4 use crate::spec::Target;
6 use std::ops::{Add, Deref, Sub, Mul, AddAssign, Range, RangeInclusive};
8 use rustc_index::vec::{Idx, IndexVec};
9 use rustc_macros::HashStable_Generic;
14 /// Parsed [Data layout](http://llvm.org/docs/LangRef.html#data-layout)
15 /// for a target, which contains everything needed to compute layouts.
16 pub struct TargetDataLayout {
18 pub i1_align: AbiAndPrefAlign,
19 pub i8_align: AbiAndPrefAlign,
20 pub i16_align: AbiAndPrefAlign,
21 pub i32_align: AbiAndPrefAlign,
22 pub i64_align: AbiAndPrefAlign,
23 pub i128_align: AbiAndPrefAlign,
24 pub f32_align: AbiAndPrefAlign,
25 pub f64_align: AbiAndPrefAlign,
26 pub pointer_size: Size,
27 pub pointer_align: AbiAndPrefAlign,
28 pub aggregate_align: AbiAndPrefAlign,
30 /// Alignments for vector types.
31 pub vector_align: Vec<(Size, AbiAndPrefAlign)>,
33 pub instruction_address_space: u32,
36 impl Default for TargetDataLayout {
37 /// Creates an instance of `TargetDataLayout`.
38 fn default() -> TargetDataLayout {
39 let align = |bits| Align::from_bits(bits).unwrap();
42 i1_align: AbiAndPrefAlign::new(align(8)),
43 i8_align: AbiAndPrefAlign::new(align(8)),
44 i16_align: AbiAndPrefAlign::new(align(16)),
45 i32_align: AbiAndPrefAlign::new(align(32)),
46 i64_align: AbiAndPrefAlign { abi: align(32), pref: align(64) },
47 i128_align: AbiAndPrefAlign { abi: align(32), pref: align(64) },
48 f32_align: AbiAndPrefAlign::new(align(32)),
49 f64_align: AbiAndPrefAlign::new(align(64)),
50 pointer_size: Size::from_bits(64),
51 pointer_align: AbiAndPrefAlign::new(align(64)),
52 aggregate_align: AbiAndPrefAlign { abi: align(0), pref: align(64) },
54 (Size::from_bits(64), AbiAndPrefAlign::new(align(64))),
55 (Size::from_bits(128), AbiAndPrefAlign::new(align(128))),
57 instruction_address_space: 0,
62 impl TargetDataLayout {
63 pub fn parse(target: &Target) -> Result<TargetDataLayout, String> {
64 // Parse an address space index from a string.
65 let parse_address_space = |s: &str, cause: &str| {
66 s.parse::<u32>().map_err(|err| {
67 format!("invalid address space `{}` for `{}` in \"data-layout\": {}",
72 // Parse a bit count from a string.
73 let parse_bits = |s: &str, kind: &str, cause: &str| {
74 s.parse::<u64>().map_err(|err| {
75 format!("invalid {} `{}` for `{}` in \"data-layout\": {}",
80 // Parse a size string.
81 let size = |s: &str, cause: &str| {
82 parse_bits(s, "size", cause).map(Size::from_bits)
85 // Parse an alignment string.
86 let align = |s: &[&str], cause: &str| {
88 return Err(format!("missing alignment for `{}` in \"data-layout\"", cause));
90 let align_from_bits = |bits| {
91 Align::from_bits(bits).map_err(|err| {
92 format!("invalid alignment for `{}` in \"data-layout\": {}",
96 let abi = parse_bits(s[0], "alignment", cause)?;
97 let pref = s.get(1).map_or(Ok(abi), |pref| parse_bits(pref, "alignment", cause))?;
99 abi: align_from_bits(abi)?,
100 pref: align_from_bits(pref)?,
104 let mut dl = TargetDataLayout::default();
105 let mut i128_align_src = 64;
106 for spec in target.data_layout.split('-') {
107 let spec_parts = spec.split(':').collect::<Vec<_>>();
110 ["e"] => dl.endian = Endian::Little,
111 ["E"] => dl.endian = Endian::Big,
112 [p] if p.starts_with("P") => {
113 dl.instruction_address_space = parse_address_space(&p[1..], "P")?
