| // Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| use abi::FnType; |
| use common::*; |
| use rustc::hir; |
| use rustc::ty::{self, Ty, TypeFoldable}; |
| use rustc::ty::layout::{self, Align, LayoutOf, Size, TyLayout}; |
| use rustc_back::PanicStrategy; |
| use trans_item::DefPathBasedNames; |
| use type_::Type; |
| |
| use std::fmt::Write; |
| |
| fn uncached_llvm_type<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>, |
| layout: TyLayout<'tcx>, |
| defer: &mut Option<(Type, TyLayout<'tcx>)>) |
| -> Type { |
| match layout.abi { |
| layout::Abi::Scalar(_) => bug!("handled elsewhere"), |
| layout::Abi::Vector { ref element, count } => { |
| // LLVM has a separate type for 64-bit SIMD vectors on X86 called |
| // `x86_mmx` which is needed for some SIMD operations. As a bit of a |
| // hack (all SIMD definitions are super unstable anyway) we |
| // recognize any one-element SIMD vector as "this should be an |
| // x86_mmx" type. In general there shouldn't be a need for other |
| // one-element SIMD vectors, so it's assumed this won't clash with |
| // much else. |
| let use_x86_mmx = count == 1 && layout.size.bits() == 64 && |
| (cx.sess().target.target.arch == "x86" || |
| cx.sess().target.target.arch == "x86_64"); |
| if use_x86_mmx { |
| return Type::x86_mmx(cx) |
| } else { |
| let element = layout.scalar_llvm_type_at(cx, element, Size::from_bytes(0)); |
| return Type::vector(&element, count); |
| } |
| } |
| layout::Abi::ScalarPair(..) => { |
| return Type::struct_(cx, &[ |
| layout.scalar_pair_element_llvm_type(cx, 0), |
| layout.scalar_pair_element_llvm_type(cx, 1), |
| ], false); |
| } |
| layout::Abi::Uninhabited | |
| layout::Abi::Aggregate { .. } => {} |
| } |
| |
| let name = match layout.ty.sty { |
| ty::TyClosure(..) | |
| ty::TyGenerator(..) | |
| ty::TyAdt(..) | |
| ty::TyDynamic(..) | |
| ty::TyForeign(..) | |
| ty::TyStr => { |
| let mut name = String::with_capacity(32); |
| let printer = DefPathBasedNames::new(cx.tcx, true, true); |
| printer.push_type_name(layout.ty, &mut name); |
| match (&layout.ty.sty, &layout.variants) { |
| (&ty::TyAdt(def, _), &layout::Variants::Single { index }) => { |
| if def.is_enum() && !def.variants.is_empty() { |
| write!(&mut name, "::{}", def.variants[index].name).unwrap(); |
| } |
| } |
| _ => {} |
| } |
| Some(name) |
| } |
| _ => None |
| }; |
| |
| match layout.fields { |
| layout::FieldPlacement::Union(_) => { |
| let fill = Type::padding_filler(cx, layout.size, layout.align); |
| let packed = false; |
| match name { |
| None => { |
| Type::struct_(cx, &[fill], packed) |
| } |
| Some(ref name) => { |
| let mut llty = Type::named_struct(cx, name); |
| llty.set_struct_body(&[fill], packed); |
| llty |
| } |
| } |
| } |
| layout::FieldPlacement::Array { count, .. } => { |
| Type::array(&layout.field(cx, 0).llvm_type(cx), count) |
| } |
| layout::FieldPlacement::Arbitrary { .. } => { |
| match name { |
| None => { |
| let (llfields, packed) = struct_llfields(cx, layout); |
| Type::struct_(cx, &llfields, packed) |
| } |
| Some(ref name) => { |
| let llty = Type::named_struct(cx, name); |
| *defer = Some((llty, layout)); |
| llty |
| } |
| } |
| } |
| } |
| } |
| |
| fn struct_llfields<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>, |
| layout: TyLayout<'tcx>) |
| -> (Vec<Type>, bool) { |
| debug!("struct_llfields: {:#?}", layout); |
| let field_count = layout.fields.count(); |
| |
| let mut packed = false; |
| let mut offset = Size::from_bytes(0); |
| let mut prev_align = layout.align; |
| let mut result: Vec<Type> = Vec::with_capacity(1 + field_count * 2); |
| for i in layout.fields.index_by_increasing_offset() { |
| let field = layout.field(cx, i); |
| packed |= layout.align.abi() < field.align.abi(); |
| |
| let target_offset = layout.fields.offset(i as usize); |
| debug!("struct_llfields: {}: {:?} offset: {:?} target_offset: {:?}", |
| i, field, offset, target_offset); |
| assert!(target_offset >= offset); |
| let padding = target_offset - offset; |
