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move some layout logic to rustc_target::abi::layout

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This commit is contained in:
hkalbasi 2022-11-01 19:50:30 +03:30
parent 09a384643e
commit 27fb904d68
15 changed files with 1232 additions and 1158 deletions
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3
Cargo.lock
View File

@ -4281,6 +4281,8 @@ name = "rustc_target"
version = "0.0.0"
dependencies = [
"bitflags",
"rand 0.8.5",
"rand_xoshiro",
"rustc_data_structures",
"rustc_feature",
"rustc_index",
@ -4336,6 +4338,7 @@ dependencies = [
"rustc_infer",
"rustc_middle",
"rustc_span",
"rustc_target",
"rustc_trait_selection",
"smallvec",
"tracing",

4
compiler/rustc_hir_analysis/src/collect.rs
View File

@ -32,8 +32,8 @@ use rustc_middle::hir::nested_filter;
use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
use rustc_middle::mir::mono::Linkage;
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::repr_options_of_def;
use rustc_middle::ty::util::{Discr, IntTypeExt};
use rustc_middle::ty::ReprOptions;
use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, IsSuggestable, Ty, TyCtxt};
use rustc_session::lint;
use rustc_session::parse::feature_err;
@ -860,7 +860,7 @@ fn adt_def<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::AdtDef<'tcx> {
bug!();
};
let repr = ReprOptions::new(tcx, def_id.to_def_id());
let repr = repr_options_of_def(tcx, def_id.to_def_id());
let (kind, variants) = match item.kind {
ItemKind::Enum(ref def, _) => {
let mut distance_from_explicit = 0;

6
compiler/rustc_lint/src/types.rs
View File

@ -12,7 +12,7 @@ use rustc_middle::ty::{self, AdtKind, DefIdTree, Ty, TyCtxt, TypeSuperVisitable,
use rustc_span::source_map;
use rustc_span::symbol::sym;
use rustc_span::{Span, Symbol};
use rustc_target::abi::{Abi, WrappingRange};
use rustc_target::abi::{Abi, Size, WrappingRange};
use rustc_target::abi::{Integer, TagEncoding, Variants};
use rustc_target::spec::abi::Abi as SpecAbi;
@ -225,11 +225,11 @@ fn report_bin_hex_error(
cx: &LateContext<'_>,
expr: &hir::Expr<'_>,
ty: attr::IntType,
size: Size,
repr_str: String,
val: u128,
negative: bool,
) {
let size = Integer::from_attr(&cx.tcx, ty).size();
cx.struct_span_lint(
OVERFLOWING_LITERALS,
expr.span,
@ -352,6 +352,7 @@ fn lint_int_literal<'tcx>(
cx,
e,
attr::IntType::SignedInt(ty::ast_int_ty(t)),
Integer::from_int_ty(cx, t).size(),
repr_str,
v,
negative,
@ -437,6 +438,7 @@ fn lint_uint_literal<'tcx>(
cx,
e,
attr::IntType::UnsignedInt(ty::ast_uint_ty(t)),
Integer::from_uint_ty(cx, t).size(),
repr_str,
lit_val,
false,

6
compiler/rustc_middle/src/ty/adt.rs
View File

@ -14,7 +14,7 @@ use rustc_index::vec::{Idx, IndexVec};
use rustc_query_system::ich::StableHashingContext;
use rustc_session::DataTypeKind;
use rustc_span::symbol::sym;
use rustc_target::abi::VariantIdx;
use rustc_target::abi::{ReprOptions, VariantIdx};
use std::cell::RefCell;
use std::cmp::Ordering;
@ -22,9 +22,7 @@ use std::hash::{Hash, Hasher};
use std::ops::Range;
use std::str;
use super::{
Destructor, FieldDef, GenericPredicates, ReprOptions, Ty, TyCtxt, VariantDef, VariantDiscr,
};
use super::{Destructor, FieldDef, GenericPredicates, Ty, TyCtxt, VariantDef, VariantDiscr};
bitflags! {
#[derive(HashStable, TyEncodable, TyDecodable)]

31
compiler/rustc_middle/src/ty/layout.rs
View File

@ -1,8 +1,6 @@
use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
use crate::ty::normalize_erasing_regions::NormalizationError;
use crate::ty::{self, ReprOptions, Ty, TyCtxt, TypeVisitable};
use rustc_ast as ast;
use rustc_attr as attr;
use rustc_errors::{DiagnosticBuilder, Handler, IntoDiagnostic};
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
@ -20,7 +18,6 @@ use std::ops::Bound;
pub trait IntegerExt {
fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>, signed: bool) -> Ty<'tcx>;
fn from_attr<C: HasDataLayout>(cx: &C, ity: attr::IntType) -> Integer;
fn from_int_ty<C: HasDataLayout>(cx: &C, ity: ty::IntTy) -> Integer;
fn from_uint_ty<C: HasDataLayout>(cx: &C, uty: ty::UintTy) -> Integer;
fn repr_discr<'tcx>(
@ -49,22 +46,6 @@ impl IntegerExt for Integer {
}
}
/// Gets the Integer type from an attr::IntType.
fn from_attr<C: HasDataLayout>(cx: &C, ity: attr::IntType) -> Integer {
let dl = cx.data_layout();
match ity {
attr::SignedInt(ast::IntTy::I8) | attr::UnsignedInt(ast::UintTy::U8) => I8,
attr::SignedInt(ast::IntTy::I16) | attr::UnsignedInt(ast::UintTy::U16) => I16,
attr::SignedInt(ast::IntTy::I32) | attr::UnsignedInt(ast::UintTy::U32) => I32,
attr::SignedInt(ast::IntTy::I64) | attr::UnsignedInt(ast::UintTy::U64) => I64,
attr::SignedInt(ast::IntTy::I128) | attr::UnsignedInt(ast::UintTy::U128) => I128,
attr::SignedInt(ast::IntTy::Isize) | attr::UnsignedInt(ast::UintTy::Usize) => {
dl.ptr_sized_integer()
}
}
}
fn from_int_ty<C: HasDataLayout>(cx: &C, ity: ty::IntTy) -> Integer {
match ity {
ty::IntTy::I8 => I8,
@ -237,6 +218,18 @@ pub struct LayoutCx<'tcx, C> {
pub param_env: ty::ParamEnv<'tcx>,
}
impl<'tcx> LayoutCalculator for LayoutCx<'tcx, TyCtxt<'tcx>> {
type TargetDataLayoutRef = &'tcx TargetDataLayout;
fn delay_bug(&self, txt: &str) {
self.tcx.sess.delay_span_bug(DUMMY_SP, txt);
}
fn current_data_layout(&self) -> Self::TargetDataLayoutRef {
&self.tcx.data_layout
}
}
/// Type size "skeleton", i.e., the only information determining a type's size.
/// While this is conservative, (aside from constant sizes, only pointers,
/// newtypes thereof and null pointer optimized enums are allowed), it is

