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 => {
47 with_no_visible_paths(|| with_no_trimmed_paths(|| layout.ty.to_string()));
48 if let (&ty::Adt(def, _), &Variants::Single { index }) =
49 (layout.ty.kind(), &layout.variants)
51 if def.is_enum() && !def.variants.is_empty() {
52 write!(&mut name, "::{}", def.variants[index].ident).unwrap();
55 if let (&ty::Generator(_, _, _), &Variants::Single { index }) =
56 (layout.ty.kind(), &layout.variants)
58 write!(&mut name, "::{}", ty::GeneratorSubsts::variant_name(index)).unwrap();
66 FieldsShape::Primitive | FieldsShape::Union(_) => {
67 let fill = cx.type_padding_filler(layout.size, layout.align.abi);
70 None => cx.type_struct(&[fill], packed),
72 let llty = cx.type_named_struct(name);
73 cx.set_struct_body(llty, &[fill], packed);
78 FieldsShape::Array { count, .. } => cx.type_array(layout.field(cx, 0).llvm_type(cx), count),
79 FieldsShape::Arbitrary { .. } => match name {
81 let (llfields, packed, new_field_remapping) = struct_llfields(cx, layout);
82 *field_remapping = new_field_remapping;
83 cx.type_struct(&llfields, packed)
86 let llty = cx.type_named_struct(name);
87 *defer = Some((llty, layout));
94 fn struct_llfields<'a, 'tcx>(
95 cx: &CodegenCx<'a, 'tcx>,
96 layout: TyAndLayout<'tcx>,
97 ) -> (Vec<&'a Type>, bool, Option<SmallVec<[u32; 4]>>) {
98 debug!("struct_llfields: {:#?}", layout);
99 let field_count = layout.fields.count();
101 let mut packed = false;
102 let mut offset = Size::ZERO;
103 let mut prev_effective_align = layout.align.abi;
104 let mut result: Vec<_> = Vec::with_capacity(1 + field_count * 2);
105 let mut field_remapping = smallvec![0; field_count];
106 for i in layout.fields.index_by_increasing_offset() {
107 let target_offset = layout.fields.offset(i as usize);
108 let field = layout.field(cx, i);
109 let effective_field_align =
110 layout.align.abi.min(field.align.abi).restrict_for_offset(target_offset);
111 packed |= effective_field_align < field.align.abi;
114 "struct_llfields: {}: {:?} offset: {:?} target_offset: {:?} \
115 effective_field_align: {}",
120 effective_field_align.bytes()
122 assert!(target_offset >= offset);
123 let padding = target_offset - offset;
124 if padding != Size::ZERO {
125 let padding_align = prev_effective_align.min(effective_field_align);
126 assert_eq!(offset.align_to(padding_align) + padding, target_offset);
127 result.push(cx.type_padding_filler(padding, padding_align));
128 debug!(" padding before: {:?}", padding);
130 field_remapping[i] = result.len() as u32;
131 result.push(field.llvm_type(cx));
132 offset = target_offset + field.size;
133 prev_effective_align = effective_field_align;
135 let padding_used = result.len() > field_count;
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 if padding != Size::ZERO {
142 let padding_align = prev_effective_align;
143 assert_eq!(offset.align_to(padding_align) + padding, layout.size);
145 "struct_llfields: pad_bytes: {:?} offset: {:?} stride: {:?}",
146 padding, offset, layout.size
148 result.push(cx.type_padding_filler(padding, padding_align));
151 debug!("struct_llfields: offset: {:?} stride: {:?}", offset, layout.size);
153 let field_remapping = if padding_used { Some(field_remapping) } else { None };
154 (result, packed, field_remapping)
157 impl<'a, 'tcx> CodegenCx<'a, 'tcx> {