| let padding_align = layout.align.min(prev_align).min(field.align); |
| assert_eq!(offset.abi_align(padding_align) + padding, target_offset); |
| result.push(Type::padding_filler(cx, padding, padding_align)); |
| debug!(" padding before: {:?}", padding); |
| |
| result.push(field.llvm_type(cx)); |
| offset = target_offset + field.size; |
| prev_align = field.align; |
| } |
| if !layout.is_unsized() && field_count > 0 { |
| if offset > layout.size { |
| bug!("layout: {:#?} stride: {:?} offset: {:?}", |
| layout, layout.size, offset); |
| } |
| let padding = layout.size - offset; |
| let padding_align = layout.align.min(prev_align); |
| assert_eq!(offset.abi_align(padding_align) + padding, layout.size); |
| debug!("struct_llfields: pad_bytes: {:?} offset: {:?} stride: {:?}", |
| padding, offset, layout.size); |
| result.push(Type::padding_filler(cx, padding, padding_align)); |
| assert!(result.len() == 1 + field_count * 2); |
| } else { |
| debug!("struct_llfields: offset: {:?} stride: {:?}", |
| offset, layout.size); |
| } |
| |
| (result, packed) |
| } |
| |
| impl<'a, 'tcx> CodegenCx<'a, 'tcx> { |
| pub fn align_of(&self, ty: Ty<'tcx>) -> Align { |
| self.layout_of(ty).align |
| } |
| |
| pub fn size_of(&self, ty: Ty<'tcx>) -> Size { |
| self.layout_of(ty).size |
| } |
| |
| pub fn size_and_align_of(&self, ty: Ty<'tcx>) -> (Size, Align) { |
| self.layout_of(ty).size_and_align() |
| } |
| } |
| |
| #[derive(Copy, Clone, PartialEq, Eq)] |
| pub enum PointerKind { |
| /// Most general case, we know no restrictions to tell LLVM. |
| Shared, |
| |
| /// `&T` where `T` contains no `UnsafeCell`, is `noalias` and `readonly`. |
| Frozen, |
| |
| /// `&mut T`, when we know `noalias` is safe for LLVM. |
| UniqueBorrowed, |
| |
| /// `Box<T>`, unlike `UniqueBorrowed`, it also has `noalias` on returns. |
| UniqueOwned |
| } |
| |
| #[derive(Copy, Clone)] |
| pub struct PointeeInfo { |
| pub size: Size, |
| pub align: Align, |
| pub safe: Option<PointerKind>, |
| } |
| |
| pub trait LayoutLlvmExt<'tcx> { |
| fn is_llvm_immediate(&self) -> bool; |
| fn is_llvm_scalar_pair<'a>(&self) -> bool; |
| fn llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> Type; |
| fn immediate_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> Type; |
| fn scalar_llvm_type_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, |
| scalar: &layout::Scalar, offset: Size) -> Type; |
| fn scalar_pair_element_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>, |
| index: usize) -> Type; |
| fn llvm_field_index(&self, index: usize) -> u64; |
| fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size) |
| -> Option<PointeeInfo>; |
| } |
| |
| impl<'tcx> LayoutLlvmExt<'tcx> for TyLayout<'tcx> { |
| fn is_llvm_immediate(&self) -> bool { |
| match self.abi { |
| layout::Abi::Uninhabited | |
| layout::Abi::Scalar(_) | |
| layout::Abi::Vector { .. } => true, |
| layout::Abi::ScalarPair(..) => false, |
| layout::Abi::Aggregate { .. } => self.is_zst() |
| } |
| } |
| |
| fn is_llvm_scalar_pair<'a>(&self) -> bool { |
| match self.abi { |
| layout::Abi::ScalarPair(..) => true, |
| layout::Abi::Uninhabited | |
| layout::Abi::Scalar(_) | |
| layout::Abi::Vector { .. } | |
| layout::Abi::Aggregate { .. } => false |
| } |
| } |
| |
| /// Get the LLVM type corresponding to a Rust type, i.e. `rustc::ty::Ty`. |
| /// The pointee type of the pointer in `PlaceRef` is always this type. |
| /// For sized types, it is also the right LLVM type for an `alloca` |
| /// containing a value of that type, and most immediates (except `bool`). |
| /// Unsized types, however, are represented by a "minimal unit", e.g. |
| /// `[T]` becomes `T`, while `str` and `Trait` turn into `i8` - this |
| /// is useful for indexing slices, as `&[T]`'s data pointer is `T*`. |
| /// If the type is an unsized struct, the regular layout is generated, |
| /// with the inner-most trailing unsized field using the "minimal unit" |
| /// of that field's type - this is useful for taking the address of |
