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-rw-r--r--compiler/rustc_ty_utils/Cargo.toml2
-rw-r--r--compiler/rustc_ty_utils/src/abi.rs551
-rw-r--r--compiler/rustc_ty_utils/src/assoc.rs18
-rw-r--r--compiler/rustc_ty_utils/src/common_traits.rs11
-rw-r--r--compiler/rustc_ty_utils/src/consts.rs15
-rw-r--r--compiler/rustc_ty_utils/src/errors.rs56
-rw-r--r--compiler/rustc_ty_utils/src/instance.rs75
-rw-r--r--compiler/rustc_ty_utils/src/layout.rs1803
-rw-r--r--compiler/rustc_ty_utils/src/layout_sanity_check.rs (renamed from compiler/rustc_middle/src/ty/layout_sanity_check.rs)2
-rw-r--r--compiler/rustc_ty_utils/src/lib.rs10
-rw-r--r--compiler/rustc_ty_utils/src/needs_drop.rs5
-rw-r--r--compiler/rustc_ty_utils/src/representability.rs451
-rw-r--r--compiler/rustc_ty_utils/src/ty.rs20
13 files changed, 2544 insertions, 475 deletions
diff --git a/compiler/rustc_ty_utils/Cargo.toml b/compiler/rustc_ty_utils/Cargo.toml
index 52fbd3ae0..5e4ba4730 100644
--- a/compiler/rustc_ty_utils/Cargo.toml
+++ b/compiler/rustc_ty_utils/Cargo.toml
@@ -4,6 +4,8 @@ version = "0.0.0"
edition = "2021"
[dependencies]
+rand = "0.8.4"
+rand_xoshiro = "0.6.0"
tracing = "0.1"
rustc_middle = { path = "../rustc_middle" }
rustc_data_structures = { path = "../rustc_data_structures" }
diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs
new file mode 100644
index 000000000..73c7eb699
--- /dev/null
+++ b/compiler/rustc_ty_utils/src/abi.rs
@@ -0,0 +1,551 @@
+use rustc_hir as hir;
+use rustc_hir::lang_items::LangItem;
+use rustc_middle::ty::layout::{
+ fn_can_unwind, FnAbiError, HasParamEnv, HasTyCtxt, LayoutCx, LayoutOf, TyAndLayout,
+};
+use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_session::config::OptLevel;
+use rustc_span::def_id::DefId;
+use rustc_target::abi::call::{
+ ArgAbi, ArgAttribute, ArgAttributes, ArgExtension, Conv, FnAbi, PassMode, Reg, RegKind,
+};
+use rustc_target::abi::*;
+use rustc_target::spec::abi::Abi as SpecAbi;
+
+use std::iter;
+
+pub fn provide(providers: &mut ty::query::Providers) {
+ *providers = ty::query::Providers { fn_abi_of_fn_ptr, fn_abi_of_instance, ..*providers };
+}
+
+// NOTE(eddyb) this is private to avoid using it from outside of
+// `fn_abi_of_instance` - any other uses are either too high-level
+// for `Instance` (e.g. typeck would use `Ty::fn_sig` instead),
+// or should go through `FnAbi` instead, to avoid losing any
+// adjustments `fn_abi_of_instance` might be performing.
+#[tracing::instrument(level = "debug", skip(tcx, param_env))]
+fn fn_sig_for_fn_abi<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ instance: ty::Instance<'tcx>,
+ param_env: ty::ParamEnv<'tcx>,
+) -> ty::PolyFnSig<'tcx> {
+ let ty = instance.ty(tcx, param_env);
+ match *ty.kind() {
+ ty::FnDef(..) => {
+ // HACK(davidtwco,eddyb): This is a workaround for polymorphization considering
+ // parameters unused if they show up in the signature, but not in the `mir::Body`
+ // (i.e. due to being inside a projection that got normalized, see
+ // `src/test/ui/polymorphization/normalized_sig_types.rs`), and codegen not keeping
+ // track of a polymorphization `ParamEnv` to allow normalizing later.
+ //
+ // We normalize the `fn_sig` again after substituting at a later point.
+ let mut sig = match *ty.kind() {
+ ty::FnDef(def_id, substs) => tcx
+ .bound_fn_sig(def_id)
+ .map_bound(|fn_sig| {
+ tcx.normalize_erasing_regions(tcx.param_env(def_id), fn_sig)
+ })
+ .subst(tcx, substs),
+ _ => unreachable!(),
+ };
+
+ if let ty::InstanceDef::VTableShim(..) = instance.def {
+ // Modify `fn(self, ...)` to `fn(self: *mut Self, ...)`.
+ sig = sig.map_bound(|mut sig| {
+ let mut inputs_and_output = sig.inputs_and_output.to_vec();
+ inputs_and_output[0] = tcx.mk_mut_ptr(inputs_and_output[0]);
+ sig.inputs_and_output = tcx.intern_type_list(&inputs_and_output);
+ sig
+ });
+ }
+ sig
+ }
+ ty::Closure(def_id, substs) => {
+ let sig = substs.as_closure().sig();
+
+ let bound_vars = tcx.mk_bound_variable_kinds(
+ sig.bound_vars().iter().chain(iter::once(ty::BoundVariableKind::Region(ty::BrEnv))),
+ );
+ let br = ty::BoundRegion {
+ var: ty::BoundVar::from_usize(bound_vars.len() - 1),
+ kind: ty::BoundRegionKind::BrEnv,
+ };
+ let env_region = ty::ReLateBound(ty::INNERMOST, br);
+ let env_ty = tcx.closure_env_ty(def_id, substs, env_region).unwrap();
+
+ let sig = sig.skip_binder();
+ ty::Binder::bind_with_vars(
+ tcx.mk_fn_sig(
+ iter::once(env_ty).chain(sig.inputs().iter().cloned()),
+ sig.output(),
+ sig.c_variadic,
+ sig.unsafety,
+ sig.abi,
+ ),
+ bound_vars,
+ )
+ }
+ ty::Generator(_, substs, _) => {
+ let sig = substs.as_generator().poly_sig();
+
+ let bound_vars = tcx.mk_bound_variable_kinds(
+ sig.bound_vars().iter().chain(iter::once(ty::BoundVariableKind::Region(ty::BrEnv))),
+ );
+ let br = ty::BoundRegion {
+ var: ty::BoundVar::from_usize(bound_vars.len() - 1),
+ kind: ty::BoundRegionKind::BrEnv,
+ };
+ let env_region = ty::ReLateBound(ty::INNERMOST, br);
+ let env_ty = tcx.mk_mut_ref(tcx.mk_region(env_region), ty);
+
+ let pin_did = tcx.require_lang_item(LangItem::Pin, None);
+ let pin_adt_ref = tcx.adt_def(pin_did);
+ let pin_substs = tcx.intern_substs(&[env_ty.into()]);
+ let env_ty = tcx.mk_adt(pin_adt_ref, pin_substs);
+
+ let sig = sig.skip_binder();
+ let state_did = tcx.require_lang_item(LangItem::GeneratorState, None);
+ let state_adt_ref = tcx.adt_def(state_did);
+ let state_substs = tcx.intern_substs(&[sig.yield_ty.into(), sig.return_ty.into()]);
+ let ret_ty = tcx.mk_adt(state_adt_ref, state_substs);
+ ty::Binder::bind_with_vars(
+ tcx.mk_fn_sig(
+ [env_ty, sig.resume_ty].iter(),
+ &ret_ty,
+ false,
+ hir::Unsafety::Normal,
+ rustc_target::spec::abi::Abi::Rust,
+ ),
+ bound_vars,
+ )
+ }
+ _ => bug!("unexpected type {:?} in Instance::fn_sig", ty),
+ }
+}
+
+#[inline]
+fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: SpecAbi) -> Conv {
+ use rustc_target::spec::abi::Abi::*;
+ match tcx.sess.target.adjust_abi(abi) {
+ RustIntrinsic | PlatformIntrinsic | Rust | RustCall => Conv::Rust,
+ RustCold => Conv::RustCold,
+
+ // It's the ABI's job to select this, not ours.
+ System { .. } => bug!("system abi should be selected elsewhere"),
+ EfiApi => bug!("eficall abi should be selected elsewhere"),
+
+ Stdcall { .. } => Conv::X86Stdcall,
+ Fastcall { .. } => Conv::X86Fastcall,
+ Vectorcall { .. } => Conv::X86VectorCall,
+ Thiscall { .. } => Conv::X86ThisCall,
+ C { .. } => Conv::C,
+ Unadjusted => Conv::C,
+ Win64 { .. } => Conv::X86_64Win64,
+ SysV64 { .. } => Conv::X86_64SysV,
+ Aapcs { .. } => Conv::ArmAapcs,
+ CCmseNonSecureCall => Conv::CCmseNonSecureCall,
+ PtxKernel => Conv::PtxKernel,
+ Msp430Interrupt => Conv::Msp430Intr,
+ X86Interrupt => Conv::X86Intr,
+ AmdGpuKernel => Conv::AmdGpuKernel,
+ AvrInterrupt => Conv::AvrInterrupt,
+ AvrNonBlockingInterrupt => Conv::AvrNonBlockingInterrupt,
+ Wasm => Conv::C,
+
+ // These API constants ought to be more specific...
+ Cdecl { .. } => Conv::C,
+ }
+}
+
+fn fn_abi_of_fn_ptr<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ query: ty::ParamEnvAnd<'tcx, (ty::PolyFnSig<'tcx>, &'tcx ty::List<Ty<'tcx>>)>,
+) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
+ let (param_env, (sig, extra_args)) = query.into_parts();
+
+ let cx = LayoutCx { tcx, param_env };
+ fn_abi_new_uncached(&cx, sig, extra_args, None, None, false)
+}
+
+fn fn_abi_of_instance<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ query: ty::ParamEnvAnd<'tcx, (ty::Instance<'tcx>, &'tcx ty::List<Ty<'tcx>>)>,
+) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
+ let (param_env, (instance, extra_args)) = query.into_parts();
+
+ let sig = fn_sig_for_fn_abi(tcx, instance, param_env);
+
+ let caller_location = if instance.def.requires_caller_location(tcx) {
+ Some(tcx.caller_location_ty())
+ } else {
+ None
+ };
+
+ fn_abi_new_uncached(
+ &LayoutCx { tcx, param_env },
+ sig,
+ extra_args,
+ caller_location,
+ Some(instance.def_id()),
+ matches!(instance.def, ty::InstanceDef::Virtual(..)),
+ )
+}
+
+// Handle safe Rust thin and fat pointers.
+fn adjust_for_rust_scalar<'tcx>(
+ cx: LayoutCx<'tcx, TyCtxt<'tcx>>,
+ attrs: &mut ArgAttributes,
+ scalar: Scalar,
+ layout: TyAndLayout<'tcx>,
+ offset: Size,
+ is_return: bool,
+) {
+ // Booleans are always a noundef i1 that needs to be zero-extended.
+ if scalar.is_bool() {
+ attrs.ext(ArgExtension::Zext);
+ attrs.set(ArgAttribute::NoUndef);
+ return;
+ }
+
+ // Scalars which have invalid values cannot be undef.
+ if !scalar.is_always_valid(&cx) {
+ attrs.set(ArgAttribute::NoUndef);
+ }
+
+ // Only pointer types handled below.
+ let Scalar::Initialized { value: Pointer, valid_range} = scalar else { return };
+
+ if !valid_range.contains(0) {
+ attrs.set(ArgAttribute::NonNull);
+ }
+
+ if let Some(pointee) = layout.pointee_info_at(&cx, offset) {
+ if let Some(kind) = pointee.safe {
+ attrs.pointee_align = Some(pointee.align);
+
+ // `Box` (`UniqueBorrowed`) are not necessarily dereferenceable
+ // for the entire duration of the function as they can be deallocated
+ // at any time. Same for shared mutable references. If LLVM had a
+ // way to say "dereferenceable on entry" we could use it here.
+ attrs.pointee_size = match kind {
+ PointerKind::UniqueBorrowed
+ | PointerKind::UniqueBorrowedPinned
+ | PointerKind::Frozen => pointee.size,
+ PointerKind::SharedMutable | PointerKind::UniqueOwned => Size::ZERO,
+ };
+
+ // `Box`, `&T`, and `&mut T` cannot be undef.
+ // Note that this only applies to the value of the pointer itself;
+ // this attribute doesn't make it UB for the pointed-to data to be undef.
+ attrs.set(ArgAttribute::NoUndef);
+
+ // The aliasing rules for `Box<T>` are still not decided, but currently we emit
+ // `noalias` for it. This can be turned off using an unstable flag.
+ // See https://github.com/rust-lang/unsafe-code-guidelines/issues/326
+ let noalias_for_box = cx.tcx.sess.opts.unstable_opts.box_noalias.unwrap_or(true);
+
+ // `&mut` pointer parameters never alias other parameters,
+ // or mutable global data
+ //
+ // `&T` where `T` contains no `UnsafeCell<U>` is immutable,
+ // and can be marked as both `readonly` and `noalias`, as
+ // LLVM's definition of `noalias` is based solely on memory
+ // dependencies rather than pointer equality
+ //
+ // Due to past miscompiles in LLVM, we apply a separate NoAliasMutRef attribute
+ // for UniqueBorrowed arguments, so that the codegen backend can decide whether
+ // or not to actually emit the attribute. It can also be controlled with the
+ // `-Zmutable-noalias` debugging option.