115 ["a", ref a @ ..] => {
116 dl.aggregate_align = align(a, "a")?
118 ["f32", ref a @ ..] => {
119 dl.f32_align = align(a, "f32")?
121 ["f64", ref a @ ..] => {
122 dl.f64_align = align(a, "f64")?
124 [p @ "p", s, ref a @ ..] | [p @ "p0", s, ref a @ ..] => {
125 dl.pointer_size = size(s, p)?;
126 dl.pointer_align = align(a, p)?;
128 [s, ref a @ ..] if s.starts_with("i") => {
129 let bits = match s[1..].parse::<u64>() {
132 size(&s[1..], "i")?; // For the user error.
136 let a = align(a, s)?;
138 1 => dl.i1_align = a,
139 8 => dl.i8_align = a,
140 16 => dl.i16_align = a,
141 32 => dl.i32_align = a,
142 64 => dl.i64_align = a,
145 if bits >= i128_align_src && bits <= 128 {
146 // Default alignment for i128 is decided by taking the alignment of
147 // largest-sized i{64..=128}.
148 i128_align_src = bits;
152 [s, ref a @ ..] if s.starts_with("v") => {
153 let v_size = size(&s[1..], "v")?;
154 let a = align(a, s)?;
155 if let Some(v) = dl.vector_align.iter_mut().find(|v| v.0 == v_size) {
159 // No existing entry, add a new one.
160 dl.vector_align.push((v_size, a));
162 _ => {} // Ignore everything else.
166 // Perform consistency checks against the Target information.
167 let endian_str = match dl.endian {
168 Endian::Little => "little",
171 if endian_str != target.target_endian {
172 return Err(format!("inconsistent target specification: \"data-layout\" claims \
173 architecture is {}-endian, while \"target-endian\" is `{}`",
174 endian_str, target.target_endian));
177 if dl.pointer_size.bits().to_string() != target.target_pointer_width {
178 return Err(format!("inconsistent target specification: \"data-layout\" claims \
179 pointers are {}-bit, while \"target-pointer-width\" is `{}`",
180 dl.pointer_size.bits(), target.target_pointer_width));
186 /// Returns exclusive upper bound on object size.
188 /// The theoretical maximum object size is defined as the maximum positive `isize` value.
189 /// This ensures that the `offset` semantics remain well-defined by allowing it to correctly
190 /// index every address within an object along with one byte past the end, along with allowing
191 /// `isize` to store the difference between any two pointers into an object.
193 /// The upper bound on 64-bit currently needs to be lower because LLVM uses a 64-bit integer
194 /// to represent object size in bits. It would need to be 1 << 61 to account for this, but is
195 /// currently conservatively bounded to 1 << 47 as that is enough to cover the current usable
196 /// address space on 64-bit ARMv8 and x86_64.
197 pub fn obj_size_bound(&self) -> u64 {
198 match self.pointer_size.bits() {
202 bits => panic!("obj_size_bound: unknown pointer bit size {}", bits)
206 pub fn ptr_sized_integer(&self) -> Integer {
207 match self.pointer_size.bits() {
211 bits => panic!("ptr_sized_integer: unknown pointer bit size {}", bits)
215 pub fn vector_align(&self, vec_size: Size) -> AbiAndPrefAlign {
216 for &(size, align) in &self.vector_align {
217 if size == vec_size {
221 // Default to natural alignment, which is what LLVM does.
222 // That is, use the size, rounded up to a power of 2.
223 AbiAndPrefAlign::new(Align::from_bytes(vec_size.bytes().next_power_of_two()).unwrap())
227 pub trait HasDataLayout {
228 fn data_layout(&self) -> &TargetDataLayout;
231 impl HasDataLayout for TargetDataLayout {
232 fn data_layout(&self) -> &TargetDataLayout {
237 /// Endianness of the target, which must match cfg(target-endian).
238 #[derive(Copy, Clone, PartialEq)]
244 /// Size of a type in bytes.
245 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
246 #[derive(HashStable_Generic)]
252 pub const ZERO: Size = Self::from_bytes(0);
255 pub fn from_bits(bits: u64) -> Size {
256 // Avoid potential overflow from `bits + 7`.
