diff options
| -rw-r--r-- | src/librustc_mir/interpret/cast.rs | 122 | ||||
| -rw-r--r-- | src/librustc_mir/interpret/step.rs | 5 |
2 files changed, 76 insertions, 51 deletions
diff --git a/src/librustc_mir/interpret/cast.rs b/src/librustc_mir/interpret/cast.rs index c1ba9ae83db..18483c70951 100644 --- a/src/librustc_mir/interpret/cast.rs +++ b/src/librustc_mir/interpret/cast.rs @@ -1,6 +1,5 @@ use std::convert::TryFrom; -use super::{FnVal, ImmTy, Immediate, InterpCx, Machine, OpTy, PlaceTy}; use rustc_apfloat::ieee::{Double, Single}; use rustc_apfloat::{Float, FloatConvert}; use rustc_ast::ast::FloatTy; @@ -12,25 +11,40 @@ use rustc_middle::ty::{self, Ty, TypeAndMut, TypeFoldable}; use rustc_span::symbol::sym; use rustc_target::abi::{LayoutOf, Size, Variants}; +use super::{truncate, FnVal, ImmTy, Immediate, InterpCx, Machine, OpTy, PlaceTy}; + impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { pub fn cast( &mut self, src: OpTy<'tcx, M::PointerTag>, - kind: CastKind, + cast_kind: CastKind, + cast_ty: Ty<'tcx>, dest: PlaceTy<'tcx, M::PointerTag>, ) -> InterpResult<'tcx> { use rustc_middle::mir::CastKind::*; - match kind { + // FIXME: In which cases should we trigger UB when the source is uninit? + match cast_kind { Pointer(PointerCast::Unsize) => { + assert_eq!( + cast_ty, dest.layout.ty, + "mismatch of cast type {} and place type {}", + cast_ty, dest.layout.ty + ); self.unsize_into(src, dest)?; } - Misc | Pointer(PointerCast::MutToConstPointer | PointerCast::ArrayToPointer) => { + Misc => { let src = self.read_immediate(src)?; - let res = self.cast_immediate(src, dest.layout)?; + let res = self.misc_cast(src, cast_ty)?; self.write_immediate(res, dest)?; } + Pointer(PointerCast::MutToConstPointer | PointerCast::ArrayToPointer) => { + // These are NOPs, but can be wide pointers. + let v = self.read_immediate(src)?; + self.write_immediate(*v, dest)?; + } + Pointer(PointerCast::ReifyFnPointer) => { // The src operand does not matter, just its type match src.layout.ty.kind { @@ -61,12 +75,12 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { Pointer(PointerCast::UnsafeFnPointer) => { let src = self.read_immediate(src)?; - match dest.layout.ty.kind { + match cast_ty.kind { ty::FnPtr(_) => { // No change to value self.write_immediate(*src, dest)?; } - _ => bug!("fn to unsafe fn cast on {:?}", dest.layout.ty), + _ => bug!("fn to unsafe fn cast on {:?}", cast_ty), } } @@ -95,21 +109,21 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { Ok(()) } - fn cast_immediate( + fn misc_cast( &self, src: ImmTy<'tcx, M::PointerTag>, - dest_layout: TyAndLayout<'tcx>, + cast_ty: Ty<'tcx>, ) -> InterpResult<'tcx, Immediate<M::PointerTag>> { use rustc_middle::ty::TyKind::*; - trace!("Casting {:?}: {:?} to {:?}", *src, src.layout.ty, dest_layout.ty); + trace!("Casting {:?}: {:?} to {:?}", *src, src.layout.ty, cast_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()); + return Ok(self.cast_from_float(src.to_scalar()?.to_f32()?, cast_ty).into()); } Float(FloatTy::F64) => { - return Ok(self.cast_from_float(src.to_scalar()?.to_f64()?, dest_layout.ty).into()); + return Ok(self.cast_from_float(src.to_scalar()?.to_f64()?, cast_ty).into()); } // The rest is integer/pointer-"like", including fn ptr casts and casts from enums that // are represented as integers. @@ -124,69 +138,79 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { ), } + // # First handle non-scalar source values. + // Handle cast from a univariant (ZST) enum. match src.layout.variants { Variants::Single { index } => { if let Some(discr) = src.layout.ty.discriminant_for_variant(*self.tcx, index) { assert!