diff options
Diffstat (limited to 'compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs')
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs | 514 |
1 files changed, 514 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs new file mode 100644 index 000000000..d6e2c8ccd --- /dev/null +++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs @@ -0,0 +1,514 @@ +use std::borrow::Cow; + +use libc::c_uint; +use rustc_codegen_ssa::debuginfo::{ + type_names::compute_debuginfo_type_name, wants_c_like_enum_debuginfo, +}; +use rustc_middle::{ + bug, + ty::{ + self, + layout::{LayoutOf, TyAndLayout}, + util::Discr, + AdtDef, GeneratorSubsts, + }, +}; +use rustc_target::abi::{Size, TagEncoding, VariantIdx, Variants}; +use smallvec::smallvec; + +use crate::{ + common::CodegenCx, + debuginfo::{ + metadata::{ + build_field_di_node, closure_saved_names_of_captured_variables, + enums::tag_base_type, + file_metadata, generator_layout_and_saved_local_names, size_and_align_of, + type_map::{self, UniqueTypeId}, + unknown_file_metadata, DINodeCreationResult, SmallVec, NO_GENERICS, NO_SCOPE_METADATA, + UNKNOWN_LINE_NUMBER, + }, + utils::DIB, + }, + llvm::{ + self, + debuginfo::{DIFile, DIFlags, DIType}, + }, +}; + +/// In CPP-like mode, we generate a union of structs for each variant and an +/// explicit discriminant field roughly equivalent to the following C/C++ code: +/// +/// ```c +/// union enum$<{fully-qualified-name}> { +/// struct {variant 0 name} { +/// <variant 0 fields> +/// } variant0; +/// <other variant structs> +/// {name} discriminant; +/// } +/// ``` +/// +/// As you can see, the type name is wrapped `enum$`. This way we can have a +/// single NatVis rule for handling all enums. +/// +/// At the LLVM IR level this looks like +/// +/// ```txt +/// DW_TAG_union_type (top-level type for enum) +/// DW_TAG_member (member for variant 1) +/// DW_TAG_member (member for variant 2) +/// DW_TAG_member (member for variant 3) +/// DW_TAG_structure_type (type of variant 1) +/// DW_TAG_structure_type (type of variant 2) +/// DW_TAG_structure_type (type of variant 3) +/// DW_TAG_enumeration_type (type of tag) +/// ``` +/// +/// The above encoding applies for enums with a direct tag. For niche-tag we have to do things +/// differently in order to allow a NatVis visualizer to extract all the information needed: +/// We generate a union of two fields, one for the dataful variant +/// and one that just points to the discriminant (which is some field within the dataful variant). +/// We also create a DW_TAG_enumeration_type DIE that contains tag values for the non-dataful +/// variants and make the discriminant field that type. We then use NatVis to render the enum type +/// correctly in Windbg/VS. This will generate debuginfo roughly equivalent to the following C: +/// +/// ```c +/// union enum$<{name}, {min niche}, {max niche}, {dataful variant name}> { +/// struct <dataful variant name> { +/// <fields in dataful variant> +/// } dataful_variant; +/// enum Discriminant$ { +/// <non-dataful variants> +/// } discriminant; +/// } +/// ``` +/// +/// The NatVis in `intrinsic.natvis` matches on the type name `enum$<*, *, *, *>` +/// and evaluates `this.discriminant`. If the value is between the min niche and max +/// niche, then the enum is in the dataful variant and `this.dataful_variant` is +/// rendered. Otherwise, the enum is in one of the non-dataful variants. In that +/// case, we just need to render the name of the `this.discriminant` enum. +pub(super) fn build_enum_type_di_node<'ll, 'tcx>( + cx: &CodegenCx<'ll, 'tcx>, + unique_type_id: UniqueTypeId<'tcx>, +) -> DINodeCreationResult<'ll> { + let enum_type = unique_type_id.expect_ty(); + let &ty::Adt(enum_adt_def, _) = enum_type.kind() else { + bug!("build_enum_type_di_node() called with non-enum type: `{:?}`", enum_type) + }; + + let enum_type_and_layout = cx.layout_of(enum_type); + let enum_type_name = compute_debuginfo_type_name(cx.tcx, enum_type, false); + + debug_assert!