2 use crate::context::TypeLowering;
3 use crate::type_::Type;
4 use rustc_codegen_ssa::traits::*;
6 use rustc_middle::ty::layout::{FnAbiOf, LayoutOf, TyAndLayout};
7 use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_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::{PointeeInfo, Scalar, Size, TyAbiInterface, Variants};
12 use smallvec::{smallvec, SmallVec};
17 fn uncached_llvm_type<'a, 'tcx>(
18 cx: &CodegenCx<'a, 'tcx>,
19 layout: TyAndLayout<'tcx>,
20 defer: &mut Option<(&'a Type, TyAndLayout<'tcx>)>,
21 field_remapping: &mut Option<SmallVec<[u32; 4]>>,
24 Abi::Scalar(_) => bug!("handled elsewhere"),
25 Abi::Vector { element, count } => {
26 let element = layout.scalar_llvm_type_at(cx, element, Size::ZERO);
27 return cx.type_vector(element, count);
29 Abi::ScalarPair(..) => {
30 return cx.type_struct(
32 layout.scalar_pair_element_llvm_type(cx, 0, false),
33 layout.scalar_pair_element_llvm_type(cx, 1, false),
38 Abi::Uninhabited | Abi::Aggregate { .. } => {}
41 let name = match layout.ty.kind() {
42 // FIXME(eddyb) producing readable type names for trait objects can result
43 // in problematically distinct types due to HRTB and subtyping (see #47638).
45 ty::Adt(..) | ty::Closure(..) | ty::Foreign(..) | ty::Generator(..) | ty::Str => {
46 let mut name = with_no_visible_paths!(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].name).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();
65 FieldsShape::Primitive | FieldsShape::Union(_) => {
66 let fill = cx.type_padding_filler(layout.size, layout.align.abi);
69 None => cx.type_struct(&[fill], packed),
71 let llty = cx.type_named_struct(name);
72 cx.set_struct_body(llty, &[fill], packed);
77 FieldsShape::Array { count, .. } => cx.type_array(layout.field(cx, 0).llvm_type(cx), count),
78 FieldsShape::Arbitrary { .. } => match name {
80 let (llfields, packed, new_field_remapping) = struct_llfields(cx, layout);
81 *field_remapping = new_field_remapping;
82 cx.type_struct(&llfields, packed)
85 let llty = cx.type_named_struct(name);
86 *defer = Some((llty, layout));
93 fn struct_llfields<'a, 'tcx>(
94 cx: &CodegenCx<'a, 'tcx>,
95 layout: TyAndLayout<'tcx>,
96 ) -> (Vec<&'a Type>, bool, Option<SmallVec<[u32; 4]>>) {
97 debug!("struct_llfields: {:#?}", layout);
98 let field_count = layout.fields.count();
100 let mut packed = false;
101 let mut offset = Size::ZERO;
102 let mut prev_effective_align = layout.align.abi;
103 let mut result: Vec<_> = Vec::with_capacity(1 + field_count * 2);
104 let mut field_remapping = smallvec![0; field_count];
105 for i in layout.fields.index_by_increasing_offset() {
106 let target_offset = layout.fields.offset(i as usize);
107 let field = layout.field(cx, i);
108 let effective_field_align =
109 layout.align.abi.min(field.align.abi).restrict_for_offset(target_offset);
110 packed |= effective_field_align < field.align.abi;
113 "struct_llfields: {}: {:?} offset: {:?} target_offset: {:?} \
114 effective_field_align: {}",
119 effective_field_align.bytes()
121 assert!(target_offset >= offset);
122 let padding = target_offset - offset;
123 if padding != Size::ZERO {
124 let padding_align = prev_effective_align.min(effective_field_align);
125 assert_eq!(offset.align_to(padding_align) + padding, target_offset);
126 result.push(cx.type_padding_filler(padding, padding_align));
127 debug!(" padding before: {:?}", padding);
129 field_remapping[i] = result.len() as u32;
130 result.push(field.llvm_type(cx));
131 offset = target_offset + field.size;
132 prev_effective_align = effective_field_align;
134 let padding_used = result.len() > field_count;
135 if !layout.is_unsized() && field_count > 0 {
136 if offset > layout.size {
137 bug!("layout: {:#?} stride: {:?} offset: {:?}", layout, layout.size, offset);
139 let padding = layout.size - offset;
140 if padding != Size::ZERO {
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));
150 debug!("struct_llfields: offset: {:?} stride: {:?}", offset, layout.size);
152 let field_remapping = if padding_used { Some(field_remapping) } else { None };
153 (result, packed, field_remapping)
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<'a>(&self, cx: &CodegenCx<'a, 'tcx>, 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(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))
234 cx.fn_ptr_backend_type(cx.fn_abi_of_fn_ptr(sig, ty::List::empty()))
236 _ => self.scalar_llvm_type_at(cx, scalar, Size::ZERO),
238 cx.scalar_lltypes.borrow_mut().insert(self.ty, llty);
243 let variant_index = match self.variants {
244 Variants::Single { index } => Some(index),
247 if let Some(llty) = cx.type_lowering.borrow().get(&(self.ty, variant_index)) {
251 debug!("llvm_type({:#?})", self);
253 assert!(!self.ty.has_escaping_bound_vars(), "{:?} has escaping bound vars", self.ty);
255 // Make sure lifetimes are erased, to avoid generating distinct LLVM
256 // types for Rust types that only differ in the choice of lifetimes.