210
compiler/rustc_middle/src/ty/mod.rs
View File

@ -48,7 +48,8 @@ use rustc_session::cstore::CrateStoreDyn;
use rustc_span::hygiene::MacroKind;
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{ExpnId, Span};
use rustc_target::abi::{Align, VariantIdx};
use rustc_target::abi::{Align, Integer, IntegerType, VariantIdx};
pub use rustc_target::abi::{ReprFlags, ReprOptions};
pub use subst::*;
pub use vtable::*;
@ -1994,161 +1995,76 @@ impl Hash for FieldDef {
}
}
bitflags! {
#[derive(TyEncodable, TyDecodable, Default, HashStable)]
pub struct ReprFlags: u8 {
const IS_C = 1 << 0;
const IS_SIMD = 1 << 1;
const IS_TRANSPARENT = 1 << 2;
// Internal only for now. If true, don't reorder fields.
const IS_LINEAR = 1 << 3;
// If true, the type's layout can be randomized using
// the seed stored in `ReprOptions.layout_seed`
const RANDOMIZE_LAYOUT = 1 << 4;
// Any of these flags being set prevent field reordering optimisation.
const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits
| ReprFlags::IS_SIMD.bits
| ReprFlags::IS_LINEAR.bits;
pub fn repr_options_of_def(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
let mut flags = ReprFlags::empty();
let mut size = None;
let mut max_align: Option<Align> = None;
let mut min_pack: Option<Align> = None;
// Generate a deterministically-derived seed from the item's path hash
// to allow for cross-crate compilation to actually work
let mut field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
// If the user defined a custom seed for layout randomization, xor the item's
// path hash with the user defined seed, this will allowing determinism while
// still allowing users to further randomize layout generation for e.g. fuzzing
if let Some(user_seed) = tcx.sess.opts.unstable_opts.layout_seed {
field_shuffle_seed ^= user_seed;
}
}
/// Represents the repr options provided by the user,
#[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
pub struct ReprOptions {
pub int: Option<attr::IntType>,
pub align: Option<Align>,
pub pack: Option<Align>,
pub flags: ReprFlags,
/// The seed to be used for randomizing a type's layout
///
/// Note: This could technically be a `[u8; 16]` (a `u128`) which would
/// be the "most accurate" hash as it'd encompass the item and crate
/// hash without loss, but it does pay the price of being larger.
/// Everything's a tradeoff, a `u64` seed should be sufficient for our
/// purposes (primarily `-Z randomize-layout`)
pub field_shuffle_seed: u64,
}
impl ReprOptions {
pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
let mut flags = ReprFlags::empty();
let mut size = None;
let mut max_align: Option<Align> = None;
let mut min_pack: Option<Align> = None;
// Generate a deterministically-derived seed from the item's path hash
// to allow for cross-crate compilation to actually work
let mut field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
// If the user defined a custom seed for layout randomization, xor the item's
// path hash with the user defined seed, this will allowing determinism while
// still allowing users to further randomize layout generation for e.g. fuzzing
if let Some(user_seed) = tcx.sess.opts.unstable_opts.layout_seed {
field_shuffle_seed ^= user_seed;
for attr in tcx.get_attrs(did, sym::repr) {
for r in attr::parse_repr_attr(&tcx.sess, attr) {
flags.insert(match r {
attr::ReprC => ReprFlags::IS_C,
attr::ReprPacked(pack) => {
let pack = Align::from_bytes(pack as u64).unwrap();
min_pack =
Some(if let Some(min_pack) = min_pack { min_pack.min(pack) } else { pack });
ReprFlags::empty()
}
attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
attr::ReprSimd => ReprFlags::IS_SIMD,
attr::ReprInt(i) => {
size = Some(match i {
attr::IntType::SignedInt(x) => match x {
ast::IntTy::Isize => IntegerType::Pointer(true),
ast::IntTy::I8 => IntegerType::Fixed(Integer::I8, true),
ast::IntTy::I16 => IntegerType::Fixed(Integer::I16, true),
ast::IntTy::I32 => IntegerType::Fixed(Integer::I32, true),
ast::IntTy::I64 => IntegerType::Fixed(Integer::I64, true),
ast::IntTy::I128 => IntegerType::Fixed(Integer::I128, true),
},
attr::IntType::UnsignedInt(x) => match x {
ast::UintTy::Usize => IntegerType::Pointer(false),
ast::UintTy::U8 => IntegerType::Fixed(Integer::I8, false),
ast::UintTy::U16 => IntegerType::Fixed(Integer::I16, false),
ast::UintTy::U32 => IntegerType::Fixed(Integer::I32, false),
ast::UintTy::U64 => IntegerType::Fixed(Integer::I64, false),
ast::UintTy::U128 => IntegerType::Fixed(Integer::I128, false),
},
});
ReprFlags::empty()
}
attr::ReprAlign(align) => {
max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
ReprFlags::empty()
}
});
}
for attr in tcx.get_attrs(did, sym::repr) {
for r in attr::parse_repr_attr(&tcx.sess, attr) {
flags.insert(match r {
attr::ReprC => ReprFlags::IS_C,
attr::ReprPacked(pack) => {
let pack = Align::from_bytes(pack as u64).unwrap();
min_pack = Some(if let Some(min_pack) = min_pack {
min_pack.min(pack)
} else {
pack
});
ReprFlags::empty()
}
attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
attr::ReprSimd => ReprFlags::IS_SIMD,
attr::ReprInt(i) => {
size = Some(i);
ReprFlags::empty()
}
attr::ReprAlign(align) => {
max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
ReprFlags::empty()
}
});
}
}
// If `-Z randomize-layout` was enabled for the type definition then we can
// consider performing layout randomization
if tcx.sess.opts.unstable_opts.randomize_layout {
flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
}
// This is here instead of layout because the choice must make it into metadata.
if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
flags.insert(ReprFlags::IS_LINEAR);
}
Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
}
#[inline]
pub fn simd(&self) -> bool {
self.flags.contains(ReprFlags::IS_SIMD)
// If `-Z randomize-layout` was enabled for the type definition then we can
// consider performing layout randomization
if tcx.sess.opts.unstable_opts.randomize_layout {
flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
}
#[inline]
pub fn c(&self) -> bool {
self.flags.contains(ReprFlags::IS_C)
// This is here instead of layout because the choice must make it into metadata.
if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
flags.insert(ReprFlags::IS_LINEAR);
}
#[inline]
pub fn packed(&self) -> bool {
self.pack.is_some()
}
#[inline]
pub fn transparent(&self) -> bool {
self.flags.contains(ReprFlags::IS_TRANSPARENT)
}
#[inline]
pub fn linear(&self) -> bool {
self.flags.contains(ReprFlags::IS_LINEAR)
}
/// Returns the discriminant type, given these `repr` options.
/// This must only be called on enums!
pub fn discr_type(&self) -> attr::IntType {
self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
}
/// Returns `true` if this `#[repr()]` should inhabit "smart enum
/// layout" optimizations, such as representing `Foo<&T>` as a
/// single pointer.
pub fn inhibit_enum_layout_opt(&self) -> bool {
self.c() || self.int.is_some()
}
/// Returns `true` if this `#[repr()]` should inhibit struct field reordering
/// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
if let Some(pack) = self.pack {
if pack.bytes() == 1 {
return true;
}
}
self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
}
/// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
/// was enabled for its declaration crate
pub fn can_randomize_type_layout(&self) -> bool {
!self.inhibit_struct_field_reordering_opt()
&& self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
}
/// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
pub fn inhibit_union_abi_opt(&self) -> bool {
self.c()
}
ReprOptions { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
}
impl<'tcx> FieldDef {

