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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:03:36 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:03:36 +0000 |
commit | 17d40c6057c88f4c432b0d7bac88e1b84cb7e67f (patch) | |
tree | 3f66c4a5918660bb8a758ab6cda5ff8ee4f6cdcd /compiler/rustc_middle/src/ty/layout.rs | |
parent | Adding upstream version 1.64.0+dfsg1. (diff) | |
download | rustc-f7f0cc2a5d72e2c61c1f6900e70eec992bea4273.tar.xz rustc-f7f0cc2a5d72e2c61c1f6900e70eec992bea4273.zip |
Adding upstream version 1.65.0+dfsg1.upstream/1.65.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | compiler/rustc_middle/src/ty/layout.rs | 720 |
1 files changed, 362 insertions, 358 deletions
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs index ad78d24e9..042eeec3f 100644 --- a/compiler/rustc_middle/src/ty/layout.rs +++ b/compiler/rustc_middle/src/ty/layout.rs @@ -2,7 +2,10 @@ use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags; use crate::mir::{GeneratorLayout, GeneratorSavedLocal}; use crate::ty::normalize_erasing_regions::NormalizationError; use crate::ty::subst::Subst; -use crate::ty::{self, subst::SubstsRef, EarlyBinder, ReprOptions, Ty, TyCtxt, TypeVisitable}; +use crate::ty::{ + self, layout_sanity_check::sanity_check_layout, subst::SubstsRef, EarlyBinder, ReprOptions, Ty, + TyCtxt, TypeVisitable, +}; use rustc_ast as ast; use rustc_attr as attr; use rustc_hir as hir; @@ -19,7 +22,7 @@ use rustc_target::abi::call::{ use rustc_target::abi::*; use rustc_target::spec::{abi::Abi as SpecAbi, HasTargetSpec, PanicStrategy, Target}; -use std::cmp; +use std::cmp::{self, Ordering}; use std::fmt; use std::iter; use std::num::NonZeroUsize; @@ -221,164 +224,46 @@ impl<'tcx> fmt::Display for LayoutError<'tcx> { } } -/// Enforce some basic invariants on layouts. -fn sanity_check_layout<'tcx>( - tcx: TyCtxt<'tcx>, - param_env: ty::ParamEnv<'tcx>, - layout: &TyAndLayout<'tcx>, -) { - // Type-level uninhabitedness should always imply ABI uninhabitedness. - if tcx.conservative_is_privately_uninhabited(param_env.and(layout.ty)) { - assert!(layout.abi.is_uninhabited()); - } - - if layout.size.bytes() % layout.align.abi.bytes() != 0 { - bug!("size is not a multiple of align, in the following layout:\n{layout:#?}"); - } - - if cfg!(debug_assertions) { - fn check_layout_abi<'tcx>(tcx: TyCtxt<'tcx>, layout: Layout<'tcx>) { - match layout.abi() { - Abi::Scalar(scalar) => { - // No padding in scalars. - assert_eq!( - layout.align().abi, - scalar.align(&tcx).abi, - "alignment mismatch between ABI and layout in {layout:#?}" - ); - assert_eq!( - layout.size(), - scalar.size(&tcx), - "size mismatch between ABI and layout in {layout:#?}" - ); - } - Abi::Vector { count, element } => { - // No padding in vectors. Alignment can be strengthened, though. - assert!( - layout.align().abi >= element.align(&tcx).abi, - "alignment mismatch between ABI and layout in {layout:#?}" - ); - let size = element.size(&tcx) * count; - assert_eq!( - layout.size(), - size.align_to(tcx.data_layout().vector_align(size).abi), - "size mismatch between ABI and layout in {layout:#?}" - ); - } - Abi::ScalarPair(scalar1, scalar2) => { - // Sanity-check scalar pairs. These are a bit more flexible and support - // padding, but we can at least ensure both fields actually fit into the layout - // and the alignment requirement has not been weakened. - let align1 = scalar1.align(&tcx).abi; - let align2 = scalar2.align(&tcx).abi; - assert!( - layout.align().abi >= cmp::max(align1, align2), - "alignment mismatch between ABI and layout in {layout:#?}", - ); - let field2_offset = scalar1.size(&tcx).align_to(align2); - assert!