4 use crate::json
::{Json, ToJson}
;
5 use crate::spec
::Target
;
7 use std
::convert
::{TryFrom, TryInto}
;
10 use std
::num
::NonZeroUsize
;
11 use std
::ops
::{Add, AddAssign, Deref, Mul, RangeInclusive, Sub}
;
12 use std
::str::FromStr
;
14 use rustc_data_structures
::intern
::Interned
;
15 use rustc_index
::vec
::{Idx, IndexVec}
;
16 use rustc_macros
::HashStable_Generic
;
20 /// Parsed [Data layout](https://llvm.org/docs/LangRef.html#data-layout)
21 /// for a target, which contains everything needed to compute layouts.
22 pub struct TargetDataLayout
{
24 pub i1_align
: AbiAndPrefAlign
,
25 pub i8_align
: AbiAndPrefAlign
,
26 pub i16_align
: AbiAndPrefAlign
,
27 pub i32_align
: AbiAndPrefAlign
,
28 pub i64_align
: AbiAndPrefAlign
,
29 pub i128_align
: AbiAndPrefAlign
,
30 pub f32_align
: AbiAndPrefAlign
,
31 pub f64_align
: AbiAndPrefAlign
,
32 pub pointer_size
: Size
,
33 pub pointer_align
: AbiAndPrefAlign
,
34 pub aggregate_align
: AbiAndPrefAlign
,
36 /// Alignments for vector types.
37 pub vector_align
: Vec
<(Size
, AbiAndPrefAlign
)>,
39 pub instruction_address_space
: AddressSpace
,
41 /// Minimum size of #[repr(C)] enums (default I32 bits)
42 pub c_enum_min_size
: Integer
,
45 impl Default
for TargetDataLayout
{
46 /// Creates an instance of `TargetDataLayout`.
47 fn default() -> TargetDataLayout
{
48 let align
= |bits
| Align
::from_bits(bits
).unwrap();
51 i1_align
: AbiAndPrefAlign
::new(align(8)),
52 i8_align
: AbiAndPrefAlign
::new(align(8)),
53 i16_align
: AbiAndPrefAlign
::new(align(16)),
54 i32_align
: AbiAndPrefAlign
::new(align(32)),
55 i64_align
: AbiAndPrefAlign { abi: align(32), pref: align(64) }
,
56 i128_align
: AbiAndPrefAlign { abi: align(32), pref: align(64) }
,
57 f32_align
: AbiAndPrefAlign
::new(align(32)),
58 f64_align
: AbiAndPrefAlign
::new(align(64)),
59 pointer_size
: Size
::from_bits(64),
60 pointer_align
: AbiAndPrefAlign
::new(align(64)),
61 aggregate_align
: AbiAndPrefAlign { abi: align(0), pref: align(64) }
,
63 (Size
::from_bits(64), AbiAndPrefAlign
::new(align(64))),
64 (Size
::from_bits(128), AbiAndPrefAlign
::new(align(128))),
66 instruction_address_space
: AddressSpace
::DATA
,
67 c_enum_min_size
: Integer
::I32
,
72 impl TargetDataLayout
{
73 pub fn parse(target
: &Target
) -> Result
<TargetDataLayout
, String
> {
74 // Parse an address space index from a string.
75 let parse_address_space
= |s
: &str, cause
: &str| {
76 s
.parse
::<u32>().map(AddressSpace
).map_err(|err
| {
77 format
!("invalid address space `{}` for `{}` in \"data-layout\": {}", s
, cause
, err
)
81 // Parse a bit count from a string.
82 let parse_bits
= |s
: &str, kind
: &str, cause
: &str| {
83 s
.parse
::<u64>().map_err(|err
| {
84 format
!("invalid {} `{}` for `{}` in \"data-layout\": {}", kind
, s
, cause
, err
)
88 // Parse a size string.
89 let size
= |s
: &str, cause
: &str| parse_bits(s
, "size", cause
).map(Size
::from_bits
);
91 // Parse an alignment string.
92 let align
= |s
: &[&str], cause
: &str| {
94 return Err(format
!("missing alignment for `{}` in \"data-layout\"", cause
));
96 let align_from_bits
= |bits
| {
97 Align
::from_bits(bits
).map_err(|err
| {
98 format
!("invalid alignment for `{}` in \"data-layout\": {}", cause
, err
)
101 let abi
= parse_bits(s
[0], "alignment", cause
)?
;
102 let pref
= s
.get(1).map_or(Ok(abi
), |pref
| parse_bits(pref
, "alignment", cause
))?
;
103 Ok(AbiAndPrefAlign { abi: align_from_bits(abi)?, pref: align_from_bits(pref)? }
)
106 let mut dl
= TargetDataLayout
::default();
107 let mut i128_align_src
= 64;
108 for spec
in target
.data_layout
.split('
-'
) {
109 let spec_parts
= spec
.split('
:'
).collect
::<Vec
<_
>>();
112 ["e"] => dl
.endian
= Endian
::Little
,
113 ["E"] => dl
.endian
= Endian
::Big
,
114 [p
] if p
.starts_with('P'
) => {
115 dl
.instruction_address_space
= parse_address_space(&p
[1..], "P")?
117 ["a", ref a @
..] => dl
.aggregate_align
= align(a
, "a")?
,
118 ["f32", ref a @
..] => dl
.f32_align
= align(a
, "f32")?
,
119 ["f64", ref a @
..] => dl
.f64_align
= align(a
, "f64")?
,
120 [p @
"p", s
, ref a @
..] | [p @
"p0", s
, ref a @
..] => {
121 dl
.pointer_size
= size(s
, p
)?
;
122 dl
.pointer_align
= align(a
, p
)?
;
124 [s
, ref a @
..] if s
.starts_with('i'
) => {
125 let Ok(bits
) = s
[1..].parse
::<u64>() else {
126 size(&s
[1..], "i")?
; // For the user error.
129 let a
= align(a
, s
)?
;
131 1 => dl
.i1_align
= a
,
132 8 => dl
.i8_align
= a
,
133 16 => dl
.i16_align
= a
,
134 32 => dl
.i32_align
= a
,
135 64 => dl
.i64_align
= a
,
138 if bits
>= i128_align_src
&& bits
<= 128 {
139 // Default alignment for i128 is decided by taking the alignment of
140 // largest-sized i{64..=128}.