+ let no_alias = match kind {
+ PointerKind::SharedMutable
+ | PointerKind::UniqueBorrowed
+ | PointerKind::UniqueBorrowedPinned => false,
+ PointerKind::UniqueOwned => noalias_for_box,
+ PointerKind::Frozen => !is_return,
+ };
+ if no_alias {
+ attrs.set(ArgAttribute::NoAlias);
+ }
+
+ if kind == PointerKind::Frozen && !is_return {
+ attrs.set(ArgAttribute::ReadOnly);
+ }
+
+ if kind == PointerKind::UniqueBorrowed && !is_return {
+ attrs.set(ArgAttribute::NoAliasMutRef);
+ }
+ }
+ }
+}
+
+// FIXME(eddyb) perhaps group the signature/type-containing (or all of them?)
+// arguments of this method, into a separate `struct`.
+#[tracing::instrument(level = "debug", skip(cx, caller_location, fn_def_id, force_thin_self_ptr))]
+fn fn_abi_new_uncached<'tcx>(
+ cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
+ sig: ty::PolyFnSig<'tcx>,
+ extra_args: &[Ty<'tcx>],
+ caller_location: Option<Ty<'tcx>>,
+ fn_def_id: Option<DefId>,
+ // FIXME(eddyb) replace this with something typed, like an `enum`.
+ force_thin_self_ptr: bool,
+) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
+ let sig = cx.tcx.normalize_erasing_late_bound_regions(cx.param_env, sig);
+
+ let conv = conv_from_spec_abi(cx.tcx(), sig.abi);
+
+ let mut inputs = sig.inputs();
+ let extra_args = if sig.abi == RustCall {
+ assert!(!sig.c_variadic && extra_args.is_empty());
+
+ if let Some(input) = sig.inputs().last() {
+ if let ty::Tuple(tupled_arguments) = input.kind() {
+ inputs = &sig.inputs()[0..sig.inputs().len() - 1];
+ tupled_arguments
+ } else {
+ bug!(
+ "argument to function with \"rust-call\" ABI \
+ is not a tuple"
+ );
+ }
+ } else {
+ bug!(
+ "argument to function with \"rust-call\" ABI \
+ is not a tuple"
+ );
+ }
+ } else {
+ assert!(sig.c_variadic || extra_args.is_empty());
+ extra_args
+ };
+
+ let target = &cx.tcx.sess.target;
+ let target_env_gnu_like = matches!(&target.env[..], "gnu" | "musl" | "uclibc");
+ let win_x64_gnu = target.os == "windows" && target.arch == "x86_64" && target.env == "gnu";
+ let linux_s390x_gnu_like =
+ target.os == "linux" && target.arch == "s390x" && target_env_gnu_like;
+ let linux_sparc64_gnu_like =
+ target.os == "linux" && target.arch == "sparc64" && target_env_gnu_like;
+ let linux_powerpc_gnu_like =
+ target.os == "linux" && target.arch == "powerpc" && target_env_gnu_like;
+ use SpecAbi::*;
+ let rust_abi = matches!(sig.abi, RustIntrinsic | PlatformIntrinsic | Rust | RustCall);
+
+ let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| -> Result<_, FnAbiError<'tcx>> {
+ let span = tracing::debug_span!("arg_of");
+ let _entered = span.enter();
+ let is_return = arg_idx.is_none();
+
+ let layout = cx.layout_of(ty)?;
+ let layout = if force_thin_self_ptr && arg_idx == Some(0) {
+ // Don't pass the vtable, it's not an argument of the virtual fn.
+ // Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait`
+ // or `&/&mut dyn Trait` because this is special-cased elsewhere in codegen
+ make_thin_self_ptr(cx, layout)
+ } else {
+ layout
+ };
+
+ let mut arg = ArgAbi::new(cx, layout, |layout, scalar, offset| {
+ let mut attrs = ArgAttributes::new();
+ adjust_for_rust_scalar(*cx, &mut attrs, scalar, *layout, offset, is_return);
+ attrs
+ });
+
+ if arg.layout.is_zst() {
+ // For some forsaken reason, x86_64-pc-windows-gnu
+ // doesn't ignore zero-sized struct arguments.
+ // The same is true for {s390x,sparc64,powerpc}-unknown-linux-{gnu,musl,uclibc}.
+ if is_return
+ || rust_abi
+ || (!win_x64_gnu
+ && !linux_s390x_gnu_like
+ && !linux_sparc64_gnu_like
+ && !linux_powerpc_gnu_like)
+ {
+ arg.mode = PassMode::Ignore;
+ }
+ }
+
+ Ok(arg)
+ };
+
+ let mut fn_abi = FnAbi {
+ ret: arg_of(sig.output(), None)?,
+ args: inputs
+ .iter()
+ .copied()
+ .chain(extra_args.iter().copied())
+ .chain(caller_location)
+ .enumerate()
+ .map(|(i, ty)| arg_of(ty, Some(i)))
+ .collect::<Result<_, _>>()?,
+ c_variadic: sig.c_variadic,
+ fixed_count: inputs.len() as u32,
+ conv,
+ can_unwind: fn_can_unwind(cx.tcx(), fn_def_id, sig.abi),
+ };
+ fn_abi_adjust_for_abi(cx, &mut fn_abi, sig.abi, fn_def_id)?;
+ debug!("fn_abi_new_uncached = {:?}", fn_abi);
+ Ok(cx.tcx.arena.alloc(fn_abi))
+}
+
+#[tracing::instrument(level = "trace", skip(cx))]
+fn fn_abi_adjust_for_abi<'tcx>(
+ cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
+ fn_abi: &mut FnAbi<'tcx, Ty<'tcx>>,
+ abi: SpecAbi,
+ fn_def_id: Option<DefId>,
+) -> Result<(), FnAbiError<'tcx>> {
+ if abi == SpecAbi::Unadjusted {
+ return Ok(());
+ }
+
+ if abi == SpecAbi::Rust
+ || abi == SpecAbi::RustCall
+ || abi == SpecAbi::RustIntrinsic
+ || abi == SpecAbi::PlatformIntrinsic
+ {
+ // Look up the deduced parameter attributes for this function, if we have its def ID and
+ // we're optimizing in non-incremental mode. We'll tag its parameters with those attributes
+ // as appropriate.
+ let deduced_param_attrs = if cx.tcx.sess.opts.optimize != OptLevel::No
+ && cx.tcx.sess.opts.incremental.is_none()
+ {
+ fn_def_id.map(|fn_def_id| cx.tcx.deduced_param_attrs(fn_def_id)).unwrap_or_default()
+ } else {
+ &[]
+ };
+
+ let fixup = |arg: &mut ArgAbi<'tcx, Ty<'tcx>>, arg_idx: Option<usize>| {
+ if arg.is_ignore() {
+ return;
+ }
+
+ match arg.layout.abi {
+ Abi::Aggregate { .. } => {}
+
+ // This is a fun case! The gist of what this is doing is
+ // that we want callers and callees to always agree on the
+ // ABI of how they pass SIMD arguments. If we were to *not*
+ // make these arguments indirect then they'd be immediates
+ // in LLVM, which means that they'd used whatever the
+ // appropriate ABI is for the callee and the caller. That
+ // means, for example, if the caller doesn't have AVX
+ // enabled but the callee does, then passing an AVX argument
+ // across this boundary would cause corrupt data to show up.
+ //
+ // This problem is fixed by unconditionally passing SIMD
+ // arguments through memory between callers and callees
+ // which should get them all to agree on ABI regardless of
+ // target feature sets. Some more information about this
+ // issue can be found in #44367.
+ //
+ // Note that the platform intrinsic ABI is exempt here as
+ // that's how we connect up to LLVM and it's unstable
+ // anyway, we control all calls to it in libstd.
+ Abi::Vector { .. }
+ if abi != SpecAbi::PlatformIntrinsic
+ && cx.tcx.sess.target.simd_types_indirect =>
+ {
+ arg.make_indirect();
+ return;
+ }
+
+ _ => return,
+ }
+
+ let size = arg.layout.size;
+ if arg.layout.is_unsized() || size > Pointer.size(cx) {
+ arg.make_indirect();
+ } else {
+ // We want to pass small aggregates as immediates, but using
+ // a LLVM aggregate type for this leads to bad optimizations,
+ // so we pick an appropriately sized integer type instead.
+ arg.cast_to(Reg { kind: RegKind::Integer, size });
+ }
+
+ // If we deduced that this parameter was read-only, add that to the attribute list now.
+ //
+ // The `readonly` parameter only applies to pointers, so we can only do this if the
+ // argument was passed indirectly. (If the argument is passed directly, it's an SSA
+ // value, so it's implicitly immutable.)
+ if let (Some(arg_idx), &mut PassMode::Indirect { ref mut attrs, .. }) =
+ (arg_idx, &mut arg.mode)
+ {
+ // The `deduced_param_attrs` list could be empty if this is a type of function
+ // we can't deduce any parameters for, so make sure the argument index is in
+ // bounds.
+ if let Some(deduced_param_attrs) = deduced_param_attrs.get(arg_idx) {
+ if deduced_param_attrs.read_only {
+ attrs.regular.insert(ArgAttribute::ReadOnly);
+ debug!("added deduced read-only attribute");
+ }
+ }
+ }
+ };
+
+ fixup(&mut fn_abi.ret, None);
+ for (arg_idx, arg) in fn_abi.args.iter_mut().enumerate() {
+ fixup(arg, Some(arg_idx));
+ }
+ } else {
+ fn_abi.adjust_for_foreign_abi(cx, abi)?;
+ }
+
+ Ok(())
+}
+
+#[tracing::instrument(level = "debug", skip(cx))]
+fn make_thin_self_ptr<'tcx>(
+ cx: &(impl HasTyCtxt<'tcx> + HasParamEnv<'tcx>),
+ layout: TyAndLayout<'tcx>,
+) -> TyAndLayout<'tcx> {
+ let tcx = cx.tcx();
+ let fat_pointer_ty = if layout.is_unsized() {
+ // unsized `self` is passed as a pointer to `self`
+ // FIXME (mikeyhew) change this to use &own if it is ever added to the language
+ tcx.mk_mut_ptr(layout.ty)
+ } else {
+ match layout.abi {
+ Abi::ScalarPair(..) | Abi::Scalar(..) => (),
+ _ => bug!("receiver type has unsupported layout: {:?}", layout),
+ }
+
+ // In the case of Rc<Self>, we need to explicitly pass a *mut RcBox<Self>
+ // with a Scalar (not ScalarPair) ABI. This is a hack that is understood
+ // elsewhere in the compiler as a method on a `dyn Trait`.
+ // To get the type `*mut RcBox<Self>`, we just keep unwrapping newtypes until we
+ // get a built-in pointer type
+ let mut fat_pointer_layout = layout;
+ 'descend_newtypes: while !fat_pointer_layout.ty.is_unsafe_ptr()
+ && !fat_pointer_layout.ty.is_region_ptr()
+ {
+ for i in 0..fat_pointer_layout.fields.count() {
+ let field_layout = fat_pointer_layout.field(cx, i);
+
+ if !field_layout.is_zst() {
+ fat_pointer_layout = field_layout;
+ continue 'descend_newtypes;
+ }
+ }
+
+ bug!("receiver has no non-zero-sized fields {:?}", fat_pointer_layout);
+ }
+
+ fat_pointer_layout.ty
+ };
+
+ // we now have a type like `*mut RcBox<dyn Trait>`
+ // change its layout to that of `*mut ()`, a thin pointer, but keep the same type
+ // this is understood as a special case elsewhere in the compiler
+ let unit_ptr_ty = tcx.mk_mut_ptr(tcx.mk_unit());
+
+ TyAndLayout {
+ ty: fat_pointer_ty,
+
+ // NOTE(eddyb) using an empty `ParamEnv`, and `unwrap`-ing the `Result`
+ // should always work because the type is always `*mut ()`.