( - layout.size() >= field2_offset + scalar2.size(&tcx), - "size mismatch between ABI and layout in {layout:#?}" - ); - } - Abi::Uninhabited | Abi::Aggregate { .. } => {} // Nothing to check. - } - } - - check_layout_abi(tcx, layout.layout); - - if let Variants::Multiple { variants, .. } = &layout.variants { - for variant in variants { - check_layout_abi(tcx, *variant); - // No nested "multiple". - assert!(matches!(variant.variants(), Variants::Single { .. })); - // Skip empty variants. - if variant.size() == Size::ZERO - || variant.fields().count() == 0 - || variant.abi().is_uninhabited() - { - // These are never actually accessed anyway, so we can skip them. (Note that - // sometimes, variants with fields have size 0, and sometimes, variants without - // fields have non-0 size.) - continue; - } - // Variants should have the same or a smaller size as the full thing. - if variant.size() > layout.size { - bug!( - "Type with size {} bytes has variant with size {} bytes: {layout:#?}", - layout.size.bytes(), - variant.size().bytes(), - ) - } - // The top-level ABI and the ABI of the variants should be coherent. - let abi_coherent = match (layout.abi, variant.abi()) { - (Abi::Scalar(..), Abi::Scalar(..)) => true, - (Abi::ScalarPair(..), Abi::ScalarPair(..)) => true, - (Abi::Uninhabited, _) => true, - (Abi::Aggregate { .. }, _) => true, - _ => false, - }; - if !abi_coherent { - bug!( - "Variant ABI is incompatible with top-level ABI:\nvariant={:#?}\nTop-level: {layout:#?}", - variant - ); - } - } - } - } -} - #[instrument(skip(tcx, query), level = "debug")] fn layout_of<'tcx>( tcx: TyCtxt<'tcx>, query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>, ) -> Result<TyAndLayout<'tcx>, LayoutError<'tcx>> { - ty::tls::with_related_context(tcx, move |icx| { - let (param_env, ty) = query.into_parts(); - debug!(?ty); - - if !tcx.recursion_limit().value_within_limit(icx.layout_depth) { - tcx.sess.fatal(&format!("overflow representing the type `{}`", ty)); + 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)); } + }; - // Update the ImplicitCtxt to increase the layout_depth - let icx = ty::tls::ImplicitCtxt { layout_depth: icx.layout_depth + 1, ..icx.clone() }; - - ty::tls::enter_context(&icx, |_| { - 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)); - } + 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 cx = LayoutCx { tcx, param_env }; - let layout = cx.layout_of_uncached(ty)?; - let layout = TyAndLayout { ty, layout }; + let layout = cx.layout_of_uncached(ty)?; + let layout = TyAndLayout { ty, layout }; - cx.record_layout_for_printing(layout); + cx.record_layout_for_printing(layout); - sanity_check_layout(tcx, param_env, &layout); + sanity_check_layout(&cx, &layout); - Ok(layout) - }) - }) + Ok(layout) } +#[derive(Clone, Copy)] pub struct LayoutCx<'tcx, C> { pub tcx: C, pub param_env: ty::ParamEnv<'tcx>, @@ -740,6 +625,14 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { tcx.intern_layout(self.scalar_pair(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(self.scalar_pair(data, vtable)) + } + // Arrays and slices. ty::Array(element, mut count) => { if count.has_projections() { @@ -794,7 +687,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { // Odd unit types. ty::FnDef(..) => univariant(&[], &ReprOptions::default(), StructKind::AlwaysSized)?, - ty::Dynamic(..) | ty::Foreign(..) => { + ty::Dynamic(_, _, ty::Dyn) | ty::Foreign(..) => { let mut unit = self.univariant_uninterned( ty, &[], @@ -872,7 +765,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { // * the element type and length of the single array field, if // the first field is of array type, or // - // * the homogenous field type and the number of fields. + // * 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: @@ -1161,131 +1054,191 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { // that allow representation optimization.) assert!