3 use crate::type_::Type;
4 use rustc_codegen_ssa::traits::*;
6 use rustc_middle::ty::layout::{FnAbiExt, TyAndLayout};
7 use rustc_middle::ty::print::with_no_trimmed_paths;
8 use rustc_middle::ty::{self, Ty, TypeFoldable};
9 use rustc_target::abi::{Abi, AddressSpace, Align, FieldsShape};
10 use rustc_target::abi::{Int, Pointer, F32, F64};
11 use rustc_target::abi::{LayoutOf, PointeeInfo, Scalar, Size, TyAndLayoutMethods, Variants};
16 fn uncached_llvm_type<'a, 'tcx>(
17 cx: &CodegenCx<'a, 'tcx>,
18 layout: TyAndLayout<'tcx>,
19 defer: &mut Option<(&'a Type, TyAndLayout<'tcx>)>,
22 Abi::Scalar(_) => bug!("handled elsewhere"),
23 Abi::Vector { ref element, count } => {
24 let element = layout.scalar_llvm_type_at(cx, element, Size::ZERO);
25 return cx.type_vector(element, count);
27 Abi::ScalarPair(..) => {
28 return cx.type_struct(
30 layout.scalar_pair_element_llvm_type(cx, 0, false),
31 layout.scalar_pair_element_llvm_type(cx, 1, false),
36 Abi::Uninhabited | Abi::Aggregate { .. } => {}
39 let name = match layout.ty.kind() {
40 // FIXME(eddyb) producing readable type names for trait objects can result
41 // in problematically distinct types due to HRTB and subtyping (see #47638).
43 ty::Adt(..) | ty::Closure(..) | ty::Foreign(..) | ty::Generator(..) | ty::Str
44 if !cx.sess().fewer_names() =>
46 let mut name = with_no_trimmed_paths(|| layout.ty.to_string());
47 if let (&ty::Adt(def, _), &Variants::Single { index }) =
48 (layout.ty.kind(), &layout.variants)
50 if def.is_enum() && !def.variants.is_empty() {
51 write!(&mut name, "::{}", def.variants[index].ident).unwrap();
54 if let (&ty::Generator(_, _, _), &Variants::Single { index }) =
55 (layout.ty.kind(), &layout.variants)
57 write!(&mut name, "::{}", ty::GeneratorSubsts::variant_name(index)).unwrap();
62 // If `Some` is returned then a named struct is created in LLVM. Name collisions are
63 // avoided by LLVM (with increasing suffixes). If rustc doesn't generate names then that
71 FieldsShape::Primitive | FieldsShape::Union(_) => {
72 let fill = cx.type_padding_filler(layout.size, layout.align.abi);
75 None => cx.type_struct(&[fill], packed),
77 let llty = cx.type_named_struct(name);
78 cx.set_struct_body(llty, &[fill], packed);
83 FieldsShape::Array { count, .. } => cx.type_array(layout.field(cx, 0).llvm_type(cx), count),
84 FieldsShape::Arbitrary { .. } => match name {
86 let (llfields, packed) = struct_llfields(cx, layout);
87 cx.type_struct(&llfields, packed)
90 let llty = cx.type_named_struct(name);
91 *defer = Some((llty, layout));
98 fn struct_llfields<'a, 'tcx>(
99 cx: &CodegenCx<'a, 'tcx>,
100 layout: TyAndLayout<'tcx>,
101 ) -> (Vec<&'a Type>, bool) {
102 debug!("struct_llfields: {:#?}", layout);
103 let field_count = layout.fields.count();
105 let mut packed = false;
106 let mut offset = Size::ZERO;
107 let mut prev_effective_align = layout.align.abi;
108 let mut result: Vec<_> = Vec::with_capacity(1 + field_count * 2);
109 for i in layout.fields.index_by_increasing_offset() {
110 let target_offset = layout.fields.offset(i as usize);
111 let field = layout.field(cx, i);
112 let effective_field_align =
113 layout.align.abi.min(field.align.abi).restrict_for_offset(target_offset);
114 packed |= effective_field_align < field.align.abi;
117 "struct_llfields: {}: {:?} offset: {:?} target_offset: {:?} \
118 effective_field_align: {}",
123 effective_field_align.bytes()
125 assert!(target_offset >= offset);
126 let padding = target_offset - offset;
127 let padding_align = prev_effective_align.min(effective_field_align);
128 assert_eq!(offset.align_to(padding_align) + padding, target_offset);
129 result.push(cx.type_padding_filler(padding, padding_align));
130 debug!(" padding before: {:?}", padding);
132 result.push(field.llvm_type(cx));
133 offset = target_offset + field.size;
134 prev_effective_align = effective_field_align;
136 if !layout.is_unsized() && field_count > 0 {