257 Size::from_bytes(bits / 8 + ((bits % 8) + 7) / 8)
261 pub const fn from_bytes(bytes: u64) -> Size {
268 pub fn bytes(self) -> u64 {
273 pub fn bits(self) -> u64 {
274 self.bytes().checked_mul(8).unwrap_or_else(|| {
275 panic!("Size::bits: {} bytes in bits doesn't fit in u64", self.bytes())
280 pub fn align_to(self, align: Align) -> Size {
281 let mask = align.bytes() - 1;
282 Size::from_bytes((self.bytes() + mask) & !mask)
286 pub fn is_aligned(self, align: Align) -> bool {
287 let mask = align.bytes() - 1;
288 self.bytes() & mask == 0
292 pub fn checked_add<C: HasDataLayout>(self, offset: Size, cx: &C) -> Option<Size> {
293 let dl = cx.data_layout();
295 let bytes = self.bytes().checked_add(offset.bytes())?;
297 if bytes < dl.obj_size_bound() {
298 Some(Size::from_bytes(bytes))
305 pub fn checked_mul<C: HasDataLayout>(self, count: u64, cx: &C) -> Option<Size> {
306 let dl = cx.data_layout();
308 let bytes = self.bytes().checked_mul(count)?;
309 if bytes < dl.obj_size_bound() {
310 Some(Size::from_bytes(bytes))
317 // Panicking addition, subtraction and multiplication for convenience.
318 // Avoid during layout computation, return `LayoutError` instead.
323 fn add(self, other: Size) -> Size {
324 Size::from_bytes(self.bytes().checked_add(other.bytes()).unwrap_or_else(|| {
325 panic!("Size::add: {} + {} doesn't fit in u64", self.bytes(), other.bytes())
333 fn sub(self, other: Size) -> Size {
334 Size::from_bytes(self.bytes().checked_sub(other.bytes()).unwrap_or_else(|| {
335 panic!("Size::sub: {} - {} would result in negative size", self.bytes(), other.bytes())
340 impl Mul<Size> for u64 {
343 fn mul(self, size: Size) -> Size {
348 impl Mul<u64> for Size {
351 fn mul(self, count: u64) -> Size {
352 match self.bytes().checked_mul(count) {
353 Some(bytes) => Size::from_bytes(bytes),
355 panic!("Size::mul: {} * {} doesn't fit in u64", self.bytes(), count)
361 impl AddAssign for Size {
363 fn add_assign(&mut self, other: Size) {
364 *self = *self + other;
368 /// Alignment of a type in bytes (always a power of two).
369 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
370 #[derive(HashStable_Generic)]
376 pub fn from_bits(bits: u64) -> Result<Align, String> {
377 Align::from_bytes(Size::from_bits(bits).bytes())
380 pub fn from_bytes(align: u64) -> Result<Align, String> {
381 // Treat an alignment of 0 bytes like 1-byte alignment.
383 return Ok(Align { pow2: 0 });
386 let mut bytes = align;
387 let mut pow2: u8 = 0;
388 while (bytes & 1) == 0 {
393 return Err(format!("`{}` is not a power of 2", align));
396 return Err(format!("`{}` is too large", align));
402 pub fn bytes(self) -> u64 {
406 pub fn bits(self) -> u64 {
410 /// Computes the best alignment possible for the given offset
411 /// (the largest power of two that the offset is a multiple of).
413 /// N.B., for an offset of `0`, this happens to return `2^64`.
414 pub fn max_for_offset(offset: Size) -> Align {
416 pow2: offset.bytes().trailing_zeros() as u8,
420 /// Lower the alignment, if necessary, such that the given offset
421 /// is aligned to it (the offset is a multiple of the alignment).
422 pub fn restrict_for_offset(self, offset: Size) -> Align {
423 self.min(Align::max_for_offset(offset))
427 /// A pair of aligments, ABI-mandated and preferred.