(def.is_enum()); - // The current code for niche-filling relies on variant indices - // instead of actual discriminants, so dataful enums with - // explicit discriminants (RFC #2363) would misbehave. - let no_explicit_discriminants = def - .variants() - .iter_enumerated() - .all(|(i, v)| v.discr == ty::VariantDiscr::Relative(i.as_u32())); - - let mut niche_filling_layout = None; - - // Niche-filling enum optimization. - if !def.repr().inhibit_enum_layout_opt() && no_explicit_discriminants { - let mut dataful_variant = None; - let mut niche_variants = VariantIdx::MAX..=VariantIdx::new(0); + // 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>>, + } - // Find one non-ZST variant. - 'variants: for (v, fields) in variants.iter_enumerated() { - if absent(fields) { - continue 'variants; + 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); } - for f in fields { - if !f.is_zst() { - if dataful_variant.is_none() { - dataful_variant = Some(v); - continue 'variants; - } else { - dataful_variant = None; - break 'variants; - } - } + + if variants.len() < 2 { + return Ok(None); } - niche_variants = *niche_variants.start().min(&v)..=v; - } - if niche_variants.start() > niche_variants.end() { - dataful_variant = None; - } + let mut align = dl.aggregate_align; + let mut variant_layouts = variants + .iter_enumerated() + .map(|(j, v)| { + let mut st = self.univariant_uninterned( + 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(); - if let Some(i) = dataful_variant { - let count = (niche_variants.end().as_u32() - - niche_variants.start().as_u32() - + 1) as u128; + let count = niche_variants.size_hint().1.unwrap() as u128; // Find the field with the largest niche - let niche_candidate = variants[i] + 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)); - - if let Some((field_index, niche, (niche_start, niche_scalar))) = - niche_candidate.and_then(|(field_index, niche)| { - Some((field_index, niche, niche.reserve(self, count)?)) - }) + .max_by_key(|(_, niche)| niche.available(dl)) + .and_then(|(j, niche)| Some((j, niche, niche.reserve(self, count)?))) { - let mut align = dl.aggregate_align; - let st = variants - .iter_enumerated() - .map(|(j, v)| { - let mut st = self.univariant_uninterned( - ty, - v, - &def.repr(), - StructKind::AlwaysSized, - )?; - st.variants = Variants::Single { index: j }; + 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); - align = align.max(st.align); + let all_variants_fit = + variant_layouts.iter_enumerated_mut().all(|(i, layout)| { + if i == largest_variant_index { + return true; + } - Ok(tcx.intern_layout(st)) - }) - .collect::<Result<IndexVec<VariantIdx, _>, _>>()?; + layout.largest_niche = None; - let offset = st[i].fields().offset(field_index) + niche.offset; + if layout.size <= niche_offset { + // This variant will fit before the niche. + return true; + } - // Align the total size to the largest alignment. - let size = st[i].size().align_to(align.abi); + // 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); - let abi = if st.iter().all(|v| v.abi().is_uninhabited()) { - Abi::Uninhabited - } else if align == st[i].align() && size == st[i].size() { - // When the total alignment and size match, we can use the - // same ABI as the scalar variant with the reserved niche. - match st[i].abi() { - Abi::Scalar(_) => Abi::Scalar(niche_scalar), - Abi::ScalarPair(first, second) => { - // Only the niche is guaranteed to be initialised, - // so use union layout for the other primitive. - if offset.bytes() == 0 { - Abi::ScalarPair(niche_scalar, second.to_union()) - } else { - Abi::ScalarPair(first.to_union(), niche_scalar) + 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; + } } } - _ => Abi::Aggregate { sized: true }, + _ => { + panic!