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, truncate
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);
139 Scalar::Ptr(ptr) => self.cast_from_ptr(ptr, dest_layout.ty),
140 Scalar::Bits { bits, size } => {
141 debug_assert_eq!(size as u64, src_layout.size.bytes());
142 debug_assert_eq!(truncate(bits, Size::from_bytes(size.into())), bits,
143 "Unexpected value of size {} before casting", size);
145 let res = match src_layout.ty.sty {
146 Float(fty) => self.cast_from_float(bits, fty, dest_layout.ty)?,
147 _ => self.cast_from_int(bits, src_layout, dest_layout)?,
152 Scalar::Ptr(_) => bug!("Fabricated a ptr value from an int...?"),
153 Scalar::Bits { bits, size } => {
154 debug_assert_eq!(size as u64, dest_layout.size.bytes());
155 debug_assert_eq!(truncate(bits, Size::from_bytes(size.into())), bits,
156 "Unexpected value of size {} after casting", size);
168 src_layout: TyLayout<'tcx>,
169 dest_layout: TyLayout<'tcx>,
170 ) -> EvalResult<'tcx, Scalar<M::PointerTag>> {
171 let signed = src_layout.abi.is_signed();
173 self.sign_extend(v, src_layout)
177 trace!("cast_from_int: {}, {}, {}", v, src_layout.ty, dest_layout.ty);
178 use rustc::ty::TyKind::*;
179 match dest_layout.ty.sty {
180 Int(_) | Uint(_) => {
181 let v = self.truncate(v, dest_layout);
182 Ok(Scalar::from_uint(v, dest_layout.size))
185 Float(FloatTy::F32) if signed => Ok(Scalar::from_uint(
186 Single::from_i128(v as i128).value.to_bits(),
189 Float(FloatTy::F64) if signed => Ok(Scalar::from_uint(
190 Double::from_i128(v as i128).value.to_bits(),
193 Float(FloatTy::F32) => Ok(Scalar::from_uint(
194 Single::from_u128(v).value.to_bits(),
197 Float(FloatTy::F64) => Ok(Scalar::from_uint(
198 Double::from_u128(v).value.to_bits(),
203 // `u8` to `char` cast
204 debug_assert_eq!(v as u8 as u128, v);
205 Ok(Scalar::from_uint(v, Size::from_bytes(4)))
208 // No alignment check needed for raw pointers.
209 // But we have to truncate to target ptr size.
211 Ok(Scalar::from_uint(
212 self.truncate_to_ptr(v).0,
217 // Casts to bool are not permitted by rustc, no need to handle them here.
218 _ => err!(Unimplemented(format!("int to {:?} cast", dest_layout.ty))),
227 ) -> EvalResult<'tcx, Scalar<M::PointerTag>> {
228 use rustc::ty::TyKind::*;
229 use rustc_apfloat::FloatConvert;
233 let width = t.bit_width().unwrap_or_else(|| self.pointer_size().bits() as usize);
235 FloatTy::F32 => Single::from_bits(bits).to_u128(width).value,
236 FloatTy::F64 => Double::from_bits(bits).to_u128(width).value,
238 // This should already fit the bit width
239 Ok(Scalar::from_uint(v, Size::from_bits(width as u64)))
243 let width = t.bit_width().unwrap_or_else(|| self.pointer_size().bits() as usize);
245 FloatTy::F32 => Single::from_bits(bits).to_i128(width).value,
246 FloatTy::F64 => Double::from_bits(bits).to_i128(width).value,
248 Ok(Scalar::from_int(v, Size::from_bits(width as u64)))
251 Float(FloatTy::F32) if fty == FloatTy::F64 => {
252 Ok(Scalar::from_uint(
253 Single::to_bits(Double::from_bits(bits).convert(&mut false).value),
258 Float(FloatTy::F64) if fty == FloatTy::F32 => {
259 Ok(Scalar::from_uint(
260 Double::to_bits(Single::from_bits(bits).convert(&mut false).value),
265 Float(FloatTy:: F64) => Ok(Scalar::from_uint(bits, Size::from_bits(64))),
266 Float(FloatTy:: F32) => Ok(Scalar::from_uint(bits, Size::from_bits(32))),
267 _ => err!(Unimplemented(format!("float to {:?} cast", dest_ty))),
273 ptr: Pointer<M::PointerTag>,
275 ) -> EvalResult<'tcx, Scalar<M::PointerTag>> {
276 use rustc::ty::TyKind::*;
278 // Casting to a reference or fn pointer is not permitted by rustc,
279 // no need to support it here.