428 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
429 #[derive(HashStable_Generic)]
430 pub struct AbiAndPrefAlign {
435 impl AbiAndPrefAlign {
436 pub fn new(align: Align) -> AbiAndPrefAlign {
443 pub fn min(self, other: AbiAndPrefAlign) -> AbiAndPrefAlign {
445 abi: self.abi.min(other.abi),
446 pref: self.pref.min(other.pref),
450 pub fn max(self, other: AbiAndPrefAlign) -> AbiAndPrefAlign {
452 abi: self.abi.max(other.abi),
453 pref: self.pref.max(other.pref),
458 /// Integers, also used for enum discriminants.
459 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, HashStable_Generic)]
469 pub fn size(self) -> Size {
471 I8 => Size::from_bytes(1),
472 I16 => Size::from_bytes(2),
473 I32 => Size::from_bytes(4),
474 I64 => Size::from_bytes(8),
475 I128 => Size::from_bytes(16),
479 pub fn align<C: HasDataLayout>(self, cx: &C) -> AbiAndPrefAlign {
480 let dl = cx.data_layout();
487 I128 => dl.i128_align,
491 /// Finds the smallest Integer type which can represent the signed value.
492 pub fn fit_signed(x: i128) -> Integer {
494 -0x0000_0000_0000_0080..=0x0000_0000_0000_007f => I8,
495 -0x0000_0000_0000_8000..=0x0000_0000_0000_7fff => I16,
496 -0x0000_0000_8000_0000..=0x0000_0000_7fff_ffff => I32,
497 -0x8000_0000_0000_0000..=0x7fff_ffff_ffff_ffff => I64,
502 /// Finds the smallest Integer type which can represent the unsigned value.
503 pub fn fit_unsigned(x: u128) -> Integer {
505 0..=0x0000_0000_0000_00ff => I8,
506 0..=0x0000_0000_0000_ffff => I16,
507 0..=0x0000_0000_ffff_ffff => I32,
508 0..=0xffff_ffff_ffff_ffff => I64,
513 /// Finds the smallest integer with the given alignment.
514 pub fn for_align<C: HasDataLayout>(cx: &C, wanted: Align) -> Option<Integer> {
515 let dl = cx.data_layout();
517 for &candidate in &[I8, I16, I32, I64, I128] {
518 if wanted == candidate.align(dl).abi && wanted.bytes() == candidate.size().bytes() {
519 return Some(candidate);
525 /// Find the largest integer with the given alignment or less.
526 pub fn approximate_align<C: HasDataLayout>(cx: &C, wanted: Align) -> Integer {
527 let dl = cx.data_layout();
529 // FIXME(eddyb) maybe include I128 in the future, when it works everywhere.
530 for &candidate in &[I64, I32, I16] {
531 if wanted >= candidate.align(dl).abi && wanted.bytes() >= candidate.size().bytes() {
539 /// Fundamental unit of memory access and layout.
540 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
542 /// The `bool` is the signedness of the `Integer` type.
544 /// One would think we would not care about such details this low down,
545 /// but some ABIs are described in terms of C types and ISAs where the
546 /// integer arithmetic is done on {sign,zero}-extended registers, e.g.
547 /// a negative integer passed by zero-extension will appear positive in
548 /// the callee, and most operations on it will produce the wrong values.
556 pub fn size<C: HasDataLayout>(self, cx: &C) -> Size {
557 let dl = cx.data_layout();
560 Int(i, _) => i.size(),
561 F32 => Size::from_bits(32),
562 F64 => Size::from_bits(64),
563 Pointer => dl.pointer_size
567 pub fn align<C: HasDataLayout>(self, cx: &C) -> AbiAndPrefAlign {
568 let dl = cx.data_layout();
571 Int(i, _) => i.align(dl),
574 Pointer => dl.pointer_align
578 pub fn is_float(self) -> bool {
585 pub fn is_int(self) -> bool {
593 /// Information about one scalar component of a Rust type.
594 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
595 #[derive(HashStable_Generic)]
597 pub value: Primitive,
599 /// Inclusive wrap-around range of valid values, that is, if
600 /// start > end, it represents `start..=max_value()`,
601 /// followed by `0..=end`.