141 i128_align_src
= bits
;
145 [s
, ref a @
..] if s
.starts_with('v'
) => {
146 let v_size
= size(&s
[1..], "v")?
;
147 let a
= align(a
, s
)?
;
148 if let Some(v
) = dl
.vector_align
.iter_mut().find(|v
| v
.0 == v_size
) {
152 // No existing entry, add a new one.
153 dl
.vector_align
.push((v_size
, a
));
155 _
=> {}
// Ignore everything else.
159 // Perform consistency checks against the Target information.
160 if dl
.endian
!= target
.endian
{
162 "inconsistent target specification: \"data-layout\" claims \
163 architecture is {}-endian, while \"target-endian\" is `{}`",
165 target
.endian
.as_str(),
169 let target_pointer_width
: u64 = target
.pointer_width
.into();
170 if dl
.pointer_size
.bits() != target_pointer_width
{
172 "inconsistent target specification: \"data-layout\" claims \
173 pointers are {}-bit, while \"target-pointer-width\" is `{}`",
174 dl
.pointer_size
.bits(),
179 dl
.c_enum_min_size
= Integer
::from_size(Size
::from_bits(target
.c_enum_min_bits
))?
;
184 /// Returns exclusive upper bound on object size.
186 /// The theoretical maximum object size is defined as the maximum positive `isize` value.
187 /// This ensures that the `offset` semantics remain well-defined by allowing it to correctly
188 /// index every address within an object along with one byte past the end, along with allowing
189 /// `isize` to store the difference between any two pointers into an object.
191 /// The upper bound on 64-bit currently needs to be lower because LLVM uses a 64-bit integer
192 /// to represent object size in bits. It would need to be 1 << 61 to account for this, but is
193 /// currently conservatively bounded to 1 << 47 as that is enough to cover the current usable
194 /// address space on 64-bit ARMv8 and x86_64.
196 pub fn obj_size_bound(&self) -> u64 {
197 match self.pointer_size
.bits() {
201 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
),
216 pub fn vector_align(&self, vec_size
: Size
) -> AbiAndPrefAlign
{
217 for &(size
, align
) in &self.vector_align
{
218 if size
== vec_size
{
222 // Default to natural alignment, which is what LLVM does.
223 // That is, use the size, rounded up to a power of 2.
224 AbiAndPrefAlign
::new(Align
::from_bytes(vec_size
.bytes().next_power_of_two()).unwrap())
228 pub trait HasDataLayout
{
229 fn data_layout(&self) -> &TargetDataLayout
;
232 impl HasDataLayout
for TargetDataLayout
{
234 fn data_layout(&self) -> &TargetDataLayout
{
239 /// Endianness of the target, which must match cfg(target-endian).
240 #[derive(Copy, Clone, PartialEq)]
247 pub fn as_str(&self) -> &'
static str {
249 Self::Little
=> "little",
255 impl fmt
::Debug
for Endian
{
256 fn fmt(&self, f
: &mut fmt
::Formatter
<'_
>) -> fmt
::Result
{
257 f
.write_str(self.as_str())
261 impl FromStr
for Endian
{
264 fn from_str(s
: &str) -> Result
<Self, Self::Err
> {
266 "little" => Ok(Self::Little
),
267 "big" => Ok(Self::Big
),
268 _
=> Err(format
!(r
#"unknown endian: "{}""#, s)),
273 impl ToJson
for Endian
{
274 fn to_json(&self) -> Json
{
275 self.as_str().to_json()
279 /// Size of a type in bytes.
280 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable)]
281 #[derive(HashStable_Generic)]
286 // This is debug-printed a lot in larger structs, don't waste too much space there
287 impl fmt
::Debug
for Size
{
288 fn fmt(&self, f
: &mut fmt
::Formatter
<'_
>) -> fmt
::Result
{
289 write
!(f
, "Size({} bytes)", self.bytes())
294 pub const ZERO
: Size
= Size { raw: 0 }
;
296 /// Rounds `bits` up to the next-higher byte boundary, if `bits` is
297 /// not a multiple of 8.
298 pub fn from_bits(bits
: impl TryInto
<u64>) -> Size
{
299 let bits
= bits
.try_into().ok().unwrap();
300 // Avoid potential overflow from `bits + 7`.
301 Size { raw: bits / 8 + ((bits % 8) + 7) / 8 }
305 pub fn from_bytes(bytes
: impl TryInto
<u64>) -> Size
{
306 let bytes
: u64 = bytes
.try_into().ok().unwrap();
311 pub fn bytes(self) -> u64 {
316 pub fn bytes_usize(self) -> usize {
317 self.bytes().try_into().unwrap()
321 pub fn bits(self) -> u64 {
323 fn overflow(bytes
: u64) -> ! {
324 panic
!("Size::bits: {} bytes in bits doesn't fit in u64", bytes
)
327 self.bytes().checked_mul(8).unwrap_or_else(|| overflow(self.bytes()))
331 pub fn bits_usize(self) -> usize {
332 self.bits().try_into().unwrap()
336 pub fn align_to(self, align
: Align
) -> Size
{
337 let mask
= align
.bytes() - 1;
338 Size
::from_bytes((self.bytes() + mask
) & !mask
)
342 pub fn is_aligned(self, align
: Align
) -> bool
{
343 let mask
= align
.bytes() - 1;
344 self.bytes() & mask
== 0
348 pub fn checked_add
<C
: HasDataLayout
>(self, offset
: Size
, cx
: &C
) -> Option
<Size
> {
349 let dl
= cx
.data_layout();
351 let bytes
= self.bytes().checked_add(offset
.bytes())?
;
353 if bytes
< dl
.obj_size_bound() { Some(Size::from_bytes(bytes)) }
else { None }
357 pub fn checked_mul
<C
: HasDataLayout
>(self, count
: u64, cx
: &C
) -> Option
<Size
> {
358 let dl
= cx
.data_layout();
360 let bytes
= self.bytes().checked_mul(count
)?
