From ee9901e65c78f70b93dab5bd1e04bd77273b7c40 Mon Sep 17 00:00:00 2001 From: Scott McMurray Date: Tue, 3 Jun 2025 23:42:21 -0700 Subject: [PATCH] Change `tag_field` to `FieldIdx` in `Variants::Multiple` It was already available as a generic parameter anyway, and it's not like we'll ever put a tag in the 5-billionth field. --- compiler/rustc_abi/src/layout.rs | 4 ++-- compiler/rustc_abi/src/layout/coroutine.rs | 4 ++-- compiler/rustc_abi/src/lib.rs | 2 +- .../rustc_codegen_cranelift/src/discriminant.rs | 6 +++--- .../src/debuginfo/metadata/enums/cpp_like.rs | 14 +++++++------- .../src/debuginfo/metadata/enums/native.rs | 2 +- compiler/rustc_codegen_ssa/src/mir/operand.rs | 4 ++-- compiler/rustc_codegen_ssa/src/mir/place.rs | 4 ++-- .../rustc_const_eval/src/interpret/discriminant.rs | 8 ++++---- .../rustc_const_eval/src/interpret/validity.rs | 2 +- compiler/rustc_middle/src/ty/layout.rs | 8 +++++--- compiler/rustc_smir/src/rustc_smir/convert/abi.rs | 2 +- compiler/rustc_transmute/src/layout/tree.rs | 2 +- compiler/rustc_ty_utils/src/layout.rs | 2 +- 14 files changed, 33 insertions(+), 31 deletions(-) diff --git a/compiler/rustc_abi/src/layout.rs b/compiler/rustc_abi/src/layout.rs index 42250aa173bbd..21fd6be39fa41 100644 --- a/compiler/rustc_abi/src/layout.rs +++ b/compiler/rustc_abi/src/layout.rs @@ -758,7 +758,7 @@ impl LayoutCalculator { niche_variants, niche_start, }, - tag_field: 0, + tag_field: FieldIdx::new(0), variants: IndexVec::new(), }, fields: FieldsShape::Arbitrary { @@ -1072,7 +1072,7 @@ impl LayoutCalculator { variants: Variants::Multiple { tag, tag_encoding: TagEncoding::Direct, - tag_field: 0, + tag_field: FieldIdx::new(0), variants: IndexVec::new(), }, fields: FieldsShape::Arbitrary { diff --git a/compiler/rustc_abi/src/layout/coroutine.rs b/compiler/rustc_abi/src/layout/coroutine.rs index 27e704d538c83..2b22276d4aed7 100644 --- a/compiler/rustc_abi/src/layout/coroutine.rs +++ b/compiler/rustc_abi/src/layout/coroutine.rs @@ -158,7 +158,7 @@ pub(super) fn layout< // 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 = prefix_layouts.len(); + let tag_index = prefix_layouts.next_index(); // `variant_fields` already accounts for the reserved variants, so no need to add them. let max_discr = (variant_fields.len() - 1) as u128; @@ -187,7 +187,7 @@ pub(super) fn layout< // "a" (`0..b_start`) and "b" (`b_start..`) correspond to // "outer" and "promoted" fields respectively. - let b_start = FieldIdx::new(tag_index + 1); + let b_start = tag_index.plus(1); let offsets_b = IndexVec::from_raw(offsets.raw.split_off(b_start.index())); let offsets_a = offsets; diff --git a/compiler/rustc_abi/src/lib.rs b/compiler/rustc_abi/src/lib.rs index b806d0aba31de..46b7a0c1e77f4 100644 --- a/compiler/rustc_abi/src/lib.rs +++ b/compiler/rustc_abi/src/lib.rs @@ -1573,7 +1573,7 @@ pub enum Variants { Multiple { tag: Scalar, tag_encoding: TagEncoding, - tag_field: usize, + tag_field: FieldIdx, variants: IndexVec>, }, } diff --git a/compiler/rustc_codegen_cranelift/src/discriminant.rs b/compiler/rustc_codegen_cranelift/src/discriminant.rs index 4d0d5dc60eba6..a08b0e0cbfc59 100644 --- a/compiler/rustc_codegen_cranelift/src/discriminant.rs +++ b/compiler/rustc_codegen_cranelift/src/discriminant.rs @@ -28,7 +28,7 @@ pub(crate) fn codegen_set_discriminant<'tcx>( tag_encoding: TagEncoding::Direct, variants: _, } => { - let ptr = place.place_field(fx, FieldIdx::new(tag_field)); + let