diff options
Diffstat (limited to 'compiler/rustc_const_eval/src/interpret/operand.rs')
| -rw-r--r-- | compiler/rustc_const_eval/src/interpret/operand.rs | 109 |
1 files changed, 74 insertions, 35 deletions
diff --git a/compiler/rustc_const_eval/src/interpret/operand.rs b/compiler/rustc_const_eval/src/interpret/operand.rs index 47383c0eabc..e6d0a73c521 100644 --- a/compiler/rustc_const_eval/src/interpret/operand.rs +++ b/compiler/rustc_const_eval/src/interpret/operand.rs @@ -13,7 +13,7 @@ use rustc_target::abi::{self, Abi, Align, HasDataLayout, Size}; use super::{ alloc_range, from_known_layout, mir_assign_valid_types, AllocId, ConstValue, Frame, GlobalId, - InterpCx, InterpResult, MPlaceTy, Machine, MemPlace, MemPlaceMeta, Place, PlaceTy, Pointer, + InterpCx, InterpResult, MPlaceTy, Machine, MemPlace, MemPlaceMeta, PlaceTy, Pointer, Provenance, Scalar, }; @@ -240,37 +240,69 @@ impl<'tcx, Prov: Provenance> ImmTy<'tcx, Prov> { let int = self.to_scalar().assert_int(); ConstInt::new(int, self.layout.ty.is_signed(), self.layout.ty.is_ptr_sized_integral()) } + + /// Compute the "sub-immediate" that is located within the `base` at the given offset with the + /// given layout. + pub(super) fn offset( + &self, + offset: Size, + layout: TyAndLayout<'tcx>, + cx: &impl HasDataLayout, + ) -> Self { + // This makes several assumptions about what layouts we will encounter; we match what + // codegen does as good as we can (see `extract_field` in `rustc_codegen_ssa/src/mir/operand.rs`). + let inner_val: Immediate<_> = match (**self, self.layout.abi) { + // if the entire value is uninit, then so is the field (can happen in ConstProp) + (Immediate::Uninit, _) => Immediate::Uninit, + // the field contains no information, can be left uninit + _ if layout.is_zst() => Immediate::Uninit, + // the field covers the entire type + _ if layout.size == self.layout.size => { + assert!(match (self.layout.abi, layout.abi) { + (Abi::Scalar(..), Abi::Scalar(..)) => true, + (Abi::ScalarPair(..), Abi::ScalarPair(..)) => true, + _ => false, + }); + assert!(offset.bytes() == 0); + **self + } + // extract fields from types with `ScalarPair` ABI + (Immediate::ScalarPair(a_val, b_val), Abi::ScalarPair(a, b)) => { + assert!(matches!(layout.abi, Abi::Scalar(..))); + Immediate::from(if offset.bytes() == 0 { + debug_assert_eq!(layout.size, a.size(cx)); + a_val + } else { + debug_assert_eq!(offset, a.size(cx).align_to(b.align(cx).abi)); + debug_assert_eq!(layout.size, b.size(cx)); + b_val + }) + } + // everything else is a bug + _ => bug!("invalid field access on immediate {}, layout {:#?}", self, self.layout), + }; + + ImmTy::from_immediate(inner_val, layout) + } } impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> { - pub fn len(&self, cx: &impl HasDataLayout) -> InterpResult<'tcx, u64> { - if self.layout.is_unsized() { - if matches!(self.op, Operand::Immediate(Immediate::Uninit)) { - // Uninit unsized places shouldn't occur. In the interpreter we have them - // temporarily for unsized arguments before their value is put in; in ConstProp they - // remain uninit and this code can actually be reached. - throw_inval!(UninitUnsizedLocal); + pub(super) fn meta(&self) -> InterpResult<'tcx, MemPlaceMeta<Prov>> { + Ok(if self.layout.is_unsized() { + if matches!(self.op, Operand::Immediate(_)) { + // Unsized immediate OpTy cannot occur. We create a MemPlace for all unsized locals during argument passing. + // However, ConstProp doesn't do that, so we can run into this nonsense situation. + throw_inval!(ConstPropNonsense); } // There are no unsized immediates. - self.assert_mem_place().len(cx) + self.assert_mem_place().meta } else { - match self.layout.fields { - abi::FieldsShape::Array { count, .. } => Ok(count), - _ => bug!("len not supported on sized type {:?}", self.layout.ty), - } - } + MemPlaceMeta::None + }) } - /// Replace the layout of this operand. There's basically no sanity check that this makes sense, - /// you better know what you are doing! If this is an immediate, applying the wrong layout can - /// not just lead to invalid data, it can actually *shift the data around* since the offsets of - /// a ScalarPair are entirely determined by the layout, not the data. - pub fn transmute(&self, layout: TyAndLayout<'tcx>) -> Self { - assert_eq!( - self.layout.size, layout.size, - "transmuting with a size change, that doesn't seem right" - ); - OpTy { layout, ..*self } + pub fn len(&self, cx: &impl HasDataLayout) -> InterpResult<'tcx, u64> { + self.meta()?.len(self.layout, cx) } /// Offset the operand in memory (if possible) and change its metadata. @@ -286,13 +318,9 @@ impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> { match self.as_mplace_or_imm() { Left(mplace) => Ok(mplace.offset_with_meta(offset, meta, layout, cx)?.into()), Right(imm) => { - assert!( - matches!(*imm, Immediate::Uninit), - "Scalar/ScalarPair cannot be offset into" - ); assert!(!meta.has_meta()); // no place to store metadata here // Every part of an uninit is uninit. - Ok(ImmTy::uninit(layout).into()) + Ok(imm.offset(offset, layout, cx).into()) } } } @@ -502,13 +530,24 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { &self, place: &PlaceTy<'tcx, M::Provenance>, ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> { - let op = match **place { - Place::Ptr(mplace) => Operand::Indirect(mplace), - Place::Local { frame, local } => { - *self.local_to_op(&self.stack()[frame], local, None)? + match place.as_mplace_or_local() { + Left(mplace) => Ok(mplace.into()), + Right((frame, local, offset)) => { + let base = self.local_to_op(&self.stack()[frame], local, None)?; + let mut field = if let Some(offset) = offset { + // This got offset. We can be sure that the field is sized. + base.offset(offset, place.layout, self)? + } else { + assert_eq!(place.layout, base.layout); + // Unsized cases are possible here since an unsized local will be a + // `Place::Local` until the first projection calls `place_to_op` to extract the + // underlying mplace. + base + }; + field.align = Some(place.align); + Ok(field) } - }; - Ok(OpTy { op, layout: place.layout, align: Some(place.align) }) + } } /// Evaluate a place with the goal of reading from it. This lets us sometimes |