;
361 if bytes
< dl
.obj_size_bound() { Some(Size::from_bytes(bytes)) }
else { None }
364 /// Truncates `value` to `self` bits and then sign-extends it to 128 bits
365 /// (i.e., if it is negative, fill with 1's on the left).
367 pub fn sign_extend(self, value
: u128
) -> u128
{
368 let size
= self.bits();
370 // Truncated until nothing is left.
374 let shift
= 128 - size
;
375 // Shift the unsigned value to the left, then shift back to the right as signed
376 // (essentially fills with sign bit on the left).
377 (((value
<< shift
) as i128
) >> shift
) as u128
380 /// Truncates `value` to `self` bits.
382 pub fn truncate(self, value
: u128
) -> u128
{
383 let size
= self.bits();
385 // Truncated until nothing is left.
388 let shift
= 128 - size
;
389 // Truncate (shift left to drop out leftover values, shift right to fill with zeroes).
390 (value
<< shift
) >> shift
394 pub fn signed_int_min(&self) -> i128
{
395 self.sign_extend(1_u128 << (self.bits() - 1)) as i128
399 pub fn signed_int_max(&self) -> i128
{
400 i128
::MAX
>> (128 - self.bits())
404 pub fn unsigned_int_max(&self) -> u128
{
405 u128
::MAX
>> (128 - self.bits())
409 // Panicking addition, subtraction and multiplication for convenience.
410 // Avoid during layout computation, return `LayoutError` instead.
415 fn add(self, other
: Size
) -> Size
{
416 Size
::from_bytes(self.bytes().checked_add(other
.bytes()).unwrap_or_else(|| {
417 panic
!("Size::add: {} + {} doesn't fit in u64", self.bytes(), other
.bytes())
425 fn sub(self, other
: Size
) -> Size
{
426 Size
::from_bytes(self.bytes().checked_sub(other
.bytes()).unwrap_or_else(|| {
427 panic
!("Size::sub: {} - {} would result in negative size", self.bytes(), other
.bytes())
432 impl Mul
<Size
> for u64 {
435 fn mul(self, size
: Size
) -> Size
{
440 impl Mul
<u64> for Size
{
443 fn mul(self, count
: u64) -> Size
{
444 match self.bytes().checked_mul(count
) {
445 Some(bytes
) => Size
::from_bytes(bytes
),
446 None
=> panic
!("Size::mul: {} * {} doesn't fit in u64", self.bytes(), count
),
451 impl AddAssign
for Size
{
453 fn add_assign(&mut self, other
: Size
) {
454 *self = *self + other
;
460 fn steps_between(start
: &Self, end
: &Self) -> Option
<usize> {
461 u64::steps_between(&start
.bytes(), &end
.bytes())
465 fn forward_checked(start
: Self, count
: usize) -> Option
<Self> {
466 u64::forward_checked(start
.bytes(), count
).map(Self::from_bytes
)
470 fn forward(start
: Self, count
: usize) -> Self {
471 Self::from_bytes(u64::forward(start
.bytes(), count
))
475 unsafe fn forward_unchecked(start
: Self, count
: usize) -> Self {
476 Self::from_bytes(u64::forward_unchecked(start
.bytes(), count
))
480 fn backward_checked(start
: Self, count
: usize) -> Option
<Self> {
481 u64::backward_checked(start
.bytes(), count
).map(Self::from_bytes
)
485 fn backward(start
: Self, count
: usize) -> Self {
486 Self::from_bytes(u64::backward(start
.bytes(), count
))
490 unsafe fn backward_unchecked(start
: Self, count
: usize) -> Self {
491 Self::from_bytes(u64::backward_unchecked(start
.bytes(), count
))
495 /// Alignment of a type in bytes (always a power of two).
496 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable)]
497 #[derive(HashStable_Generic)]
502 // This is debug-printed a lot in larger structs, don't waste too much space there
503 impl fmt
::Debug
for Align
{
504 fn fmt(&self, f
: &mut fmt
::Formatter
<'_
>) -> fmt
::Result
{
505 write
!(f
, "Align({} bytes)", self.bytes())
510 pub const ONE
: Align
= Align { pow2: 0 }
;
513 pub fn from_bits(bits
: u64) -> Result
<Align
, String
> {
514 Align
::from_bytes(Size
::from_bits(bits
).bytes())
518 pub fn from_bytes(align
: u64) -> Result
<Align
, String
> {
519 // Treat an alignment of 0 bytes like 1-byte alignment.
521 return Ok(Align
::ONE
);
525 fn not_power_of_2(align
: u64) -> String
{
526 format
!("`{}` is not a power of 2", align
)
530 fn too_large(align
: u64) -> String
{
531 format
!("`{}` is too large", align
)
534 let mut bytes
= align
;
535 let mut pow2
: u8 = 0;
536 while (bytes
& 1) == 0 {
541 return Err(not_power_of_2(align
));
544 return Err(too_large(align
));
551 pub fn bytes(self) -> u64 {
556 pub fn bits(self) -> u64 {
560 /// Computes the best alignment possible for the given offset
561 /// (the largest power of two that the offset is a multiple of).
563 /// N.B., for an offset of `0`, this happens to return `2^64`.
565 pub fn max_for_offset(offset
: Size
) -> Align
{
566 Align { pow2: offset.bytes().trailing_zeros() as u8 }
569 /// Lower the alignment, if necessary, such that the given offset
570 /// is aligned to it (the offset is a multiple of the alignment).
572 pub fn restrict_for_offset(self, offset
: Size
) -> Align
{
573 self.min(Align
::max_for_offset(offset
))
577 /// A pair of alignments, ABI-mandated and preferred.
578 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
579 #[derive(HashStable_Generic)]
580 pub struct AbiAndPrefAlign
{
585 impl AbiAndPrefAlign
{
587 pub fn new(align
: Align
) -> AbiAndPrefAlign
{
588 AbiAndPrefAlign { abi: align, pref: align }
592 pub fn min(self, other
: AbiAndPrefAlign
) -> AbiAndPrefAlign
{
593 AbiAndPrefAlign { abi: self.abi.min(other.abi), pref: self.pref.min(other.pref) }
597 pub fn max(self, other
: AbiAndPrefAlign
) -> AbiAndPrefAlign
{
598 AbiAndPrefAlign { abi: self.abi.max(other.abi), pref: self.pref.max(other.pref) }
602 /// Integers, also used for enum discriminants.