(src.layout.is_zst()); let discr_layout = self.layout_of(discr.ty)?; - return Ok(self - .cast_from_int_like(discr.val, discr_layout, dest_layout) - .into()); + return Ok(self.cast_from_scalar(discr.val, discr_layout, cast_ty).into()); } } 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); + if src.layout.ty.is_any_ptr() && cast_ty.is_unsafe_ptr() { + let dest_layout = self.layout_of(cast_ty)?; + if dest_layout.size == src.layout.size { + // Thin or fat pointer that just hast the ptr kind of target type changed. + return Ok(*src); + } else { + // Casting the metadata away from a fat ptr. + assert_eq!(src.layout.size, 2 * self.memory.pointer_size()); + assert_eq!(dest_layout.size, self.memory.pointer_size()); + assert!(src.layout.ty.is_unsafe_ptr()); + return match *src { + Immediate::ScalarPair(data, _) => Ok(data.into()), + Immediate::Scalar(..) => bug!( + "{:?} input to a fat-to-thin cast ({:?} -> {:?})", + *src, + src.layout.ty, + cast_ty + ), + }; + } } + // # The remaining source values are scalar. + // 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_like(bits, src.layout, dest_layout).into()) + Ok(self.cast_from_scalar(bits, src.layout, cast_ty).into()) } - pub(super) fn cast_from_int_like( + pub(super) fn cast_from_scalar( &self, - v: u128, // raw bits + v: u128, // raw bits (there is no ScalarTy so we separate data+layout) src_layout: TyAndLayout<'tcx>, - dest_layout: TyAndLayout<'tcx>, + cast_ty: Ty<'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 signed = src_layout.abi.is_signed(); // also checks that abi is `Scalar`. let v = if signed { self.sign_extend(v, src_layout) } else { v }; - trace!("cast_from_int: {}, {}, {}", v, src_layout.ty, dest_layout.ty); + trace!("cast_from_scalar: {}, {} -> {}", v, src_layout.ty, cast_ty); use rustc_middle::ty::TyKind::*; - match dest_layout.ty.kind { + match cast_ty.kind { Int(_) | Uint(_) | RawPtr(_) => { - let v = self.truncate(v, dest_layout); - Scalar::from_uint(v, dest_layout.size) + let size = match cast_ty.kind { + // FIXME: Isn't there a helper for this? The same pattern occurs below. + Int(t) => { + t.bit_width().map(Size::from_bits).unwrap_or_else(|| self.pointer_size()) + } + Uint(t) => { + t.bit_width().map(Size::from_bits).unwrap_or_else(|| self.pointer_size()) + } + RawPtr(_) => self.pointer_size(), + _ => bug!(), + }; + let v = truncate(v, size); + Scalar::from_uint(v, size) } Float(FloatTy::F32) if signed => Scalar::from_f32(Single::from_i128(v as i128).value), @@ -200,7 +224,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { } // Casts to bool are not permitted by rustc, no need to handle them here. - _ => bug!("invalid int to {:?} cast", dest_layout.ty), + _ => bug!("invalid int to {:?} cast", cast_ty), } } @@ -283,7 +307,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { src: OpTy<'tcx, M::PointerTag>, dest: PlaceTy<'tcx, M::PointerTag>, ) -> InterpResult<'tcx> { - trace!("Unsizing {:?} into {:?}", src, dest); + trace!("Unsizing {:?} of type {} into {:?}", *src, src.layout.ty, dest.layout.ty); match (&src.layout.ty.kind, &dest.layout.ty.kind) { (&ty::Ref(_, s, _), &ty::Ref(_, d, _) | &ty::RawPtr(TypeAndMut { ty: d, .. })) | (&ty::RawPtr(TypeAndMut { ty: s, .. }), &ty::RawPtr(TypeAndMut { ty: d, .. })) => { diff --git a/src/librustc_mir/interpret/step.rs b/src/librustc_mir/interpret/step.rs index bb4c0156c88..fd9815975c1 100644 --- a/src/librustc_mir/interpret/step.rs +++ b/src/librustc_mir/interpret/step.rs @@ -253,9 +253,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { self.write_scalar(Scalar::from_machine_usize(layout.size.bytes(), self), dest)?; } - Cast(kind, ref operand, _) => { + Cast(cast_kind, ref operand, cast_ty) => { let src = self.eval_operand(operand, None)?; - self.cast(src, kind, dest)?; + let cast_ty = self.subst_from_current_frame_and_normalize_erasing_regions(cast_ty); + self.cast(src, cast_kind, cast_ty, dest)?; } Discriminant(place) => { |