603 /// That is, for an i8 primitive, a range of `254..=2` means following
606 /// 254 (-2), 255 (-1), 0, 1, 2
608 /// This is intended specifically to mirror LLVM’s `!range` metadata,
610 // FIXME(eddyb) always use the shortest range, e.g., by finding
611 // the largest space between two consecutive valid values and
612 // taking everything else as the (shortest) valid range.
613 pub valid_range: RangeInclusive<u128>,
617 pub fn is_bool(&self) -> bool {
618 if let Int(I8, _) = self.value {
619 self.valid_range == (0..=1)
625 /// Returns the valid range as a `x..y` range.
627 /// If `x` and `y` are equal, the range is full, not empty.
628 pub fn valid_range_exclusive<C: HasDataLayout>(&self, cx: &C) -> Range<u128> {
629 // For a (max) value of -1, max will be `-1 as usize`, which overflows.
630 // However, that is fine here (it would still represent the full range),
631 // i.e., if the range is everything.
632 let bits = self.value.size(cx).bits();
633 assert!(bits <= 128);
634 let mask = !0u128 >> (128 - bits);
635 let start = *self.valid_range.start();
636 let end = *self.valid_range.end();
637 assert_eq!(start, start & mask);
638 assert_eq!(end, end & mask);
639 start..(end.wrapping_add(1) & mask)
643 /// Describes how the fields of a type are located in memory.
644 #[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
645 pub enum FieldPlacement {
646 /// All fields start at no offset. The `usize` is the field count.
648 /// In the case of primitives the number of fields is `0`.
651 /// Array/vector-like placement, with all fields of identical types.
657 /// Struct-like placement, with precomputed offsets.
659 /// Fields are guaranteed to not overlap, but note that gaps
660 /// before, between and after all the fields are NOT always
661 /// padding, and as such their contents may not be discarded.
662 /// For example, enum variants leave a gap at the start,
663 /// where the discriminant field in the enum layout goes.
665 /// Offsets for the first byte of each field,
666 /// ordered to match the source definition order.
667 /// This vector does not go in increasing order.
668 // FIXME(eddyb) use small vector optimization for the common case.
671 /// Maps source order field indices to memory order indices,
672 /// depending on how the fields were reordered (if at all).
673 /// This is a permutation, with both the source order and the
674 /// memory order using the same (0..n) index ranges.
676 /// Note that during computation of `memory_index`, sometimes
677 /// it is easier to operate on the inverse mapping (that is,
678 /// from memory order to source order), and that is usually
679 /// named `inverse_memory_index`.
681 // FIXME(eddyb) build a better abstraction for permutations, if possible.
682 // FIXME(camlorn) also consider small vector optimization here.
683 memory_index: Vec<u32>
687 impl FieldPlacement {
688 pub fn count(&self) -> usize {
690 FieldPlacement::Union(count) => count,
691 FieldPlacement::Array { count, .. } => {
692 let usize_count = count as usize;
693 assert_eq!(usize_count as u64, count);
696 FieldPlacement::Arbitrary { ref offsets, .. } => offsets.len()
700 pub fn offset(&self, i: usize) -> Size {
702 FieldPlacement::Union(_) => Size::ZERO,
703 FieldPlacement::Array { stride, count } => {
708 FieldPlacement::Arbitrary { ref offsets, .. } => offsets[i]
712 pub fn memory_index(&self, i: usize) -> usize {
714 FieldPlacement::Union(_) |
715 FieldPlacement::Array { .. } => i,
716 FieldPlacement::Arbitrary { ref memory_index, .. } => {
717 let r = memory_index[i];
718 assert_eq!(r as usize as u32, r);
724 /// Gets source indices of the fields by increasing offsets.
726 pub fn index_by_increasing_offset<'a>(&'a self) -> impl Iterator<Item=usize>+'a {
727 let mut inverse_small = [0u8; 64];
728 let mut inverse_big = vec![];
729 let use_small = self.count() <= inverse_small.len();
731 // We have to write this logic twice in order to keep the array small.