603 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, HashStable_Generic)]
614 pub fn size(self) -> Size
{
616 I8
=> Size
::from_bytes(1),
617 I16
=> Size
::from_bytes(2),
618 I32
=> Size
::from_bytes(4),
619 I64
=> Size
::from_bytes(8),
620 I128
=> Size
::from_bytes(16),
624 pub fn align
<C
: HasDataLayout
>(self, cx
: &C
) -> AbiAndPrefAlign
{
625 let dl
= cx
.data_layout();
632 I128
=> dl
.i128_align
,
636 /// Finds the smallest Integer type which can represent the signed value.
638 pub fn fit_signed(x
: i128
) -> Integer
{
640 -0x0000_0000_0000_0080..=0x0000_0000_0000_007f => I8
,
641 -0x0000_0000_0000_8000..=0x0000_0000_0000_7fff => I16
,
642 -0x0000_0000_8000_0000..=0x0000_0000_7fff_ffff => I32
,
643 -0x8000_0000_0000_0000..=0x7fff_ffff_ffff_ffff => I64
,
648 /// Finds the smallest Integer type which can represent the unsigned value.
650 pub fn fit_unsigned(x
: u128
) -> Integer
{
652 0..=0x0000_0000_0000_00ff => I8
,
653 0..=0x0000_0000_0000_ffff => I16
,
654 0..=0x0000_0000_ffff_ffff => I32
,
655 0..=0xffff_ffff_ffff_ffff => I64
,
660 /// Finds the smallest integer with the given alignment.
661 pub fn for_align
<C
: HasDataLayout
>(cx
: &C
, wanted
: Align
) -> Option
<Integer
> {
662 let dl
= cx
.data_layout();
664 for candidate
in [I8
, I16
, I32
, I64
, I128
] {
665 if wanted
== candidate
.align(dl
).abi
&& wanted
.bytes() == candidate
.size().bytes() {
666 return Some(candidate
);
672 /// Find the largest integer with the given alignment or less.
673 pub fn approximate_align
<C
: HasDataLayout
>(cx
: &C
, wanted
: Align
) -> Integer
{
674 let dl
= cx
.data_layout();
676 // FIXME(eddyb) maybe include I128 in the future, when it works everywhere.
677 for candidate
in [I64
, I32
, I16
] {
678 if wanted
>= candidate
.align(dl
).abi
&& wanted
.bytes() >= candidate
.size().bytes() {
685 // FIXME(eddyb) consolidate this and other methods that find the appropriate
686 // `Integer` given some requirements.
688 fn from_size(size
: Size
) -> Result
<Self, String
> {
690 8 => Ok(Integer
::I8
),
691 16 => Ok(Integer
::I16
),
692 32 => Ok(Integer
::I32
),
693 64 => Ok(Integer
::I64
),
694 128 => Ok(Integer
::I128
),
695 _
=> Err(format
!("rust does not support integers with {} bits", size
.bits())),
700 /// Fundamental unit of memory access and layout.
701 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
703 /// The `bool` is the signedness of the `Integer` type.
705 /// One would think we would not care about such details this low down,
706 /// but some ABIs are described in terms of C types and ISAs where the
707 /// integer arithmetic is done on {sign,zero}-extended registers, e.g.
708 /// a negative integer passed by zero-extension will appear positive in
709 /// the callee, and most operations on it will produce the wrong values.
717 pub fn size
<C
: HasDataLayout
>(self, cx
: &C
) -> Size
{
718 let dl
= cx
.data_layout();
721 Int(i
, _
) => i
.size(),
722 F32
=> Size
::from_bits(32),
723 F64
=> Size
::from_bits(64),
724 Pointer
=> dl
.pointer_size
,
728 pub fn align
<C
: HasDataLayout
>(self, cx
: &C
) -> AbiAndPrefAlign
{
729 let dl
= cx
.data_layout();
732 Int(i
, _
) => i
.align(dl
),
735 Pointer
=> dl
.pointer_align
,
739 // FIXME(eddyb) remove, it's trivial thanks to `matches!`.
741 pub fn is_float(self) -> bool
{
742 matches
!(self, F32
| F64
)
745 // FIXME(eddyb) remove, it's completely unused.
747 pub fn is_int(self) -> bool
{
748 matches
!(self, Int(..))
752 pub fn is_ptr(self) -> bool
{
753 matches
!(self, Pointer
)
757 /// Inclusive wrap-around range of valid values, that is, if
758 /// start > end, it represents `start..=MAX`,
759 /// followed by `0..=end`.
761 /// That is, for an i8 primitive, a range of `254..=2` means following
764 /// 254 (-2), 255 (-1), 0, 1, 2
766 /// This is intended specifically to mirror LLVM’s `!range` metadata semantics.
767 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
768 #[derive(HashStable_Generic)]
769 pub struct WrappingRange
{
775 pub fn full(size
: Size
) -> Self {
776 Self { start: 0, end: size.unsigned_int_max() }
779 /// Returns `true` if `v` is contained in the range.
781 pub fn contains(&self, v
: u128
) -> bool
{
782 if self.start
<= self.end
{
783 self.start
<= v
&& v
<= self.end
785 self.start
<= v
|| v
<= self.end
789 /// Returns `self` with replaced `start`
791 pub fn with_start(mut self, start
: u128
) -> Self {
796 /// Returns `self` with replaced `end`
798 pub fn with_end(mut self, end
: u128
) -> Self {
803 /// Returns `true` if `size` completely fills the range.
805 pub fn is_full_for(&self, size
: Size
) -> bool
{
806 let max_value
= size
.unsigned_int_max();
807 debug_assert
!(self.start
<= max_value
&& self.end
<= max_value
);
808 self.start
== (self.end
.wrapping_add(1) & max_value
)
812 impl fmt
::Debug
for WrappingRange
{
813 fn fmt(&self, fmt
: &mut fmt
::Formatter
<'_
>) -> fmt
::Result
{
814 if self.start
> self.end
{
815 write
!(fmt
, "(..={}) | ({}..)", self.end
, self.start
)?
