout.size, 2*self.memory.pointer_size()); |
| assert_eq!(dest_layout.size, self.memory.pointer_size()); |
| assert!(dest_layout.ty.is_unsafe_ptr()); |
| match *src { |
| Immediate::ScalarPair(data, _) => |
| return Ok(data.into()), |
| Immediate::Scalar(..) => |
| bug!( |
| "{:?} input to a fat-to-thin cast ({:?} -> {:?})", |
| *src, src.layout.ty, dest_layout.ty |
| ), |
| }; |
| } |
| |
| // Handle casting any ptr to raw ptr (might be a fat ptr). |
| if src.layout.ty.is_any_ptr() && dest_layout.ty.is_unsafe_ptr() |
| { |
| // The only possible size-unequal case was handled above. |
| assert_eq!(src.layout.size, dest_layout.size); |
| return Ok(*src); |
| } |
| |
| // For all remaining casts, we either |
| // (a) cast a raw ptr to usize, or |
| // (b) cast from an integer-like (including bool, char, enums). |
| // In both cases we want the bits. |
| let bits = self.force_bits(src.to_scalar()?, src.layout.size)?; |
| Ok(self.cast_from_int(bits, src.layout, dest_layout)?.into()) |
| } |
| |
| fn cast_from_int( |
| &self, |
| v: u128, // raw bits |
| src_layout: TyLayout<'tcx>, |
| dest_layout: TyLayout<'tcx>, |
| ) -> InterpResult<'tcx, Scalar<M::PointerTag>> { |
| // Let's make sure v is sign-extended *if* it has a signed type. |
| let signed = src_layout.abi.is_signed(); |
| let v = if signed { |
| self.sign_extend(v, src_layout) |
| } else { |
| v |
| }; |
| trace!("cast_from_int: {}, {}, {}", v, src_layout.ty, dest_layout.ty); |
| use rustc::ty::TyKind::*; |
| match dest_layout.ty.kind { |
| Int(_) | Uint(_) | RawPtr(_) => { |
| let v = self.truncate(v, dest_layout); |
| Ok(Scalar::from_uint(v, dest_layout.size)) |
| } |
| |
| Float(FloatTy::F32) if signed => Ok(Scalar::from_f32( |
| Single::from_i128(v as i128).value |
| )), |
| Float(FloatTy::F64) if signed => Ok(Scalar::from_f64( |
| Double::from_i128(v as i128).value |
| )), |
| Float(FloatTy::F32) => Ok(Scalar::from_f32( |
| Single::from_u128(v).value |
| )), |
| Float(FloatTy::F64) => Ok(Scalar::from_f64( |
| Double::from_u128(v).value |
| )), |
| |
| Char => { |
| // `u8` to `char` cast |
| debug_assert_eq!(v as u8 as u128, v); |
| Ok(Scalar::from_uint(v, Size::from_bytes(4))) |
| }, |
| |
| // Casts to bool are not permitted by rustc, no need to handle them here. |
| _ => bug!("invalid int to {:?} cast", dest_layout.ty), |
| } |
| } |
| |
| fn cast_from_float<F>( |
| &self, |
| f: F, |
| dest_ty: Ty<'tcx> |
| ) -> InterpResult<'tcx, Scalar<M::PointerTag>> |
| where F: Float + Into<Scalar<M::PointerTag>> + FloatConvert<Single> + FloatConvert<Double> |
| { |
| use rustc::ty::TyKind::*; |
| match dest_ty.kind { |
| // float -> uint |
| Uint(t) => { |
| let width = t.bit_width().unwrap_or_else(|| self.pointer_size().bits() as usize); |
| let v = f.to_u128(width).value; |
| // This should already fit the bit width |
| Ok(Scalar::from_uint(v, Size::from_bits(width as u64))) |
| }, |
| // float -> int |
| Int(t) => { |
| let width = t.bit_width().unwrap_or_else(|| self.pointer_size().bits() as usize); |
| let v = f.to_i128(width).value; |
| Ok(Scalar::from_int(v, Size::from_bits(width as u64))) |
| }, |
| // float -> f32 |
| Float(FloatTy::F32) => |
| Ok(Scalar::from_f32(f.convert(&mut false).value)), |