23
compiler/rustc_middle/src/ty/util.rs
View File

@ -8,8 +8,6 @@ use crate::ty::{
};
use crate::ty::{GenericArgKind, SubstsRef};
use rustc_apfloat::Float as _;
use rustc_ast as ast;
use rustc_attr::{self as attr, SignedInt, UnsignedInt};
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_errors::ErrorGuaranteed;
@ -19,7 +17,7 @@ use rustc_hir::def_id::DefId;
use rustc_index::bit_set::GrowableBitSet;
use rustc_macros::HashStable;
use rustc_span::{sym, DUMMY_SP};
use rustc_target::abi::{Integer, Size, TargetDataLayout};
use rustc_target::abi::{Integer, IntegerType, Size, TargetDataLayout};
use rustc_target::spec::abi::Abi;
use smallvec::SmallVec;
use std::{fmt, iter};
@ -104,21 +102,12 @@ pub trait IntTypeExt {
fn initial_discriminant<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Discr<'tcx>;
}
impl IntTypeExt for attr::IntType {
impl IntTypeExt for IntegerType {
fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
match *self {
SignedInt(ast::IntTy::I8) => tcx.types.i8,
SignedInt(ast::IntTy::I16) => tcx.types.i16,
SignedInt(ast::IntTy::I32) => tcx.types.i32,
SignedInt(ast::IntTy::I64) => tcx.types.i64,
SignedInt(ast::IntTy::I128) => tcx.types.i128,
SignedInt(ast::IntTy::Isize) => tcx.types.isize,
UnsignedInt(ast::UintTy::U8) => tcx.types.u8,
UnsignedInt(ast::UintTy::U16) => tcx.types.u16,
UnsignedInt(ast::UintTy::U32) => tcx.types.u32,
UnsignedInt(ast::UintTy::U64) => tcx.types.u64,
UnsignedInt(ast::UintTy::U128) => tcx.types.u128,
UnsignedInt(ast::UintTy::Usize) => tcx.types.usize,
match self {
IntegerType::Pointer(true) => tcx.types.isize,
IntegerType::Pointer(false) => tcx.types.usize,
IntegerType::Fixed(i, s) => i.to_ty(tcx, *s),
}
}

4
compiler/rustc_target/Cargo.toml
View File

@ -6,6 +6,8 @@ edition = "2021"
[dependencies]
bitflags = "1.2.1"
tracing = "0.1"
rand = "0.8.4"
rand_xoshiro = "0.6.0"
serde_json = "1.0.59"
rustc_data_structures = { path = "../rustc_data_structures", optional = true }
rustc_feature = { path = "../rustc_feature", optional = true }
@ -23,4 +25,4 @@ nightly = [
"rustc_macros",
"rustc_serialize",
"rustc_span",
]
]