ptr = place.place_field(fx, tag_field); let to = layout.ty.discriminant_for_variant(fx.tcx, variant_index).unwrap().val; let to = match ptr.layout().ty.kind() { ty::Uint(UintTy::U128) | ty::Int(IntTy::I128) => { @@ -53,7 +53,7 @@ pub(crate) fn codegen_set_discriminant<'tcx>( variants: _, } => { if variant_index != untagged_variant { - let niche = place.place_field(fx, FieldIdx::new(tag_field)); + let niche = place.place_field(fx, tag_field); let niche_type = fx.clif_type(niche.layout().ty).unwrap(); let niche_value = variant_index.as_u32() - niche_variants.start().as_u32(); let niche_value = (niche_value as u128).wrapping_add(niche_start); @@ -118,7 +118,7 @@ pub(crate) fn codegen_get_discriminant<'tcx>( let cast_to = fx.clif_type(dest_layout.ty).unwrap(); // Read the tag/niche-encoded discriminant from memory. - let tag = value.value_field(fx, FieldIdx::new(tag_field)); + let tag = value.value_field(fx, tag_field); let tag = tag.load_scalar(fx); // Decode the discriminant (specifically if it's niche-encoded). 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 index e9574108696ba..a5c808957410e 100644 --- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs +++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs @@ -1,7 +1,7 @@ use std::borrow::Cow; use libc::c_uint; -use rustc_abi::{Align, Endian, Size, TagEncoding, VariantIdx, Variants}; +use rustc_abi::{Align, Endian, FieldIdx, Size, TagEncoding, VariantIdx, Variants}; use rustc_codegen_ssa::debuginfo::type_names::compute_debuginfo_type_name; use rustc_codegen_ssa::debuginfo::{tag_base_type, wants_c_like_enum_debuginfo}; use rustc_codegen_ssa::traits::{ConstCodegenMethods, MiscCodegenMethods}; @@ -401,7 +401,7 @@ fn build_union_fields_for_enum<'ll, 'tcx>( enum_type_and_layout: TyAndLayout<'tcx>, enum_type_di_node: &'ll DIType, variant_indices: impl Iterator + Clone, - tag_field: usize, + tag_field: FieldIdx, untagged_variant_index: Option, ) -> SmallVec<&'ll DIType> { let tag_base_type = tag_base_type(cx.tcx, enum_type_and_layout); @@ -805,7 +805,7 @@ fn build_union_fields_for_direct_tag_enum_or_coroutine<'ll, 'tcx>( variant_field_infos: &[VariantFieldInfo<'ll>], discr_type_di_node: &'ll DIType, tag_base_type: Ty<'tcx>, - tag_field: usize, + tag_field: FieldIdx, untagged_variant_index: Option, di_flags: DIFlags, ) -> SmallVec<&'ll DIType> { @@ -858,7 +858,7 @@ fn build_union_fields_for_direct_tag_enum_or_coroutine<'ll, 'tcx>( })); assert_eq!( - cx.size_and_align_of(enum_type_and_layout.field(cx, tag_field).ty), + cx.size_and_align_of(enum_type_and_layout.field(cx, tag_field.as_usize()).ty), cx.size_and_align_of(self::tag_base_type(cx.tcx, enum_type_and_layout)) ); @@ -875,7 +875,7 @@ fn build_union_fields_for_direct_tag_enum_or_coroutine<'ll, 'tcx>( Endian::Big => (8, 0), }; - let tag_field_offset = enum_type_and_layout.fields.offset(tag_field).bytes(); + let tag_field_offset = enum_type_and_layout.fields.offset(tag_field.as_usize()).bytes(); let lo_offset = Size::from_bytes(tag_field_offset + lo_offset); let hi_offset = Size::from_bytes(tag_field_offset + hi_offset); @@ -905,8 +905,8 @@ fn build_union_fields_for_direct_tag_enum_or_coroutine<'ll, 'tcx>( cx, enum_type_di_node, TAG_FIELD_NAME, - enum_type_and_layout.field(cx, tag_field), - enum_type_and_layout.fields.offset(tag_field), + enum_type_and_layout.field(cx, tag_field.as_usize()), + enum_type_and_layout.fields.offset(tag_field.as_usize()), di_flags, tag_base_type_di_node, None, diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/native.