;
817 write
!(fmt
, "{}..={}", self.start
, self.end
)?
;
823 /// Information about one scalar component of a Rust type.
824 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
825 #[derive(HashStable_Generic)]
830 // FIXME(eddyb) always use the shortest range, e.g., by finding
831 // the largest space between two consecutive valid values and
832 // taking everything else as the (shortest) valid range.
833 valid_range
: WrappingRange
,
836 /// Even for unions, we need to use the correct registers for the kind of
837 /// values inside the union, so we keep the `Primitive` type around. We
838 /// also use it to compute the size of the scalar.
839 /// However, unions never have niches and even allow undef,
840 /// so there is no `valid_range`.
847 pub fn is_bool(&self) -> bool
{
850 Scalar
::Initialized
{
851 value
: Int(I8
, false),
852 valid_range
: WrappingRange { start: 0, end: 1 }
857 /// Get the primitive representation of this type, ignoring the valid range and whether the
858 /// value is allowed to be undefined (due to being a union).
859 pub fn primitive(&self) -> Primitive
{
861 Scalar
::Initialized { value, .. }
| Scalar
::Union { value }
=> value
,
865 pub fn align(self, cx
: &impl HasDataLayout
) -> AbiAndPrefAlign
{
866 self.primitive().align(cx
)
869 pub fn size(self, cx
: &impl HasDataLayout
) -> Size
{
870 self.primitive().size(cx
)
874 pub fn to_union(&self) -> Self {
875 Self::Union { value: self.primitive() }
879 pub fn valid_range(&self, cx
: &impl HasDataLayout
) -> WrappingRange
{
881 Scalar
::Initialized { valid_range, .. }
=> valid_range
,
882 Scalar
::Union { value }
=> WrappingRange
::full(value
.size(cx
)),
887 /// Allows the caller to mutate the valid range. This operation will panic if attempted on a union.
888 pub fn valid_range_mut(&mut self) -> &mut WrappingRange
{
890 Scalar
::Initialized { valid_range, .. }
=> valid_range
,
891 Scalar
::Union { .. }
=> panic
!("cannot change the valid range of a union"),
895 /// Returns `true` if all possible numbers are valid, i.e `valid_range` covers the whole layout
897 pub fn is_always_valid
<C
: HasDataLayout
>(&self, cx
: &C
) -> bool
{
899 Scalar
::Initialized { valid_range, .. }
=> valid_range
.is_full_for(self.size(cx
)),
900 Scalar
::Union { .. }
=> true,
904 /// Returns `true` if this type can be left uninit.
906 pub fn is_uninit_valid(&self) -> bool
{
908 Scalar
::Initialized { .. }
=> false,
909 Scalar
::Union { .. }
=> true,
914 /// Describes how the fields of a type are located in memory.
915 #[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
916 pub enum FieldsShape
{
917 /// Scalar primitives and `!`, which never have fields.
920 /// All fields start at no offset. The `usize` is the field count.
923 /// Array/vector-like placement, with all fields of identical types.
924 Array { stride: Size, count: u64 }
,
926 /// Struct-like placement, with precomputed offsets.
928 /// Fields are guaranteed to not overlap, but note that gaps
929 /// before, between and after all the fields are NOT always
930 /// padding, and as such their contents may not be discarded.
931 /// For example, enum variants leave a gap at the start,
932 /// where the discriminant field in the enum layout goes.
934 /// Offsets for the first byte of each field,
935 /// ordered to match the source definition order.
936 /// This vector does not go in increasing order.
937 // FIXME(eddyb) use small vector optimization for the common case.
940 /// Maps source order field indices to memory order indices,
941 /// depending on how the fields were reordered (if at all).
942 /// This is a permutation, with both the source order and the
943 /// memory order using the same (0..n) index ranges.
945 /// Note that during computation of `memory_index`, sometimes
946 /// it is easier to operate on the inverse mapping (that is,
947 /// from memory order to source order), and that is usually
948 /// named `inverse_memory_index`.
950 // FIXME(eddyb) build a better abstraction for permutations, if possible.
951 // FIXME(camlorn) also consider small vector optimization here.
952 memory_index
: Vec
<u32>,
958 pub fn count(&self) -> usize {
960 FieldsShape
::Primitive
=> 0,
961 FieldsShape
::Union(count
) => count
.get(),
962 FieldsShape
::Array { count, .. }
=> count
.try_into().unwrap(),
963 FieldsShape
::Arbitrary { ref offsets, .. }
=> offsets
.len(),
968 pub fn offset(&self, i
: usize) -> Size
{
970 FieldsShape
::Primitive
=> {
971 unreachable
!("FieldsShape::offset: `Primitive`s have no fields")
973 FieldsShape
::Union(count
) => {
976 "tried to access field {} of union with {} fields",
982 FieldsShape
::Array { stride, count }
=> {
983 let i
= u64::try_from(i
).unwrap();
987 FieldsShape
::Arbitrary { ref offsets, .. }
=> offsets
[i
],
992 pub fn memory_index(&self, i
: usize) -> usize {
994 FieldsShape
::Primitive
=> {
995 unreachable
!("FieldsShape::memory_index: `Primitive`s have no fields")
997 FieldsShape
::Union(_
) | FieldsShape
::Array { .. }
=> i
,
998 FieldsShape
::Arbitrary { ref memory_index, .. }
=> memory_index
[i
].try_into().unwrap(),
1002 /// Gets source indices of the fields by increasing offsets.
1004 pub fn index_by_increasing_offset
<'a
>(&'a
self) -> impl Iterator
<Item
= usize> + 'a
{
1005 let mut inverse_small
= [0u8; 64];
1006 let mut inverse_big
= vec
![];
1007 let use_small
= self.count() <= inverse_small
.len();
1009 // We have to write this logic twice in order to keep the array small.