943
compiler/rustc_target/src/abi/layout.rs Normal file
View File

@ -0,0 +1,943 @@
use super::*;
use std::{
borrow::Borrow,
cmp,
fmt::Debug,
iter,
ops::{Bound, Deref},
};
use rand::{seq::SliceRandom, SeedableRng};
use rand_xoshiro::Xoshiro128StarStar;
use tracing::debug;
// Invert a bijective mapping, i.e. `invert(map)[y] = x` if `map[x] = y`.
// This is used to go between `memory_index` (source field order to memory order)
// and `inverse_memory_index` (memory order to source field order).
// See also `FieldsShape::Arbitrary::memory_index` for more details.
// FIXME(eddyb) build a better abstraction for permutations, if possible.
fn invert_mapping(map: &[u32]) -> Vec<u32> {
let mut inverse = vec![0; map.len()];
for i in 0..map.len() {
inverse[map[i] as usize] = i as u32;
}
inverse
}
pub trait LayoutCalculator {
type TargetDataLayoutRef: Borrow<TargetDataLayout>;
fn delay_bug(&self, txt: &str);
fn current_data_layout(&self) -> Self::TargetDataLayoutRef;
fn scalar_pair<V: Idx>(&self, a: Scalar, b: Scalar) -> LayoutS<V> {
let dl = self.current_data_layout();
let dl = dl.borrow();
let b_align = b.align(dl);
let align = a.align(dl).max(b_align).max(dl.aggregate_align);
let b_offset = a.size(dl).align_to(b_align.abi);
let size = (b_offset + b.size(dl)).align_to(align.abi);
// HACK(nox): We iter on `b` and then `a` because `max_by_key`
// returns the last maximum.
let largest_niche = Niche::from_scalar(dl, b_offset, b)
.into_iter()
.chain(Niche::from_scalar(dl, Size::ZERO, a))
.max_by_key(|niche| niche.available(dl));
LayoutS {
variants: Variants::Single { index: V::new(0) },
fields: FieldsShape::Arbitrary {
offsets: vec![Size::ZERO, b_offset],
memory_index: vec![0, 1],
},
abi: Abi::ScalarPair(a, b),
largest_niche,
align,
size,
}
}
fn univariant<'a, V: Idx, F: Deref<Target = &'a LayoutS<V>> + Debug>(
&self,
dl: &TargetDataLayout,
fields: &[F],
repr: &ReprOptions,
kind: StructKind,
) -> Option<LayoutS<V>> {
let pack = repr.pack;
let mut align = if pack.is_some() { dl.i8_align } else { dl.aggregate_align };
let mut inverse_memory_index: Vec<u32> = (0..fields.len() as u32).collect();
let optimize = !repr.inhibit_struct_field_reordering_opt();
if optimize {
let end =
if let StructKind::MaybeUnsized = kind { fields.len() - 1 } else { fields.len() };
let optimizing = &mut inverse_memory_index[..end];
let effective_field_align = |f: &F| {
if let Some(pack) = pack {
// return the packed alignment in bytes
f.align.abi.min(pack).bytes()
} else {
// returns log2(effective-align).
// This is ok since `pack` applies to all fields equally.
// The calculation assumes that size is an integer multiple of align, except for ZSTs.
//
// group [u8; 4] with align-4 or [u8; 6] with align-2 fields
f.align.abi.bytes().max(f.size.bytes()).trailing_zeros() as u64
}
};
// If `-Z randomize-layout` was enabled for the type definition we can shuffle
// the field ordering to try and catch some code making assumptions about layouts
// we don't guarantee
if repr.can_randomize_type_layout() {
// `ReprOptions.layout_seed` is a deterministic seed that we can use to
// randomize field ordering with
let mut rng = Xoshiro128StarStar::seed_from_u64(repr.field_shuffle_seed);
// Shuffle the ordering of the fields
optimizing.shuffle(&mut rng);
// Otherwise we just leave things alone and actually optimize the type's fields
} else {
match kind {
StructKind::AlwaysSized | StructKind::MaybeUnsized => {
optimizing.sort_by_key(|&x| {
// Place ZSTs first to avoid "interesting offsets",
// especially with only one or two non-ZST fields.
// Then place largest alignments first, largest niches within an alignment group last
let f = &fields[x as usize];
let niche_size = f.largest_niche.map_or(0, |n| n.available(dl));
(!f.is_zst(), cmp::Reverse(effective_field_align(f)), niche_size)
});
}
StructKind::Prefixed(..) => {
// Sort in ascending alignment so that the layout stays optimal
// regardless of the prefix.
// And put the largest niche in an alignment group at the end
// so it can be used as discriminant in jagged enums
optimizing.sort_by_key(|&x| {
let f = &fields[x as usize];
let niche_size = f.largest_niche.map_or(0, |n| n.available(dl));
(effective_field_align(f), niche_size)
});
}
}
// FIXME(Kixiron): We can always shuffle fields within a given alignment class
// regardless of the status of `-Z randomize-layout`
}
}
// inverse_memory_index holds field indices by increasing memory offset.
// That is, if field 5 has offset 0, the first element of inverse_memory_index is 5.
// We now write field offsets to the corresponding offset slot;
// field 5 with offset 0 puts 0 in offsets[5].
// At the bottom of this function, we invert `inverse_memory_index` to
// produce `memory_index` (see `invert_mapping`).
let mut sized = true;
let mut offsets = vec![Size::ZERO; fields.len()];
let mut offset = Size::ZERO;
let mut largest_niche = None;
let mut largest_niche_available = 0;
if let StructKind::Prefixed(prefix_size, prefix_align) = kind {
let prefix_align =
if let Some(pack) = pack { prefix_align.min(pack) } else { prefix_align };
align = align.max(AbiAndPrefAlign::new(prefix_align));
offset = prefix_size.align_to(prefix_align);
}
for &i in &inverse_memory_index {
let field = &fields[i as usize];
if !sized {
self.delay_bug(&format!(
"univariant: field #{} comes after unsized field",
offsets.len(),
));
}
if field.is_unsized() {
sized = false;
}
// Invariant: offset < dl.obj_size_bound() <= 1<<61
let field_align = if let Some(pack) = pack {
field.align.min(AbiAndPrefAlign::new(pack))
} else {
field.align
};
offset = offset.align_to(field_align.abi);
align = align.max(field_align);
debug!("univariant offset: {:?} field: {:#?}", offset, field);
offsets[i as usize] = offset;
if let Some(mut niche) = field.largest_niche {
let available = niche.available(dl);
if available > largest_niche_available {
largest_niche_available = available;
niche.offset += offset;
largest_niche = Some(niche);
}
}
offset = offset.checked_add(field.size, dl)?;
}
if let Some(repr_align) = repr.align {
align = align.max(AbiAndPrefAlign::new(repr_align));
}
debug!("univariant min_size: {:?}", offset);
let min_size = offset;
// As stated above, inverse_memory_index holds field indices by increasing offset.
// This makes it an already-sorted view of the offsets vec.
// To invert it, consider:
// If field 5 has offset 0, offsets[0] is 5, and memory_index[5] should be 0.
// Field 5 would be the first element, so memory_index is i:
// Note: if we didn't optimize, it's already right.
let memory_index =
if optimize { invert_mapping(&inverse_memory_index) } else { inverse_memory_index };
let size = min_size.align_to(align.abi);
let mut abi = Abi::Aggregate { sized };
// Unpack newtype ABIs and find scalar pairs.
if sized && size.bytes() > 0 {
// All other fields must be ZSTs.
let mut non_zst_fields = fields.iter().enumerate().filter(|&(_, f)| !f.is_zst());
match (non_zst_fields.next(), non_zst_fields.next(), non_zst_fields.next()) {
// We have exactly one non-ZST field.
(Some((i, field)), None, None) => {
// Field fills the struct and it has a scalar or scalar pair ABI.
if offsets[i].bytes() == 0 && align.abi == field.align.abi && size == field.size
{
match field.abi {
// For plain scalars, or vectors of them, we can't unpack
// newtypes for `#[repr(C)]`, as that affects C ABIs.
Abi::Scalar(_) | Abi::Vector { .. } if optimize => {
abi = field.abi;
}
// But scalar pairs are Rust-specific and get
// treated as aggregates by C ABIs anyway.
Abi::ScalarPair(..) => {
abi = field.abi;
}
_ => {}
}
}
}
// Two non-ZST fields, and they're both scalars.
(Some((i, a)), Some((j, b)), None) => {
match (a.abi, b.abi) {
(Abi::Scalar(a), Abi::Scalar(b)) => {
// Order by the memory placement, not source order.
let ((i, a), (j, b)) = if offsets[i] < offsets[j] {
((i, a), (j, b))
} else {
((j, b), (i, a))
};
let pair = self.scalar_pair::<V>(a, b);
let pair_offsets = match pair.fields {
FieldsShape::Arbitrary { ref offsets, ref memory_index } => {
assert_eq!(memory_index, &[0, 1]);
offsets
}
_ => panic!(),
};
if offsets[i] == pair_offsets[0]
&& offsets[j] == pair_offsets[1]
&& align == pair.align
&& size == pair.size
{
// We can use `ScalarPair` only when it matches our
// already computed layout (including `#[repr(C)]`).
abi = pair.abi;
}
}
_ => {}
}
}
_ => {}
}
}
if fields.iter().any(|f| f.abi.is_uninhabited()) {
abi = Abi::Uninhabited;
}
Some(LayoutS {
variants: Variants::Single { index: V::new(0) },
fields: FieldsShape::Arbitrary { offsets, memory_index },
abi,
largest_niche,
align,
size,
})
}
fn layout_of_never_type<V: Idx>(&self) -> LayoutS<V> {
let dl = self.current_data_layout();
let dl = dl.borrow();
LayoutS {
variants: Variants::Single { index: V::new(0) },
fields: FieldsShape::Primitive,
abi: Abi::Uninhabited,
largest_niche: None,
align: dl.i8_align,
size: Size::ZERO,
}
}
fn layout_of_struct_or_enum<'a, V: Idx, F: Deref<Target = &'a LayoutS<V>> + Debug>(
&self,
repr: &ReprOptions,
variants: &IndexVec<V, Vec<F>>,
is_enum: bool,
is_unsafe_cell: bool,
scalar_valid_range: (Bound<u128>, Bound<u128>),
discr_range_of_repr: impl Fn(i128, i128) -> (Integer, bool),
discriminants: impl Iterator<Item = (V, i128)>,
niche_optimize_enum: bool,
always_sized: bool,
) -> Option<LayoutS<V>> {
let dl = self.current_data_layout();
let dl = dl.borrow();
let scalar_unit = |value: Primitive| {
let size = value.size(dl);
assert!(size.bits() <= 128);