| /// that field and ensuring the struct has the right alignment. |
| fn llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> Type { |
| if let layout::Abi::Scalar(ref scalar) = self.abi { |
| // Use a different cache for scalars because pointers to DSTs |
| // can be either fat or thin (data pointers of fat pointers). |
| if let Some(&llty) = cx.scalar_lltypes.borrow().get(&self.ty) { |
| return llty; |
| } |
| let llty = match self.ty.sty { |
| ty::TyRef(_, ty::TypeAndMut { ty, .. }) | |
| ty::TyRawPtr(ty::TypeAndMut { ty, .. }) => { |
| cx.layout_of(ty).llvm_type(cx).ptr_to() |
| } |
| ty::TyAdt(def, _) if def.is_box() => { |
| cx.layout_of(self.ty.boxed_ty()).llvm_type(cx).ptr_to() |
| } |
| ty::TyFnPtr(sig) => { |
| let sig = cx.tcx.erase_late_bound_regions_and_normalize(&sig); |
| FnType::new(cx, sig, &[]).llvm_type(cx).ptr_to() |
| } |
| _ => self.scalar_llvm_type_at(cx, scalar, Size::from_bytes(0)) |
| }; |
| cx.scalar_lltypes.borrow_mut().insert(self.ty, llty); |
| return llty; |
| } |
| |
| |
| // Check the cache. |
| let variant_index = match self.variants { |
| layout::Variants::Single { index } => Some(index), |
| _ => None |
| }; |
| if let Some(&llty) = cx.lltypes.borrow().get(&(self.ty, variant_index)) { |
| return llty; |
| } |
| |
| debug!("llvm_type({:#?})", self); |
| |
| assert!(!self.ty.has_escaping_regions(), "{:?} has escaping regions", self.ty); |
| |
| // Make sure lifetimes are erased, to avoid generating distinct LLVM |
| // types for Rust types that only differ in the choice of lifetimes. |
| let normal_ty = cx.tcx.erase_regions(&self.ty); |
| |
| let mut defer = None; |
| let llty = if self.ty != normal_ty { |
| let mut layout = cx.layout_of(normal_ty); |
| if let Some(v) = variant_index { |
| layout = layout.for_variant(cx, v); |
| } |
| layout.llvm_type(cx) |
| } else { |
| uncached_llvm_type(cx, *self, &mut defer) |
| }; |
| debug!("--> mapped {:#?} to llty={:?}", self, llty); |
| |
| cx.lltypes.borrow_mut().insert((self.ty, variant_index), llty); |
| |
| if let Some((mut llty, layout)) = defer { |
| let (llfields, packed) = struct_llfields(cx, layout); |
| llty.set_struct_body(&llfields, packed) |
| } |
| |
| llty |
| } |
| |
| fn immediate_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> Type { |
| if let layout::Abi::Scalar(ref scalar) = self.abi { |
| if scalar.is_bool() { |
| return Type::i1(cx); |
| } |
| } |
| self.llvm_type(cx) |
| } |
| |
| fn scalar_llvm_type_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, |
| scalar: &layout::Scalar, offset: Size) -> Type { |
| match scalar.value { |
| layout::Int(i, _) => Type::from_integer(cx, i), |
| layout::F32 => Type::f32(cx), |
| layout::F64 => Type::f64(cx), |
| layout::Pointer => { |
| // If we know the alignment, pick something better than i8. |
| let pointee = if let Some(pointee) = self.pointee_info_at(cx, offset) { |
| Type::pointee_for_abi_align(cx, pointee.align) |
| } else { |
| Type::i8(cx) |
| }; |
| pointee.ptr_to() |
| } |
| } |
| } |
| |
| fn scalar_pair_element_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>, |
| index: usize) -> Type { |
| // HACK(eddyb) special-case fat pointers until LLVM removes |
| // pointee types, to avoid bitcasting every `OperandRef::deref`. |
| match self.ty.sty { |
| ty::TyRef(..) | |
| ty::TyRawPtr(_) => { |
| return self.field(cx, index).llvm_type(cx); |
| } |
| ty::TyAdt(def, _) if def.is_box() => { |
| let ptr_ty = cx.tcx.mk_mut_ptr(self.ty.boxed_ty()); |
| return cx.layout_of(ptr_ty).scalar_pair_element_llvm_type(cx, index); |
| } |
| _ => {} |
| } |
| |
| let (a, b) = match self.abi { |
| layout::Abi::ScalarPair(ref a, ref b) => (a, b), |
| _ => bug!("TyLayout::scalar_pair_element_llty({:?}): not applicable", self) |
| }; |
| let scalar = [a, b][index]; |
| |
| // Make sure to return the same type `immediate_llvm_type` would, |
| // to avoid dealing with two types and the associated conversions. |
| // This means that `(bool, bool)` is represented as `{i1, i1}`, |
