1 use rustc::ty::{self, Ty, TypeAndMut};
2 use rustc::ty::layout::{self, TyLayout, Size};
3 use rustc::ty::adjustment::{PointerCast};
4 use syntax::ast::{FloatTy, IntTy, UintTy};
5 use syntax::symbol::sym;
7 use rustc_apfloat::ieee::{Single, Double};
8 use rustc::mir::interpret::{
9 Scalar, EvalResult, Pointer, PointerArithmetic, InterpError,
11 use rustc::mir::CastKind;
12 use rustc_apfloat::Float;
14 use super::{InterpretCx, Machine, PlaceTy, OpTy, ImmTy, Immediate};
16 impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> InterpretCx<'a, 'mir, 'tcx, M> {
17 fn type_is_fat_ptr(&self, ty: Ty<'tcx>) -> bool {
19 ty::RawPtr(ty::TypeAndMut { ty, .. }) |
20 ty::Ref(_, ty, _) => !self.type_is_sized(ty),
21 ty::Adt(def, _) if def.is_box() => !self.type_is_sized(ty.boxed_ty()),
28 src: OpTy<'tcx, M::PointerTag>,
30 dest: PlaceTy<'tcx, M::PointerTag>,
31 ) -> EvalResult<'tcx> {
32 use rustc::mir::CastKind::*;
34 Pointer(PointerCast::Unsize) => {
35 self.unsize_into(src, dest)?;
38 Misc | Pointer(PointerCast::MutToConstPointer) => {
39 let src = self.read_immediate(src)?;
41 if self.type_is_fat_ptr(src.layout.ty) {
42 match (*src, self.type_is_fat_ptr(dest.layout.ty)) {
43 // pointers to extern types
44 (Immediate::Scalar(_),_) |
45 // slices and trait objects to other slices/trait objects
46 (Immediate::ScalarPair(..), true) => {
47 // No change to immediate
48 self.write_immediate(*src, dest)?;
50 // slices and trait objects to thin pointers (dropping the metadata)
51 (Immediate::ScalarPair(data, _), false) => {
52 self.write_scalar(data, dest)?;
56 match src.layout.variants {
57 layout::Variants::Single { index } => {
59 src.layout.ty.discriminant_for_variant(*self.tcx, index)
61 // Cast from a univariant enum
62 assert!(src.layout.is_zst());
63 return self.write_scalar(
64 Scalar::from_uint(discr.val, dest.layout.size),
68 layout::Variants::Multiple { .. } => {},
71 let dest_val = self.cast_scalar(src.to_scalar()?, src.layout, dest.layout)?;
72 self.write_scalar(dest_val, dest)?;
76 Pointer(PointerCast::ReifyFnPointer) => {
77 // The src operand does not matter, just its type
78 match src.layout.ty.sty {
79 ty::FnDef(def_id, substs) => {
80 if self.tcx.has_attr(def_id, sym::rustc_args_required_const) {
81 bug!("reifying a fn ptr that requires const arguments");
83 let instance: EvalResult<'tcx, _> = ty::Instance::resolve(
88 ).ok_or_else(|| InterpError::TooGeneric.into());
89 let fn_ptr = self.memory.create_fn_alloc(instance?).with_default_tag();
90 self.write_scalar(Scalar::Ptr(fn_ptr.into()), dest)?;
92 _ => bug!("reify fn pointer on {:?}", src.layout.ty),
96 Pointer(PointerCast::UnsafeFnPointer) => {
97 let src = self.read_immediate(src)?;
98 match dest.layout.ty.sty {
100 // No change to value
101 self.write_immediate(*src, dest)?;
103 _ => bug!("fn to unsafe fn cast on {:?}", dest.layout.ty),
107 Pointer(PointerCast::ClosureFnPointer(_)) => {
108 // The src operand does not matter, just its type
109 match src.layout.ty.sty {
110 ty::Closure(def_id, substs) => {
111 let substs = self.subst_and_normalize_erasing_regions(substs)?;
112 let instance = ty::Instance::resolve_closure(
116 ty::ClosureKind::FnOnce,
118 let fn_ptr = self.memory.create_fn_alloc(instance).with_default_tag();
119 let val = Immediate::Scalar(Scalar::Ptr(fn_ptr.into()).into());