158 pub fn align_of(&self, ty: Ty<'tcx>) -> Align {
159 self.layout_of(ty).align.abi
162 pub fn size_of(&self, ty: Ty<'tcx>) -> Size {
163 self.layout_of(ty).size
166 pub fn size_and_align_of(&self, ty: Ty<'tcx>) -> (Size, Align) {
167 let layout = self.layout_of(ty);
168 (layout.size, layout.align.abi)
172 pub trait LayoutLlvmExt<'tcx> {
173 fn is_llvm_immediate(&self) -> bool;
174 fn is_llvm_scalar_pair(&self) -> bool;
175 fn llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type;
176 fn immediate_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type;
177 fn scalar_llvm_type_at<'a>(
179 cx: &CodegenCx<'a, 'tcx>,
183 fn scalar_pair_element_llvm_type<'a>(
185 cx: &CodegenCx<'a, 'tcx>,
189 fn llvm_field_index<'a>(&self, cx: &CodegenCx<'a, 'tcx>, index: usize) -> u64;
190 fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size) -> Option<PointeeInfo>;
193 impl<'tcx> LayoutLlvmExt<'tcx> for TyAndLayout<'tcx> {
194 fn is_llvm_immediate(&self) -> bool {
196 Abi::Scalar(_) | Abi::Vector { .. } => true,
197 Abi::ScalarPair(..) => false,
198 Abi::Uninhabited | Abi::Aggregate { .. } => self.is_zst(),
202 fn is_llvm_scalar_pair(&self) -> bool {
204 Abi::ScalarPair(..) => true,
205 Abi::Uninhabited | Abi::Scalar(_) | Abi::Vector { .. } | Abi::Aggregate { .. } => false,
209 /// Gets the LLVM type corresponding to a Rust type, i.e., `rustc_middle::ty::Ty`.
210 /// The pointee type of the pointer in `PlaceRef` is always this type.
211 /// For sized types, it is also the right LLVM type for an `alloca`
212 /// containing a value of that type, and most immediates (except `bool`).
213 /// Unsized types, however, are represented by a "minimal unit", e.g.
214 /// `[T]` becomes `T`, while `str` and `Trait` turn into `i8` - this
215 /// is useful for indexing slices, as `&[T]`'s data pointer is `T*`.
216 /// If the type is an unsized struct, the regular layout is generated,
217 /// with the inner-most trailing unsized field using the "minimal unit"
218 /// of that field's type - this is useful for taking the address of
219 /// that field and ensuring the struct has the right alignment.
220 fn llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type {
221 if let Abi::Scalar(scalar) = self.abi {
222 // Use a different cache for scalars because pointers to DSTs
223 // can be either fat or thin (data pointers of fat pointers).
224 if let Some(&llty) = cx.scalar_lltypes.borrow().get(&self.ty) {
227 let llty = match *self.ty.kind() {
228 ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
229 cx.type_ptr_to(cx.layout_of(ty).llvm_type(cx))
231 ty::Adt(def, _) if def.is_box() => {
232 cx.type_ptr_to(cx.layout_of(self.ty.boxed_ty()).llvm_type(cx))
235 cx.fn_ptr_backend_type(&cx.fn_abi_of_fn_ptr(sig, ty::List::empty()))
237 _ => self.scalar_llvm_type_at(cx, scalar, Size::ZERO),
239 cx.scalar_lltypes.borrow_mut().insert(self.ty, llty);
244 let variant_index = match self.variants {
245 Variants::Single { index } => Some(index),
248 if let Some(ref llty) = cx.type_lowering.borrow().get(&(self.ty, variant_index)) {
252 debug!("llvm_type({:#?})", self);
254 assert!(!self.ty.has_escaping_bound_vars(), "{:?} has escaping bound vars", self.ty);
256 // Make sure lifetimes are erased, to avoid generating distinct LLVM
257 // types for Rust types that only differ in the choice of lifetimes.