Scalar::Initialized { value, valid_range: WrappingRange::full(size) }
};
// A variant is absent if it's uninhabited and only has ZST fields.
// Present uninhabited variants only require space for their fields,
// but *not* an encoding of the discriminant (e.g., a tag value).
// See issue #49298 for more details on the need to leave space
// for non-ZST uninhabited data (mostly partial initialization).
let absent = |fields: &[F]| {
let uninhabited = fields.iter().any(|f| f.abi.is_uninhabited());
let is_zst = fields.iter().all(|f| f.is_zst());
uninhabited && is_zst
};
let (present_first, present_second) = {
let mut present_variants = variants
.iter_enumerated()
.filter_map(|(i, v)| if absent(v) { None } else { Some(i) });
(present_variants.next(), present_variants.next())
};
let present_first = match present_first {
Some(present_first) => present_first,
// Uninhabited because it has no variants, or only absent ones.
None if is_enum => {
return Some(self.layout_of_never_type());
}
// If it's a struct, still compute a layout so that we can still compute the
// field offsets.
None => V::new(0),
};
let is_struct = !is_enum ||
// Only one variant is present.
(present_second.is_none() &&
// Representation optimizations are allowed.
!repr.inhibit_enum_layout_opt());
if is_struct {
// Struct, or univariant enum equivalent to a struct.
// (Typechecking will reject discriminant-sizing attrs.)
let v = present_first;
let kind = if is_enum || variants[v].is_empty() {
StructKind::AlwaysSized
} else {
if !always_sized { StructKind::MaybeUnsized } else { StructKind::AlwaysSized }
};
let mut st = self.univariant(dl, &variants[v], &repr, kind)?;
st.variants = Variants::Single { index: v };
if is_unsafe_cell {
let hide_niches = |scalar: &mut _| match scalar {
Scalar::Initialized { value, valid_range } => {
*valid_range = WrappingRange::full(value.size(dl))
}
// Already doesn't have any niches
Scalar::Union { .. } => {}
};
match &mut st.abi {
Abi::Uninhabited => {}
Abi::Scalar(scalar) => hide_niches(scalar),
Abi::ScalarPair(a, b) => {
hide_niches(a);
hide_niches(b);
}
Abi::Vector { element, count: _ } => hide_niches(element),
Abi::Aggregate { sized: _ } => {}
}
st.largest_niche = None;
return Some(st);
}
let (start, end) = scalar_valid_range;
match st.abi {
Abi::Scalar(ref mut scalar) | Abi::ScalarPair(ref mut scalar, _) => {
// the asserts ensure that we are not using the
// `#[rustc_layout_scalar_valid_range(n)]`
// attribute to widen the range of anything as that would probably
// result in UB somewhere
// FIXME(eddyb) the asserts are probably not needed,
// as larger validity ranges would result in missed
// optimizations, *not* wrongly assuming the inner
// value is valid. e.g. unions enlarge validity ranges,
// because the values may be uninitialized.
if let Bound::Included(start) = start {
// FIXME(eddyb) this might be incorrect - it doesn't
// account for wrap-around (end < start) ranges.
let valid_range = scalar.valid_range_mut();
assert!(valid_range.start <= start);
valid_range.start = start;
}
if let Bound::Included(end) = end {
// FIXME(eddyb) this might be incorrect - it doesn't
// account for wrap-around (end < start) ranges.
let valid_range = scalar.valid_range_mut();
assert!(valid_range.end >= end);
valid_range.end = end;
}
// Update `largest_niche` if we have introduced a larger niche.
let niche = Niche::from_scalar(dl, Size::ZERO, *scalar);
if let Some(niche) = niche {
match st.largest_niche {
Some(largest_niche) => {
// Replace the existing niche even if they're equal,
// because this one is at a lower offset.
if largest_niche.available(dl) <= niche.available(dl) {
st.largest_niche = Some(niche);
}
}
None => st.largest_niche = Some(niche),
}
}
}
_ => assert!(
start == Bound::Unbounded && end == Bound::Unbounded,
"nonscalar layout for layout_scalar_valid_range type: {:#?}",
st,
),
}
return Some(st);
}
// At this point, we have handled all unions and
// structs. (We have also handled univariant enums
// that allow representation optimization.)
assert!(is_enum);
// Until we've decided whether to use the tagged or
// niche filling LayoutS, we don't want to intern the
// variant layouts, so we can't store them in the
// overall LayoutS. Store the overall LayoutS
// and the variant LayoutSs here until then.
struct TmpLayout<V: Idx> {
layout: LayoutS<V>,
variants: IndexVec<V, LayoutS<V>>,
}
let calculate_niche_filling_layout = || -> Option<TmpLayout<V>> {
if niche_optimize_enum {
return None;
}
if variants.len() < 2 {
return None;
}
let mut align = dl.aggregate_align;
let mut variant_layouts = variants
.iter_enumerated()
.map(|(j, v)| {
let mut st = self.univariant(dl, v, &repr, StructKind::AlwaysSized)?;
st.variants = Variants::Single { index: j };
align = align.max(st.align);
Some(st)
})
.collect::<Option<IndexVec<V, _>>>()?;
let largest_variant_index = variant_layouts
.iter_enumerated()
.max_by_key(|(_i, layout)| layout.size.bytes())
.map(|(i, _layout)| i)?;
let all_indices = (0..=variants.len() - 1).map(V::new);
let needs_disc = |index: V| index != largest_variant_index && !absent(&variants[index]);
let niche_variants = all_indices.clone().find(|v| needs_disc(*v)).unwrap().index()
..=all_indices.rev().find(|v| needs_disc(*v)).unwrap().index();
let count = niche_variants.size_hint().1.unwrap() as u128;
// Find the field with the largest niche
let (field_index, niche, (niche_start, niche_scalar)) = variants[largest_variant_index]
.iter()
.enumerate()
.filter_map(|(j, field)| Some((j, field.largest_niche?)))
.max_by_key(|(_, niche)| niche.available(dl))
.and_then(|(j, niche)| Some((j, niche, niche.reserve(dl, count)?)))?;
let niche_offset =
niche.offset + variant_layouts[largest_variant_index].fields.offset(field_index);
let niche_size = niche.value.size(dl);
let size = variant_layouts[largest_variant_index].size.align_to(align.abi);
let all_variants_fit = variant_layouts.iter_enumerated_mut().all(|(i, layout)| {
if i == largest_variant_index {
return true;
}
layout.largest_niche = None;
if layout.size <= niche_offset {
// This variant will fit before the niche.
return true;
}
// Determine if it'll fit after the niche.
let this_align = layout.align.abi;
let this_offset = (niche_offset + niche_size).align_to(this_align);
if this_offset + layout.size > size {
return false;
}
// It'll fit, but we need to make some adjustments.
match layout.fields {
FieldsShape::Arbitrary { ref mut offsets, .. } => {
for (j, offset) in offsets.iter_mut().enumerate() {
if !variants[i][j].is_zst() {
*offset += this_offset;
}
}
}
_ => {
panic!("Layout of fields should be Arbitrary for variants")
}
}
// It can't be a Scalar or ScalarPair because the offset isn't 0.
if !layout.abi.is_uninhabited() {
layout.abi = Abi::Aggregate { sized: true };
}
layout.size += this_offset;
true
});
if !all_variants_fit {
return None;
}
let largest_niche = Niche::from_scalar(dl, niche_offset, niche_scalar);
let others_zst = variant_layouts
.iter_enumerated()
.all(|(i, layout)| i == largest_variant_index || layout.size == Size::ZERO);
let same_size = size == variant_layouts[largest_variant_index].size;
let same_align = align == variant_layouts[largest_variant_index].align;
let abi = if variant_layouts.iter().all(|v| v.abi.is_uninhabited()) {
Abi::Uninhabited
} else if same_size && same_align && others_zst {
match variant_layouts[largest_variant_index].abi {
// When the total alignment and size match, we can use the
// same ABI as the scalar variant with the reserved niche.
Abi::Scalar(_) => Abi::Scalar(niche_scalar),
Abi::ScalarPair(first, second) => {
// Only the niche is guaranteed to be initialised,
// so use union layouts for the other primitive.
if niche_offset == Size::ZERO {
Abi::ScalarPair(niche_scalar, second.to_union())
} else {
Abi::ScalarPair(first.to_union(), niche_scalar)
}
}
_ => Abi::Aggregate { sized: true },
}
} else {
Abi::Aggregate { sized: true }
};
let layout = LayoutS {
variants: Variants::Multiple {
tag: niche_scalar,
tag_encoding: TagEncoding::Niche {
untagged_variant: largest_variant_index,
niche_variants: (V::new(*niche_variants.start())
..=V::new(*niche_variants.end())),
niche_start,
},
tag_field: 0,
variants: IndexVec::new(),
},
fields: FieldsShape::Arbitrary {
offsets: vec![niche_offset],
memory_index: vec![0],
},
abi,
largest_niche,
size,
align,
};
Some(TmpLayout { layout, variants: variant_layouts })
};
let niche_filling_layout = calculate_niche_filling_layout();
let (mut min, mut max) = (i128::MAX, i128::MIN);
let discr_type = repr.discr_type();
let bits = Integer::from_attr(dl, discr_type).size().bits();
for (i, mut val) in discriminants {
if variants[i].iter().any(|f| f.abi.is_uninhabited()) {
continue;
}
if discr_type.is_signed() {
// sign extend the raw representation to be an i128
val = (val << (128 - bits)) >> (128 - bits);
}
if val < min {
min = val;
}
if val > max {
max = val;
}
}
// We might have no inhabited variants, so pretend there's at least one.
if (min, max) == (i128::MAX, i128::MIN) {
min = 0;
max = 0;
}
assert!(min <= max, "discriminant range is {}...{}", min, max);
let (min_ity, signed) = discr_range_of_repr(min, max); //Integer::repr_discr(tcx, ty, &repr, min, max);
let mut align = dl.aggregate_align;
let mut size = Size::ZERO;
// We're interested in the smallest alignment, so start large.
let mut start_align = Align::from_bytes(256).unwrap();
assert_eq!(Integer::for_align(dl, start_align), None);
// repr(C) on an enum tells us to make a (tag, union) layout,