120 self.write_immediate(val, dest)?;
122 _ => bug!("closure fn pointer on {:?}", src.layout.ty),
129 pub(super) fn cast_scalar(
131 val: Scalar<M::PointerTag>,
132 src_layout: TyLayout<'tcx>,
133 dest_layout: TyLayout<'tcx>,
134 ) -> EvalResult<'tcx, Scalar<M::PointerTag>> {
135 use rustc::ty::TyKind::*;
136 trace!("Casting {:?}: {:?} to {:?}", val, src_layout.ty, dest_layout.ty);
138 match val.to_bits_or_ptr(src_layout.size, self) {
139 Err(ptr) => self.cast_from_ptr(ptr, dest_layout.ty),
141 match src_layout.ty.sty {
142 Float(fty) => self.cast_from_float(data, fty, dest_layout.ty),
143 _ => self.cast_from_int(data, src_layout, dest_layout),
152 src_layout: TyLayout<'tcx>,
153 dest_layout: TyLayout<'tcx>,
154 ) -> EvalResult<'tcx, Scalar<M::PointerTag>> {
155 let signed = src_layout.abi.is_signed();
157 self.sign_extend(v, src_layout)
161 trace!("cast_from_int: {}, {}, {}", v, src_layout.ty, dest_layout.ty);
162 use rustc::ty::TyKind::*;
163 match dest_layout.ty.sty {
164 Int(_) | Uint(_) | RawPtr(_) => {
165 let v = self.truncate(v, dest_layout);
166 Ok(Scalar::from_uint(v, dest_layout.size))
169 Float(FloatTy::F32) if signed => Ok(Scalar::from_uint(
170 Single::from_i128(v as i128).value.to_bits(),
173 Float(FloatTy::F64) if signed => Ok(Scalar::from_uint(
174 Double::from_i128(v as i128).value.to_bits(),
177 Float(FloatTy::F32) => Ok(Scalar::from_uint(
178 Single::from_u128(v).value.to_bits(),
181 Float(FloatTy::F64) => Ok(Scalar::from_uint(
182 Double::from_u128(v).value.to_bits(),
187 // `u8` to `char` cast
188 debug_assert_eq!(v as u8 as u128, v);
189 Ok(Scalar::from_uint(v, Size::from_bytes(4)))
192 // Casts to bool are not permitted by rustc, no need to handle them here.
193 _ => err!(Unimplemented(format!("int to {:?} cast", dest_layout.ty))),
202 ) -> EvalResult<'tcx, Scalar<M::PointerTag>> {
203 use rustc::ty::TyKind::*;
204 use rustc_apfloat::FloatConvert;
208 let width = t.bit_width().unwrap_or_else(|| self.pointer_size().bits() as usize);
210 FloatTy::F32 => Single::from_bits(bits).to_u128(width).value,
211 FloatTy::F64 => Double::from_bits(bits).to_u128(width).value,
213 // This should already fit the bit width
214 Ok(Scalar::from_uint(v, Size::from_bits(width as u64)))
218 let width = t.bit_width().unwrap_or_else(|| self.pointer_size().bits() as usize);
220 FloatTy::F32 => Single::from_bits(bits).to_i128(width).value,
221 FloatTy::F64 => Double::from_bits(bits).to_i128(width).value,
223 Ok(Scalar::from_int(v, Size::from_bits(width as u64)))
226 Float(FloatTy::F32) if fty == FloatTy::F64 => {
227 Ok(Scalar::from_uint(
228 Single::to_bits(Double::from_bits(bits).convert(&mut false).value),
233 Float(FloatTy::F64) if fty == FloatTy::F32 => {
234 Ok(Scalar::from_uint(
235 Double::to_bits(Single::from_bits(bits).convert(&mut false).value),
240 Float(FloatTy:: F64) => Ok(Scalar::from_uint(bits, Size::from_bits(64))),
241 Float(FloatTy:: F32) => Ok(Scalar::from_uint(bits, Size::from_bits(32))),
242 _ => err!(Unimplemented(format!("float to {:?} cast", dest_ty))),
248 ptr: Pointer<M::PointerTag>,
250 ) -> EvalResult<'tcx, Scalar<M::PointerTag>> {
251 use rustc::ty::TyKind::*;
253 // Casting to a reference or fn pointer is not permitted by rustc,
254 // no need to support it here.