1010 if let FieldsShape
::Arbitrary { ref memory_index, .. }
= *self {
1012 for i
in 0..self.count() {
1013 inverse_small
[memory_index
[i
] as usize] = i
as u8;
1016 inverse_big
= vec
![0; self.count()];
1017 for i
in 0..self.count() {
1018 inverse_big
[memory_index
[i
] as usize] = i
as u32;
1023 (0..self.count()).map(move |i
| match *self {
1024 FieldsShape
::Primitive
| FieldsShape
::Union(_
) | FieldsShape
::Array { .. }
=> i
,
1025 FieldsShape
::Arbitrary { .. }
=> {
1027 inverse_small
[i
] as usize
1029 inverse_big
[i
] as usize
1036 /// An identifier that specifies the address space that some operation
1037 /// should operate on. Special address spaces have an effect on code generation,
1038 /// depending on the target and the address spaces it implements.
1039 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
1040 pub struct AddressSpace(pub u32);
1043 /// The default address space, corresponding to data space.
1044 pub const DATA
: Self = AddressSpace(0);
1047 /// Describes how values of the type are passed by target ABIs,
1048 /// in terms of categories of C types there are ABI rules for.
1049 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
1053 ScalarPair(Scalar
, Scalar
),
1059 /// If true, the size is exact, otherwise it's only a lower bound.
1065 /// Returns `true` if the layout corresponds to an unsized type.
1067 pub fn is_unsized(&self) -> bool
{
1069 Abi
::Uninhabited
| Abi
::Scalar(_
) | Abi
::ScalarPair(..) | Abi
::Vector { .. }
=> false,
1070 Abi
::Aggregate { sized }
=> !sized
,
1074 /// Returns `true` if this is a single signed integer scalar
1076 pub fn is_signed(&self) -> bool
{
1078 Abi
::Scalar(scal
) => match scal
.primitive() {
1079 Primitive
::Int(_
, signed
) => signed
,
1082 _
=> panic
!("`is_signed` on non-scalar ABI {:?}", self),
1086 /// Returns `true` if this is an uninhabited type
1088 pub fn is_uninhabited(&self) -> bool
{
1089 matches
!(*self, Abi
::Uninhabited
)
1092 /// Returns `true` is this is a scalar type
1094 pub fn is_scalar(&self) -> bool
{
1095 matches
!(*self, Abi
::Scalar(_
))
1099 rustc_index
::newtype_index
! {
1100 pub struct VariantIdx
{
1101 derive
[HashStable_Generic
]
1105 #[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
1106 pub enum Variants
<'a
> {
1107 /// Single enum variants, structs/tuples, unions, and all non-ADTs.
1108 Single { index: VariantIdx }
,
1110 /// Enum-likes with more than one inhabited variant: each variant comes with
1111 /// a *discriminant* (usually the same as the variant index but the user can
1112 /// assign explicit discriminant values). That discriminant is encoded
1113 /// as a *tag* on the machine. The layout of each variant is
1114 /// a struct, and they all have space reserved for the tag.
1115 /// For enums, the tag is the sole field of the layout.
1118 tag_encoding
: TagEncoding
,
1120 variants
: IndexVec
<VariantIdx
, Layout
<'a
>>,
1124 #[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
1125 pub enum TagEncoding
{
1126 /// The tag directly stores the discriminant, but possibly with a smaller layout
1127 /// (so converting the tag to the discriminant can require sign extension).
1130 /// Niche (values invalid for a type) encoding the discriminant:
1131 /// Discriminant and variant index coincide.
1132 /// The variant `dataful_variant` contains a niche at an arbitrary
1133 /// offset (field `tag_field` of the enum), which for a variant with
1134 /// discriminant `d` is set to
1135 /// `(d - niche_variants.start).wrapping_add(niche_start)`.
1137 /// For example, `Option<(usize, &T)>` is represented such that
1138 /// `None` has a null pointer for the second tuple field, and
1139 /// `Some` is the identity function (with a non-null reference).
1141 dataful_variant
: VariantIdx
,
1142 niche_variants
: RangeInclusive
<VariantIdx
>,
1147 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
1150 pub value
: Primitive
,
1151 pub valid_range
: WrappingRange
,
1155 pub fn from_scalar
<C
: HasDataLayout
>(cx
: &C
, offset
: Size
, scalar
: Scalar
) -> Option
<Self> {
1156 let Scalar
::Initialized { value, valid_range }
= scalar
else { return None }
;
1157 let niche
= Niche { offset, value, valid_range }
;
1158 if niche
.available(cx
) > 0 { Some(niche) }
else { None }
1161 pub fn available
<C
: HasDataLayout
>(&self, cx
: &C
) -> u128
{
1162 let Self { value, valid_range: v, .. }
= *self;
1163 let size
= value
.size(cx
);
1164 assert
!(size
.bits() <= 128);
1165 let max_value
= size
.unsigned_int_max();
1167 // Find out how many values are outside the valid range.
1168 let niche
= v
.end
.wrapping_add(1)..v
.start
;
1169 niche
.end
.wrapping_sub(niche
.start
) & max_value
1172 pub fn reserve
<C
: HasDataLayout
>(&self, cx
: &C
, count
: u128
) -> Option
<(u128
, Scalar
)> {
1175 let Self { value, valid_range: v, .. }
= *self;
1176 let size
= value
.size(cx
);
1177 assert
!(size
.bits() <= 128);
1178 let max_value
= size
.unsigned_int_max();
1180 let niche
= v
.end
.wrapping_add(1)..v
.start
;
1181 let available
= niche
.end
.wrapping_sub(niche
.start
) & max_value
;
1182 if count
> available
{
1186 // Extend the range of valid values being reserved by moving either `v.start` or `v.end` bound.
1187 // Given an eventual `Option<T>`, we try to maximize the chance for `None` to occupy the niche of zero.
1188 // This is accomplished by preferring enums with 2 variants(`count==1`) and always taking the shortest path to niche zero.
1189 // Having `None` in niche zero can enable some special optimizations.
1191 // Bound selection criteria:
1192 // 1. Select closest to zero given wrapping semantics.
1193 // 2. Avoid moving past zero if possible.
1195 // In practice this means that enums with `count > 1` are unlikely to claim niche zero, since they have to fit perfectly.