(!wants_c_like_enum_debuginfo(enum_type_and_layout)); + + type_map::build_type_with_children( + cx, + type_map::stub( + cx, + type_map::Stub::Union, + unique_type_id, + &enum_type_name, + cx.size_and_align_of(enum_type), + NO_SCOPE_METADATA, + DIFlags::FlagZero, + ), + |cx, enum_type_di_node| { + match enum_type_and_layout.variants { + Variants::Single { index: variant_index } => { + if enum_adt_def.variants().is_empty() { + // Uninhabited enums have Variants::Single. We don't generate + // any members for them. + return smallvec![]; + } + + build_single_variant_union_fields( + cx, + enum_adt_def, + enum_type_and_layout, + enum_type_di_node, + variant_index, + ) + } + Variants::Multiple { + tag_encoding: TagEncoding::Direct, + ref variants, + tag_field, + .. + } => build_union_fields_for_direct_tag_enum( + cx, + enum_adt_def, + enum_type_and_layout, + enum_type_di_node, + &mut variants.indices(), + tag_field, + ), + Variants::Multiple { + tag_encoding: TagEncoding::Niche { dataful_variant, .. }, + ref variants, + tag_field, + .. + } => build_union_fields_for_niche_tag_enum( + cx, + enum_adt_def, + enum_type_and_layout, + enum_type_di_node, + dataful_variant, + &mut variants.indices(), + tag_field, + ), + } + }, + NO_GENERICS, + ) +} + +/// A generator debuginfo node looks the same as a that of an enum type. +/// +/// See [build_enum_type_di_node] for more information. +pub(super) fn build_generator_di_node<'ll, 'tcx>( + cx: &CodegenCx<'ll, 'tcx>, + unique_type_id: UniqueTypeId<'tcx>, +) -> DINodeCreationResult<'ll> { + let generator_type = unique_type_id.expect_ty(); + let generator_type_and_layout = cx.layout_of(generator_type); + let generator_type_name = compute_debuginfo_type_name(cx.tcx, generator_type, false); + + debug_assert!(!wants_c_like_enum_debuginfo(generator_type_and_layout)); + + type_map::build_type_with_children( + cx, + type_map::stub( + cx, + type_map::Stub::Union, + unique_type_id, + &generator_type_name, + size_and_align_of(generator_type_and_layout), + NO_SCOPE_METADATA, + DIFlags::FlagZero, + ), + |cx, generator_type_di_node| match generator_type_and_layout.variants { + Variants::Multiple { tag_encoding: TagEncoding::Direct, .. } => { + build_union_fields_for_direct_tag_generator( + cx, + generator_type_and_layout, + generator_type_di_node, + ) + } + Variants::Single { .. } + | Variants::Multiple { tag_encoding: TagEncoding::Niche { .. }, .. } => { + bug!( + "Encountered generator with non-direct-tag layout: {:?}", + generator_type_and_layout + ) + } + }, + NO_GENERICS, + ) +} + +fn build_single_variant_union_fields<'ll, 'tcx>( + cx: &CodegenCx<'ll, 'tcx>, + enum_adt_def: AdtDef<'tcx>, + enum_type_and_layout: TyAndLayout<'tcx>, + enum_type_di_node: &'ll DIType, + variant_index: VariantIdx, +) -> SmallVec<&'ll DIType> { + let variant_layout = enum_type_and_layout.for_variant(cx, variant_index); + let variant_struct_type_di_node = super::build_enum_variant_struct_type_di_node( + cx, + enum_type_and_layout.ty, + enum_type_di_node, + variant_index, + enum_adt_def.variant(variant_index), + variant_layout, + ); + + // NOTE: The field name of the union is the same as the variant name, not "variant0". + let variant_name = enum_adt_def.variant(variant_index).name.as_str(); + + smallvec![build_field_di_node( + cx, + enum_type_di_node, + variant_name, + // NOTE: We use the size and align of the entire type, not from variant_layout + // since the later is sometimes smaller (if it has fewer fields). + size_and_align_of(enum_type_and_layout), + Size::ZERO, + DIFlags::FlagZero, + variant_struct_type_di_node, + )] +} + +fn build_union_fields_for_direct_tag_enum<'ll, 'tcx>( + cx: &CodegenCx<'ll, 'tcx>, + enum_adt_def: AdtDef<'tcx>, + enum_type_and_layout: TyAndLayout<'tcx>, + enum_type_di_node: &'ll DIType, + variant_indices: &mut dyn Iterator<Item = VariantIdx>, + tag_field: usize, +) -> SmallVec<&'ll DIType> { + let variant_field_infos: SmallVec<VariantFieldInfo<'ll>> = variant_indices + .map(|variant_index| { + let variant_layout = enum_type_and_layout.for_variant(cx, variant_index); + + VariantFieldInfo { + variant_index, + variant_struct_type_di_node: super::build_enum_variant_struct_type_di_node( + cx, + enum_type_and_layout.ty, + enum_type_di_node, + variant_index, + enum_adt_def.variant(variant_index), + variant_layout, + ), + source_info: None, + } + }) + .collect(); + + let discr_type_name = cx.tcx.item_name(enum_adt_def.did()); + let tag_base_type = super::tag_base_type(cx, enum_type_and_layout); + let discr_type_di_node = super::build_enumeration_type_di_node( + cx, + discr_type_name.as_str(), + tag_base_type, + &mut enum_adt_def.discriminants(cx.tcx).map(|(variant_index, discr)| { + (discr, Cow::from(enum_adt_def.variant(variant_index).name.as_str())) + }), + enum_type_di_node, + ); + + build_union_fields_for_direct_tag_enum_or_generator( + cx, + enum_type_and_layout, + enum_type_di_node, + &variant_field_infos, + discr_type_di_node, + tag_field, + ) +} + +fn build_union_fields_for_niche_tag_enum<'ll, 'tcx>( + cx: &CodegenCx<'ll, 'tcx>, + enum_adt_def: AdtDef<'tcx>, + enum_type_and_layout: TyAndLayout<'tcx>, + enum_type_di_node: &'ll DIType, + dataful_variant_index: VariantIdx, + variant_indices: &mut dyn Iterator<Item = VariantIdx>, + tag_field: usize, +) -> SmallVec<&'ll DIType> { + let dataful_variant_struct_type_di_node = super::build_enum_variant_struct_type_di_node( + cx, + enum_type_and_layout.ty, + enum_type_di_node, + dataful_variant_index, + &enum_adt_def.variant(dataful_variant_index), + enum_type_and_layout.for_variant(cx, dataful_variant_index), + ); + + let tag_base_type = super::tag_base_type(cx, enum_type_and_layout); + // Create an DW_TAG_enumerator for each variant except the dataful one. + let discr_type_di_node = super::build_enumeration_type_di_node( + cx, + "Discriminant$", + tag_base_type, + &mut variant_indices.filter_map(|variant_index| { + if let Some(discr_val) = + super::compute_discriminant_value(cx, enum_type_and_layout, variant_index) + { + let discr = Discr { val: discr_val as u128, ty: tag_base_type }; + let variant_name = Cow::from(enum_adt_def.variant(variant_index).name.as_str()); + Some((discr, variant_name)) + } else { + debug_assert_eq!(variant_index, dataful_variant_index); + None + } + }), + enum_type_di_node, + ); + + smallvec![ + build_field_di_node( + cx, + enum_type_di_node, + "dataful_variant", + size_and_align_of(enum_type_and_layout), + Size::ZERO, + DIFlags::FlagZero, + dataful_variant_struct_type_di_node, + ), + build_field_di_node( + cx, + enum_type_di_node, + "discriminant", + cx.size_and_align_of(tag_base_type), + enum_type_and_layout.fields.offset(tag_field), + DIFlags::FlagZero, + discr_type_di_node, + ), + ] +} + +fn build_union_fields_for_direct_tag_generator<'ll, 'tcx>( + cx: &CodegenCx<'ll, 'tcx>, + generator_type_and_layout: TyAndLayout<'tcx>, + generator_type_di_node: &'ll DIType, +) -> SmallVec<&'ll DIType> { + let Variants::Multiple { tag_encoding: TagEncoding::Direct, tag_field, .. } = generator_type_and_layout.variants else { + bug!("This function only supports layouts with directly encoded tags.") + }; + + let (generator_def_id, generator_substs) = match generator_type_and_layout.ty.kind() { + &ty::Generator(def_id, substs, _) => (def_id, substs.as_generator()), + _ => unreachable!