+ ..tcx.layout_of(ty::ParamEnv::reveal_all().and(unit_ptr_ty)).unwrap()
+ }
+}
diff --git a/compiler/rustc_ty_utils/src/assoc.rs b/compiler/rustc_ty_utils/src/assoc.rs
index 515a73ead..424b52309 100644
--- a/compiler/rustc_ty_utils/src/assoc.rs
+++ b/compiler/rustc_ty_utils/src/assoc.rs
@@ -17,10 +17,10 @@ fn associated_item_def_ids(tcx: TyCtxt<'_>, def_id: DefId) -> &[DefId] {
let item = tcx.hir().expect_item(def_id.expect_local());
match item.kind {
hir::ItemKind::Trait(.., ref trait_item_refs) => tcx.arena.alloc_from_iter(
- trait_item_refs.iter().map(|trait_item_ref| trait_item_ref.id.def_id.to_def_id()),
+ trait_item_refs.iter().map(|trait_item_ref| trait_item_ref.id.owner_id.to_def_id()),
),
hir::ItemKind::Impl(ref impl_) => tcx.arena.alloc_from_iter(
- impl_.items.iter().map(|impl_item_ref| impl_item_ref.id.def_id.to_def_id()),
+ impl_.items.iter().map(|impl_item_ref| impl_item_ref.id.owner_id.to_def_id()),
),
hir::ItemKind::TraitAlias(..) => &[],
_ => span_bug!(item.span, "associated_item_def_ids: not impl or trait"),
@@ -42,11 +42,11 @@ fn impl_item_implementor_ids(tcx: TyCtxt<'_>, impl_id: DefId) -> FxHashMap<DefId
fn associated_item(tcx: TyCtxt<'_>, def_id: DefId) -> ty::AssocItem {
let id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
let parent_def_id = tcx.hir().get_parent_item(id);
- let parent_item = tcx.hir().expect_item(parent_def_id);
+ let parent_item = tcx.hir().expect_item(parent_def_id.def_id);
match parent_item.kind {
hir::ItemKind::Impl(ref impl_) => {
if let Some(impl_item_ref) =
- impl_.items.iter().find(|i| i.id.def_id.to_def_id() == def_id)
+ impl_.items.iter().find(|i| i.id.owner_id.to_def_id() == def_id)
{
let assoc_item = associated_item_from_impl_item_ref(impl_item_ref);
debug_assert_eq!(assoc_item.def_id, def_id);
@@ -56,7 +56,7 @@ fn associated_item(tcx: TyCtxt<'_>, def_id: DefId) -> ty::AssocItem {
hir::ItemKind::Trait(.., ref trait_item_refs) => {
if let Some(trait_item_ref) =
- trait_item_refs.iter().find(|i| i.id.def_id.to_def_id() == def_id)
+ trait_item_refs.iter().find(|i| i.id.owner_id.to_def_id() == def_id)
{
let assoc_item = associated_item_from_trait_item_ref(trait_item_ref);
debug_assert_eq!(assoc_item.def_id, def_id);
@@ -75,7 +75,7 @@ fn associated_item(tcx: TyCtxt<'_>, def_id: DefId) -> ty::AssocItem {
}
fn associated_item_from_trait_item_ref(trait_item_ref: &hir::TraitItemRef) -> ty::AssocItem {
- let def_id = trait_item_ref.id.def_id;
+ let owner_id = trait_item_ref.id.owner_id;
let (kind, has_self) = match trait_item_ref.kind {
hir::AssocItemKind::Const => (ty::AssocKind::Const, false),
hir::AssocItemKind::Fn { has_self } => (ty::AssocKind::Fn, has_self),
@@ -85,15 +85,15 @@ fn associated_item_from_trait_item_ref(trait_item_ref: &hir::TraitItemRef) -> ty
ty::AssocItem {
name: trait_item_ref.ident.name,
kind,
- def_id: def_id.to_def_id(),
- trait_item_def_id: Some(def_id.to_def_id()),
+ def_id: owner_id.to_def_id(),
+ trait_item_def_id: Some(owner_id.to_def_id()),
container: ty::TraitContainer,
fn_has_self_parameter: has_self,
}
}
fn associated_item_from_impl_item_ref(impl_item_ref: &hir::ImplItemRef) -> ty::AssocItem {
- let def_id = impl_item_ref.id.def_id;
+ let def_id = impl_item_ref.id.owner_id;
let (kind, has_self) = match impl_item_ref.kind {
hir::AssocItemKind::Const => (ty::AssocKind::Const, false),
hir::AssocItemKind::Fn { has_self } => (ty::AssocKind::Fn, has_self),
diff --git a/compiler/rustc_ty_utils/src/common_traits.rs b/compiler/rustc_ty_utils/src/common_traits.rs
index cedc84d97..d3169b6d9 100644
--- a/compiler/rustc_ty_utils/src/common_traits.rs
+++ b/compiler/rustc_ty_utils/src/common_traits.rs
@@ -29,15 +29,8 @@ fn is_item_raw<'tcx>(
) -> bool {
let (param_env, ty) = query.into_parts();
let trait_def_id = tcx.require_lang_item(item, None);
- tcx.infer_ctxt().enter(|infcx| {
- traits::type_known_to_meet_bound_modulo_regions(
- &infcx,
- param_env,
- ty,
- trait_def_id,
- DUMMY_SP,
- )
- })
+ let infcx = tcx.infer_ctxt().build();
+ traits::type_known_to_meet_bound_modulo_regions(&infcx, param_env, ty, trait_def_id, DUMMY_SP)
}
pub(crate) fn provide(providers: &mut ty::query::Providers) {
diff --git a/compiler/rustc_ty_utils/src/consts.rs b/compiler/rustc_ty_utils/src/consts.rs
index 44c4fc48d..e057bb668 100644
--- a/compiler/rustc_ty_utils/src/consts.rs
+++ b/compiler/rustc_ty_utils/src/consts.rs
@@ -135,30 +135,30 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
impl<'a, 'tcx> IsThirPolymorphic<'a, 'tcx> {
fn expr_is_poly(&mut self, expr: &thir::Expr<'tcx>) -> bool {
- if expr.ty.has_param_types_or_consts() {
+ if expr.ty.has_non_region_param() {
return true;
}
match expr.kind {
- thir::ExprKind::NamedConst { substs, .. } => substs.has_param_types_or_consts(),
+ thir::ExprKind::NamedConst { substs, .. } => substs.has_non_region_param(),
thir::ExprKind::ConstParam { .. } => true,
thir::ExprKind::Repeat { value, count } => {
self.visit_expr(&self.thir()[value]);
- count.has_param_types_or_consts()
+ count.has_non_region_param()
}
_ => false,
}
}
fn pat_is_poly(&mut self, pat: &thir::Pat<'tcx>) -> bool {
- if pat.ty.has_param_types_or_consts() {
+ if pat.ty.has_non_region_param() {
return true;
}
match pat.kind {
- thir::PatKind::Constant { value } => value.has_param_types_or_consts(),
+ thir::PatKind::Constant { value } => value.has_non_region_param(),
thir::PatKind::Range(box thir::PatRange { lo, hi, .. }) => {
- lo.has_param_types_or_consts() || hi.has_param_types_or_consts()
+ lo.has_non_region_param() || hi.has_non_region_param()
}
_ => false,
}
@@ -258,7 +258,8 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
self.nodes.push(Node::Leaf(ty::Const::from_value(self.tcx, val, node.ty)))
}
&ExprKind::NamedConst { def_id, substs, user_ty: _ } => {
- let uneval = ty::Unevaluated::new(ty::WithOptConstParam::unknown(def_id), substs);
+ let uneval =
+ ty::UnevaluatedConst::new(ty::WithOptConstParam::unknown(def_id), substs);
let constant = self
.tcx
diff --git a/compiler/rustc_ty_utils/src/errors.rs b/compiler/rustc_ty_utils/src/errors.rs
index 3a8ef96c9..c05eeb353 100644
--- a/compiler/rustc_ty_utils/src/errors.rs
+++ b/compiler/rustc_ty_utils/src/errors.rs
@@ -1,69 +1,69 @@
//! Errors emitted by ty_utils
-use rustc_macros::{SessionDiagnostic, SessionSubdiagnostic};
+use rustc_macros::{Diagnostic, Subdiagnostic};
use rustc_middle::ty::Ty;
use rustc_span::Span;
-#[derive(SessionDiagnostic)]
-#[diag(ty_utils::needs_drop_overflow)]
+#[derive(Diagnostic)]
+#[diag(ty_utils_needs_drop_overflow)]
pub struct NeedsDropOverflow<'tcx> {
pub query_ty: Ty<'tcx>,
}
-#[derive(SessionDiagnostic)]
-#[diag(ty_utils::generic_constant_too_complex)]
+#[derive(Diagnostic)]
+#[diag(ty_utils_generic_constant_too_complex)]
#[help]
pub struct GenericConstantTooComplex {
#[primary_span]
pub span: Span,
- #[note(ty_utils::maybe_supported)]
+ #[note(maybe_supported)]
pub maybe_supported: Option<()>,
#[subdiagnostic]
pub sub: GenericConstantTooComplexSub,
}
-#[derive(SessionSubdiagnostic)]
+#[derive(Subdiagnostic)]
pub enum GenericConstantTooComplexSub {
- #[label(ty_utils::borrow_not_supported)]
+ #[label(ty_utils_borrow_not_supported)]
BorrowNotSupported(#[primary_span] Span),
- #[label(ty_utils::address_and_deref_not_supported)]
+ #[label(ty_utils_address_and_deref_not_supported)]
AddressAndDerefNotSupported(#[primary_span] Span),
- #[label(ty_utils::array_not_supported)]
+ #[label(ty_utils_array_not_supported)]
ArrayNotSupported(#[primary_span] Span),
- #[label(ty_utils::block_not_supported)]
+ #[label(ty_utils_block_not_supported)]
BlockNotSupported(#[primary_span] Span),
- #[label(ty_utils::never_to_any_not_supported)]
+ #[label(ty_utils_never_to_any_not_supported)]
NeverToAnyNotSupported(#[primary_span] Span),
- #[label(ty_utils::tuple_not_supported)]
+ #[label(ty_utils_tuple_not_supported)]
TupleNotSupported(#[primary_span] Span),
- #[label(ty_utils::index_not_supported)]
+ #[label(ty_utils_index_not_supported)]
IndexNotSupported(#[primary_span] Span),
- #[label(ty_utils::field_not_supported)]
+ #[label(ty_utils_field_not_supported)]
FieldNotSupported(#[primary_span] Span),
- #[label(ty_utils::const_block_not_supported)]
+ #[label(ty_utils_const_block_not_supported)]
ConstBlockNotSupported(#[primary_span] Span),
- #[label(ty_utils::adt_not_supported)]
+ #[label(ty_utils_adt_not_supported)]
AdtNotSupported(#[primary_span] Span),
- #[label(ty_utils::pointer_not_supported)]
+ #[label(ty_utils_pointer_not_supported)]
PointerNotSupported(#[primary_span] Span),
- #[label(ty_utils::yield_not_supported)]
+ #[label(ty_utils_yield_not_supported)]
YieldNotSupported(#[primary_span] Span),
- #[label(ty_utils::loop_not_supported)]
+ #[label(ty_utils_loop_not_supported)]
LoopNotSupported(#[primary_span] Span),
- #[label(ty_utils::box_not_supported)]
+ #[label(ty_utils_box_not_supported)]
BoxNotSupported(#[primary_span] Span),
- #[label(ty_utils::binary_not_supported)]
+ #[label(ty_utils_binary_not_supported)]
BinaryNotSupported(#[primary_span] Span),
- #[label(ty_utils::logical_op_not_supported)]
+ #[label(ty_utils_logical_op_not_supported)]
LogicalOpNotSupported(#[primary_span] Span),
- #[label(ty_utils::assign_not_supported)]
+ #[label(ty_utils_assign_not_supported)]
AssignNotSupported(#[primary_span] Span),
- #[label(ty_utils::closure_and_return_not_supported)]
+ #[label(ty_utils_closure_and_return_not_supported)]
ClosureAndReturnNotSupported(#[primary_span] Span),
- #[label(ty_utils::control_flow_not_supported)]
+ #[label(ty_utils_control_flow_not_supported)]
ControlFlowNotSupported(#[primary_span] Span),
- #[label(ty_utils::inline_asm_not_supported)]
+ #[label(ty_utils_inline_asm_not_supported)]
InlineAsmNotSupported(#[primary_span] Span),
- #[label(ty_utils::operation_not_supported)]
+ #[label(ty_utils_operation_not_supported)]
OperationNotSupported(#[primary_span] Span),
}
diff --git a/compiler/rustc_ty_utils/src/instance.rs b/compiler/rustc_ty_utils/src/instance.rs
index 05738b6c4..6436713b3 100644
--- a/compiler/rustc_ty_utils/src/instance.rs
+++ b/compiler/rustc_ty_utils/src/instance.rs
@@ -4,7 +4,7 @@ use rustc_infer::infer::TyCtxtInferExt;
use rustc_middle::traits::CodegenObligationError;
use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::{self, Instance, TyCtxt, TypeVisitable};
-use rustc_span::{sym, DUMMY_SP};
+use rustc_span::sym;
use rustc_trait_selection::traits;
use traits::{translate_substs, Reveal};
@@ -134,19 +134,17 @@ fn resolve_associated_item<'tcx>(
.unwrap_or_else(|| {
bug!("{:?} not found in {:?}", trait_item_id, impl_data.impl_def_id);
});
-
- let substs = tcx.infer_ctxt().enter(|infcx| {
- let param_env = param_env.with_reveal_all_normalized(tcx);
- let substs = rcvr_substs.rebase_onto(tcx, trait_def_id, impl_data.substs);
- let substs = translate_substs(
- &infcx,
- param_env,
- impl_data.impl_def_id,
- substs,
- leaf_def.defining_node,
- );
- infcx.tcx.erase_regions(substs)
- });
+ let infcx = tcx.infer_ctxt().build();
+ let param_env = param_env.with_reveal_all_normalized(tcx);
+ let substs = rcvr_substs.rebase_onto(tcx, trait_def_id, impl_data.substs);
+ let substs = translate_substs(
+ &infcx,
+ param_env,
+ impl_data.impl_def_id,
+ substs,
+ leaf_def.defining_node,
+ );
+ let substs = infcx.tcx.erase_regions(substs);
// Since this is a trait item, we need to see if the item is either a trait default item
// or a specialization because we can't resolve those unless we can `Reveal::All`.
@@ -171,9 +169,13 @@ fn resolve_associated_item<'tcx>(
return Ok(None);
}
- // If the item does not have a value, then we cannot return an instance.
+ // Any final impl is required to define all associated items.
if !leaf_def.item.defaultness(tcx).has_value() {
- return Ok(None);
+ let guard = tcx.sess.delay_span_bug(
+ tcx.def_span(leaf_def.item.def_id),
+ "missing value for assoc item in impl",
+ );
+ return Err(guard);
}
let substs = tcx.erase_regions(substs);
@@ -182,40 +184,14 @@ fn resolve_associated_item<'tcx>(
// a `trait` to an associated `const` definition in an `impl`, where
// the definition in the `impl` has the wrong type (for which an
// error has already been/will be emitted elsewhere).
- //
- // NB: this may be expensive, we try to skip it in all the cases where
- // we know the error would've been caught (e.g. in an upstream crate).