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/native.rs index 20a841f2287ae..62d38d463aba7 100644 --- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/native.rs +++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/native.rs @@ -373,7 +373,7 @@ fn build_discr_member_di_node<'ll, 'tcx>( file, UNKNOWN_LINE_NUMBER, layout, - enum_or_coroutine_type_and_layout.fields.offset(tag_field), + enum_or_coroutine_type_and_layout.fields.offset(tag_field.as_usize()), DIFlags::FlagArtificial, ty, )) diff --git a/compiler/rustc_codegen_ssa/src/mir/operand.rs b/compiler/rustc_codegen_ssa/src/mir/operand.rs index eade9e52de95a..b7f2277bfda2d 100644 --- a/compiler/rustc_codegen_ssa/src/mir/operand.rs +++ b/compiler/rustc_codegen_ssa/src/mir/operand.rs @@ -462,10 +462,10 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> { let tag_op = match self.val { OperandValue::ZeroSized => bug!(), OperandValue::Immediate(_) | OperandValue::Pair(_, _) => { - self.extract_field(fx, bx, tag_field) + self.extract_field(fx, bx, tag_field.as_usize()) } OperandValue::Ref(place) => { - let tag = place.with_type(self.layout).project_field(bx, tag_field); + let tag = place.with_type(self.layout).project_field(bx, tag_field.as_usize()); bx.load_operand(tag) } }; diff --git a/compiler/rustc_codegen_ssa/src/mir/place.rs b/compiler/rustc_codegen_ssa/src/mir/place.rs index 31db7fa9a1888..937063c24a63d 100644 --- a/compiler/rustc_codegen_ssa/src/mir/place.rs +++ b/compiler/rustc_codegen_ssa/src/mir/place.rs @@ -250,7 +250,7 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> { Variants::Single { index } => assert_eq!(index, variant_index), Variants::Multiple { tag_encoding: TagEncoding::Direct, tag_field, .. } => { - let ptr = self.project_field(bx, tag_field); + let ptr = self.project_field(bx, tag_field.as_usize()); let to = self.layout.ty.discriminant_for_variant(bx.tcx(), variant_index).unwrap().val; bx.store_to_place( @@ -265,7 +265,7 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> { .. } => { if variant_index != untagged_variant { - let niche = self.project_field(bx, tag_field); + let niche = self.project_field(bx, tag_field.as_usize()); let niche_llty = bx.cx().immediate_backend_type(niche.layout); let BackendRepr::Scalar(scalar) = niche.layout.backend_repr else { bug!("expected a scalar placeref for the niche"); diff --git a/compiler/rustc_const_eval/src/interpret/discriminant.rs b/compiler/rustc_const_eval/src/interpret/discriminant.rs index 2f0b1cb6d1ee5..020cd65d75dca 100644 --- a/compiler/rustc_const_eval/src/interpret/discriminant.rs +++ b/compiler/rustc_const_eval/src/interpret/discriminant.rs @@ -1,6 +1,6 @@ //! Functions for reading and writing discriminants of multi-variant layouts (enums and coroutines). -use rustc_abi::{self as abi, TagEncoding, VariantIdx, Variants}; +use rustc_abi::{self as abi, FieldIdx, TagEncoding, VariantIdx, Variants}; use rustc_middle::ty::layout::{LayoutOf, PrimitiveExt, TyAndLayout}; use rustc_middle::ty::{self, CoroutineArgsExt, ScalarInt, Ty}; use rustc_middle::{mir, span_bug}; @@ -26,7 +26,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { // No need to validate that the discriminant here because the // `TyAndLayout::for_variant()` call earlier already checks the // variant is valid. - let tag_dest = self.project_field(dest, tag_field)?; + let tag_dest = self.project_field(dest, tag_field.as_usize())?; self.write_scalar(tag, &tag_dest) } None => { @@ -96,7 +96,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { let tag_layout = self.layout_of(tag_scalar_layout.primitive().to_int_ty(*self.tcx))?; // Read tag and sanity-check `tag_layout`. - let tag_val = self.read_immediate(&self.project_field(op, tag_field)?)