// so we need to grow the prefix alignment to be at least
// the alignment of the union. (This value is used both for
// determining the alignment of the overall enum, and the
// determining the alignment of the payload after the tag.)
let mut prefix_align = min_ity.align(dl).abi;
if repr.c() {
for fields in variants {
for field in fields {
prefix_align = prefix_align.max(field.align.abi);
}
}
}
// Create the set of structs that represent each variant.
let mut layout_variants = variants
.iter_enumerated()
.map(|(i, field_layouts)| {
let mut st = self.univariant(
dl,
&field_layouts,
&repr,
StructKind::Prefixed(min_ity.size(), prefix_align),
)?;
st.variants = Variants::Single { index: i };
// Find the first field we can't move later
// to make room for a larger discriminant.
for field in st.fields.index_by_increasing_offset().map(|j| &field_layouts[j]) {
if !field.is_zst() || field.align.abi.bytes() != 1 {
start_align = start_align.min(field.align.abi);
break;
}
}
size = cmp::max(size, st.size);
align = align.max(st.align);
Some(st)
})
.collect::<Option<IndexVec<V, _>>>()?;
// Align the maximum variant size to the largest alignment.
size = size.align_to(align.abi);
if size.bytes() >= dl.obj_size_bound() {
return None;
}
let typeck_ity = Integer::from_attr(dl, repr.discr_type());
if typeck_ity < min_ity {
// It is a bug if Layout decided on a greater discriminant size than typeck for
// some reason at this point (based on values discriminant can take on). Mostly
// because this discriminant will be loaded, and then stored into variable of
// type calculated by typeck. Consider such case (a bug): typeck decided on
// byte-sized discriminant, but layout thinks we need a 16-bit to store all
// discriminant values. That would be a bug, because then, in codegen, in order
// to store this 16-bit discriminant into 8-bit sized temporary some of the
// space necessary to represent would have to be discarded (or layout is wrong
// on thinking it needs 16 bits)
panic!(
"layout decided on a larger discriminant type ({:?}) than typeck ({:?})",
min_ity, typeck_ity
);
// However, it is fine to make discr type however large (as an optimisation)
// after this point – we’ll just truncate the value we load in codegen.
}
// Check to see if we should use a different type for the
// discriminant. We can safely use a type with the same size
// as the alignment of the first field of each variant.
// We increase the size of the discriminant to avoid LLVM copying
// padding when it doesn't need to. This normally causes unaligned
// load/stores and excessive memcpy/memset operations. By using a
// bigger integer size, LLVM can be sure about its contents and
// won't be so conservative.
// Use the initial field alignment
let mut ity = if repr.c() || repr.int.is_some() {
min_ity
} else {
Integer::for_align(dl, start_align).unwrap_or(min_ity)
};
// If the alignment is not larger than the chosen discriminant size,
// don't use the alignment as the final size.
if ity <= min_ity {
ity = min_ity;
} else {
// Patch up the variants' first few fields.
let old_ity_size = min_ity.size();
let new_ity_size = ity.size();
for variant in &mut layout_variants {
match variant.fields {
FieldsShape::Arbitrary { ref mut offsets, .. } => {
for i in offsets {
if *i <= old_ity_size {
assert_eq!(*i, old_ity_size);
*i = new_ity_size;
}
}
// We might be making the struct larger.
if variant.size <= old_ity_size {
variant.size = new_ity_size;
}
}
_ => panic!(),
}
}
}
let tag_mask = ity.size().unsigned_int_max();
let tag = Scalar::Initialized {
value: Int(ity, signed),
valid_range: WrappingRange {
start: (min as u128 & tag_mask),
end: (max as u128 & tag_mask),
},
};
let mut abi = Abi::Aggregate { sized: true };
if layout_variants.iter().all(|v| v.abi.is_uninhabited()) {
abi = Abi::Uninhabited;
} else if tag.size(dl) == size {
// Make sure we only use scalar layout when the enum is entirely its
// own tag (i.e. it has no padding nor any non-ZST variant fields).
abi = Abi::Scalar(tag);
} else {
// Try to use a ScalarPair for all tagged enums.
let mut common_prim = None;
let mut common_prim_initialized_in_all_variants = true;
for (field_layouts, layout_variant) in iter::zip(&*variants, &layout_variants) {
let FieldsShape::Arbitrary { ref offsets, .. } = layout_variant.fields else {
panic!();
};
let mut fields = iter::zip(field_layouts, offsets).filter(|p| !p.0.is_zst());
let (field, offset) = match (fields.next(), fields.next()) {
(None, None) => {
common_prim_initialized_in_all_variants = false;
continue;
}
(Some(pair), None) => pair,
_ => {
common_prim = None;
break;
}
};
let prim = match field.abi {
Abi::Scalar(scalar) => {
common_prim_initialized_in_all_variants &=
matches!(scalar, Scalar::Initialized { .. });
scalar.primitive()
}
_ => {
common_prim = None;
break;
}
};
if let Some(pair) = common_prim {
// This is pretty conservative. We could go fancier
// by conflating things like i32 and u32, or even
// realising that (u8, u8) could just cohabit with
// u16 or even u32.
if pair != (prim, offset) {
common_prim = None;
break;
}
} else {
common_prim = Some((prim, offset));
}
}
if let Some((prim, offset)) = common_prim {
let prim_scalar = if common_prim_initialized_in_all_variants {
scalar_unit(prim)
} else {
// Common prim might be uninit.
Scalar::Union { value: prim }
};
let pair = self.scalar_pair::<V>(tag, prim_scalar);
let pair_offsets = match pair.fields {
FieldsShape::Arbitrary { ref offsets, ref memory_index } => {
assert_eq!(memory_index, &[0, 1]);
offsets
}
_ => panic!(),
};
if pair_offsets[0] == Size::ZERO
&& pair_offsets[1] == *offset
&& align == pair.align
&& size == pair.size
{
// We can use `ScalarPair` only when it matches our
// already computed layout (including `#[repr(C)]`).
abi = pair.abi;
}
}
}
// If we pick a "clever" (by-value) ABI, we might have to adjust the ABI of the
// variants to ensure they are consistent. This is because a downcast is
// semantically a NOP, and thus should not affect layout.
if matches!(abi, Abi::Scalar(..) | Abi::ScalarPair(..)) {
for variant in &mut layout_variants {
// We only do this for variants with fields; the others are not accessed anyway.
// Also do not overwrite any already existing "clever" ABIs.
if variant.fields.count() > 0 && matches!(variant.abi, Abi::Aggregate { .. }) {
variant.abi = abi;
// Also need to bump up the size and alignment, so that the entire value fits in here.
variant.size = cmp::max(variant.size, size);
variant.align.abi = cmp::max(variant.align.abi, align.abi);
}
}
}
let largest_niche = Niche::from_scalar(dl, Size::ZERO, tag);
let tagged_layout = LayoutS {
variants: Variants::Multiple {
tag,
tag_encoding: TagEncoding::Direct,
tag_field: 0,
variants: IndexVec::new(),
},
fields: FieldsShape::Arbitrary { offsets: vec![Size::ZERO], memory_index: vec![0] },
largest_niche,
abi,
align,
size,
};
let tagged_layout = TmpLayout { layout: tagged_layout, variants: layout_variants };
let mut best_layout = match (tagged_layout, niche_filling_layout) {
(tl, Some(nl)) => {
// Pick the smaller layout; otherwise,
// pick the layout with the larger niche; otherwise,
// pick tagged as it has simpler codegen.
use cmp::Ordering::*;
let niche_size = |tmp_l: &TmpLayout<V>| {
tmp_l.layout.largest_niche.map_or(0, |n| n.available(dl))
};
match (tl.layout.size.cmp(&nl.layout.size), niche_size(&tl).cmp(&niche_size(&nl))) {
(Greater, _) => nl,
(Equal, Less) => nl,
_ => tl,
}
}
(tl, None) => tl,
};
// Now we can intern the variant layouts and store them in the enum layout.
best_layout.layout.variants = match best_layout.layout.variants {
Variants::Multiple { tag, tag_encoding, tag_field, .. } => {
Variants::Multiple { tag, tag_encoding, tag_field, variants: best_layout.variants }
}
_ => panic!(),
};
Some(best_layout.layout)
}
fn layout_of_union<'a, V: Idx, F: Deref<Target = &'a LayoutS<V>> + Debug>(
&self,
repr: &ReprOptions,
variants: &IndexVec<V, Vec<F>>,
) -> Option<LayoutS<V>> {
let dl = self.current_data_layout();
let dl = dl.borrow();
let mut align = if repr.pack.is_some() { dl.i8_align } else { dl.aggregate_align };
if let Some(repr_align) = repr.align {
align = align.max(AbiAndPrefAlign::new(repr_align));
}
let optimize = !repr.inhibit_union_abi_opt();
let mut size = Size::ZERO;
let mut abi = Abi::Aggregate { sized: true };
let index = V::new(0);
for field in &variants[index] {
assert!(!field.is_unsized());
align = align.max(field.align);
// If all non-ZST fields have the same ABI, forward this ABI
if optimize && !field.is_zst() {
// Discard valid range information and allow undef
let field_abi = match field.abi {
Abi::Scalar(x) => Abi::Scalar(x.to_union()),
Abi::ScalarPair(x, y) => Abi::ScalarPair(x.to_union(), y.to_union()),
Abi::Vector { element: x, count } => {
Abi::Vector { element: x.to_union(), count }
}
Abi::Uninhabited | Abi::Aggregate { .. } => Abi::Aggregate { sized: true },
};
if size == Size::ZERO {
// first non ZST: initialize 'abi'
abi = field_abi;
} else if abi != field_abi {
// different fields have different ABI: reset to Aggregate
abi = Abi::Aggregate { sized: true };
}
}
size = cmp::max(size, field.size);
}
if let Some(pack) = repr.pack {
align = align.min(AbiAndPrefAlign::new(pack));
}
Some(LayoutS {
variants: Variants::Single { index },
fields: FieldsShape::Union(NonZeroUsize::new(variants[index].len())?),
abi,
largest_niche: None,
align,
size: size.align_to(align.abi),
})
}
}