- //
- // A better approach might be to just introduce a query (returning
- // `Result<(), ErrorGuaranteed>`) for the check that `rustc_typeck`
- // performs (i.e. that the definition's type in the `impl` matches
- // the declaration in the `trait`), so that we can cheaply check
- // here if it failed, instead of approximating it.
if leaf_def.item.kind == ty::AssocKind::Const
&& trait_item_id != leaf_def.item.def_id
- && leaf_def.item.def_id.is_local()
+ && let Some(leaf_def_item) = leaf_def.item.def_id.as_local()
{
- let normalized_type_of = |def_id, substs| {
- tcx.subst_and_normalize_erasing_regions(substs, param_env, tcx.type_of(def_id))
- };
-
- let original_ty = normalized_type_of(trait_item_id, rcvr_substs);
- let resolved_ty = normalized_type_of(leaf_def.item.def_id, substs);
-
- if original_ty != resolved_ty {
- let msg = format!(
- "Instance::resolve: inconsistent associated `const` type: \
- was `{}: {}` but resolved to `{}: {}`",
- tcx.def_path_str_with_substs(trait_item_id, rcvr_substs),
- original_ty,
- tcx.def_path_str_with_substs(leaf_def.item.def_id, substs),
- resolved_ty,
- );
- let span = tcx.def_span(leaf_def.item.def_id);
- let reported = tcx.sess.delay_span_bug(span, &msg);
-
- return Err(reported);
- }
+ tcx.compare_assoc_const_impl_item_with_trait_item((
+ leaf_def_item,
+ trait_item_id,
+ ))?;
}
Some(ty::Instance::new(leaf_def.item.def_id, substs))
@@ -260,7 +236,7 @@ fn resolve_associated_item<'tcx>(
if name == sym::clone {
let self_ty = trait_ref.self_ty();
- let is_copy = self_ty.is_copy_modulo_regions(tcx.at(DUMMY_SP), param_env);
+ let is_copy = self_ty.is_copy_modulo_regions(tcx, param_env);
match self_ty.kind() {
_ if is_copy => (),
ty::Generator(..)
@@ -291,8 +267,7 @@ fn resolve_associated_item<'tcx>(
| traits::ImplSource::DiscriminantKind(..)
| traits::ImplSource::Pointee(..)
| traits::ImplSource::TraitUpcasting(_)
- | traits::ImplSource::ConstDestruct(_)
- | traits::ImplSource::Tuple => None,
+ | traits::ImplSource::ConstDestruct(_) => None,
})
}
diff --git a/compiler/rustc_ty_utils/src/layout.rs b/compiler/rustc_ty_utils/src/layout.rs
new file mode 100644
index 000000000..52ba0eee9
--- /dev/null
+++ b/compiler/rustc_ty_utils/src/layout.rs
@@ -0,0 +1,1803 @@
+use rustc_hir as hir;
+use rustc_index::bit_set::BitSet;
+use rustc_index::vec::{Idx, IndexVec};
+use rustc_middle::mir::{GeneratorLayout, GeneratorSavedLocal};
+use rustc_middle::ty::layout::{
+ IntegerExt, LayoutCx, LayoutError, LayoutOf, TyAndLayout, MAX_SIMD_LANES,
+};
+use rustc_middle::ty::{
+ self, subst::SubstsRef, EarlyBinder, ReprOptions, Ty, TyCtxt, TypeVisitable,
+};
+use rustc_session::{DataTypeKind, FieldInfo, SizeKind, VariantInfo};
+use rustc_span::symbol::Symbol;
+use rustc_span::DUMMY_SP;
+use rustc_target::abi::*;
+
+use std::cmp::{self, Ordering};
+use std::iter;
+use std::num::NonZeroUsize;
+use std::ops::Bound;
+
+use rand::{seq::SliceRandom, SeedableRng};
+use rand_xoshiro::Xoshiro128StarStar;
+
+use crate::layout_sanity_check::sanity_check_layout;
+
+pub fn provide(providers: &mut ty::query::Providers) {
+ *providers = ty::query::Providers { layout_of, ..*providers };
+}
+
+#[instrument(skip(tcx, query), level = "debug")]
+fn layout_of<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
+) -> Result<TyAndLayout<'tcx>, LayoutError<'tcx>> {
+ let (param_env, ty) = query.into_parts();
+ debug!(?ty);
+
+ let param_env = param_env.with_reveal_all_normalized(tcx);
+ let unnormalized_ty = ty;
+
+ // FIXME: We might want to have two different versions of `layout_of`:
+ // One that can be called after typecheck has completed and can use
+ // `normalize_erasing_regions` here and another one that can be called
+ // before typecheck has completed and uses `try_normalize_erasing_regions`.
+ let ty = match tcx.try_normalize_erasing_regions(param_env, ty) {
+ Ok(t) => t,
+ Err(normalization_error) => {
+ return Err(LayoutError::NormalizationFailure(ty, normalization_error));
+ }
+ };
+
+ if ty != unnormalized_ty {
+ // Ensure this layout is also cached for the normalized type.
+ return tcx.layout_of(param_env.and(ty));
+ }
+
+ let cx = LayoutCx { tcx, param_env };
+
+ let layout = layout_of_uncached(&cx, ty)?;
+ let layout = TyAndLayout { ty, layout };
+
+ record_layout_for_printing(&cx, layout);
+
+ sanity_check_layout(&cx, &layout);
+
+ Ok(layout)
+}
+
+#[derive(Copy, Clone, Debug)]
+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),
+}
+
+// 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
+}
+
+fn scalar_pair<'tcx>(cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, a: Scalar, b: Scalar) -> LayoutS<'tcx> {
+ let dl = cx.data_layout();
+ 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: VariantIdx::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_uninterned<'tcx>(
+ cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
+ ty: Ty<'tcx>,
+ fields: &[TyAndLayout<'_>],
+ repr: &ReprOptions,
+ kind: StructKind,
+) -> Result<LayoutS<'tcx>, LayoutError<'tcx>> {
+ let dl = cx.data_layout();
+ let pack = repr.pack;
+ if pack.is_some() && repr.align.is_some() {
+ cx.tcx.sess.delay_span_bug(DUMMY_SP, "struct cannot be packed and aligned");
+ return Err(LayoutError::Unknown(ty));
+ }
+
+ 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 field_align = |f: &TyAndLayout<'_>| {
+ if let Some(pack) = pack { f.align.abi.min(pack) } else { f.align.abi }
+ };
+
+ // 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.
+ let f = &fields[x as usize];
+ (!f.is_zst(), cmp::Reverse(field_align(f)))
+ });
+ }
+
+ StructKind::Prefixed(..) => {
+ // Sort in ascending alignment so that the layout stays optimal
+ // regardless of the prefix
+ optimizing.sort_by_key(|&x| field_align(&fields[x as usize]));
+ }
+ }
+
+ // 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 {
+ cx.tcx.sess.delay_span_bug(
+ DUMMY_SP,
+ &format!(
+ "univariant: field #{} of `{}` comes after unsized field",
+ offsets.len(),
+ ty
+ ),
+ );
+ }
+
+ 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).ok_or(LayoutError::SizeOverflow(ty))?;
+ }
+
+ 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 = scalar_pair(cx, a, b);
+ let pair_offsets = match pair.fields {
+ FieldsShape::Arbitrary { ref offsets, ref memory_index } => {
+ assert_eq!(memory_index, &[0, 1]);
+ offsets
+ }
+ _ => bug!(),
+ };
+ 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;
+ }
+
+ Ok(LayoutS {
+ variants: Variants::Single { index: VariantIdx::new(0) },
+ fields: FieldsShape::Arbitrary { offsets, memory_index },
+ abi,
+ largest_niche,
+ align,
+ size,
+ })
+}
+
+fn layout_of_uncached<'tcx>(
+ cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
+ ty: Ty<'tcx>,
+) -> Result<Layout<'tcx>, LayoutError<'tcx>> {
+ let tcx = cx.tcx;
+ let param_env = cx.param_env;
+ let dl = cx.data_layout();
+ let scalar_unit = |value: Primitive| {
+ let size = value.size(dl);
+ assert!(size.bits() <= 128);
+ Scalar::Initialized { value, valid_range: WrappingRange::full(size) }
+ };
+ let scalar = |value: Primitive| tcx.intern_layout(LayoutS::scalar(cx, scalar_unit(value)));
+
+ let univariant = |fields: &[TyAndLayout<'_>], repr: &ReprOptions, kind| {
+ Ok(tcx.intern_layout(univariant_uninterned(cx, ty, fields, repr, kind)?))
+ };
+ debug_assert!(!ty.has_non_region_infer());
+
+ Ok(match *ty.kind() {
+ // Basic scalars.
+ ty::Bool => tcx.intern_layout(LayoutS::scalar(
+ cx,
+ Scalar::Initialized {
+ value: Int(I8, false),
+ valid_range: WrappingRange { start: 0, end: 1 },
+ },
+ )),
+ ty::Char => tcx.intern_layout(LayoutS::scalar(
+ cx,
+ Scalar::Initialized {
+ value: Int(I32, false),
+ valid_range: WrappingRange { start: 0, end: 0x10FFFF },
+ },
+ )),
+ ty::Int(ity) => scalar(Int(Integer::from_int_ty(dl, ity), true)),
+ ty::Uint(ity) => scalar(Int(Integer::from_uint_ty(dl, ity), false)),
+ ty::Float(fty) => scalar(match fty {
+ ty::FloatTy::F32 => F32,
+ ty::FloatTy::F64 => F64,
+ }),
+ ty::FnPtr(_) => {
+ let mut ptr = scalar_unit(Pointer);
+ ptr.valid_range_mut().start = 1;
+ tcx.intern_layout(LayoutS::scalar(cx, ptr))
+ }
+
+ // The never type.
+ ty::Never => tcx.intern_layout(LayoutS {
+ variants: Variants::Single { index: VariantIdx::new(0) },
+ fields: FieldsShape::Primitive,
+ abi: Abi::Uninhabited,
+ largest_niche: None,
+ align: dl.i8_align,
+ size: Size::ZERO,
+ }),
+
+ // Potentially-wide pointers.
+ ty::Ref(_, pointee, _) | ty::RawPtr(ty::TypeAndMut { ty: pointee, .. }) => {
+ let mut data_ptr = scalar_unit(Pointer);
+ if !ty.is_unsafe_ptr() {
+ data_ptr.valid_range_mut().start = 1;
+ }
+
+ let pointee = tcx.normalize_erasing_regions(param_env, pointee);
+ if pointee.is_sized(tcx, param_env) {
+ return Ok(tcx.intern_layout(LayoutS::scalar(cx, data_ptr)));
+ }
+
+ let unsized_part = tcx.struct_tail_erasing_lifetimes(pointee, param_env);
+ let metadata = match unsized_part.kind() {
+ ty::Foreign(..) => {
+ return Ok(tcx.intern_layout(LayoutS::scalar(cx, data_ptr)));
+ }
+ ty::Slice(_) | ty::Str => scalar_unit(Int(dl.ptr_sized_integer(), false)),
+ ty::Dynamic(..) => {
+ let mut vtable = scalar_unit(Pointer);
+ vtable.valid_range_mut().start = 1;
+ vtable
+ }
+ _ => return Err(LayoutError::Unknown(unsized_part)),
+ };
+
+ // Effectively a (ptr, meta) tuple.
+ tcx.intern_layout(scalar_pair(cx, data_ptr, metadata))
+ }
+
+ ty::Dynamic(_, _, ty::DynStar) => {
+ let mut data = scalar_unit(Int(dl.ptr_sized_integer(), false));
+ data.valid_range_mut().start = 0;
+ let mut vtable = scalar_unit(Pointer);
+ vtable.valid_range_mut().start = 1;
+ tcx.intern_layout(scalar_pair(cx, data, vtable))
+ }
+
+ // Arrays and slices.
+ ty::Array(element, mut count) => {
+ if count.has_projections() {
+ count = tcx.normalize_erasing_regions(param_env, count);
+ if count.has_projections() {
+ return Err(LayoutError::Unknown(ty));
+ }
+ }
+
+ let count = count.try_eval_usize(tcx, param_env).ok_or(LayoutError::Unknown(ty))?;
+ let element = cx.layout_of(element)?;
+ let size = element.size.checked_mul(count, dl).ok_or(LayoutError::SizeOverflow(ty))?;
+
+ let abi = if count != 0 && tcx.conservative_is_privately_uninhabited(param_env.and(ty))
+ {
+ Abi::Uninhabited
+ } else {
+ Abi::Aggregate { sized: true }
+ };
+
+ let largest_niche = if count != 0 { element.largest_niche } else { None };
+
+ tcx.intern_layout(LayoutS {
+ variants: Variants::Single { index: VariantIdx::new(0) },
+ fields: FieldsShape::Array { stride: element.size, count },
+ abi,
+ largest_niche,
+ align: element.align,
+ size,
+ })
+ }
+ ty::Slice(element) => {
+ let element = cx.layout_of(element)?;
+ tcx.intern_layout(LayoutS {
+ variants: Variants::Single { index: VariantIdx::new(0) },
+ fields: FieldsShape::Array { stride: element.size, count: 0 },
+ abi: Abi::Aggregate { sized: false },
+ largest_niche: None,
+ align: element.align,
+ size: Size::ZERO,
+ })
+ }
+ ty::Str => tcx.intern_layout(LayoutS {
+ variants: Variants::Single { index: VariantIdx::new(0) },
+ fields: FieldsShape::Array { stride: Size::from_bytes(1), count: 0 },
+ abi: Abi::Aggregate { sized: false },
+ largest_niche: None,
+ align: dl.i8_align,
+ size: Size::ZERO,
+ }),
+
+ // Odd unit types.