1196 // If niche zero is already reserved, the selection of bounds are of little interest.
1197 let move_start
= |v
: WrappingRange
| {
1198 let start
= v
.start
.wrapping_sub(count
) & max_value
;
1199 Some((start
, Scalar
::Initialized { value, valid_range: v.with_start(start) }
))
1201 let move_end
= |v
: WrappingRange
| {
1202 let start
= v
.end
.wrapping_add(1) & max_value
;
1203 let end
= v
.end
.wrapping_add(count
) & max_value
;
1204 Some((start
, Scalar
::Initialized { value, valid_range: v.with_end(end) }
))
1206 let distance_end_zero
= max_value
- v
.end
;
1207 if v
.start
> v
.end
{
1208 // zero is unavailable because wrapping occurs
1210 } else if v
.start
<= distance_end_zero
{
1211 if count
<= v
.start
{
1214 // moved past zero, use other bound
1218 let end
= v
.end
.wrapping_add(count
) & max_value
;
1219 let overshot_zero
= (1..=v
.end
).contains(&end
);
1221 // moved past zero, use other bound
1230 #[derive(PartialEq, Eq, Hash, HashStable_Generic)]
1231 pub struct LayoutS
<'a
> {
1232 /// Says where the fields are located within the layout.
1233 pub fields
: FieldsShape
,
1235 /// Encodes information about multi-variant layouts.
1236 /// Even with `Multiple` variants, a layout still has its own fields! Those are then
1237 /// shared between all variants. One of them will be the discriminant,
1238 /// but e.g. generators can have more.
1240 /// To access all fields of this layout, both `fields` and the fields of the active variant
1241 /// must be taken into account.
1242 pub variants
: Variants
<'a
>,
1244 /// The `abi` defines how this data is passed between functions, and it defines
1245 /// value restrictions via `valid_range`.
1247 /// Note that this is entirely orthogonal to the recursive structure defined by
1248 /// `variants` and `fields`; for example, `ManuallyDrop<Result<isize, isize>>` has
1249 /// `Abi::ScalarPair`! So, even with non-`Aggregate` `abi`, `fields` and `variants`
1250 /// have to be taken into account to find all fields of this layout.
1253 /// The leaf scalar with the largest number of invalid values
1254 /// (i.e. outside of its `valid_range`), if it exists.
1255 pub largest_niche
: Option
<Niche
>,
1257 pub align
: AbiAndPrefAlign
,
1261 impl<'a
> LayoutS
<'a
> {
1262 pub fn scalar
<C
: HasDataLayout
>(cx
: &C
, scalar
: Scalar
) -> Self {
1263 let largest_niche
= Niche
::from_scalar(cx
, Size
::ZERO
, scalar
);
1264 let size
= scalar
.size(cx
);
1265 let align
= scalar
.align(cx
);
1267 variants
: Variants
::Single { index: VariantIdx::new(0) }
,
1268 fields
: FieldsShape
::Primitive
,
1269 abi
: Abi
::Scalar(scalar
),
1277 impl<'a
> fmt
::Debug
for LayoutS
<'a
> {
1278 fn fmt(&self, f
: &mut fmt
::Formatter
<'_
>) -> fmt
::Result
{
1279 // This is how `Layout` used to print before it become
1280 // `Interned<LayoutS>`. We print it like this to avoid having to update
1281 // expected output in a lot of tests.
1282 f
.debug_struct("Layout")
1283 .field("fields", &self.fields
)
1284 .field("variants", &self.variants
)
1285 .field("abi", &self.abi
)
1286 .field("largest_niche", &self.largest_niche
)
1287 .field("align", &self.align
)
1288 .field("size", &self.size
)
1293 #[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable_Generic)]
1294 #[rustc_pass_by_value]
1295 pub struct Layout
<'a
>(pub Interned
<'a
, LayoutS
<'a
>>);
1297 impl<'a
> fmt
::Debug
for Layout
<'a
> {
1298 fn fmt(&self, f
: &mut fmt
::Formatter
<'_
>) -> fmt
::Result
{
1299 // See comment on `<LayoutS as Debug>::fmt` above.
1304 impl<'a
> Layout
<'a
> {
1305 pub fn fields(self) -> &'a FieldsShape
{
1309 pub fn variants(self) -> &'a Variants
<'a
> {
1313 pub fn abi(self) -> Abi
{
1317 pub fn largest_niche(self) -> Option
<Niche
> {
1318 self.0.0.largest_niche
1321 pub fn align(self) -> AbiAndPrefAlign
{
1325 pub fn size(self) -> Size
{
1330 /// The layout of a type, alongside the type itself.
1331 /// Provides various type traversal APIs (e.g., recursing into fields).
1333 /// Note that the layout is NOT guaranteed to always be identical
1334 /// to that obtained from `layout_of(ty)`, as we need to produce
1335 /// layouts for which Rust types do not exist, such as enum variants
1336 /// or synthetic fields of enums (i.e., discriminants) and fat pointers.
1337 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable_Generic)]
1338 pub struct TyAndLayout
<'a
, Ty
> {
1340 pub layout
: Layout
<'a
>,
1343 impl<'a
, Ty
> Deref
for TyAndLayout
<'a
, Ty
> {
1344 type Target
= &'a LayoutS
<'a
>;
1345 fn deref(&self) -> &&'a LayoutS
<'a
> {
1350 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
1351 pub enum PointerKind
{
1352 /// Most general case, we know no restrictions to tell LLVM.
1355 /// `&T` where `T` contains no `UnsafeCell`, is `noalias` and `readonly`.
1358 /// `&mut T` which is `noalias` but not `readonly`.
1361 /// `Box<T>`, unlike `UniqueBorrowed`, it also has `noalias` on returns.
1365 #[derive(Copy, Clone, Debug)]
1366 pub struct PointeeInfo
{
1369 pub safe
: Option
<PointerKind
>,
1370 pub address_space
: AddressSpace
,
1373 /// Used in `might_permit_raw_init` to indicate the kind of initialisation
1374 /// that is checked to be valid
1375 #[derive(Copy, Clone, Debug)]
1381 /// Trait that needs to be implemented by the higher-level type representation
1382 /// (e.g. `rustc_middle::ty::Ty`), to provide `rustc_target::abi` functionality.