("Layout of fields should be Arbitrary for variants") + } } - } else { - Abi::Aggregate { sized: true } - }; - let largest_niche = Niche::from_scalar(dl, offset, niche_scalar); - - niche_filling_layout = Some(LayoutS { - variants: Variants::Multiple { - tag: niche_scalar, - tag_encoding: TagEncoding::Niche { - dataful_variant: i, - niche_variants, - niche_start, - }, - tag_field: 0, - variants: st, - }, - fields: FieldsShape::Arbitrary { - offsets: vec![offset], - memory_index: vec![0], - }, - abi, - largest_niche, - size, - align, + // 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(); @@ -1540,15 +1493,12 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { let largest_niche = Niche::from_scalar(dl, Size::ZERO, tag); - let layout_variants = - layout_variants.into_iter().map(|v| tcx.intern_layout(v)).collect(); - let tagged_layout = LayoutS { variants: Variants::Multiple { tag, tag_encoding: TagEncoding::Direct, tag_field: 0, - variants: layout_variants, + variants: IndexVec::new(), }, fields: FieldsShape::Arbitrary { offsets: vec![Size::ZERO], @@ -1560,20 +1510,45 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { size, }; - let best_layout = match (tagged_layout, niche_filling_layout) { - (tagged_layout, Some(niche_filling_layout)) => { + 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. - cmp::min_by_key(tagged_layout, niche_filling_layout, |layout| { - let niche_size = layout.largest_niche.map_or(0, |n| n.available(dl)); - (layout.size, cmp::Reverse(niche_size)) - }) + 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, + } } - (tagged_layout, None) => tagged_layout, + (tl, None) => tl, }; - tcx.intern_layout(best_layout) + // 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. @@ -2468,7 +2443,9 @@ where | ty::FnDef(..) | ty::GeneratorWitness(..) | ty::Foreign(..) - | ty::Dynamic(..) => bug!("TyAndLayout::field({:?}): not applicable", this), + | ty::Dynamic(_, _, ty::Dyn) => { + bug!("TyAndLayout::field({:?}): not applicable", this) + } // Potentially-fat pointers. ty::Ref(_, pointee, _) | ty::RawPtr(ty::TypeAndMut { ty: pointee, .. }) => { @@ -2497,7 +2474,7 @@ where match tcx.struct_tail_erasing_lifetimes(pointee, cx.param_env()).kind() { ty::Slice(_) | ty::Str => TyMaybeWithLayout::Ty(tcx.types.usize), - ty::Dynamic(_, _) => { + ty::Dynamic(_, _, ty::Dyn) => { TyMaybeWithLayout::Ty(tcx.mk_imm_ref( tcx.lifetimes.re_static, tcx.mk_array(tcx.types.usize, 3), @@ -2566,6 +2543,22 @@ where } } + ty::Dynamic(_, _, ty::DynStar) => { + if i == 0 { + TyMaybeWithLayout::Ty(tcx.types.usize) + } else if i == 1 { + // FIXME(dyn-star) same FIXME as above applies here too + TyMaybeWithLayout::Ty( + tcx.mk_imm_ref( + tcx.lifetimes.re_static, + tcx.mk_array(tcx.types.usize, 3), + ), + ) + } else { + bug!("no field {i} on dyn*") + } + } + ty::Projection(_) | ty::Bound(..) | ty::Placeholder(..) @@ -2674,11 +2667,11 @@ where // using more niches than just null (e.g., the first page of // the address space, or unaligned pointers). Variants::Multiple { - tag_encoding: TagEncoding::Niche { dataful_variant, .. }, + tag_encoding: TagEncoding::Niche { untagged_variant, .. }, tag_field, .. } if this.fields.offset(tag_field) == offset => { - Some(this.for_variant(cx, dataful_variant)) + Some(this.for_variant(cx, untagged_variant)) } _ => Some(this), }; @@ -2761,6 +2754,7 @@ impl<'tcx> ty::Instance<'tcx> { // 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( &self, tcx: TyCtxt<'tcx>, @@ -2907,6 +2901,7 @@ impl<'tcx> ty::Instance<'tcx> { /// with `-Cpanic=abort` will look like they can't unwind when in fact they /// might (from a foreign exception or similar). #[inline] +#[tracing::instrument(level = "debug", skip(tcx))] pub fn fn_can_unwind<'tcx>(tcx: TyCtxt<'tcx>, fn_def_id: Option<DefId>, abi: SpecAbi) -> bool { if let Some(did) = fn_def_id { // Special attribute for functions which can't unwind. @@ -3123,6 +3118,7 @@ pub trait FnAbiOf<'tcx>: FnAbiOfHelpers<'tcx> { /// NB: that includes virtual calls, which are represented by "direct calls" /// to an `InstanceDef::Virtual` instance (of `<dyn Trait as Trait>::fn`). #[inline] + #[tracing::instrument(level = "debug", skip(self))] fn fn_abi_of_instance( &self, instance: ty::Instance<'tcx>, @@ -3179,9 +3175,100 @@ fn fn_abi_of_instance<'tcx>( ) } +// Handle safe Rust thin and fat pointers. +pub 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); + } + } + } +} + impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { // 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(self, caller_location, fn_def_id, force_thin_self_ptr) + )] fn fn_abi_new_uncached( &self, sig: ty::PolyFnSig<'tcx>, @@ -3191,8 +3278,6 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { // FIXME(eddyb) replace this with something typed, like an `enum`. force_thin_self_ptr: bool, ) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> { - debug!("fn_abi_new_uncached({:?}, {:?})", sig, extra_args); - let sig = self.tcx.normalize_erasing_late_bound_regions(self.param_env, sig); let conv = conv_from_spec_abi(self.tcx(), sig.abi); @@ -3234,92 +3319,9 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { use SpecAbi::*; let rust_abi = matches!(sig.abi, RustIntrinsic | PlatformIntrinsic | Rust | RustCall); - // Handle safe Rust thin and fat pointers. - let adjust_for_rust_scalar = |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(self) { - 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(self, 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 = - self.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); - } - } - } - }; - 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 = self.layout_of(ty)?; @@ -3334,7 +3336,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { let mut arg = ArgAbi::new(self, layout, |layout, scalar, offset| { let mut attrs = ArgAttributes::new(); - adjust_for_rust_scalar(&mut attrs, scalar, *layout, offset, is_return); + adjust_for_rust_scalar(*self, &mut attrs, scalar, *layout, offset, is_return); attrs }); @@ -3367,7 +3369,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { .map(|(i, ty)| arg_of(ty, Some(i))) .collect::<Result<_, _>>()?, c_variadic: sig.c_variadic, - fixed_count: inputs.len(), + fixed_count: inputs.len() as u32, conv, can_unwind: fn_can_unwind(self.tcx(), fn_def_id, sig.abi), }; @@ -3376,6 +3378,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { Ok(self.tcx.arena.alloc(fn_abi)) } + #[tracing::instrument(level = "trace", skip(self))] fn fn_abi_adjust_for_abi( &self, fn_abi: &mut FnAbi<'tcx, Ty<'tcx>>, @@ -3439,7 +3442,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { } }; fixup(&mut fn_abi.ret); - for arg in &mut fn_abi.args { + for arg in fn_abi.args.iter_mut() { fixup(arg); } } else { @@ -3450,6 +3453,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { } } +#[tracing::instrument(level = "debug", skip(cx))] fn make_thin_self_ptr<'tcx>( cx: &(impl HasTyCtxt<'tcx> + HasParamEnv<'tcx>), layout: TyAndLayout<'tcx>, @@ -3461,7 +3465,7 @@ fn make_thin_self_ptr<'tcx>( tcx.mk_mut_ptr(layout.ty) } else { match layout.abi { - Abi::ScalarPair(..) => (), + Abi::ScalarPair(..) | Abi::Scalar(..) => (), _ => bug!("receiver type has unsupported layout: {:?}", layout), } |