+ ty::FnDef(..) => univariant(&[], &ReprOptions::default(), StructKind::AlwaysSized)?,
+ ty::Dynamic(_, _, ty::Dyn) | ty::Foreign(..) => {
+ let mut unit = univariant_uninterned(
+ cx,
+ ty,
+ &[],
+ &ReprOptions::default(),
+ StructKind::AlwaysSized,
+ )?;
+ match unit.abi {
+ Abi::Aggregate { ref mut sized } => *sized = false,
+ _ => bug!(),
+ }
+ tcx.intern_layout(unit)
+ }
+
+ ty::Generator(def_id, substs, _) => generator_layout(cx, ty, def_id, substs)?,
+
+ ty::Closure(_, ref substs) => {
+ let tys = substs.as_closure().upvar_tys();
+ univariant(
+ &tys.map(|ty| cx.layout_of(ty)).collect::<Result<Vec<_>, _>>()?,
+ &ReprOptions::default(),
+ StructKind::AlwaysSized,
+ )?
+ }
+
+ ty::Tuple(tys) => {
+ let kind =
+ if tys.len() == 0 { StructKind::AlwaysSized } else { StructKind::MaybeUnsized };
+
+ univariant(
+ &tys.iter().map(|k| cx.layout_of(k)).collect::<Result<Vec<_>, _>>()?,
+ &ReprOptions::default(),
+ kind,
+ )?
+ }
+
+ // SIMD vector types.
+ ty::Adt(def, substs) if def.repr().simd() => {
+ if !def.is_struct() {
+ // Should have yielded E0517 by now.
+ tcx.sess.delay_span_bug(
+ DUMMY_SP,
+ "#[repr(simd)] was applied to an ADT that is not a struct",
+ );
+ return Err(LayoutError::Unknown(ty));
+ }
+
+ // Supported SIMD vectors are homogeneous ADTs with at least one field:
+ //
+ // * #[repr(simd)] struct S(T, T, T, T);
+ // * #[repr(simd)] struct S { x: T, y: T, z: T, w: T }
+ // * #[repr(simd)] struct S([T; 4])
+ //
+ // where T is a primitive scalar (integer/float/pointer).
+
+ // SIMD vectors with zero fields are not supported.
+ // (should be caught by typeck)
+ if def.non_enum_variant().fields.is_empty() {
+ tcx.sess.fatal(&format!("monomorphising SIMD type `{}` of zero length", ty));
+ }
+
+ // Type of the first ADT field:
+ let f0_ty = def.non_enum_variant().fields[0].ty(tcx, substs);
+
+ // Heterogeneous SIMD vectors are not supported:
+ // (should be caught by typeck)
+ for fi in &def.non_enum_variant().fields {
+ if fi.ty(tcx, substs) != f0_ty {
+ tcx.sess.fatal(&format!("monomorphising heterogeneous SIMD type `{}`", ty));
+ }
+ }
+
+ // The element type and number of elements of the SIMD vector
+ // are obtained from:
+ //
+ // * the element type and length of the single array field, if
+ // the first field is of array type, or
+ //
+ // * the homogeneous field type and the number of fields.
+ let (e_ty, e_len, is_array) = if let ty::Array(e_ty, _) = f0_ty.kind() {
+ // First ADT field is an array:
+
+ // SIMD vectors with multiple array fields are not supported:
+ // (should be caught by typeck)
+ if def.non_enum_variant().fields.len() != 1 {
+ tcx.sess.fatal(&format!(
+ "monomorphising SIMD type `{}` with more than one array field",
+ ty
+ ));
+ }
+
+ // Extract the number of elements from the layout of the array field:
+ let FieldsShape::Array { count, .. } = cx.layout_of(f0_ty)?.layout.fields() else {
+ return Err(LayoutError::Unknown(ty));
+ };
+
+ (*e_ty, *count, true)
+ } else {
+ // First ADT field is not an array:
+ (f0_ty, def.non_enum_variant().fields.len() as _, false)
+ };
+
+ // SIMD vectors of zero length are not supported.
+ // Additionally, lengths are capped at 2^16 as a fixed maximum backends must
+ // support.
+ //
+ // Can't be caught in typeck if the array length is generic.
+ if e_len == 0 {
+ tcx.sess.fatal(&format!("monomorphising SIMD type `{}` of zero length", ty));
+ } else if e_len > MAX_SIMD_LANES {
+ tcx.sess.fatal(&format!(
+ "monomorphising SIMD type `{}` of length greater than {}",
+ ty, MAX_SIMD_LANES,
+ ));
+ }
+
+ // Compute the ABI of the element type:
+ let e_ly = cx.layout_of(e_ty)?;
+ let Abi::Scalar(e_abi) = e_ly.abi else {
+ // This error isn't caught in typeck, e.g., if
+ // the element type of the vector is generic.
+ tcx.sess.fatal(&format!(
+ "monomorphising SIMD type `{}` with a non-primitive-scalar \
+ (integer/float/pointer) element type `{}`",
+ ty, e_ty
+ ))
+ };
+
+ // Compute the size and alignment of the vector:
+ let size = e_ly.size.checked_mul(e_len, dl).ok_or(LayoutError::SizeOverflow(ty))?;
+ let align = dl.vector_align(size);
+ let size = size.align_to(align.abi);
+
+ // Compute the placement of the vector fields:
+ let fields = if is_array {
+ FieldsShape::Arbitrary { offsets: vec![Size::ZERO], memory_index: vec![0] }
+ } else {
+ FieldsShape::Array { stride: e_ly.size, count: e_len }
+ };
+
+ tcx.intern_layout(LayoutS {
+ variants: Variants::Single { index: VariantIdx::new(0) },
+ fields,
+ abi: Abi::Vector { element: e_abi, count: e_len },
+ largest_niche: e_ly.largest_niche,
+ size,
+ align,
+ })
+ }
+
+ // ADTs.
+ ty::Adt(def, substs) => {
+ // Cache the field layouts.
+ let variants = def
+ .variants()
+ .iter()
+ .map(|v| {
+ v.fields
+ .iter()
+ .map(|field| cx.layout_of(field.ty(tcx, substs)))
+ .collect::<Result<Vec<_>, _>>()
+ })
+ .collect::<Result<IndexVec<VariantIdx, _>, _>>()?;
+
+ if def.is_union() {
+ if def.repr().pack.is_some() && def.repr().align.is_some() {
+ cx.tcx.sess.delay_span_bug(
+ tcx.def_span(def.did()),
+ "union cannot be packed and aligned",
+ );
+ return Err(LayoutError::Unknown(ty));
+ }
+
+ let mut align =
+ if def.repr().pack.is_some() { dl.i8_align } else { dl.aggregate_align };
+
+ if let Some(repr_align) = def.repr().align {
+ align = align.max(AbiAndPrefAlign::new(repr_align));
+ }
+
+ let optimize = !def.repr().inhibit_union_abi_opt();
+ let mut size = Size::ZERO;
+ let mut abi = Abi::Aggregate { sized: true };
+ let index = VariantIdx::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) = def.repr().pack {
+ align = align.min(AbiAndPrefAlign::new(pack));
+ }
+
+ return Ok(tcx.intern_layout(LayoutS {
+ variants: Variants::Single { index },
+ fields: FieldsShape::Union(
+ NonZeroUsize::new(variants[index].len()).ok_or(LayoutError::Unknown(ty))?,
+ ),
+ abi,
+ largest_niche: None,
+ align,
+ size: size.align_to(align.abi),
+ }));
+ }
+
+ // 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: &[TyAndLayout<'_>]| {
+ 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 def.is_enum() => {
+ return Ok(tcx.layout_of(param_env.and(tcx.types.never))?.layout);
+ }
+ // If it's a struct, still compute a layout so that we can still compute the
+ // field offsets.
+ None => VariantIdx::new(0),
+ };
+
+ let is_struct = !def.is_enum() ||
+ // Only one variant is present.
+ (present_second.is_none() &&
+ // Representation optimizations are allowed.
+ !def.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 def.is_enum() || variants[v].is_empty() {
+ StructKind::AlwaysSized
+ } else {
+ let param_env = tcx.param_env(def.did());
+ let last_field = def.variant(v).fields.last().unwrap();
+ let always_sized = tcx.type_of(last_field.did).is_sized(tcx, param_env);
+ if !always_sized { StructKind::MaybeUnsized } else { StructKind::AlwaysSized }
+ };
+
+ let mut st = univariant_uninterned(cx, ty, &variants[v], &def.repr(), kind)?;
+ st.variants = Variants::Single { index: v };
+
+ if def.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 Ok(tcx.intern_layout(st));
+ }
+
+ let (start, end) = cx.tcx.layout_scalar_valid_range(def.did());
+ 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 {:?}: {:#?}",
+ def,
+ st,
+ ),
+ }
+
+ return Ok(tcx.intern_layout(st));
+ }
+
+ // At this point, we have handled all unions and
+ // structs. (We have also handled univariant enums
+ // that allow representation optimization.)
+ assert!(def.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<'tcx> {
+ layout: LayoutS<'tcx>,
+ variants: IndexVec<VariantIdx, LayoutS<'tcx>>,
+ }
+
+ let calculate_niche_filling_layout =
+ || -> Result<Option<TmpLayout<'tcx>>, LayoutError<'tcx>> {
+ // The current code for niche-filling relies on variant indices
+ // instead of actual discriminants, so enums with
+ // explicit discriminants (RFC #2363) would misbehave.
+ if def.repr().inhibit_enum_layout_opt()
+ || def
+ .variants()
+ .iter_enumerated()
+ .any(|(i, v)| v.discr != ty::VariantDiscr::Relative(i.as_u32()))
+ {
+ return Ok(None);
+ }
+
+ if variants.len() < 2 {
+ return Ok(None);
+ }
+
+ let mut align = dl.aggregate_align;
+ let mut variant_layouts = variants
+ .iter_enumerated()
+ .map(|(j, v)| {
+ let mut st = univariant_uninterned(
+ cx,
+ ty,
+ v,
+ &def.repr(),
+ StructKind::AlwaysSized,
+ )?;
+ st.variants = Variants::Single { index: j };
+
+ align = align.max(st.align);
+
+ Ok(st)
+ })
+ .collect::<Result<IndexVec<VariantIdx, _>, _>>()?;
+
+ let largest_variant_index = match variant_layouts
+ .iter_enumerated()
+ .max_by_key(|(_i, layout)| layout.size.bytes())
+ .map(|(i, _layout)| i)
+ {
+ None => return Ok(None),
+ Some(i) => i,
+ };
+
+ let all_indices = VariantIdx::new(0)..=VariantIdx::new(variants.len() - 1);
+ let needs_disc = |index: VariantIdx| {
+ index != largest_variant_index && !absent(&variants[index])
+ };
+ let niche_variants = all_indices.clone().find(|v| needs_disc(*v)).unwrap()
+ ..=all_indices.rev().find(|v| needs_disc(*v)).unwrap();
+
+ 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)) = match 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(cx, count)?)))
+ {
+ None => return Ok(None),
+ Some(x) => x,
+ };
+
+ 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 Ok(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,
+ niche_start,
+ },
+ tag_field: 0,
+ variants: IndexVec::new(),
+ },
+ fields: FieldsShape::Arbitrary {
+ offsets: vec![niche_offset],
+ memory_index: vec![0],
+ },
+ abi,
+ largest_niche,
+ size,
+ align,
+ };
+
+ Ok(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 = def.repr().discr_type();
+ let bits = Integer::from_attr(cx, discr_type).size().bits();
+ for (i, discr) in def.discriminants(tcx) {
+ if variants[i].iter().any(|f| f.abi.is_uninhabited()) {
+ continue;
+ }
+ let mut x = discr.val as i128;
+ if discr_type.is_signed() {
+ // sign extend the raw representation to be an i128
+ x = (x << (128 - bits)) >> (128 - bits);
+ }
+ if x < min {
+ min = x;
+ }
+ if x > max {
+ max = x;
+ }
+ }
+ // 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) = Integer::repr_discr(tcx, ty, &def.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 def.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 = univariant_uninterned(
+ cx,
+ ty,
+ &field_layouts,
+ &def.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);
+ Ok(st)
+ })
+ .collect::<Result<IndexVec<VariantIdx, _>, _>>()?;
+
+ // Align the maximum variant size to the largest alignment.
+ size = size.align_to(align.abi);
+
+ if size.bytes() >= dl.obj_size_bound() {
+ return Err(LayoutError::SizeOverflow(ty));
+ }
+
+ let typeck_ity = Integer::from_attr(dl, def.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)
+ bug!(
+ "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 def.repr().c() || def.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;
+ }
+ }
+ _ => bug!(),
+ }
+ }
+ }
+
+ 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 {
+ bug!();
+ };
+ 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 = scalar_pair(cx, tag, prim_scalar);
+ let pair_offsets = match pair.fields {
+ FieldsShape::Arbitrary { ref offsets, ref memory_index } => {
+ assert_eq!(memory_index, &[0, 1]);
+ offsets
+ }
+ _ => bug!(),
+ };
+ 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 Ordering::*;
+ let niche_size = |tmp_l: &TmpLayout<'_>| {
+ 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
+ .into_iter()
+ .map(|layout| tcx.intern_layout(layout))
+ .collect(),
+ },
+ _ => bug!(),
+ };
+
+ tcx.intern_layout(best_layout.layout)
+ }
+
+ // Types with no meaningful known layout.
+ ty::Projection(_) | ty::Opaque(..) => {
+ // NOTE(eddyb) `layout_of` query should've normalized these away,
+ // if that was possible, so there's no reason to try again here.
+ return Err(LayoutError::Unknown(ty));
+ }
+
+ ty::Placeholder(..) | ty::GeneratorWitness(..) | ty::Infer(_) => {
+ bug!("Layout::compute: unexpected type `{}`", ty)
+ }
+
+ ty::Bound(..) | ty::Param(_) | ty::Error(_) => {
+ return Err(LayoutError::Unknown(ty));
+ }
+ })
+}
+
+/// Overlap eligibility and variant assignment for each GeneratorSavedLocal.
