3 use crate::type_::Type;
5 use rustc_codegen_ssa::traits::*;
7 use rustc_middle::ty::layout::{FnAbiExt, TyAndLayout};
8 use rustc_middle::ty::print::obsolete::DefPathBasedNames;
9 use rustc_middle::ty::{self, Ty, TypeFoldable};
10 use rustc_target::abi::{Abi, Align, FieldsShape};
11 use rustc_target::abi::{Int, Pointer, F32, F64};
12 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 // LLVM has a separate type for 64-bit SIMD vectors on X86 called
25 // `x86_mmx` which is needed for some SIMD operations. As a bit of a
26 // hack (all SIMD definitions are super unstable anyway) we
27 // recognize any one-element SIMD vector as "this should be an
28 // x86_mmx" type. In general there shouldn't be a need for other
29 // one-element SIMD vectors, so it's assumed this won't clash with
31 let use_x86_mmx = count == 1
32 && layout.size.bits() == 64
33 && (cx.sess().target.target.arch == "x86"
34 || cx.sess().target.target.arch == "x86_64");
36 return cx.type_x86_mmx();
38 let element = layout.scalar_llvm_type_at(cx, element, Size::ZERO);
39 return cx.type_vector(element, count);
42 Abi::ScalarPair(..) => {
43 return cx.type_struct(
45 layout.scalar_pair_element_llvm_type(cx, 0, false),
46 layout.scalar_pair_element_llvm_type(cx, 1, false),
51 Abi::Uninhabited | Abi::Aggregate { .. } => {}
54 let name = match layout.ty.kind {
58 // FIXME(eddyb) producing readable type names for trait objects can result
59 // in problematically distinct types due to HRTB and subtyping (see #47638).
63 let mut name = String::with_capacity(32);
64 let printer = DefPathBasedNames::new(cx.tcx, true, true);
65 printer.push_type_name(layout.ty, &mut name, false);
66 if let (&ty::Adt(def, _), &Variants::Single { index })
67 = (&layout.ty.kind, &layout.variants)
69 if def.is_enum() && !def.variants.is_empty() {
70 write!(&mut name, "::{}", def.variants[index].ident).unwrap();
73 if let (&ty::Generator(_, substs, _), &Variants::Single { index })
74 = (&layout.ty.kind, &layout.variants)
76 write!(&mut name, "::{}", substs.as_generator().variant_name(index)).unwrap();
84 FieldsShape::Primitive | FieldsShape::Union(_) => {
85 let fill = cx.type_padding_filler(layout.size, layout.align.abi);
88 None => cx.type_struct(&[fill], packed),
90 let llty = cx.type_named_struct(name);
91 cx.set_struct_body(llty, &[fill], packed);
96 FieldsShape::Array { count, .. } => cx.type_array(layout.field(cx, 0).llvm_type(cx), count),
97 FieldsShape::Arbitrary { .. } => match name {
99 let (llfields, packed) = struct_llfields(cx, layout);
100 cx.type_struct(&llfields, packed)
103 let llty = cx.type_named_struct(name);
104 *defer = Some((llty, layout));
111 fn struct_llfields<'a, 'tcx>(
112 cx: &CodegenCx<'a, 'tcx>,
113 layout: TyAndLayout<'tcx>,
114 ) -> (Vec<&'a Type>, bool) {
115 debug!("struct_llfields: {:#?}", layout);
116 let field_count = layout.fields.count();
118 let mut packed = false;
119 let mut offset = Size::ZERO;
120 let mut prev_effective_align = layout.align.abi;
121 let mut result: Vec<_> = Vec::with_capacity(1 + field_count * 2);
122 for i in layout.fields.index_by_increasing_offset() {
123 let target_offset = layout.fields.offset(i as usize);
124 let field = layout.field(cx, i);
125 let effective_field_align =
126 layout.align.abi.min(field.align.abi).restrict_for_offset(target_offset);
127 packed |= effective_field_align < field.align.abi;
130 "struct_llfields: {}: {:?} offset: {:?} target_offset: {:?} \
131 effective_field_align: {}",
136 effective_field_align.bytes()
138 assert!(target_offset >= offset);
139 let padding = target_offset - offset;
140 let padding_align = prev_effective_align.min(effective_field_align);
141 assert_eq!(offset.align_to(padding_align) + padding, target_offset);
142 result.push(cx.type_padding_filler(padding, padding_align));
143 debug!(" padding before: {:?}", padding);
145 result.push(field.llvm_type(cx));
146 offset = target_offset + field.size;
147 prev_effective_align = effective_field_align;