257 Uint(UintTy::Usize) => Ok(ptr.into()),
258 Int(_) | Uint(_) => err!(ReadPointerAsBytes),
259 _ => err!(Unimplemented(format!("ptr to {:?} cast", ty))),
265 src: OpTy<'tcx, M::PointerTag>,
266 dest: PlaceTy<'tcx, M::PointerTag>,
270 ) -> EvalResult<'tcx> {
271 // A<Struct> -> A<Trait> conversion
272 let (src_pointee_ty, dest_pointee_ty) = self.tcx.struct_lockstep_tails(sty, dty);
274 match (&src_pointee_ty.sty, &dest_pointee_ty.sty) {
275 (&ty::Array(_, length), &ty::Slice(_)) => {
276 let ptr = self.read_immediate(src)?.to_scalar_ptr()?;
277 // u64 cast is from usize to u64, which is always good
278 let val = Immediate::new_slice(
280 length.unwrap_usize(self.tcx.tcx),
283 self.write_immediate(val, dest)
285 (&ty::Dynamic(..), &ty::Dynamic(..)) => {
286 // For now, upcasts are limited to changes in marker
287 // traits, and hence never actually require an actual
288 // change to the vtable.
289 let val = self.read_immediate(src)?;
290 self.write_immediate(*val, dest)
292 (_, &ty::Dynamic(ref data, _)) => {
293 // Initial cast from sized to dyn trait
294 let vtable = self.get_vtable(src_pointee_ty, data.principal())?;
295 let ptr = self.read_immediate(src)?.to_scalar_ptr()?;
296 let val = Immediate::new_dyn_trait(ptr, vtable);
297 self.write_immediate(val, dest)
300 _ => bug!("invalid unsizing {:?} -> {:?}", src.layout.ty, dest.layout.ty),
306 src: OpTy<'tcx, M::PointerTag>,
307 dest: PlaceTy<'tcx, M::PointerTag>,
308 ) -> EvalResult<'tcx> {
309 match (&src.layout.ty.sty, &dest.layout.ty.sty) {
310 (&ty::Ref(_, s, _), &ty::Ref(_, d, _)) |
311 (&ty::Ref(_, s, _), &ty::RawPtr(TypeAndMut { ty: d, .. })) |
312 (&ty::RawPtr(TypeAndMut { ty: s, .. }),
313 &ty::RawPtr(TypeAndMut { ty: d, .. })) => {
314 self.unsize_into_ptr(src, dest, s, d)
316 (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
317 assert_eq!(def_a, def_b);
318 if def_a.is_box() || def_b.is_box() {
319 if !def_a.is_box() || !def_b.is_box() {
320 bug!("invalid unsizing between {:?} -> {:?}", src.layout, dest.layout);
322 return self.unsize_into_ptr(
325 src.layout.ty.boxed_ty(),
326 dest.layout.ty.boxed_ty(),
330 // unsizing of generic struct with pointer fields
331 // Example: `Arc<T>` -> `Arc<Trait>`
332 // here we need to increase the size of every &T thin ptr field to a fat ptr
333 for i in 0..src.layout.fields.count() {
334 let dst_field = self.place_field(dest, i as u64)?;
335 if dst_field.layout.is_zst() {
338 let src_field = match src.try_as_mplace() {
340 let src_field = self.mplace_field(mplace, i as u64)?;
344 let src_field_layout = src.layout.field(self, i)?;
345 // this must be a field covering the entire thing
346 assert_eq!(src.layout.fields.offset(i).bytes(), 0);
347 assert_eq!(src_field_layout.size, src.layout.size);
348 // just sawp out the layout
349 OpTy::from(ImmTy { imm: src.to_immediate(), layout: src_field_layout })
352 if src_field.layout.ty == dst_field.layout.ty {
353 self.copy_op(src_field, dst_field)?;
355 self.unsize_into(src_field, dst_field)?;
362 "unsize_into: invalid conversion: {:?} -> {:?}",