+#[derive(Clone, Debug, PartialEq)]
+enum SavedLocalEligibility {
+ Unassigned,
+ Assigned(VariantIdx),
+ // FIXME: Use newtype_index so we aren't wasting bytes
+ Ineligible(Option<u32>),
+}
+
+// When laying out generators, we divide our saved local fields into two
+// categories: overlap-eligible and overlap-ineligible.
+//
+// Those fields which are ineligible for overlap go in a "prefix" at the
+// beginning of the layout, and always have space reserved for them.
+//
+// Overlap-eligible fields are only assigned to one variant, so we lay
+// those fields out for each variant and put them right after the
+// prefix.
+//
+// Finally, in the layout details, we point to the fields from the
+// variants they are assigned to. It is possible for some fields to be
+// included in multiple variants. No field ever "moves around" in the
+// layout; its offset is always the same.
+//
+// Also included in the layout are the upvars and the discriminant.
+// These are included as fields on the "outer" layout; they are not part
+// of any variant.
+
+/// Compute the eligibility and assignment of each local.
+fn generator_saved_local_eligibility<'tcx>(
+ info: &GeneratorLayout<'tcx>,
+) -> (BitSet<GeneratorSavedLocal>, IndexVec<GeneratorSavedLocal, SavedLocalEligibility>) {
+ use SavedLocalEligibility::*;
+
+ let mut assignments: IndexVec<GeneratorSavedLocal, SavedLocalEligibility> =
+ IndexVec::from_elem_n(Unassigned, info.field_tys.len());
+
+ // The saved locals not eligible for overlap. These will get
+ // "promoted" to the prefix of our generator.
+ let mut ineligible_locals = BitSet::new_empty(info.field_tys.len());
+
+ // Figure out which of our saved locals are fields in only
+ // one variant. The rest are deemed ineligible for overlap.
+ for (variant_index, fields) in info.variant_fields.iter_enumerated() {
+ for local in fields {
+ match assignments[*local] {
+ Unassigned => {
+ assignments[*local] = Assigned(variant_index);
+ }
+ Assigned(idx) => {
+ // We've already seen this local at another suspension
+ // point, so it is no longer a candidate.
+ trace!(
+ "removing local {:?} in >1 variant ({:?}, {:?})",
+ local,
+ variant_index,
+ idx
+ );
+ ineligible_locals.insert(*local);
+ assignments[*local] = Ineligible(None);
+ }
+ Ineligible(_) => {}
+ }
+ }
+ }
+
+ // Next, check every pair of eligible locals to see if they
+ // conflict.
+ for local_a in info.storage_conflicts.rows() {
+ let conflicts_a = info.storage_conflicts.count(local_a);
+ if ineligible_locals.contains(local_a) {
+ continue;
+ }
+
+ for local_b in info.storage_conflicts.iter(local_a) {
+ // local_a and local_b are storage live at the same time, therefore they
+ // cannot overlap in the generator layout. The only way to guarantee
+ // this is if they are in the same variant, or one is ineligible
+ // (which means it is stored in every variant).
+ if ineligible_locals.contains(local_b) || assignments[local_a] == assignments[local_b] {
+ continue;
+ }
+
+ // If they conflict, we will choose one to make ineligible.
+ // This is not always optimal; it's just a greedy heuristic that
+ // seems to produce good results most of the time.
+ let conflicts_b = info.storage_conflicts.count(local_b);
+ let (remove, other) =
+ if conflicts_a > conflicts_b { (local_a, local_b) } else { (local_b, local_a) };
+ ineligible_locals.insert(remove);
+ assignments[remove] = Ineligible(None);
+ trace!("removing local {:?} due to conflict with {:?}", remove, other);
+ }
+ }
+
+ // Count the number of variants in use. If only one of them, then it is
+ // impossible to overlap any locals in our layout. In this case it's
+ // always better to make the remaining locals ineligible, so we can
+ // lay them out with the other locals in the prefix and eliminate
+ // unnecessary padding bytes.
+ {
+ let mut used_variants = BitSet::new_empty(info.variant_fields.len());
+ for assignment in &assignments {
+ if let Assigned(idx) = assignment {
+ used_variants.insert(*idx);
+ }
+ }
+ if used_variants.count() < 2 {
+ for assignment in assignments.iter_mut() {
+ *assignment = Ineligible(None);
+ }
+ ineligible_locals.insert_all();
+ }
+ }
+
+ // Write down the order of our locals that will be promoted to the prefix.
+ {
+ for (idx, local) in ineligible_locals.iter().enumerate() {
+ assignments[local] = Ineligible(Some(idx as u32));
+ }
+ }
+ debug!("generator saved local assignments: {:?}", assignments);
+
+ (ineligible_locals, assignments)
+}
+
+/// Compute the full generator layout.
+fn generator_layout<'tcx>(
+ cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
+ ty: Ty<'tcx>,
+ def_id: hir::def_id::DefId,
+ substs: SubstsRef<'tcx>,
+) -> Result<Layout<'tcx>, LayoutError<'tcx>> {
+ use SavedLocalEligibility::*;
+ let tcx = cx.tcx;
+ let subst_field = |ty: Ty<'tcx>| EarlyBinder(ty).subst(tcx, substs);
+
+ let Some(info) = tcx.generator_layout(def_id) else {
+ return Err(LayoutError::Unknown(ty));
+ };
+ let (ineligible_locals, assignments) = generator_saved_local_eligibility(&info);
+
+ // Build a prefix layout, including "promoting" all ineligible
+ // locals as part of the prefix. We compute the layout of all of
+ // these fields at once to get optimal packing.
+ let tag_index = substs.as_generator().prefix_tys().count();
+
+ // `info.variant_fields` already accounts for the reserved variants, so no need to add them.
+ let max_discr = (info.variant_fields.len() - 1) as u128;
+ let discr_int = Integer::fit_unsigned(max_discr);
+ let discr_int_ty = discr_int.to_ty(tcx, false);
+ let tag = Scalar::Initialized {
+ value: Primitive::Int(discr_int, false),
+ valid_range: WrappingRange { start: 0, end: max_discr },
+ };
+ let tag_layout = cx.tcx.intern_layout(LayoutS::scalar(cx, tag));
+ let tag_layout = TyAndLayout { ty: discr_int_ty, layout: tag_layout };
+
+ let promoted_layouts = ineligible_locals
+ .iter()
+ .map(|local| subst_field(info.field_tys[local]))
+ .map(|ty| tcx.mk_maybe_uninit(ty))
+ .map(|ty| cx.layout_of(ty));
+ let prefix_layouts = substs
+ .as_generator()
+ .prefix_tys()
+ .map(|ty| cx.layout_of(ty))
+ .chain(iter::once(Ok(tag_layout)))
+ .chain(promoted_layouts)
+ .collect::<Result<Vec<_>, _>>()?;
+ let prefix = univariant_uninterned(
+ cx,
+ ty,
+ &prefix_layouts,
+ &ReprOptions::default(),
+ StructKind::AlwaysSized,
+ )?;
+
+ let (prefix_size, prefix_align) = (prefix.size, prefix.align);
+
+ // Split the prefix layout into the "outer" fields (upvars and
+ // discriminant) and the "promoted" fields. Promoted fields will
+ // get included in each variant that requested them in
+ // GeneratorLayout.
+ debug!("prefix = {:#?}", prefix);
+ let (outer_fields, promoted_offsets, promoted_memory_index) = match prefix.fields {
+ FieldsShape::Arbitrary { mut offsets, memory_index } => {
+ let mut inverse_memory_index = invert_mapping(&memory_index);
+
+ // "a" (`0..b_start`) and "b" (`b_start..`) correspond to
+ // "outer" and "promoted" fields respectively.
+ let b_start = (tag_index + 1) as u32;
+ let offsets_b = offsets.split_off(b_start as usize);
+ let offsets_a = offsets;
+
+ // Disentangle the "a" and "b" components of `inverse_memory_index`
+ // by preserving the order but keeping only one disjoint "half" each.
+ // FIXME(eddyb) build a better abstraction for permutations, if possible.
+ let inverse_memory_index_b: Vec<_> =
+ inverse_memory_index.iter().filter_map(|&i| i.checked_sub(b_start)).collect();
+ inverse_memory_index.retain(|&i| i < b_start);
+ let inverse_memory_index_a = inverse_memory_index;
+
+ // Since `inverse_memory_index_{a,b}` each only refer to their
+ // respective fields, they can be safely inverted
+ let memory_index_a = invert_mapping(&inverse_memory_index_a);
+ let memory_index_b = invert_mapping(&inverse_memory_index_b);
+
+ let outer_fields =
+ FieldsShape::Arbitrary { offsets: offsets_a, memory_index: memory_index_a };
+ (outer_fields, offsets_b, memory_index_b)
+ }
+ _ => bug!(),
+ };
+
+ let mut size = prefix.size;
+ let mut align = prefix.align;
+ let variants = info
+ .variant_fields
+ .iter_enumerated()
+ .map(|(index, variant_fields)| {
+ // Only include overlap-eligible fields when we compute our variant layout.
+ let variant_only_tys = variant_fields
+ .iter()
+ .filter(|local| match assignments[**local] {
+ Unassigned => bug!(),
+ Assigned(v) if v == index => true,
+ Assigned(_) => bug!("assignment does not match variant"),
+ Ineligible(_) => false,
+ })
+ .map(|local| subst_field(info.field_tys[*local]));
+
+ let mut variant = univariant_uninterned(
+ cx,
+ ty,
+ &variant_only_tys.map(|ty| cx.layout_of(ty)).collect::<Result<Vec<_>, _>>()?,
+ &ReprOptions::default(),
+ StructKind::Prefixed(prefix_size, prefix_align.abi),
+ )?;
+ variant.variants = Variants::Single { index };
+
+ let FieldsShape::Arbitrary { offsets, memory_index } = variant.fields else {
+ bug!();
+ };
+
+ // Now, stitch the promoted and variant-only fields back together in
+ // the order they are mentioned by our GeneratorLayout.
+ // Because we only use some subset (that can differ between variants)
+ // of the promoted fields, we can't just pick those elements of the
+ // `promoted_memory_index` (as we'd end up with gaps).
+ // So instead, we build an "inverse memory_index", as if all of the
+ // promoted fields were being used, but leave the elements not in the
+ // subset as `INVALID_FIELD_IDX`, which we can filter out later to
+ // obtain a valid (bijective) mapping.
+ const INVALID_FIELD_IDX: u32 = !0;
+ let mut combined_inverse_memory_index =
+ vec![INVALID_FIELD_IDX; promoted_memory_index.len() + memory_index.len()];
+ let mut offsets_and_memory_index = iter::zip(offsets, memory_index);
+ let combined_offsets = variant_fields
+ .iter()
+ .enumerate()
+ .map(|(i, local)| {
+ let (offset, memory_index) = match assignments[*local] {
+ Unassigned => bug!(),
+ Assigned(_) => {
+ let (offset, memory_index) = offsets_and_memory_index.next().unwrap();
+ (offset, promoted_memory_index.len() as u32 + memory_index)
+ }
+ Ineligible(field_idx) => {
+ let field_idx = field_idx.unwrap() as usize;
+ (promoted_offsets[field_idx], promoted_memory_index[field_idx])
+ }
+ };
+ combined_inverse_memory_index[memory_index as usize] = i as u32;
+ offset
+ })
+ .collect();
+
+ // Remove the unused slots and invert the mapping to obtain the
+ // combined `memory_index` (also see previous comment).
+ combined_inverse_memory_index.retain(|&i| i != INVALID_FIELD_IDX);
+ let combined_memory_index = invert_mapping(&combined_inverse_memory_index);
+
+ variant.fields = FieldsShape::Arbitrary {
+ offsets: combined_offsets,
+ memory_index: combined_memory_index,
+ };
+
+ size = size.max(variant.size);
+ align = align.max(variant.align);
+ Ok(tcx.intern_layout(variant))
+ })
+ .collect::<Result<IndexVec<VariantIdx, _>, _>>()?;
+
+ size = size.align_to(align.abi);
+
+ let abi = if prefix.abi.is_uninhabited() || variants.iter().all(|v| v.abi().is_uninhabited()) {
+ Abi::Uninhabited
+ } else {
+ Abi::Aggregate { sized: true }
+ };
+
+ let layout = tcx.intern_layout(LayoutS {
+ variants: Variants::Multiple {
+ tag,
+ tag_encoding: TagEncoding::Direct,
+ tag_field: tag_index,
+ variants,
+ },
+ fields: outer_fields,
+ abi,
+ largest_niche: prefix.largest_niche,
+ size,
+ align,
+ });
+ debug!("generator layout ({:?}): {:#?}", ty, layout);
+ Ok(layout)
+}
+
+/// This is invoked by the `layout_of` query to record the final
+/// layout of each type.
+#[inline(always)]
+fn record_layout_for_printing<'tcx>(cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, layout: TyAndLayout<'tcx>) {
+ // If we are running with `-Zprint-type-sizes`, maybe record layouts
+ // for dumping later.
+ if cx.tcx.sess.opts.unstable_opts.print_type_sizes {
+ record_layout_for_printing_outlined(cx, layout)
+ }
+}
+
+fn record_layout_for_printing_outlined<'tcx>(
+ cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
+ layout: TyAndLayout<'tcx>,
+) {
+ // Ignore layouts that are done with non-empty environments or
+ // non-monomorphic layouts, as the user only wants to see the stuff
+ // resulting from the final codegen session.