732 if let FieldPlacement::Arbitrary { ref memory_index, .. } = *self {
734 for i in 0..self.count() {
735 inverse_small[memory_index[i] as usize] = i as u8;
738 inverse_big = vec![0; self.count()];
739 for i in 0..self.count() {
740 inverse_big[memory_index[i] as usize] = i as u32;
745 (0..self.count()).map(move |i| {
747 FieldPlacement::Union(_) |
748 FieldPlacement::Array { .. } => i,
749 FieldPlacement::Arbitrary { .. } => {
750 if use_small { inverse_small[i] as usize }
751 else { inverse_big[i] as usize }
758 /// Describes how values of the type are passed by target ABIs,
759 /// in terms of categories of C types there are ABI rules for.
760 #[derive(Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
764 ScalarPair(Scalar, Scalar),
770 /// If true, the size is exact, otherwise it's only a lower bound.
776 /// Returns `true` if the layout corresponds to an unsized type.
777 pub fn is_unsized(&self) -> bool {
781 Abi::ScalarPair(..) |
782 Abi::Vector { .. } => false,
783 Abi::Aggregate { sized } => !sized
787 /// Returns `true` if this is a single signed integer scalar
788 pub fn is_signed(&self) -> bool {
790 Abi::Scalar(ref scal) => match scal.value {
791 Primitive::Int(_, signed) => signed,
798 /// Returns `true` if this is an uninhabited type
799 pub fn is_uninhabited(&self) -> bool {
801 Abi::Uninhabited => true,
807 rustc_index::newtype_index! {
808 pub struct VariantIdx {
809 derive [HashStable_Generic]
813 #[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
815 /// Single enum variants, structs/tuples, unions, and all non-ADTs.
820 /// Enum-likes with more than one inhabited variant: for each case there is
821 /// a struct, and they all have space reserved for the discriminant.
822 /// For enums this is the sole field of the layout.
825 discr_kind: DiscriminantKind,
827 variants: IndexVec<VariantIdx, LayoutDetails>,
831 #[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
832 pub enum DiscriminantKind {
833 /// Integer tag holding the discriminant value itself.
836 /// Niche (values invalid for a type) encoding the discriminant:
837 /// the variant `dataful_variant` contains a niche at an arbitrary
838 /// offset (field `discr_index` of the enum), which for a variant with
839 /// discriminant `d` is set to
840 /// `(d - niche_variants.start).wrapping_add(niche_start)`.
842 /// For example, `Option<(usize, &T)>` is represented such that
843 /// `None` has a null pointer for the second tuple field, and
844 /// `Some` is the identity function (with a non-null reference).
846 dataful_variant: VariantIdx,
847 niche_variants: RangeInclusive<VariantIdx>,
852 #[derive(Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
859 pub fn from_scalar<C: HasDataLayout>(cx: &C, offset: Size, scalar: Scalar) -> Option<Self> {
864 if niche.available(cx) > 0 {
871 pub fn available<C: HasDataLayout>(&self, cx: &C) -> u128 {
872 let Scalar { value, valid_range: ref v } = self.scalar;
873 let bits = value.size(cx).bits();
874 assert!(bits <= 128);
875 let max_value = !0u128 >> (128 - bits);
877 // Find out how many values are outside the valid range.
878 let niche = v.end().wrapping_add(1)..*v.start();
879 niche.end.wrapping_sub(niche.start) & max_value
882 pub fn reserve<C: HasDataLayout>(&self, cx: &C, count: u128) -> Option<(u128, Scalar)> {
885 let Scalar { value, valid_range: ref v } = self.scalar;
886 let bits = value.size(cx).bits();
887 assert!(bits <= 128);
888 let max_value = !0u128 >> (128 - bits);
890 if count > max_value {
894 // Compute the range of invalid values being reserved.
895 let start = v.end().wrapping_add(1) & max_value;
896 let end = v.end().wrapping_add(count) & max_value;
898 // If the `end` of our range is inside the valid range,
899 // then we ran out of invalid values.
900 // FIXME(eddyb) abstract this with a wraparound range type.
901 let valid_range_contains = |x| {
902 if v.start() <= v.end() {
903 *v.start() <= x && x <= *v.end()
905 *v.start() <= x || x <= *v.end()
908 if valid_range_contains(end) {
912 Some((start, Scalar { value, valid_range: *v.start()..=end }))
916 #[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
917 pub struct LayoutDetails {
918 pub variants: Variants,
919 pub fields: FieldPlacement,
922 /// The leaf scalar with the largest number of invalid values
923 /// (i.e. outside of its `valid_range`), if it exists.