151
compiler/rustc_target/src/abi/mod.rs
View File

@ -13,6 +13,7 @@ use std::num::{NonZeroUsize, ParseIntError};
use std::ops::{Add, AddAssign, Deref, Mul, RangeInclusive, Sub};
use std::str::FromStr;
use bitflags::bitflags;
#[cfg(feature = "nightly")]
use rustc_data_structures::intern::Interned;
use rustc_index::vec::{Idx, IndexVec};
@ -22,6 +23,127 @@ use rustc_macros::HashStable_Generic;
#[cfg(feature = "nightly")]
pub mod call;
mod layout;
pub use layout::LayoutCalculator;
bitflags! {
#[derive(Default)]
#[cfg_attr(feature = "nightly", derive(Encodable, Decodable, HashStable_Generic))]
pub struct ReprFlags: u8 {
const IS_C = 1 << 0;
const IS_SIMD = 1 << 1;
const IS_TRANSPARENT = 1 << 2;
// Internal only for now. If true, don't reorder fields.
const IS_LINEAR = 1 << 3;
// If true, the type's layout can be randomized using
// the seed stored in `ReprOptions.layout_seed`
const RANDOMIZE_LAYOUT = 1 << 4;
// Any of these flags being set prevent field reordering optimisation.
const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits
| ReprFlags::IS_SIMD.bits
| ReprFlags::IS_LINEAR.bits;
}
}
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
#[cfg_attr(feature = "nightly", derive(Encodable, Decodable, HashStable_Generic))]
pub enum IntegerType {
Pointer(bool),
Fixed(Integer, bool),
}
impl IntegerType {
pub fn is_signed(&self) -> bool {
match self {
IntegerType::Pointer(b) => *b,
IntegerType::Fixed(_, b) => *b,
}
}
}
/// Represents the repr options provided by the user,
#[derive(Copy, Clone, Debug, Eq, PartialEq, Default)]
#[cfg_attr(feature = "nightly", derive(Encodable, Decodable, HashStable_Generic))]
pub struct ReprOptions {
pub int: Option<IntegerType>,
pub align: Option<Align>,
pub pack: Option<Align>,
pub flags: ReprFlags,
/// The seed to be used for randomizing a type's layout
///
/// Note: This could technically be a `[u8; 16]` (a `u128`) which would
/// be the "most accurate" hash as it'd encompass the item and crate
/// hash without loss, but it does pay the price of being larger.
/// Everything's a tradeoff, a `u64` seed should be sufficient for our
/// purposes (primarily `-Z randomize-layout`)
pub field_shuffle_seed: u64,
}
impl ReprOptions {
#[inline]
pub fn simd(&self) -> bool {
self.flags.contains(ReprFlags::IS_SIMD)
}
#[inline]
pub fn c(&self) -> bool {
self.flags.contains(ReprFlags::IS_C)
}
#[inline]
pub fn packed(&self) -> bool {
self.pack.is_some()
}
#[inline]
pub fn transparent(&self) -> bool {
self.flags.contains(ReprFlags::IS_TRANSPARENT)
}
#[inline]
pub fn linear(&self) -> bool {
self.flags.contains(ReprFlags::IS_LINEAR)
}
/// Returns the discriminant type, given these `repr` options.
/// This must only be called on enums!
pub fn discr_type(&self) -> IntegerType {
self.int.unwrap_or(IntegerType::Pointer(true))
}
/// Returns `true` if this `#[repr()]` should inhabit "smart enum
/// layout" optimizations, such as representing `Foo<&T>` as a
/// single pointer.
pub fn inhibit_enum_layout_opt(&self) -> bool {
self.c() || self.int.is_some()
}
/// Returns `true` if this `#[repr()]` should inhibit struct field reordering
/// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
if let Some(pack) = self.pack {
if pack.bytes() == 1 {
return true;
}
}
self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
}
/// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
/// was enabled for its declaration crate
pub fn can_randomize_type_layout(&self) -> bool {
!self.inhibit_struct_field_reordering_opt()
&& self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
}
/// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
pub fn inhibit_union_abi_opt(&self) -> bool {
self.c()
}
}
/// Parsed [Data layout](https://llvm.org/docs/LangRef.html#data-layout)
/// for a target, which contains everything needed to compute layouts.
#[derive(Debug, PartialEq, Eq)]
@ -622,7 +744,7 @@ impl AbiAndPrefAlign {
/// Integers, also used for enum discriminants.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
#[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
#[cfg_attr(feature = "nightly", derive(Encodable, Decodable, HashStable_Generic))]
pub enum Integer {
I8,
@ -644,6 +766,16 @@ impl Integer {
}
}
/// Gets the Integer type from an attr::IntType.
pub fn from_attr<C: HasDataLayout>(cx: &C, ity: IntegerType) -> Integer {
let dl = cx.data_layout();
match ity {
IntegerType::Pointer(_) => dl.ptr_sized_integer(),
IntegerType::Fixed(x, _) => x,
}
}
pub fn align<C: HasDataLayout>(self, cx: &C) -> AbiAndPrefAlign {
let dl = cx.data_layout();
@ -1172,12 +1304,7 @@ pub enum TagEncoding<V: Idx> {
/// For example, `Option<(usize, &T)>` is represented such that
/// `None` has a null pointer for the second tuple field, and
/// `Some` is the identity function (with a non-null reference).
Niche {
untagged_variant: V,
#[cfg(feature = "nightly")]
niche_variants: RangeInclusive<V>,
niche_start: u128,
},
Niche { untagged_variant: V, niche_variants: RangeInclusive<V>, niche_start: u128 },
}
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
@ -1568,3 +1695,13 @@ impl<V: Idx> LayoutS<V> {
}
}
}
#[derive(Copy, Clone, Debug)]
pub enum StructKind {
/// A tuple, closure, or univariant which cannot be coerced to unsized.
AlwaysSized,
/// A univariant, the last field of which may be coerced to unsized.
MaybeUnsized,
/// A univariant, but with a prefix of an arbitrary size & alignment (e.g., enum tag).
Prefixed(Size, Align),
}