258 let normal_ty = cx.tcx.erase_regions(self.ty);
260 let mut defer = None;
261 let mut field_remapping = None;
262 let llty = if self.ty != normal_ty {
263 let mut layout = cx.layout_of(normal_ty);
264 if let Some(v) = variant_index {
265 layout = layout.for_variant(cx, v);
269 uncached_llvm_type(cx, *self, &mut defer, &mut field_remapping)
271 debug!("--> mapped {:#?} to llty={:?}", self, llty);
273 cx.type_lowering.borrow_mut().insert(
274 (self.ty, variant_index),
275 TypeLowering { lltype: llty, field_remapping: field_remapping },
278 if let Some((llty, layout)) = defer {
279 let (llfields, packed, new_field_remapping) = struct_llfields(cx, layout);
280 cx.set_struct_body(llty, &llfields, packed);
283 .get_mut(&(self.ty, variant_index))
285 .field_remapping = new_field_remapping;
290 fn immediate_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type {
291 if let Abi::Scalar(scalar) = self.abi {
292 if scalar.is_bool() {
299 fn scalar_llvm_type_at<'a>(
301 cx: &CodegenCx<'a, 'tcx>,
306 Int(i, _) => cx.type_from_integer(i),
307 F32 => cx.type_f32(),
308 F64 => cx.type_f64(),
310 // If we know the alignment, pick something better than i8.
311 let (pointee, address_space) =
312 if let Some(pointee) = self.pointee_info_at(cx, offset) {
313 (cx.type_pointee_for_align(pointee.align), pointee.address_space)
315 (cx.type_i8(), AddressSpace::DATA)
317 cx.type_ptr_to_ext(pointee, address_space)
322 fn scalar_pair_element_llvm_type<'a>(
324 cx: &CodegenCx<'a, 'tcx>,
328 // HACK(eddyb) special-case fat pointers until LLVM removes
329 // pointee types, to avoid bitcasting every `OperandRef::deref`.
330 match self.ty.kind() {
331 ty::Ref(..) | ty::RawPtr(_) => {
332 return self.field(cx, index).llvm_type(cx);
334 ty::Adt(def, _) if def.is_box() => {
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 (a, b) = match self.abi {
342 Abi::ScalarPair(a, b) => (a, b),
343 _ => bug!("TyAndLayout::scalar_pair_element_llty({:?}): not applicable", self),
345 let scalar = [a, b][index];
347 // Make sure to return the same type `immediate_llvm_type` would when
348 // dealing with an immediate pair. This means that `(bool, bool)` is
349 // effectively represented as `{i8, i8}` in memory and two `i1`s as an
350 // immediate, just like `bool` is typically `i8` in memory and only `i1`
351 // when immediate. We need to load/store `bool` as `i8` to avoid
352 // crippling LLVM optimizations or triggering other LLVM bugs with `i1`.
353 if immediate && scalar.is_bool() {
358 if index == 0 { Size::ZERO } else { a.value.size(cx).align_to(b.value.align(cx).abi) };
359 self.scalar_llvm_type_at(cx, scalar, offset)
362 fn llvm_field_index<'a>(&self, cx: &CodegenCx<'a, 'tcx>, index: usize) -> u64 {
364 Abi::Scalar(_) | Abi::ScalarPair(..) => {
365 bug!("TyAndLayout::llvm_field_index({:?}): not applicable", self)
370 FieldsShape::Primitive | FieldsShape::Union(_) => {
371 bug!("TyAndLayout::llvm_field_index({:?}): not applicable", self)
374 FieldsShape::Array { .. } => index as u64,
376 FieldsShape::Arbitrary { .. } => {
377 let variant_index = match self.variants {
378 Variants::Single { index } => Some(index),
382 // Look up llvm field if indexes do not match memory order due to padding. If
383 // `field_remapping` is `None` no padding was used and the llvm field index
384 // matches the memory index.
385 match cx.type_lowering.borrow().get(&(self.ty, variant_index)) {
386 Some(TypeLowering { field_remapping: Some(ref remap), .. }) => {
389 Some(_) => self.fields.memory_index(index) as u64,
391 bug!("TyAndLayout::llvm_field_index({:?}): type info not found", self)
398 // FIXME(eddyb) this having the same name as `TyAndLayout::pointee_info_at`
399 // (the inherent method, which is lacking this caching logic) can result in
400 // the uncached version being called - not wrong, but potentially inefficient.
401 fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size) -> Option<PointeeInfo> {
402 if let Some(&pointee) = cx.pointee_infos.borrow().get(&(self.ty, offset)) {
406 let result = Ty::ty_and_layout_pointee_info_at(*self, cx, offset);
408 cx.pointee_infos.borrow_mut().insert((self.ty, offset), result);