+ if layout.ty.has_non_region_param() || !cx.param_env.caller_bounds().is_empty() {
+ return;
+ }
+
+ // (delay format until we actually need it)
+ let record = |kind, packed, opt_discr_size, variants| {
+ let type_desc = format!("{:?}", layout.ty);
+ cx.tcx.sess.code_stats.record_type_size(
+ kind,
+ type_desc,
+ layout.align.abi,
+ layout.size,
+ packed,
+ opt_discr_size,
+ variants,
+ );
+ };
+
+ let adt_def = match *layout.ty.kind() {
+ ty::Adt(ref adt_def, _) => {
+ debug!("print-type-size t: `{:?}` process adt", layout.ty);
+ adt_def
+ }
+
+ ty::Closure(..) => {
+ debug!("print-type-size t: `{:?}` record closure", layout.ty);
+ record(DataTypeKind::Closure, false, None, vec![]);
+ return;
+ }
+
+ _ => {
+ debug!("print-type-size t: `{:?}` skip non-nominal", layout.ty);
+ return;
+ }
+ };
+
+ let adt_kind = adt_def.adt_kind();
+ let adt_packed = adt_def.repr().pack.is_some();
+
+ let build_variant_info = |n: Option<Symbol>, flds: &[Symbol], layout: TyAndLayout<'tcx>| {
+ let mut min_size = Size::ZERO;
+ let field_info: Vec<_> = flds
+ .iter()
+ .enumerate()
+ .map(|(i, &name)| {
+ let field_layout = layout.field(cx, i);
+ let offset = layout.fields.offset(i);
+ let field_end = offset + field_layout.size;
+ if min_size < field_end {
+ min_size = field_end;
+ }
+ FieldInfo {
+ name,
+ offset: offset.bytes(),
+ size: field_layout.size.bytes(),
+ align: field_layout.align.abi.bytes(),
+ }
+ })
+ .collect();
+
+ VariantInfo {
+ name: n,
+ kind: if layout.is_unsized() { SizeKind::Min } else { SizeKind::Exact },
+ align: layout.align.abi.bytes(),
+ size: if min_size.bytes() == 0 { layout.size.bytes() } else { min_size.bytes() },
+ fields: field_info,
+ }
+ };
+
+ match layout.variants {
+ Variants::Single { index } => {
+ if !adt_def.variants().is_empty() && layout.fields != FieldsShape::Primitive {
+ debug!("print-type-size `{:#?}` variant {}", layout, adt_def.variant(index).name);
+ let variant_def = &adt_def.variant(index);
+ let fields: Vec<_> = variant_def.fields.iter().map(|f| f.name).collect();
+ record(
+ adt_kind.into(),
+ adt_packed,
+ None,
+ vec![build_variant_info(Some(variant_def.name), &fields, layout)],
+ );
+ } else {
+ // (This case arises for *empty* enums; so give it
+ // zero variants.)
+ record(adt_kind.into(), adt_packed, None, vec![]);
+ }
+ }
+
+ Variants::Multiple { tag, ref tag_encoding, .. } => {
+ debug!(
+ "print-type-size `{:#?}` adt general variants def {}",
+ layout.ty,
+ adt_def.variants().len()
+ );
+ let variant_infos: Vec<_> = adt_def
+ .variants()
+ .iter_enumerated()
+ .map(|(i, variant_def)| {
+ let fields: Vec<_> = variant_def.fields.iter().map(|f| f.name).collect();
+ build_variant_info(Some(variant_def.name), &fields, layout.for_variant(cx, i))
+ })
+ .collect();
+ record(
+ adt_kind.into(),
+ adt_packed,
+ match tag_encoding {
+ TagEncoding::Direct => Some(tag.size(cx)),
+ _ => None,
+ },
+ variant_infos,
+ );
+ }
+ }
+}
diff --git a/compiler/rustc_middle/src/ty/layout_sanity_check.rs b/compiler/rustc_ty_utils/src/layout_sanity_check.rs
index 87c85dcff..100926ad4 100644
--- a/compiler/rustc_middle/src/ty/layout_sanity_check.rs
+++ b/compiler/rustc_ty_utils/src/layout_sanity_check.rs
@@ -1,4 +1,4 @@
-use crate::ty::{
+use rustc_middle::ty::{
layout::{LayoutCx, TyAndLayout},
TyCtxt,
};
diff --git a/compiler/rustc_ty_utils/src/lib.rs b/compiler/rustc_ty_utils/src/lib.rs
index 8524e57cb..cce5a79dd 100644
--- a/compiler/rustc_ty_utils/src/lib.rs
+++ b/compiler/rustc_ty_utils/src/lib.rs
@@ -5,13 +5,11 @@
//! This API is completely unstable and subject to change.
#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
+#![feature(let_chains)]
#![feature(control_flow_enum)]
-#![cfg_attr(bootstrap, feature(let_else))]
#![feature(never_type)]
#![feature(box_patterns)]
#![recursion_limit = "256"]
-#![deny(rustc::untranslatable_diagnostic)]
-#![deny(rustc::diagnostic_outside_of_impl)]
#[macro_use]
extern crate rustc_middle;
@@ -20,22 +18,28 @@ extern crate tracing;
use rustc_middle::ty::query::Providers;
+mod abi;
mod assoc;
mod common_traits;
mod consts;
mod errors;
mod implied_bounds;
pub mod instance;
+mod layout;
+mod layout_sanity_check;
mod needs_drop;
pub mod representability;
mod ty;
pub fn provide(providers: &mut Providers) {
+ abi::provide(providers);
assoc::provide(providers);
common_traits::provide(providers);
consts::provide(providers);
implied_bounds::provide(providers);
+ layout::provide(providers);
needs_drop::provide(providers);
+ representability::provide(providers);
ty::provide(providers);
instance::provide(providers);
}
diff --git a/compiler/rustc_ty_utils/src/needs_drop.rs b/compiler/rustc_ty_utils/src/needs_drop.rs
index ab5a3d8ae..024dcd591 100644
--- a/compiler/rustc_ty_utils/src/needs_drop.rs
+++ b/compiler/rustc_ty_utils/src/needs_drop.rs
@@ -2,7 +2,6 @@
use rustc_data_structures::fx::FxHashSet;
use rustc_hir::def_id::DefId;
-use rustc_middle::ty::subst::Subst;
use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::util::{needs_drop_components, AlwaysRequiresDrop};
use rustc_middle::ty::{self, EarlyBinder, Ty, TyCtxt};
@@ -110,7 +109,7 @@ where
for component in components {
match *component.kind() {
- _ if component.is_copy_modulo_regions(tcx.at(DUMMY_SP), self.param_env) => (),
+ _ if component.is_copy_modulo_regions(tcx, self.param_env) => (),
ty::Closure(_, substs) => {
queue_type(self, substs.as_closure().tupled_upvars_ty());
@@ -265,7 +264,7 @@ fn adt_consider_insignificant_dtor<'tcx>(
if is_marked_insig {
// In some cases like `std::collections::HashMap` where the struct is a wrapper around
// a type that is a Drop type, and the wrapped type (eg: `hashbrown::HashMap`) lies
- // outside stdlib, we might choose to still annotate the the wrapper (std HashMap) with
+ // outside stdlib, we might choose to still annotate the wrapper (std HashMap) with
// `rustc_insignificant_dtor`, even if the type itself doesn't have a `Drop` impl.
Some(DtorType::Insignificant)
} else if adt_def.destructor(tcx).is_some() {
diff --git a/compiler/rustc_ty_utils/src/representability.rs b/compiler/rustc_ty_utils/src/representability.rs
index eded78916..7f48fb804 100644
--- a/compiler/rustc_ty_utils/src/representability.rs
+++ b/compiler/rustc_ty_utils/src/representability.rs
@@ -1,386 +1,119 @@
-//! Check whether a type is representable.
-use rustc_data_structures::fx::FxHashMap;
-use rustc_hir as hir;
-use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_span::Span;
-use std::cmp;
+#![allow(rustc::untranslatable_diagnostic, rustc::diagnostic_outside_of_impl)]
-/// Describes whether a type is representable. For types that are not
-/// representable, 'SelfRecursive' and 'ContainsRecursive' are used to
-/// distinguish between types that are recursive with themselves and types that
-/// contain a different recursive type. These cases can therefore be treated
-/// differently when reporting errors.
-///
-/// The ordering of the cases is significant. They are sorted so that cmp::max
-/// will keep the "more erroneous" of two values.
-#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
-pub enum Representability {
- Representable,
- ContainsRecursive,
- /// Return a list of types that are included in themselves:
- /// the spans where they are self-included, and (if found)
- /// the HirId of the FieldDef that defines the self-inclusion.
- SelfRecursive(Vec<(Span, Option<hir::HirId>)>),
-}
+use rustc_hir::def::DefKind;
+use rustc_index::bit_set::BitSet;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::{self, Representability, Ty, TyCtxt};
+use rustc_span::def_id::{DefId, LocalDefId};
-/// Check whether a type is representable. This means it cannot contain unboxed
-/// structural recursion. This check is needed for structs and enums.
-pub fn ty_is_representable<'tcx>(
- tcx: TyCtxt<'tcx>,
- ty: Ty<'tcx>,
- sp: Span,
- field_id: Option<hir::HirId>,
-) -> Representability {
- debug!("is_type_representable: {:?}", ty);
- // To avoid a stack overflow when checking an enum variant or struct that
- // contains a different, structurally recursive type, maintain a stack of
- // seen types and check recursion for each of them (issues #3008, #3779,
- // #74224, #84611). `shadow_seen` contains the full stack and `seen` only
- // the one for the current type (e.g. if we have structs A and B, B contains
- // a field of type A, and we're currently looking at B, then `seen` will be
- // cleared when recursing to check A, but `shadow_seen` won't, so that we
- // can catch cases of mutual recursion where A also contains B).
- let mut seen: Vec<Ty<'_>> = Vec::new();
- let mut shadow_seen: Vec<ty::AdtDef<'tcx>> = Vec::new();
- let mut representable_cache = FxHashMap::default();
- let mut force_result = false;
- let r = is_type_structurally_recursive(
- tcx,
- &mut seen,
- &mut shadow_seen,
- &mut representable_cache,
- ty,
- sp,
- field_id,
- &mut force_result,
- );
- debug!("is_type_representable: {:?} is {:?}", ty, r);
- r
+pub fn provide(providers: &mut Providers) {
+ *providers =
+ Providers { representability, representability_adt_ty, params_in_repr, ..*providers };
}
-// Iterate until something non-representable is found
-fn fold_repr<It: Iterator<Item = Representability>>(iter: It) -> Representability {
- iter.fold(Representability::Representable, |r1, r2| match (r1, r2) {
- (Representability::SelfRecursive(v1), Representability::SelfRecursive(v2)) => {
- Representability::SelfRecursive(v1.into_iter().chain(v2).collect())
+macro_rules! rtry {
+ ($e:expr) => {
+ match $e {
+ e @ Representability::Infinite => return e,
+ Representability::Representable => {}
}
- (r1, r2) => cmp::max(r1, r2),
- })
+ };
}
-fn are_inner_types_recursive<'tcx>(
- tcx: TyCtxt<'tcx>,
- seen: &mut Vec<Ty<'tcx>>,
- shadow_seen: &mut Vec<ty::AdtDef<'tcx>>,
- representable_cache: &mut FxHashMap<Ty<'tcx>, Representability>,
- ty: Ty<'tcx>,
- sp: Span,
- field_id: Option<hir::HirId>,
- force_result: &mut bool,
-) -> Representability {
- debug!("are_inner_types_recursive({:?}, {:?}, {:?})", ty, seen, shadow_seen);
- match ty.kind() {
- ty::Tuple(fields) => {
- // Find non representable
- fold_repr(fields.iter().map(|ty| {
- is_type_structurally_recursive(
- tcx,
- seen,
- shadow_seen,
- representable_cache,
- ty,
- sp,
- field_id,
- force_result,
- )
- }))
- }
- // Fixed-length vectors.
- // FIXME(#11924) Behavior undecided for zero-length vectors.
- ty::Array(ty, _) => is_type_structurally_recursive(
- tcx,
- seen,
- shadow_seen,
- representable_cache,
- *ty,
- sp,
- field_id,
- force_result,
- ),
- ty::Adt(def, substs) => {
- // Find non representable fields with their spans
- fold_repr(def.all_fields().map(|field| {
- let ty = field.ty(tcx, substs);
- let (sp, field_id) = match field
- .did
- .as_local()
- .map(|id| tcx.hir().local_def_id_to_hir_id(id))
- .and_then(|id| tcx.hir().find(id))
- {
- Some(hir::Node::Field(field)) => (field.ty.span, Some(field.hir_id)),
- _ => (sp, field_id),
- };
-
- let mut result = None;
-
- // First, we check whether the field type per se is representable.
- // This catches cases as in #74224 and #84611. There is a special
- // case related to mutual recursion, though; consider this example:
- //
- // struct A<T> {
- // z: T,
- // x: B<T>,
- // }
- //
- // struct B<T> {
- // y: A<T>
- // }
- //
- // Here, without the following special case, both A and B are
- // ContainsRecursive, which is a problem because we only report
- // errors for SelfRecursive. We fix this by detecting this special
- // case (shadow_seen.first() is the type we are originally
- // interested in, and if we ever encounter the same AdtDef again,
- // we know that it must be SelfRecursive) and "forcibly" returning
- // SelfRecursive (by setting force_result, which tells the calling
- // invocations of are_inner_types_representable to forward the
- // result without adjusting).
- if shadow_seen.len() > seen.len() && shadow_seen.first() == Some(def) {
- *force_result = true;
- result = Some(Representability::SelfRecursive(vec![(sp, field_id)]));
- }
-
- if result == None {
- result = Some(Representability::Representable);
-
- // Now, we check whether the field types per se are representable, e.g.