282 Uint(UintTy::Usize) => Ok(ptr.into()),
283 Int(_) | Uint(_) => err!(ReadPointerAsBytes),
284 _ => err!(Unimplemented(format!("ptr to {:?} cast", ty))),
290 src: OpTy<'tcx, M::PointerTag>,
291 dest: PlaceTy<'tcx, M::PointerTag>,
295 ) -> EvalResult<'tcx> {
296 // A<Struct> -> A<Trait> conversion
297 let (src_pointee_ty, dest_pointee_ty) = self.tcx.struct_lockstep_tails(sty, dty);
299 match (&src_pointee_ty.sty, &dest_pointee_ty.sty) {
300 (&ty::Array(_, length), &ty::Slice(_)) => {
301 let ptr = self.read_immediate(src)?.to_scalar_ptr()?;
302 // u64 cast is from usize to u64, which is always good
303 let val = Immediate::new_slice(
305 length.unwrap_usize(self.tcx.tcx),
308 self.write_immediate(val, dest)
310 (&ty::Dynamic(..), &ty::Dynamic(..)) => {
311 // For now, upcasts are limited to changes in marker
312 // traits, and hence never actually require an actual
313 // change to the vtable.
314 let val = self.read_immediate(src)?;
315 self.write_immediate(*val, dest)
317 (_, &ty::Dynamic(ref data, _)) => {
318 // Initial cast from sized to dyn trait
319 let vtable = self.get_vtable(src_pointee_ty, data.principal())?;
320 let ptr = self.read_immediate(src)?.to_scalar_ptr()?;
321 let val = Immediate::new_dyn_trait(ptr, vtable);
322 self.write_immediate(val, dest)
325 _ => bug!("invalid unsizing {:?} -> {:?}", src.layout.ty, dest.layout.ty),
331 src: OpTy<'tcx, M::PointerTag>,
332 dest: PlaceTy<'tcx, M::PointerTag>,
333 ) -> EvalResult<'tcx> {
334 match (&src.layout.ty.sty, &dest.layout.ty.sty) {
335 (&ty::Ref(_, s, _), &ty::Ref(_, d, _)) |
336 (&ty::Ref(_, s, _), &ty::RawPtr(TypeAndMut { ty: d, .. })) |
337 (&ty::RawPtr(TypeAndMut { ty: s, .. }),
338 &ty::RawPtr(TypeAndMut { ty: d, .. })) => {
339 self.unsize_into_ptr(src, dest, s, d)
341 (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
342 assert_eq!(def_a, def_b);
343 if def_a.is_box() || def_b.is_box() {
344 if !def_a.is_box() || !def_b.is_box() {
345 bug!("invalid unsizing between {:?} -> {:?}", src.layout, dest.layout);
347 return self.unsize_into_ptr(
350 src.layout.ty.boxed_ty(),
351 dest.layout.ty.boxed_ty(),
355 // unsizing of generic struct with pointer fields
356 // Example: `Arc<T>` -> `Arc<Trait>`
357 // here we need to increase the size of every &T thin ptr field to a fat ptr
358 for i in 0..src.layout.fields.count() {
359 let dst_field = self.place_field(dest, i as u64)?;
360 if dst_field.layout.is_zst() {
363 let src_field = match src.try_as_mplace() {
365 let src_field = self.mplace_field(mplace, i as u64)?;
369 let src_field_layout = src.layout.field(self, i)?;
370 // this must be a field covering the entire thing
371 assert_eq!(src.layout.fields.offset(i).bytes(), 0);
372 assert_eq!(src_field_layout.size, src.layout.size);
373 // just sawp out the layout
374 OpTy::from(ImmTy { imm: src.to_immediate(), layout: src_field_layout })
377 if src_field.layout.ty == dst_field.layout.ty {
378 self.copy_op(src_field, dst_field)?;
380 self.unsize_into(src_field, dst_field)?;
387 "unsize_into: invalid conversion: {:?} -> {:?}",