?; + let tag_val = self.read_immediate(&self.project_field(op, tag_field.as_usize())?)?; assert_eq!(tag_layout.size, tag_val.layout.size); assert_eq!(tag_layout.backend_repr.is_signed(), tag_val.layout.backend_repr.is_signed()); trace!("tag value: {}", tag_val); @@ -231,7 +231,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { &self, layout: TyAndLayout<'tcx>, variant_index: VariantIdx, - ) -> InterpResult<'tcx, Option<(ScalarInt, usize)>> { + ) -> InterpResult<'tcx, Option<(ScalarInt, FieldIdx)>> { // Layout computation excludes uninhabited variants from consideration. // Therefore, there's no way to represent those variants in the given layout. // Essentially, uninhabited variants do not have a tag that corresponds to their diff --git a/compiler/rustc_const_eval/src/interpret/validity.rs b/compiler/rustc_const_eval/src/interpret/validity.rs index 8f39afa642aef..7d76d925ef23e 100644 --- a/compiler/rustc_const_eval/src/interpret/validity.rs +++ b/compiler/rustc_const_eval/src/interpret/validity.rs @@ -294,7 +294,7 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> { // First, check if we are projecting to a variant. match layout.variants { Variants::Multiple { tag_field, .. } => { - if tag_field == field { + if tag_field.as_usize() == field { return match layout.ty.kind() { ty::Adt(def, ..) if def.is_enum() => PathElem::EnumTag, ty::Coroutine(..) => PathElem::CoroutineTag, diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs index 7ebfebea44e56..c2ae6b06192a9 100644 --- a/compiler/rustc_middle/src/ty/layout.rs +++ b/compiler/rustc_middle/src/ty/layout.rs @@ -934,7 +934,7 @@ where .unwrap(), ), Variants::Multiple { tag, tag_field, .. } => { - if i == tag_field { + if FieldIdx::from_usize(i) == tag_field { return TyMaybeWithLayout::TyAndLayout(tag_layout(tag)); } TyMaybeWithLayout::Ty(args.as_coroutine().prefix_tys()[i]) @@ -1060,8 +1060,10 @@ where tag_field, variants, .. - } if variants.len() == 2 && this.fields.offset(*tag_field) == offset => { - let tagged_variant = if untagged_variant.as_u32() == 0 { + } if variants.len() == 2 + && this.fields.offset(tag_field.as_usize()) == offset => + { + let tagged_variant = if *untagged_variant == VariantIdx::ZERO { VariantIdx::from_u32(1) } else { VariantIdx::from_u32(0) diff --git a/compiler/rustc_smir/src/rustc_smir/convert/abi.rs b/compiler/rustc_smir/src/rustc_smir/convert/abi.rs index 06dfaf079a334..64901ee050224 100644 --- a/compiler/rustc_smir/src/rustc_smir/convert/abi.rs +++ b/compiler/rustc_smir/src/rustc_smir/convert/abi.rs @@ -180,7 +180,7 @@ impl<'tcx> Stable<'tcx> for rustc_abi::Variants( // However, if the discriminant is placed past the end of the variant, then we need // to factor in the size of the discriminant manually. This really should be refactored // better, but this "works" for now. - if layout.fields.offset(tag_field) >= variant_size { + if layout.fields.offset(tag_field.as_usize()) >= variant_size { variant_size += match tag_encoding { TagEncoding::Direct => tag.size(cx), _ => Size::ZERO,