149 if !layout.is_unsized() && field_count > 0 {
150 if offset > layout.size {
151 bug!("layout: {:#?} stride: {:?} offset: {:?}", layout, layout.size, offset);
153 let padding = layout.size - offset;
154 let padding_align = prev_effective_align;
155 assert_eq!(offset.align_to(padding_align) + padding, layout.size);
157 "struct_llfields: pad_bytes: {:?} offset: {:?} stride: {:?}",
158 padding, offset, layout.size
160 result.push(cx.type_padding_filler(padding, padding_align));
161 assert_eq!(result.len(), 1 + field_count * 2);
163 debug!("struct_llfields: offset: {:?} stride: {:?}", offset, layout.size);
169 impl<'a, 'tcx> CodegenCx<'a, 'tcx> {
170 pub fn align_of(&self, ty: Ty<'tcx>) -> Align {
171 self.layout_of(ty).align.abi
174 pub fn size_of(&self, ty: Ty<'tcx>) -> Size {
175 self.layout_of(ty).size
178 pub fn size_and_align_of(&self, ty: Ty<'tcx>) -> (Size, Align) {
179 let layout = self.layout_of(ty);
180 (layout.size, layout.align.abi)
184 pub trait LayoutLlvmExt<'tcx> {
185 fn is_llvm_immediate(&self) -> bool;
186 fn is_llvm_scalar_pair(&self) -> bool;
187 fn llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type;
188 fn immediate_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type;
189 fn scalar_llvm_type_at<'a>(
191 cx: &CodegenCx<'a, 'tcx>,
195 fn scalar_pair_element_llvm_type<'a>(
197 cx: &CodegenCx<'a, 'tcx>,
201 fn llvm_field_index(&self, index: usize) -> u64;
202 fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size) -> Option<PointeeInfo>;
205 impl<'tcx> LayoutLlvmExt<'tcx> for TyAndLayout<'tcx> {
206 fn is_llvm_immediate(&self) -> bool {
208 Abi::Scalar(_) | Abi::Vector { .. } => true,
209 Abi::ScalarPair(..) => false,
210 Abi::Uninhabited | Abi::Aggregate { .. } => self.is_zst(),
214 fn is_llvm_scalar_pair(&self) -> bool {
216 Abi::ScalarPair(..) => true,
217 Abi::Uninhabited | Abi::Scalar(_) | Abi::Vector { .. } | Abi::Aggregate { .. } => false,
221 /// Gets the LLVM type corresponding to a Rust type, i.e., `rustc_middle::ty::Ty`.
222 /// The pointee type of the pointer in `PlaceRef` is always this type.
223 /// For sized types, it is also the right LLVM type for an `alloca`
224 /// containing a value of that type, and most immediates (except `bool`).
225 /// Unsized types, however, are represented by a "minimal unit", e.g.
226 /// `[T]` becomes `T`, while `str` and `Trait` turn into `i8` - this
227 /// is useful for indexing slices, as `&[T]`'s data pointer is `T*`.
228 /// If the type is an unsized struct, the regular layout is generated,
229 /// with the inner-most trailing unsized field using the "minimal unit"
230 /// of that field's type - this is useful for taking the address of
231 /// that field and ensuring the struct has the right alignment.
232 fn llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type {
233 if let Abi::Scalar(ref scalar) = self.abi {
234 // Use a different cache for scalars because pointers to DSTs
235 // can be either fat or thin (data pointers of fat pointers).
236 if let Some(&llty) = cx.scalar_lltypes.borrow().get(&self.ty) {
239 let llty = match self.ty.kind {
240 ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
241 cx.type_ptr_to(cx.layout_of(ty).llvm_type(cx))
243 ty::Adt(def, _) if def.is_box() => {
244 cx.type_ptr_to(cx.layout_of(self.ty.boxed_ty()).llvm_type(cx))
246 ty::FnPtr(sig) => cx.fn_ptr_backend_type(&FnAbi::of_fn_ptr(cx, sig, &[])),
247 _ => self.scalar_llvm_type_at(cx, scalar, Size::ZERO),
249 cx.scalar_lltypes.borrow_mut().insert(self.ty, llty);
254 let variant_index = match self.variants {
255 Variants::Single { index } => Some(index),
258 if let Some(&llty) = cx.lltypes.borrow().get(&(self.ty, variant_index)) {
262 debug!("llvm_type({:#?})", self);
264 assert!(!self.ty.has_escaping_bound_vars(), "{:?} has escaping bound vars", self.ty);
266 // Make sure lifetimes are erased, to avoid generating distinct LLVM
267 // types for Rust types that only differ in the choice of lifetimes.