| // float -> f64 |
| Float(FloatTy::F64) => |
| Ok(Scalar::from_f64(f.convert(&mut false).value)), |
| // That's it. |
| _ => bug!("invalid float to {:?} cast", dest_ty), |
| } |
| } |
| |
| fn unsize_into_ptr( |
| &mut self, |
| src: OpTy<'tcx, M::PointerTag>, |
| dest: PlaceTy<'tcx, M::PointerTag>, |
| // The pointee types |
| source_ty: Ty<'tcx>, |
| dest_ty: Ty<'tcx>, |
| ) -> InterpResult<'tcx> { |
| // A<Struct> -> A<Trait> conversion |
| let (src_pointee_ty, dest_pointee_ty) = |
| self.tcx.struct_lockstep_tails_erasing_lifetimes(source_ty, dest_ty, self.param_env); |
| |
| match (&src_pointee_ty.kind, &dest_pointee_ty.kind) { |
| (&ty::Array(_, length), &ty::Slice(_)) => { |
| let ptr = self.read_immediate(src)?.to_scalar()?; |
| // u64 cast is from usize to u64, which is always good |
| let val = Immediate::new_slice( |
| ptr, |
| length.eval_usize(self.tcx.tcx, self.param_env), |
| self, |
| ); |
| self.write_immediate(val, dest) |
| } |
| (&ty::Dynamic(..), &ty::Dynamic(..)) => { |
| // For now, upcasts are limited to changes in marker |
| // traits, and hence never actually require an actual |
| // change to the vtable. |
| let val = self.read_immediate(src)?; |
| self.write_immediate(*val, dest) |
| } |
| (_, &ty::Dynamic(ref data, _)) => { |
| // Initial cast from sized to dyn trait |
| let vtable = self.get_vtable(src_pointee_ty, data.principal())?; |
| let ptr = self.read_immediate(src)?.to_scalar()?; |
| let val = Immediate::new_dyn_trait(ptr, vtable); |
| self.write_immediate(val, dest) |
| } |
| |
| _ => bug!("invalid unsizing {:?} -> {:?}", src.layout.ty, dest.layout.ty), |
| } |
| } |
| |
| fn unsize_into( |
| &mut self, |
| src: OpTy<'tcx, M::PointerTag>, |
| dest: PlaceTy<'tcx, M::PointerTag>, |
| ) -> InterpResult<'tcx> { |
| trace!("Unsizing {:?} into {:?}", src, dest); |
| match (&src.layout.ty.kind, &dest.layout.ty.kind) { |
| (&ty::Ref(_, s, _), &ty::Ref(_, d, _)) | |
| (&ty::Ref(_, s, _), &ty::RawPtr(TypeAndMut { ty: d, .. })) | |
| (&ty::RawPtr(TypeAndMut { ty: s, .. }), |
| &ty::RawPtr(TypeAndMut { ty: d, .. })) => { |
| self.unsize_into_ptr(src, dest, s, d) |
| } |
| (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => { |
| assert_eq!(def_a, def_b); |
| if def_a.is_box() || def_b.is_box() { |
| if !def_a.is_box() || !def_b.is_box() { |
| bug!("invalid unsizing between {:?} -> {:?}", src.layout, dest.layout); |
| } |
| return self.unsize_into_ptr( |
| src, |
| dest, |
| src.layout.ty.boxed_ty(), |
| dest.layout.ty.boxed_ty(), |
| ); |
| } |
| |
| // unsizing of generic struct with pointer fields |
| // Example: `Arc<T>` -> `Arc<Trait>` |
| // here we need to increase the size of every &T thin ptr field to a fat ptr |
| for i in 0..src.layout.fields.count() { |
| let dst_field = self.place_field(dest, i as u64)?; |
| if dst_field.layout.is_zst() { |
| continue; |
| } |
| let src_field = self.operand_field(src, i as u64)?; |
| if src_field.layout.ty == dst_field.layout.ty { |
| self.copy_op(src_field, dst_field)?; |
| } else { |
| self.unsize_into(src_field, dst_field)?; |
| } |
| } |
| Ok(()) |
| } |
| _ => { |
| bug!( |
| "unsize_into: invalid conversion: {:?} -> {:?}", |
| src.layout, |
| dest.layout |
| ) |
| } |
| } |
| } |
| } |