257 let normal_ty = cx.tcx.erase_regions(self.ty);
259 let mut defer = None;
260 let mut field_remapping = None;
261 let llty = if self.ty != normal_ty {
262 let mut layout = cx.layout_of(normal_ty);
263 if let Some(v) = variant_index {
264 layout = layout.for_variant(cx, v);
268 uncached_llvm_type(cx, *self, &mut defer, &mut field_remapping)
270 debug!("--> mapped {:#?} to llty={:?}", self, llty);
274 .insert((self.ty, variant_index), TypeLowering { lltype: llty, field_remapping });
276 if let Some((llty, layout)) = defer {
277 let (llfields, packed, new_field_remapping) = struct_llfields(cx, layout);
278 cx.set_struct_body(llty, &llfields, packed);
281 .get_mut(&(self.ty, variant_index))
283 .field_remapping = new_field_remapping;
288 fn immediate_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type {
289 if let Abi::Scalar(scalar) = self.abi {
290 if scalar.is_bool() {
297 fn scalar_llvm_type_at<'a>(
299 cx: &CodegenCx<'a, 'tcx>,
304 Int(i, _) => cx.type_from_integer(i),
305 F32 => cx.type_f32(),
306 F64 => cx.type_f64(),
308 // If we know the alignment, pick something better than i8.
309 let (pointee, address_space) =
310 if let Some(pointee) = self.pointee_info_at(cx, offset) {
311 (cx.type_pointee_for_align(pointee.align), pointee.address_space)
313 (cx.type_i8(), AddressSpace::DATA)
315 cx.type_ptr_to_ext(pointee, address_space)
320 fn scalar_pair_element_llvm_type<'a>(
322 cx: &CodegenCx<'a, 'tcx>,
326 // HACK(eddyb) special-case fat pointers until LLVM removes
327 // pointee types, to avoid bitcasting every `OperandRef::deref`.
328 match self.ty.kind() {
329 ty::Ref(..) | ty::RawPtr(_) => {
330 return self.field(cx, index).llvm_type(cx);
332 // only wide pointer boxes are handled as pointers
333 // thin pointer boxes with scalar allocators are handled by the general logic below
334 ty::Adt(def, substs) if def.is_box() && cx.layout_of(substs.type_at(1)).is_zst() => {
335 let ptr_ty = cx.tcx.mk_mut_ptr(self.ty.boxed_ty());
336 return cx.layout_of(ptr_ty).scalar_pair_element_llvm_type(cx, index, immediate);
341 let Abi::ScalarPair(a, b) = self.abi else {
342 bug!("TyAndLayout::scalar_pair_element_llty({:?}): not applicable", self);
344 let scalar = [a, b][index];
346 // Make sure to return the same type `immediate_llvm_type` would when
347 // dealing with an immediate pair. This means that `(bool, bool)` is
348 // effectively represented as `{i8, i8}` in memory and two `i1`s as an
349 // immediate, just like `bool` is typically `i8` in memory and only `i1`
350 // when immediate. We need to load/store `bool` as `i8` to avoid
351 // crippling LLVM optimizations or triggering other LLVM bugs with `i1`.
352 if immediate && scalar.is_bool() {
357 if index == 0 { Size::ZERO } else { a.value.size(cx).align_to(b.value.align(cx).abi) };
358 self.scalar_llvm_type_at(cx, scalar, offset)
361 fn llvm_field_index<'a>(&self, cx: &CodegenCx<'a, 'tcx>, index: usize) -> u64 {
363 Abi::Scalar(_) | Abi::ScalarPair(..) => {
364 bug!("TyAndLayout::llvm_field_index({:?}): not applicable", self)
369 FieldsShape::Primitive | FieldsShape::Union(_) => {
370 bug!("TyAndLayout::llvm_field_index({:?}): not applicable", self)
373 FieldsShape::Array { .. } => index as u64,
375 FieldsShape::Arbitrary { .. } => {
376 let variant_index = match self.variants {
377 Variants::Single { index } => Some(index),
381 // Look up llvm field if indexes do not match memory order due to padding. If
382 // `field_remapping` is `None` no padding was used and the llvm field index
383 // matches the memory index.
384 match cx.type_lowering.borrow().get(&(self.ty, variant_index)) {
385 Some(TypeLowering { field_remapping: Some(ref remap), .. }) => {
388 Some(_) => self.fields.memory_index(index) as u64,
390 bug!("TyAndLayout::llvm_field_index({:?}): type info not found", self)
397 // FIXME(eddyb) this having the same name as `TyAndLayout::pointee_info_at`
398 // (the inherent method, which is lacking this caching logic) can result in
399 // the uncached version being called - not wrong, but potentially inefficient.
400 fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size) -> Option<PointeeInfo> {
401 if let Some(&pointee) = cx.pointee_infos.borrow().get(&(self.ty, offset)) {
405 let result = Ty::ty_and_layout_pointee_info_at(*self, cx, offset);
407 cx.pointee_infos.borrow_mut().insert((self.ty, offset), result);