268 let normal_ty = cx.tcx.erase_regions(&self.ty);
270 let mut defer = None;
271 let llty = if self.ty != normal_ty {
272 let mut layout = cx.layout_of(normal_ty);
273 if let Some(v) = variant_index {
274 layout = layout.for_variant(cx, v);
278 uncached_llvm_type(cx, *self, &mut defer)
280 debug!("--> mapped {:#?} to llty={:?}", self, llty);
282 cx.lltypes.borrow_mut().insert((self.ty, variant_index), llty);
284 if let Some((llty, layout)) = defer {
285 let (llfields, packed) = struct_llfields(cx, layout);
286 cx.set_struct_body(llty, &llfields, packed)
292 fn immediate_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type {
293 if let Abi::Scalar(ref scalar) = self.abi {
294 if scalar.is_bool() {
301 fn scalar_llvm_type_at<'a>(
303 cx: &CodegenCx<'a, 'tcx>,
308 Int(i, _) => cx.type_from_integer(i),
309 F32 => cx.type_f32(),
310 F64 => cx.type_f64(),
312 // If we know the alignment, pick something better than i8.
313 let pointee = if let Some(pointee) = self.pointee_info_at(cx, offset) {
314 cx.type_pointee_for_align(pointee.align)
318 cx.type_ptr_to(pointee)
323 fn scalar_pair_element_llvm_type<'a>(
325 cx: &CodegenCx<'a, 'tcx>,
329 // HACK(eddyb) special-case fat pointers until LLVM removes
330 // pointee types, to avoid bitcasting every `OperandRef::deref`.
332 ty::Ref(..) | ty::RawPtr(_) => {
333 return self.field(cx, index).llvm_type(cx);
335 ty::Adt(def, _) if def.is_box() => {
336 let ptr_ty = cx.tcx.mk_mut_ptr(self.ty.boxed_ty());
337 return cx.layout_of(ptr_ty).scalar_pair_element_llvm_type(cx, index, immediate);
342 let (a, b) = match self.abi {
343 Abi::ScalarPair(ref a, ref b) => (a, b),
344 _ => bug!("TyAndLayout::scalar_pair_element_llty({:?}): not applicable", self),
346 let scalar = [a, b][index];
348 // Make sure to return the same type `immediate_llvm_type` would when
349 // dealing with an immediate pair. This means that `(bool, bool)` is
350 // effectively represented as `{i8, i8}` in memory and two `i1`s as an
351 // immediate, just like `bool` is typically `i8` in memory and only `i1`
352 // when immediate. We need to load/store `bool` as `i8` to avoid
353 // crippling LLVM optimizations or triggering other LLVM bugs with `i1`.
354 if immediate && scalar.is_bool() {
359 if index == 0 { Size::ZERO } else { a.value.size(cx).align_to(b.value.align(cx).abi) };
360 self.scalar_llvm_type_at(cx, scalar, offset)
363 fn llvm_field_index(&self, index: usize) -> u64 {
365 Abi::Scalar(_) | Abi::ScalarPair(..) => {
366 bug!("TyAndLayout::llvm_field_index({:?}): not applicable", self)
371 FieldsShape::Primitive | FieldsShape::Union(_) => {
372 bug!("TyAndLayout::llvm_field_index({:?}): not applicable", self)
375 FieldsShape::Array { .. } => index as u64,
377 FieldsShape::Arbitrary { .. } => 1 + (self.fields.memory_index(index) as u64) * 2,
381 fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size) -> Option<PointeeInfo> {
382 if let Some(&pointee) = cx.pointee_infos.borrow().get(&(self.ty, offset)) {
386 let result = Ty::pointee_info_at(*self, cx, offset);
388 cx.pointee_infos.borrow_mut().insert((self.ty, offset), result);