(), + }; + + let (generator_layout, state_specific_upvar_names) = + generator_layout_and_saved_local_names(cx.tcx, generator_def_id); + + let common_upvar_names = closure_saved_names_of_captured_variables(cx.tcx, generator_def_id); + let variant_range = generator_substs.variant_range(generator_def_id, cx.tcx); + + // Build the type node for each field. + let variant_field_infos: SmallVec<VariantFieldInfo<'ll>> = variant_range + .map(|variant_index| { + let variant_struct_type_di_node = super::build_generator_variant_struct_type_di_node( + cx, + variant_index, + generator_type_and_layout, + generator_type_di_node, + generator_layout, + &state_specific_upvar_names, + &common_upvar_names, + ); + + let span = generator_layout.variant_source_info[variant_index].span; + let source_info = if !span.is_dummy() { + let loc = cx.lookup_debug_loc(span.lo()); + Some((file_metadata(cx, &loc.file), loc.line as c_uint)) + } else { + None + }; + + VariantFieldInfo { variant_index, variant_struct_type_di_node, source_info } + }) + .collect(); + + let tag_base_type = tag_base_type(cx, generator_type_and_layout); + let discr_type_name = "Discriminant$"; + let discr_type_di_node = super::build_enumeration_type_di_node( + cx, + discr_type_name, + tag_base_type, + &mut generator_substs + .discriminants(generator_def_id, cx.tcx) + .map(|(variant_index, discr)| (discr, GeneratorSubsts::variant_name(variant_index))), + generator_type_di_node, + ); + + build_union_fields_for_direct_tag_enum_or_generator( + cx, + generator_type_and_layout, + generator_type_di_node, + &variant_field_infos[..], + discr_type_di_node, + tag_field, + ) +} + +/// This is a helper function shared between enums and generators that makes sure fields have the +/// expect names. +fn build_union_fields_for_direct_tag_enum_or_generator<'ll, 'tcx>( + cx: &CodegenCx<'ll, 'tcx>, + enum_type_and_layout: TyAndLayout<'tcx>, + enum_type_di_node: &'ll DIType, + variant_field_infos: &[VariantFieldInfo<'ll>], + discr_type_di_node: &'ll DIType, + tag_field: usize, +) -> SmallVec<&'ll DIType> { + let mut unions_fields = SmallVec::with_capacity(variant_field_infos.len() + 1); + + // We create a field in the union for each variant ... + unions_fields.extend(variant_field_infos.into_iter().map(|variant_member_info| { + let (file_di_node, line_number) = variant_member_info + .source_info + .unwrap_or_else(|| (unknown_file_metadata(cx), UNKNOWN_LINE_NUMBER)); + + let field_name = variant_union_field_name(variant_member_info.variant_index); + let (size, align) = size_and_align_of(enum_type_and_layout); + + // We use LLVMRustDIBuilderCreateMemberType() member type directly because + // the build_field_di_node() function does not support specifying a source location, + // which is something that we don't do anywhere else. + unsafe { + llvm::LLVMRustDIBuilderCreateMemberType( + DIB(cx), + enum_type_di_node, + field_name.as_ptr().cast(), + field_name.len(), + file_di_node, + line_number, + // NOTE: We use the size and align of the entire type, not from variant_layout + // since the later is sometimes smaller (if it has fewer fields). + size.bits(), + align.bits() as u32, + // Union fields are always at offset zero + Size::ZERO.bits(), + DIFlags::FlagZero, + variant_member_info.variant_struct_type_di_node, + ) + } + })); + + debug_assert_eq!( + cx.size_and_align_of(enum_type_and_layout.field(cx, tag_field).ty), + cx.size_and_align_of(super::tag_base_type(cx, enum_type_and_layout)) + ); + + // ... and a field for the discriminant. + unions_fields.push(build_field_di_node( + cx, + enum_type_di_node, + "discriminant", + cx.size_and_align_of(enum_type_and_layout.field(cx, tag_field).ty), + enum_type_and_layout.fields.offset(tag_field), + DIFlags::FlagZero, + discr_type_di_node, + )); + + unions_fields +} + +/// Information about a single field of the top-level DW_TAG_union_type. +struct VariantFieldInfo<'ll> { + variant_index: VariantIdx, + variant_struct_type_di_node: &'ll DIType, + source_info: Option<(&'ll DIFile, c_uint)>, +} + +fn variant_union_field_name(variant_index: VariantIdx) -> Cow<'static, str> { + const PRE_ALLOCATED: [&str; 16] = [ + "variant0", + "variant1", + "variant2", + "variant3", + "variant4", + "variant5", + "variant6", + "variant7", + "variant8", + "variant9", + "variant10", + "variant11", + "variant12", + "variant13", + "variant14", + "variant15", + ]; + + PRE_ALLOCATED + .get(variant_index.as_usize()) + .map(|&s| Cow::from(s)) + .unwrap_or_else(|| format!("variant{}", variant_index.as_usize()).into()) +} |