1383 pub trait TyAbiInterface
<'a
, C
>: Sized
{
1384 fn ty_and_layout_for_variant(
1385 this
: TyAndLayout
<'a
, Self>,
1387 variant_index
: VariantIdx
,
1388 ) -> TyAndLayout
<'a
, Self>;
1389 fn ty_and_layout_field(this
: TyAndLayout
<'a
, Self>, cx
: &C
, i
: usize) -> TyAndLayout
<'a
, Self>;
1390 fn ty_and_layout_pointee_info_at(
1391 this
: TyAndLayout
<'a
, Self>,
1394 ) -> Option
<PointeeInfo
>;
1395 fn is_adt(this
: TyAndLayout
<'a
, Self>) -> bool
;
1396 fn is_never(this
: TyAndLayout
<'a
, Self>) -> bool
;
1397 fn is_tuple(this
: TyAndLayout
<'a
, Self>) -> bool
;
1398 fn is_unit(this
: TyAndLayout
<'a
, Self>) -> bool
;
1401 impl<'a
, Ty
> TyAndLayout
<'a
, Ty
> {
1402 pub fn for_variant
<C
>(self, cx
: &C
, variant_index
: VariantIdx
) -> Self
1404 Ty
: TyAbiInterface
<'a
, C
>,
1406 Ty
::ty_and_layout_for_variant(self, cx
, variant_index
)
1409 pub fn field
<C
>(self, cx
: &C
, i
: usize) -> Self
1411 Ty
: TyAbiInterface
<'a
, C
>,
1413 Ty
::ty_and_layout_field(self, cx
, i
)
1416 pub fn pointee_info_at
<C
>(self, cx
: &C
, offset
: Size
) -> Option
<PointeeInfo
>
1418 Ty
: TyAbiInterface
<'a
, C
>,
1420 Ty
::ty_and_layout_pointee_info_at(self, cx
, offset
)
1423 pub fn is_single_fp_element
<C
>(self, cx
: &C
) -> bool
1425 Ty
: TyAbiInterface
<'a
, C
>,
1429 Abi
::Scalar(scalar
) => scalar
.primitive().is_float(),
1430 Abi
::Aggregate { .. }
=> {
1431 if self.fields
.count() == 1 && self.fields
.offset(0).bytes() == 0 {
1432 self.field(cx
, 0).is_single_fp_element(cx
)
1441 pub fn is_adt
<C
>(self) -> bool
1443 Ty
: TyAbiInterface
<'a
, C
>,
1448 pub fn is_never
<C
>(self) -> bool
1450 Ty
: TyAbiInterface
<'a
, C
>,
1455 pub fn is_tuple
<C
>(self) -> bool
1457 Ty
: TyAbiInterface
<'a
, C
>,
1462 pub fn is_unit
<C
>(self) -> bool
1464 Ty
: TyAbiInterface
<'a
, C
>,
1470 impl<'a
, Ty
> TyAndLayout
<'a
, Ty
> {
1471 /// Returns `true` if the layout corresponds to an unsized type.
1472 pub fn is_unsized(&self) -> bool
{
1473 self.abi
.is_unsized()
1476 /// Returns `true` if the type is a ZST and not unsized.
1477 pub fn is_zst(&self) -> bool
{
1479 Abi
::Scalar(_
) | Abi
::ScalarPair(..) | Abi
::Vector { .. }
=> false,
1480 Abi
::Uninhabited
=> self.size
.bytes() == 0,
1481 Abi
::Aggregate { sized }
=> sized
&& self.size
.bytes() == 0,
1485 /// Determines if this type permits "raw" initialization by just transmuting some
1486 /// memory into an instance of `T`.
1488 /// `init_kind` indicates if the memory is zero-initialized or left uninitialized.
1490 /// `strict` is an opt-in debugging flag added in #97323 that enables more checks.
1492 /// This is conservative: in doubt, it will answer `true`.
1494 /// FIXME: Once we removed all the conservatism, we could alternatively
1495 /// create an all-0/all-undef constant and run the const value validator to see if
1496 /// this is a valid value for the given type.
1497 pub fn might_permit_raw_init
<C
>(self, cx
: &C
, init_kind
: InitKind
, strict
: bool
) -> bool
1500 Ty
: TyAbiInterface
<'a
, C
>,
1503 let scalar_allows_raw_init
= move |s
: Scalar
| -> bool
{
1506 // The range must contain 0.
1507 s
.valid_range(cx
).contains(0)
1509 InitKind
::Uninit
=> {
1511 // The type must be allowed to be uninit (which means "is a union").
1514 // The range must include all values.
1515 s
.is_always_valid(cx
)
1522 let valid
= match self.abi
{
1523 Abi
::Uninhabited
=> false, // definitely UB
1524 Abi
::Scalar(s
) => scalar_allows_raw_init(s
),
1525 Abi
::ScalarPair(s1
, s2
) => scalar_allows_raw_init(s1
) && scalar_allows_raw_init(s2
),
1526 Abi
::Vector { element: s, count }
=> count
== 0 || scalar_allows_raw_init(s
),
1527 Abi
::Aggregate { .. }
=> true, // Fields are checked below.
1530 // This is definitely not okay.
1534 // If we have not found an error yet, we need to recursively descend into fields.
1535 match &self.fields
{
1536 FieldsShape
::Primitive
| FieldsShape
::Union { .. }
=> {}
1537 FieldsShape
::Array { count, .. }
=> {
1538 // FIXME(#66151): For now, we are conservative and do not check arrays by default.
1541 && !self.field(cx
, 0).might_permit_raw_init(cx
, init_kind
, strict
)
1543 // Found non empty array with a type that is unhappy about this kind of initialization
1547 FieldsShape
::Arbitrary { offsets, .. }
=> {
1548 for idx
in 0..offsets
.len() {
1549 if !self.field(cx
, idx
).might_permit_raw_init(cx
, init_kind
, strict
) {
1550 // We found a field that is unhappy with this kind of initialization.
1557 // FIXME(#66151): For now, we are conservative and do not check `self.variants`.