| // both in memory and as an immediate, while `bool` is typically |
| // `i8` in memory and only `i1` when immediate. While we need to |
| // load/store `bool` as `i8` to avoid crippling LLVM optimizations, |
| // `i1` in a LLVM aggregate is valid and mostly equivalent to `i8`. |
| if scalar.is_bool() { |
| return Type::i1(cx); |
| } |
| |
| let offset = if index == 0 { |
| Size::from_bytes(0) |
| } else { |
| a.value.size(cx).abi_align(b.value.align(cx)) |
| }; |
| self.scalar_llvm_type_at(cx, scalar, offset) |
| } |
| |
| fn llvm_field_index(&self, index: usize) -> u64 { |
| match self.abi { |
| layout::Abi::Scalar(_) | |
| layout::Abi::ScalarPair(..) => { |
| bug!("TyLayout::llvm_field_index({:?}): not applicable", self) |
| } |
| _ => {} |
| } |
| match self.fields { |
| layout::FieldPlacement::Union(_) => { |
| bug!("TyLayout::llvm_field_index({:?}): not applicable", self) |
| } |
| |
| layout::FieldPlacement::Array { .. } => { |
| index as u64 |
| } |
| |
| layout::FieldPlacement::Arbitrary { .. } => { |
| 1 + (self.fields.memory_index(index) as u64) * 2 |
| } |
| } |
| } |
| |
| fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size) |
| -> Option<PointeeInfo> { |
| if let Some(&pointee) = cx.pointee_infos.borrow().get(&(self.ty, offset)) { |
| return pointee; |
| } |
| |
| let mut result = None; |
| match self.ty.sty { |
| ty::TyRawPtr(mt) if offset.bytes() == 0 => { |
| let (size, align) = cx.size_and_align_of(mt.ty); |
| result = Some(PointeeInfo { |
| size, |
| align, |
| safe: None |
| }); |
| } |
| |
| ty::TyRef(_, mt) if offset.bytes() == 0 => { |
| let (size, align) = cx.size_and_align_of(mt.ty); |
| |
| let kind = match mt.mutbl { |
| hir::MutImmutable => if cx.type_is_freeze(mt.ty) { |
| PointerKind::Frozen |
| } else { |
| PointerKind::Shared |
| }, |
| hir::MutMutable => { |
| if cx.tcx.sess.opts.debugging_opts.mutable_noalias || |
| cx.tcx.sess.panic_strategy() == PanicStrategy::Abort { |
| PointerKind::UniqueBorrowed |
| } else { |
| PointerKind::Shared |
| } |
| } |
| }; |
| |
| result = Some(PointeeInfo { |
| size, |
| align, |
| safe: Some(kind) |
| }); |
| } |
| |
| _ => { |
| let mut data_variant = match self.variants { |
| layout::Variants::NicheFilling { dataful_variant, .. } => { |
| // Only the niche itself is always initialized, |
| // so only check for a pointer at its offset. |
| // |
| // If the niche is a pointer, it's either valid |
| // (according to its type), or null (which the |
| // niche field's scalar validity range encodes). |
| // This allows using `dereferenceable_or_null` |
| // for e.g. `Option<&T>`, and this will continue |
| // to work as long as we don't start using more |
| // niches than just null (e.g. the first page |
| // of the address space, or unaligned pointers). |
| if self.fields.offset(0) == offset { |
| Some(self.for_variant(cx, dataful_variant)) |
| } else { |
| None |
| } |
| } |
| _ => Some(*self) |
| }; |
| |
| if let Some(variant) = data_variant { |
| // We're not interested in any unions. |
| if let layout::FieldPlacement::Union(_) = variant.fields { |
| data_variant = None; |
| } |
| } |
| |
| if let Some(variant) = data_variant { |
| let ptr_end = offset + layout::Pointer.size(cx); |
| for i in 0..variant.fields.count() { |
| let field_start = variant.fields.offset(i); |
| if field_start <= offset { |
| let field = variant.field(cx, i); |
| if ptr_end <= field_start + field.size { |
| // We found the right field, look inside it. |
| result = field.pointee_info_at(cx, offset - field_start); |
| break; |
| } |
| } |
| } |
| } |
| |
| // FIXME(eddyb) This should be for `ptr::Unique<T>`, not `Box<T>`. |
| if let Some(ref mut pointee) = result { |
| if let ty::TyAdt(def, _) = self.ty.sty { |
| if def.is_box() && offset.bytes() == 0 { |
| pointee.safe = Some(PointerKind::UniqueOwned); |
| } |
| } |
| } |
| } |
| } |
| |
| cx.pointee_infos.borrow_mut().insert((self.ty, offset), result); |
| result |
| } |
| } |