1
compiler/rustc_traits/Cargo.toml
View File

@ -12,6 +12,7 @@ rustc_hir = { path = "../rustc_hir" }
rustc_index = { path = "../rustc_index" }
rustc_ast = { path = "../rustc_ast" }
rustc_span = { path = "../rustc_span" }
rustc_target = { path = "../rustc_target" }
chalk-ir = "0.87.0"
chalk-engine = "0.87.0"
chalk-solve = "0.87.0"

30
compiler/rustc_traits/src/chalk/db.rs
View File

@ -9,9 +9,9 @@
use rustc_middle::traits::ChalkRustInterner as RustInterner;
use rustc_middle::ty::{self, AssocKind, EarlyBinder, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable};
use rustc_middle::ty::{InternalSubsts, SubstsRef};
use rustc_target::abi::{Integer, IntegerType};
use rustc_ast::ast;
use rustc_attr as attr;
use rustc_hir::def_id::DefId;
@ -218,21 +218,21 @@ impl<'tcx> chalk_solve::RustIrDatabase<RustInterner<'tcx>> for RustIrDatabase<'t
c: adt_def.repr().c(),
packed: adt_def.repr().packed(),
int: adt_def.repr().int.map(|i| match i {
attr::IntType::SignedInt(ty) => match ty {
ast::IntTy::Isize => int(chalk_ir::IntTy::Isize),
ast::IntTy::I8 => int(chalk_ir::IntTy::I8),
ast::IntTy::I16 => int(chalk_ir::IntTy::I16),
ast::IntTy::I32 => int(chalk_ir::IntTy::I32),
ast::IntTy::I64 => int(chalk_ir::IntTy::I64),
ast::IntTy::I128 => int(chalk_ir::IntTy::I128),
IntegerType::Pointer(true) => int(chalk_ir::IntTy::Isize),
IntegerType::Pointer(false) => uint(chalk_ir::UintTy::Usize),
IntegerType::Fixed(i, true) => match i {
Integer::I8 => int(chalk_ir::IntTy::I8),
Integer::I16 => int(chalk_ir::IntTy::I16),
Integer::I32 => int(chalk_ir::IntTy::I32),
Integer::I64 => int(chalk_ir::IntTy::I64),
Integer::I128 => int(chalk_ir::IntTy::I128),
},
attr::IntType::UnsignedInt(ty) => match ty {
ast::UintTy::Usize => uint(chalk_ir::UintTy::Usize),
ast::UintTy::U8 => uint(chalk_ir::UintTy::U8),
ast::UintTy::U16 => uint(chalk_ir::UintTy::U16),
ast::UintTy::U32 => uint(chalk_ir::UintTy::U32),
ast::UintTy::U64 => uint(chalk_ir::UintTy::U64),
ast::UintTy::U128 => uint(chalk_ir::UintTy::U128),
IntegerType::Fixed(i, false) => match i {
Integer::I8 => uint(chalk_ir::UintTy::U8),
Integer::I16 => uint(chalk_ir::UintTy::U16),
Integer::I32 => uint(chalk_ir::UintTy::U32),
Integer::I64 => uint(chalk_ir::UintTy::U64),
Integer::I128 => uint(chalk_ir::UintTy::U128),
},
}),
})

972
compiler/rustc_ty_utils/src/layout.rs
View File

File diff suppressed because it is too large Load Diff

5
src/tools/clippy/clippy_lints/src/casts/cast_possible_truncation.rs
View File

@ -2,12 +2,11 @@ use clippy_utils::consts::{constant, Constant};
use clippy_utils::diagnostics::span_lint;
use clippy_utils::expr_or_init;
use clippy_utils::ty::{get_discriminant_value, is_isize_or_usize};
use rustc_ast::ast;
use rustc_attr::IntType;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::{BinOpKind, Expr, ExprKind};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, FloatTy, Ty};
use rustc_target::abi::IntegerType;
use super::{utils, CAST_ENUM_TRUNCATION, CAST_POSSIBLE_TRUNCATION};
@ -122,7 +121,7 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>,
let cast_from_ptr_size = def.repr().int.map_or(true, |ty| {
matches!(
ty,
IntType::SignedInt(ast::IntTy::Isize) | IntType::UnsignedInt(ast::UintTy::Usize)
IntegerType::Pointer(_),
)
});
let suffix = match (cast_from_ptr_size, is_isize_or_usize(cast_to)) {

1
src/tools/clippy/clippy_lints/src/lib.rs
View File

@ -26,7 +26,6 @@
extern crate rustc_arena;
extern crate rustc_ast;
extern crate rustc_ast_pretty;
extern crate rustc_attr;
extern crate rustc_data_structures;
extern crate rustc_driver;
extern crate rustc_errors;