- // for struct Foo { x: Option<Foo> }, we first check whether Option<_>
- // by itself is representable (which it is), and the nesting of Foo
- // will be detected later. This is necessary for #74224 and #84611.
-
- // If we have encountered an ADT definition that we have not seen
- // before (no need to check them twice), recurse to see whether that
- // definition is SelfRecursive. If so, we must be ContainsRecursive.
- if shadow_seen.len() > 1
- && !shadow_seen
- .iter()
- .take(shadow_seen.len() - 1)
- .any(|seen_def| seen_def == def)
- {
- let adt_def_id = def.did();
- let raw_adt_ty = tcx.type_of(adt_def_id);
- debug!("are_inner_types_recursive: checking nested type: {:?}", raw_adt_ty);
-
- // Check independently whether the ADT is SelfRecursive. If so,
- // we must be ContainsRecursive (except for the special case
- // mentioned above).
- let mut nested_seen: Vec<Ty<'_>> = vec![];
- result = Some(
- match is_type_structurally_recursive(
- tcx,
- &mut nested_seen,
- shadow_seen,
- representable_cache,
- raw_adt_ty,
- sp,
- field_id,
- force_result,
- ) {
- Representability::SelfRecursive(_) => {
- if *force_result {
- Representability::SelfRecursive(vec![(sp, field_id)])
- } else {
- Representability::ContainsRecursive
- }
- }
- x => x,
- },
- );
- }
-
- // We only enter the following block if the type looks representable
- // so far. This is necessary for cases such as this one (#74224):
- //
- // struct A<T> {
- // x: T,
- // y: A<A<T>>,
- // }
- //
- // struct B {
- // z: A<usize>
- // }
- //
- // When checking B, we recurse into A and check field y of type
- // A<A<usize>>. We haven't seen this exact type before, so we recurse
- // into A<A<usize>>, which contains, A<A<A<usize>>>, and so forth,
- // ad infinitum. We can prevent this from happening by first checking
- // A separately (the code above) and only checking for nested Bs if
- // A actually looks representable (which it wouldn't in this example).
- if result == Some(Representability::Representable) {
- // Now, even if the type is representable (e.g. Option<_>),
- // it might still contribute to a recursive type, e.g.:
- // struct Foo { x: Option<Option<Foo>> }
- // These cases are handled by passing the full `seen`
- // stack to is_type_structurally_recursive (instead of the
- // empty `nested_seen` above):
- result = Some(
- match is_type_structurally_recursive(
- tcx,
- seen,
- shadow_seen,
- representable_cache,
- ty,
- sp,
- field_id,
- force_result,
- ) {
- Representability::SelfRecursive(_) => {
- Representability::SelfRecursive(vec![(sp, field_id)])
- }
- x => x,
- },
- );
- }
+fn representability(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Representability {
+ match tcx.def_kind(def_id) {
+ DefKind::Struct | DefKind::Union | DefKind::Enum => {
+ let adt_def = tcx.adt_def(def_id);
+ for variant in adt_def.variants() {
+ for field in variant.fields.iter() {
+ rtry!(tcx.representability(field.did.expect_local()));
}
-
- result.unwrap()
- }))
- }
- ty::Closure(..) => {
- // this check is run on type definitions, so we don't expect
- // to see closure types
- bug!("requires check invoked on inapplicable type: {:?}", ty)
+ }
+ Representability::Representable
}
- _ => Representability::Representable,
+ DefKind::Field => representability_ty(tcx, tcx.type_of(def_id)),
+ def_kind => bug!("unexpected {def_kind:?}"),
}
}
-fn same_adt<'tcx>(ty: Ty<'tcx>, def: ty::AdtDef<'tcx>) -> bool {
+fn representability_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Representability {
match *ty.kind() {
- ty::Adt(ty_def, _) => ty_def == def,
- _ => false,
+ ty::Adt(..) => tcx.representability_adt_ty(ty),
+ // FIXME(#11924) allow zero-length arrays?
+ ty::Array(ty, _) => representability_ty(tcx, ty),
+ ty::Tuple(tys) => {
+ for ty in tys {
+ rtry!(representability_ty(tcx, ty));
+ }
+ Representability::Representable
+ }
+ _ => Representability::Representable,
}
}
-// Does the type `ty` directly (without indirection through a pointer)
-// contain any types on stack `seen`?
-fn is_type_structurally_recursive<'tcx>(
- tcx: TyCtxt<'tcx>,
- seen: &mut Vec<Ty<'tcx>>,
- shadow_seen: &mut Vec<ty::AdtDef<'tcx>>,
- representable_cache: &mut FxHashMap<Ty<'tcx>, Representability>,
- ty: Ty<'tcx>,
- sp: Span,
- field_id: Option<hir::HirId>,
- force_result: &mut bool,
-) -> Representability {
- debug!("is_type_structurally_recursive: {:?} {:?} {:?}", ty, sp, field_id);
- if let Some(representability) = representable_cache.get(&ty) {
- debug!(
- "is_type_structurally_recursive: {:?} {:?} {:?} - (cached) {:?}",
- ty, sp, field_id, representability
- );
- return representability.clone();
+/*
+The reason for this being a separate query is very subtle:
+Consider this infinitely sized struct: `struct Foo(Box<Foo>, Bar<Foo>)`:
+When calling representability(Foo), a query cycle will occur:
+ representability(Foo)
+ -> representability_adt_ty(Bar<Foo>)
+ -> representability(Foo)
+For the diagnostic output (in `Value::from_cycle_error`), we want to detect that
+the `Foo` in the *second* field of the struct is culpable. This requires
+traversing the HIR of the struct and calling `params_in_repr(Bar)`. But we can't
+call params_in_repr for a given type unless it is known to be representable.
+params_in_repr will cycle/panic on infinitely sized types. Looking at the query
+cycle above, we know that `Bar` is representable because
+representability_adt_ty(Bar<..>) is in the cycle and representability(Bar) is
+*not* in the cycle.
+*/
+fn representability_adt_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Representability {
+ let ty::Adt(adt, substs) = ty.kind() else { bug!("expected adt") };
+ if let Some(def_id) = adt.did().as_local() {
+ rtry!(tcx.representability(def_id));
}
-
- let representability = is_type_structurally_recursive_inner(
- tcx,
- seen,
- shadow_seen,
- representable_cache,
- ty,
- sp,
- field_id,
- force_result,
- );
-
- representable_cache.insert(ty, representability.clone());
- representability
+ // At this point, we know that the item of the ADT type is representable;
+ // but the type parameters may cause a cycle with an upstream type
+ let params_in_repr = tcx.params_in_repr(adt.did());
+ for (i, subst) in substs.iter().enumerate() {
+ if let ty::GenericArgKind::Type(ty) = subst.unpack() {
+ if params_in_repr.contains(i as u32) {
+ rtry!(representability_ty(tcx, ty));
+ }
+ }
+ }
+ Representability::Representable
}
-fn is_type_structurally_recursive_inner<'tcx>(
- tcx: TyCtxt<'tcx>,
- seen: &mut Vec<Ty<'tcx>>,
- shadow_seen: &mut Vec<ty::AdtDef<'tcx>>,
- representable_cache: &mut FxHashMap<Ty<'tcx>, Representability>,
- ty: Ty<'tcx>,
- sp: Span,
- field_id: Option<hir::HirId>,
- force_result: &mut bool,
-) -> Representability {
- match ty.kind() {
- ty::Adt(def, _) => {
- {
- debug!("is_type_structurally_recursive_inner: adt: {:?}, seen: {:?}", ty, seen);
-
- // Iterate through stack of previously seen types.
- let mut iter = seen.iter();
-
- // The first item in `seen` is the type we are actually curious about.
- // We want to return SelfRecursive if this type contains itself.
- // It is important that we DON'T take generic parameters into account
- // for this check, so that Bar<T> in this example counts as SelfRecursive:
- //
- // struct Foo;
- // struct Bar<T> { x: Bar<Foo> }
-
- if let Some(&seen_adt) = iter.next() {
- if same_adt(seen_adt, *def) {
- debug!("SelfRecursive: {:?} contains {:?}", seen_adt, ty);
- return Representability::SelfRecursive(vec![(sp, field_id)]);
- }
- }
-
- // We also need to know whether the first item contains other types
- // that are structurally recursive. If we don't catch this case, we
- // will recurse infinitely for some inputs.
- //
- // It is important that we DO take generic parameters into account
- // here, because nesting e.g. Options is allowed (as long as the
- // definition of Option doesn't itself include an Option field, which
- // would be a case of SelfRecursive above). The following, too, counts
- // as SelfRecursive:
- //
- // struct Foo { Option<Option<Foo>> }
+fn params_in_repr(tcx: TyCtxt<'_>, def_id: DefId) -> BitSet<u32> {
+ let adt_def = tcx.adt_def(def_id);
+ let generics = tcx.generics_of(def_id);
+ let mut params_in_repr = BitSet::new_empty(generics.params.len());
+ for variant in adt_def.variants() {
+ for field in variant.fields.iter() {
+ params_in_repr_ty(tcx, tcx.type_of(field.did), &mut params_in_repr);
+ }
+ }
+ params_in_repr
+}
- for &seen_adt in iter {
- if ty == seen_adt {
- debug!("ContainsRecursive: {:?} contains {:?}", seen_adt, ty);
- return Representability::ContainsRecursive;
+fn params_in_repr_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, params_in_repr: &mut BitSet<u32>) {
+ match *ty.kind() {
+ ty::Adt(adt, substs) => {
+ let inner_params_in_repr = tcx.params_in_repr(adt.did());
+ for (i, subst) in substs.iter().enumerate() {
+ if let ty::GenericArgKind::Type(ty) = subst.unpack() {
+ if inner_params_in_repr.contains(i as u32) {
+ params_in_repr_ty(tcx, ty, params_in_repr);
}
}
}
-
- // For structs and enums, track all previously seen types by pushing them
- // onto the 'seen' stack.
- seen.push(ty);
- shadow_seen.push(*def);
- let out = are_inner_types_recursive(
- tcx,
- seen,
- shadow_seen,
- representable_cache,
- ty,
- sp,
- field_id,
- force_result,
- );
- shadow_seen.pop();
- seen.pop();
- out
}
- _ => {
- // No need to push in other cases.
- are_inner_types_recursive(
- tcx,
- seen,
- shadow_seen,
- representable_cache,
- ty,
- sp,
- field_id,
- force_result,
- )
+ ty::Array(ty, _) => params_in_repr_ty(tcx, ty, params_in_repr),
+ ty::Tuple(tys) => tys.iter().for_each(|ty| params_in_repr_ty(tcx, ty, params_in_repr)),
+ ty::Param(param) => {
+ params_in_repr.insert(param.index);
}
+ _ => {}
}
}
diff --git a/compiler/rustc_ty_utils/src/ty.rs b/compiler/rustc_ty_utils/src/ty.rs
index 9266e4e3f..3eebb4ace 100644
--- a/compiler/rustc_ty_utils/src/ty.rs
+++ b/compiler/rustc_ty_utils/src/ty.rs
@@ -1,7 +1,6 @@
use rustc_data_structures::fx::FxIndexSet;
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
-use rustc_middle::ty::subst::Subst;
use rustc_middle::ty::{self, Binder, Predicate, PredicateKind, ToPredicate, Ty, TyCtxt};
use rustc_trait_selection::traits;
@@ -86,9 +85,13 @@ fn impl_defaultness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Defaultness {
/// - a type parameter or projection whose Sizedness can't be known
/// - a tuple of type parameters or projections, if there are multiple
/// such.
-/// - an Error, if a type contained itself. The representability
-/// check should catch this case.
-fn adt_sized_constraint(tcx: TyCtxt<'_>, def_id: DefId) -> ty::AdtSizedConstraint<'_> {
+/// - an Error, if a type is infinitely sized
+fn adt_sized_constraint(tcx: TyCtxt<'_>, def_id: DefId) -> &[Ty<'_>] {
+ if let Some(def_id) = def_id.as_local() {
+ if matches!(tcx.representability(def_id), ty::Representability::Infinite) {
+ return tcx.intern_type_list(&[tcx.ty_error()]);
+ }
+ }
let def = tcx.adt_def(def_id);
let result = tcx.mk_type_list(
@@ -100,7 +103,7 @@ fn adt_sized_constraint(tcx: TyCtxt<'_>, def_id: DefId) -> ty::AdtSizedConstrain
debug!("adt_sized_constraint: {:?} => {:?}", def, result);
- ty::AdtSizedConstraint(result)
+ result
}
/// See `ParamEnv` struct definition for details.
@@ -134,6 +137,7 @@ fn param_env(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamEnv<'_> {
let local_did = def_id.as_local();
let hir_id = local_did.map(|def_id| tcx.hir().local_def_id_to_hir_id(def_id));
+ // FIXME(consts): This is not exactly in line with the constness query.
let constness = match hir_id {
Some(hir_id) => match tcx.hir().get(hir_id) {
hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Fn(..), .. })
@@ -162,7 +166,7 @@ fn param_env(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamEnv<'_> {
}) => hir::Constness::Const,
hir::Node::ImplItem(hir::ImplItem {
- kind: hir::ImplItemKind::TyAlias(..) | hir::ImplItemKind::Fn(..),
+ kind: hir::ImplItemKind::Type(..) | hir::ImplItemKind::Fn(..),
..
}) => {
let parent_hir_id = tcx.hir().get_parent_node(hir_id);
@@ -198,6 +202,10 @@ fn param_env(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamEnv<'_> {
_ => hir::Constness::NotConst,
},
+ // FIXME(consts): It's suspicious that a param-env for a foreign item
+ // will always have NotConst param-env, though we don't typically use
+ // that param-env for anything meaningful right now, so it's likely
+ // not an issue.
None => hir::Constness::NotConst,
};