924 pub largest_niche: Option<Niche>,
926 pub align: AbiAndPrefAlign,
931 pub fn scalar<C: HasDataLayout>(cx: &C, scalar: Scalar) -> Self {
932 let largest_niche = Niche::from_scalar(cx, Size::ZERO, scalar.clone());
933 let size = scalar.value.size(cx);
934 let align = scalar.value.align(cx);
936 variants: Variants::Single { index: VariantIdx::new(0) },
937 fields: FieldPlacement::Union(0),
938 abi: Abi::Scalar(scalar),
946 /// The details of the layout of a type, alongside the type itself.
947 /// Provides various type traversal APIs (e.g., recursing into fields).
949 /// Note that the details are NOT guaranteed to always be identical
950 /// to those obtained from `layout_of(ty)`, as we need to produce
951 /// layouts for which Rust types do not exist, such as enum variants
952 /// or synthetic fields of enums (i.e., discriminants) and fat pointers.
953 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
954 pub struct TyLayout<'a, Ty> {
956 pub details: &'a LayoutDetails
959 impl<'a, Ty> Deref for TyLayout<'a, Ty> {
960 type Target = &'a LayoutDetails;
961 fn deref(&self) -> &&'a LayoutDetails {
970 fn layout_of(&self, ty: Self::Ty) -> Self::TyLayout;
971 fn spanned_layout_of(&self, ty: Self::Ty, _span: Span) -> Self::TyLayout {
976 #[derive(Copy, Clone, PartialEq, Eq)]
977 pub enum PointerKind {
978 /// Most general case, we know no restrictions to tell LLVM.
981 /// `&T` where `T` contains no `UnsafeCell`, is `noalias` and `readonly`.
984 /// `&mut T`, when we know `noalias` is safe for LLVM.
987 /// `Box<T>`, unlike `UniqueBorrowed`, it also has `noalias` on returns.
991 #[derive(Copy, Clone)]
992 pub struct PointeeInfo {
995 pub safe: Option<PointerKind>,
998 pub trait TyLayoutMethods<'a, C: LayoutOf<Ty = Self>>: Sized {
1000 this: TyLayout<'a, Self>,
1002 variant_index: VariantIdx,
1003 ) -> TyLayout<'a, Self>;
1004 fn field(this: TyLayout<'a, Self>, cx: &C, i: usize) -> C::TyLayout;
1006 this: TyLayout<'a, Self>,
1009 ) -> Option<PointeeInfo>;
1012 impl<'a, Ty> TyLayout<'a, Ty> {
1013 pub fn for_variant<C>(self, cx: &C, variant_index: VariantIdx) -> Self
1014 where Ty: TyLayoutMethods<'a, C>, C: LayoutOf<Ty = Ty> {
1015 Ty::for_variant(self, cx, variant_index)
1017 pub fn field<C>(self, cx: &C, i: usize) -> C::TyLayout
1018 where Ty: TyLayoutMethods<'a, C>, C: LayoutOf<Ty = Ty> {
1019 Ty::field(self, cx, i)
1021 pub fn pointee_info_at<C>(self, cx: &C, offset: Size) -> Option<PointeeInfo>
1022 where Ty: TyLayoutMethods<'a, C>, C: LayoutOf<Ty = Ty> {
1023 Ty::pointee_info_at(self, cx, offset)
1027 impl<'a, Ty> TyLayout<'a, Ty> {
1028 /// Returns `true` if the layout corresponds to an unsized type.
1029 pub fn is_unsized(&self) -> bool {
1030 self.abi.is_unsized()
1033 /// Returns `true` if the type is a ZST and not unsized.
1034 pub fn is_zst(&self) -> bool {
1037 Abi::ScalarPair(..) |
1038 Abi::Vector { .. } => false,
1039 Abi::Uninhabited => self.size.bytes() == 0,
1040 Abi::Aggregate { sized } => sized && self.size.bytes() == 0