137 if offset > layout.size {
138 bug!("layout: {:#?} stride: {:?} offset: {:?}", layout, layout.size, offset);
140 let padding = layout.size - offset;
141 let padding_align = prev_effective_align;
142 assert_eq!(offset.align_to(padding_align) + padding, layout.size);
144 "struct_llfields: pad_bytes: {:?} offset: {:?} stride: {:?}",
145 padding, offset, layout.size
147 result.push(cx.type_padding_filler(padding, padding_align));
148 assert_eq!(result.len(), 1 + field_count * 2);
150 debug!("struct_llfields: offset: {:?} stride: {:?}", offset, layout.size);
156 impl<'a, 'tcx> CodegenCx<'a, 'tcx> {
157 pub fn align_of(&self, ty: Ty<'tcx>) -> Align {
158 self.layout_of(ty).align.abi
161 pub fn size_of(&self, ty: Ty<'tcx>) -> Size {
162 self.layout_of(ty).size
165 pub fn size_and_align_of(&self, ty: Ty<'tcx>) -> (Size, Align) {
166 let layout = self.layout_of(ty);
167 (layout.size, layout.align.abi)
171 pub trait LayoutLlvmExt<'tcx> {
172 fn is_llvm_immediate(&self) -> bool;
173 fn is_llvm_scalar_pair(&self) -> bool;
174 fn llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type;
175 fn immediate_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type;
176 fn scalar_llvm_type_at<'a>(
178 cx: &CodegenCx<'a, 'tcx>,
182 fn scalar_pair_element_llvm_type<'a>(
184 cx: &CodegenCx<'a, 'tcx>,
188 fn llvm_field_index(&self, index: usize) -> u64;
189 fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size) -> Option<PointeeInfo>;
192 impl<'tcx> LayoutLlvmExt<'tcx> for TyAndLayout<'tcx> {
193 fn is_llvm_immediate(&self) -> bool {
195 Abi::Scalar(_) | Abi::Vector { .. } => true,
196 Abi::ScalarPair(..) => false,
197 Abi::Uninhabited | Abi::Aggregate { .. } => self.is_zst(),
201 fn is_llvm_scalar_pair(&self) -> bool {
203 Abi::ScalarPair(..) => true,
204 Abi::Uninhabited | Abi::Scalar(_) | Abi::Vector { .. } | Abi::Aggregate { .. } => false,
208 /// Gets the LLVM type corresponding to a Rust type, i.e., `rustc_middle::ty::Ty`.
209 /// The pointee type of the pointer in `PlaceRef` is always this type.
210 /// For sized types, it is also the right LLVM type for an `alloca`
211 /// containing a value of that type, and most immediates (except `bool`).
212 /// Unsized types, however, are represented by a "minimal unit", e.g.
213 /// `[T]` becomes `T`, while `str` and `Trait` turn into `i8` - this
214 /// is useful for indexing slices, as `&[T]`'s data pointer is `T*`.
215 /// If the type is an unsized struct, the regular layout is generated,
216 /// with the inner-most trailing unsized field using the "minimal unit"
217 /// of that field's type - this is useful for taking the address of
218 /// that field and ensuring the struct has the right alignment.
219 fn llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type {
220 if let Abi::Scalar(ref scalar) = self.abi {
221 // Use a different cache for scalars because pointers to DSTs
222 // can be either fat or thin (data pointers of fat pointers).
223 if let Some(&llty) = cx.scalar_lltypes.borrow().get(&self.ty) {
226 let llty = match *self.ty.kind() {
227 ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
228 cx.type_ptr_to(cx.layout_of(ty).llvm_type(cx))
230 ty::Adt(def, _) if def.is_box() => {
231 cx.type_ptr_to(cx.layout_of(self.ty.boxed_ty()).llvm_type(cx))
233 ty::FnPtr(sig) => cx.fn_ptr_backend_type(&FnAbi::of_fn_ptr(cx, sig, &[])),
234 _ => self.scalar_llvm_type_at(cx, scalar, Size::ZERO),
236 cx.scalar_lltypes.borrow_mut().insert(self.ty, llty);
241 let variant_index = match self.variants {
242 Variants::Single { index } => Some(index),
245 if let Some(&llty) = cx.lltypes.borrow().get(&(self.ty, variant_index)) {
249 debug!("llvm_type({:#?})", self);
251 assert!(!self.ty.has_escaping_bound_vars(), "{:?} has escaping bound vars", self.ty);
253 // Make sure lifetimes are erased, to avoid generating distinct LLVM
254 // types for Rust types that only differ in the choice of lifetimes.
