From 0807ad19ef0b7e1d56b040f79a3192c4229c2224 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Wed, 15 Aug 2018 20:22:28 +0200 Subject: [PATCH] fix union field access and DST computations and dumping of places --- src/librustc_mir/interpret/eval_context.rs | 33 +++++++++++----------- src/librustc_mir/interpret/place.rs | 27 ++++++++++-------- 2 files changed, 33 insertions(+), 27 deletions(-) diff --git a/src/librustc_mir/interpret/eval_context.rs b/src/librustc_mir/interpret/eval_context.rs index 3a1f0db227f..06e015cc4e6 100644 --- a/src/librustc_mir/interpret/eval_context.rs +++ b/src/librustc_mir/interpret/eval_context.rs @@ -465,36 +465,38 @@ pub fn layout_of_local( /// Return the size and alignment of the value at the given type. /// Note that the value does not matter if the type is sized. For unsized types, /// the value has to be a fat pointer, and we only care about the "extra" data in it. - pub fn size_and_align_of_dst( + pub fn size_and_align_of_val( &self, val: ValTy<'tcx>, ) -> EvalResult<'tcx, (Size, Align)> { - if !val.layout.is_unsized() { - Ok(val.layout.size_and_align()) + let pointee_ty = val.layout.ty.builtin_deref(true).unwrap().ty; + let layout = self.layout_of(pointee_ty)?; + if !layout.is_unsized() { + Ok(layout.size_and_align()) } else { - match val.layout.ty.sty { + match layout.ty.sty { ty::TyAdt(..) | ty::TyTuple(..) => { // First get the size of all statically known fields. // Don't use type_of::sizing_type_of because that expects t to be sized, // and it also rounds up to alignment, which we want to avoid, // as the unsized field's alignment could be smaller. - assert!(!val.layout.ty.is_simd()); - debug!("DST layout: {:?}", val.layout); + assert!(!layout.ty.is_simd()); + debug!("DST layout: {:?}", layout); - let sized_size = val.layout.fields.offset(val.layout.fields.count() - 1); - let sized_align = val.layout.align; + let sized_size = layout.fields.offset(layout.fields.count() - 1); + let sized_align = layout.align; debug!( "DST {} statically sized prefix size: {:?} align: {:?}", - val.layout.ty, + layout.ty, sized_size, sized_align ); // Recurse to get the size of the dynamically sized field (must be // the last field). - let field_layout = val.layout.field(self, val.layout.fields.count() - 1)?; + let field_layout = layout.field(self, layout.fields.count() - 1)?; let (unsized_size, unsized_align) = - self.size_and_align_of_dst(ValTy { + self.size_and_align_of_val(ValTy { value: val.value, layout: field_layout })?; @@ -533,12 +535,12 @@ pub fn size_and_align_of_dst( } ty::TySlice(_) | ty::TyStr => { - let (elem_size, align) = val.layout.field(self, 0)?.size_and_align(); + let (elem_size, align) = layout.field(self, 0)?.size_and_align(); let (_, len) = val.to_scalar_slice(self)?; Ok((elem_size * len, align)) } - _ => bug!("size_of_val::<{:?}>", val.layout.ty), + _ => bug!("size_of_val::<{:?}>", layout.ty), } } } @@ -963,10 +965,9 @@ pub fn dump_place(&self, place: Place) { self.memory.dump_allocs(allocs); } Place::Ptr(mplace) => { - let (ptr, align) = mplace.to_scalar_ptr_align(); - match ptr { + match mplace.ptr { Scalar::Ptr(ptr) => { - trace!("by align({}) ref:", align.abi()); + trace!("by align({}) ref:", mplace.align.abi()); self.memory.dump_alloc(ptr.alloc_id); } ptr => trace!(" integral by ref: {:?}", ptr), diff --git a/src/librustc_mir/interpret/place.rs b/src/librustc_mir/interpret/place.rs index c3ae78dbecf..a9b85f318dc 100644 --- a/src/librustc_mir/interpret/place.rs +++ b/src/librustc_mir/interpret/place.rs @@ -7,7 +7,7 @@ use rustc::mir; use rustc::ty::{self, Ty}; -use rustc::ty::layout::{self, Align, LayoutOf, TyLayout, HasDataLayout}; +use rustc::ty::layout::{self, Size, Align, LayoutOf, TyLayout, HasDataLayout}; use rustc_data_structures::indexed_vec::Idx; use rustc::mir::interpret::{ @@ -275,22 +275,27 @@ pub fn mplace_field( assert!(field < len, "Tried to access element {} of array/slice with length {}", field, len); stride * field } - _ => bug!("Unexpected layout for field access: {:#?}", base.layout), + layout::FieldPlacement::Union(count) => { + assert!(field < count as u64, "Tried to access field {} of union with {} fields", field, count); + // Offset is always 0 + Size::from_bytes(0) + } }; // the only way conversion can fail if is this is an array (otherwise we already panicked // above). In that case, all fields are equal. let field = base.layout.field(self, usize::try_from(field).unwrap_or(0))?; // Adjust offset - let offset = match base.extra { - PlaceExtra::Vtable(tab) => { - let (_, align) = self.size_and_align_of_dst(ValTy { - layout: base.layout, - value: Value::new_dyn_trait(base.ptr, tab), - })?; - offset.abi_align(align) - } - _ => offset, + let offset = if field.is_unsized() { + let vtable = match base.extra { + PlaceExtra::Vtable(tab) => tab, + _ => bug!("Unsized place with unsized field must come with vtable"), + }; + let (_, align) = self.read_size_and_align_from_vtable(vtable)?; + offset.abi_align(align) + } else { + // No adjustment needed + offset }; let ptr = base.ptr.ptr_offset(offset, self)?; -- 2.44.0