255 let normal_ty = cx.tcx.erase_regions(self.ty);
257 let mut defer = None;
258 let llty = if self.ty != normal_ty {
259 let mut layout = cx.layout_of(normal_ty);
260 if let Some(v) = variant_index {
261 layout = layout.for_variant(cx, v);
265 uncached_llvm_type(cx, *self, &mut defer)
267 debug!("--> mapped {:#?} to llty={:?}", self, llty);
269 cx.lltypes.borrow_mut().insert((self.ty, variant_index), llty);
271 if let Some((llty, layout)) = defer {
272 let (llfields, packed) = struct_llfields(cx, layout);
273 cx.set_struct_body(llty, &llfields, packed)
279 fn immediate_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type {
280 if let Abi::Scalar(ref scalar) = self.abi {
281 if scalar.is_bool() {
288 fn scalar_llvm_type_at<'a>(
290 cx: &CodegenCx<'a, 'tcx>,
295 Int(i, _) => cx.type_from_integer(i),
296 F32 => cx.type_f32(),
297 F64 => cx.type_f64(),
299 // If we know the alignment, pick something better than i8.
300 let (pointee, address_space) =
301 if let Some(pointee) = self.pointee_info_at(cx, offset) {
302 (cx.type_pointee_for_align(pointee.align), pointee.address_space)
304 (cx.type_i8(), AddressSpace::DATA)
306 cx.type_ptr_to_ext(pointee, address_space)
311 fn scalar_pair_element_llvm_type<'a>(
313 cx: &CodegenCx<'a, 'tcx>,
317 // HACK(eddyb) special-case fat pointers until LLVM removes
318 // pointee types, to avoid bitcasting every `OperandRef::deref`.
319 match self.ty.kind() {
320 ty::Ref(..) | ty::RawPtr(_) => {
321 return self.field(cx, index).llvm_type(cx);
323 ty::Adt(def, _) if def.is_box() => {
324 let ptr_ty = cx.tcx.mk_mut_ptr(self.ty.boxed_ty());
325 return cx.layout_of(ptr_ty).scalar_pair_element_llvm_type(cx, index, immediate);
330 let (a, b) = match self.abi {
331 Abi::ScalarPair(ref a, ref b) => (a, b),
332 _ => bug!("TyAndLayout::scalar_pair_element_llty({:?}): not applicable", self),
334 let scalar = [a, b][index];
336 // Make sure to return the same type `immediate_llvm_type` would when
337 // dealing with an immediate pair. This means that `(bool, bool)` is
338 // effectively represented as `{i8, i8}` in memory and two `i1`s as an
339 // immediate, just like `bool` is typically `i8` in memory and only `i1`
340 // when immediate. We need to load/store `bool` as `i8` to avoid
341 // crippling LLVM optimizations or triggering other LLVM bugs with `i1`.
342 if immediate && scalar.is_bool() {
347 if index == 0 { Size::ZERO } else { a.value.size(cx).align_to(b.value.align(cx).abi) };
348 self.scalar_llvm_type_at(cx, scalar, offset)
351 fn llvm_field_index(&self, index: usize) -> u64 {
353 Abi::Scalar(_) | Abi::ScalarPair(..) => {
354 bug!("TyAndLayout::llvm_field_index({:?}): not applicable", self)
359 FieldsShape::Primitive | FieldsShape::Union(_) => {
360 bug!("TyAndLayout::llvm_field_index({:?}): not applicable", self)
363 FieldsShape::Array { .. } => index as u64,
365 FieldsShape::Arbitrary { .. } => 1 + (self.fields.memory_index(index) as u64) * 2,
369 fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size) -> Option<PointeeInfo> {
370 if let Some(&pointee) = cx.pointee_infos.borrow().get(&(self.ty, offset)) {
374 let result = Ty::pointee_info_at(*self, cx, offset);
376 cx.pointee_infos.borrow_mut().insert((self.ty, offset), result);