diff options
Diffstat (limited to 'compiler/rustc_builtin_macros/src/deriving/cmp')
4 files changed, 101 insertions, 19 deletions
diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs index 3e994f037..af9719586 100644 --- a/compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs +++ b/compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs @@ -7,7 +7,7 @@ use rustc_data_structures::fx::FxHashSet; use rustc_expand::base::{Annotatable, ExtCtxt}; use rustc_span::symbol::sym; use rustc_span::Span; -use thin_vec::thin_vec; +use thin_vec::{thin_vec, ThinVec}; pub fn expand_deriving_eq( cx: &mut ExtCtxt<'_>, @@ -27,6 +27,7 @@ pub fn expand_deriving_eq( span, path: path_std!(cmp::Eq), skip_path_as_bound: false, + needs_copy_as_bound_if_packed: true, additional_bounds: Vec::new(), supports_unions: true, methods: vec![MethodDef { @@ -55,7 +56,7 @@ fn cs_total_eq_assert( trait_span: Span, substr: &Substructure<'_>, ) -> BlockOrExpr { - let mut stmts = Vec::new(); + let mut stmts = ThinVec::new(); let mut seen_type_names = FxHashSet::default(); let mut process_variant = |variant: &ast::VariantData| { for field in variant.fields() { diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs index a926fca4e..cfd36f030 100644 --- a/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs +++ b/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs @@ -20,6 +20,7 @@ pub fn expand_deriving_ord( span, path: path_std!(cmp::Ord), skip_path_as_bound: false, + needs_copy_as_bound_if_packed: true, additional_bounds: Vec::new(), supports_unions: false, methods: vec![MethodDef { @@ -63,14 +64,14 @@ pub fn cs_cmp(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> Bl let [other_expr] = &field.other_selflike_exprs[..] else { cx.span_bug(field.span, "not exactly 2 arguments in `derive(Ord)`"); }; - let args = vec![field.self_expr.clone(), other_expr.clone()]; + let args = thin_vec![field.self_expr.clone(), other_expr.clone()]; cx.expr_call_global(field.span, cmp_path.clone(), args) } CsFold::Combine(span, expr1, expr2) => { let eq_arm = cx.arm(span, cx.pat_path(span, equal_path.clone()), expr1); let neq_arm = cx.arm(span, cx.pat_ident(span, test_id), cx.expr_ident(span, test_id)); - cx.expr_match(span, expr2, vec![eq_arm, neq_arm]) + cx.expr_match(span, expr2, thin_vec![eq_arm, neq_arm]) } CsFold::Fieldless => cx.expr_path(equal_path.clone()), }, diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs index 9051fe0b2..bad47db0d 100644 --- a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs +++ b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs @@ -29,16 +29,30 @@ pub fn expand_deriving_partial_eq( cx.span_bug(field.span, "not exactly 2 arguments in `derive(PartialEq)`"); }; - // We received `&T` arguments. Convert them to `T` by - // stripping `&` or adding `*`. This isn't necessary for - // type checking, but it results in much better error - // messages if something goes wrong. + // We received arguments of type `&T`. Convert them to type `T` by stripping + // any leading `&` or adding `*`. This isn't necessary for type checking, but + // it results in better error messages if something goes wrong. + // + // Note: for arguments that look like `&{ x }`, which occur with packed + // structs, this would cause expressions like `{ self.x } == { other.x }`, + // which isn't valid Rust syntax. This wouldn't break compilation because these + // AST nodes are constructed within the compiler. But it would mean that code + // printed by `-Zunpretty=expanded` (or `cargo expand`) would have invalid + // syntax, which would be suboptimal. So we wrap these in parens, giving + // `({ self.x }) == ({ other.x })`, which is valid syntax. let convert = |expr: &P<Expr>| { if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner) = &expr.kind { - inner.clone() + if let ExprKind::Block(..) = &inner.kind { + // `&{ x }` form: remove the `&`, add parens. + cx.expr_paren(field.span, inner.clone()) + } else { + // `&x` form: remove the `&`. + inner.clone() + } } else { + // No leading `&`: add a leading `*`. cx.expr_deref(field.span, expr.clone()) } }; @@ -84,6 +98,7 @@ pub fn expand_deriving_partial_eq( span, path: path_std!(cmp::PartialEq), skip_path_as_bound: false, + needs_copy_as_bound_if_packed: true, additional_bounds: Vec::new(), supports_unions: false, methods, diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs index c9dc89212..9f4624790 100644 --- a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs +++ b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs @@ -1,7 +1,7 @@ use crate::deriving::generic::ty::*; use crate::deriving::generic::*; use crate::deriving::{path_std, pathvec_std}; -use rustc_ast::MetaItem; +use rustc_ast::{ExprKind, ItemKind, MetaItem, PatKind}; use rustc_expand::base::{Annotatable, ExtCtxt}; use rustc_span::symbol::{sym, Ident}; use rustc_span::Span; @@ -21,6 +21,27 @@ pub fn expand_deriving_partial_ord( let attrs = thin_vec![cx.attr_word(sym::inline, span)]; + // Order in which to perform matching + let tag_then_data = if let Annotatable::Item(item) = item + && let ItemKind::Enum(def, _) = &item.kind { + let dataful: Vec<bool> = def.variants.iter().map(|v| !v.data.fields().is_empty()).collect(); + match dataful.iter().filter(|&&b| b).count() { + // No data, placing the tag check first makes codegen simpler + 0 => true, + 1..=2 => false, + _ => { + (0..dataful.len()-1).any(|i| { + if dataful[i] && let Some(idx) = dataful[i+1..].iter().position(|v| *v) { + idx >= 2 + } else { + false + } + }) + } + } + } else { + true + }; let partial_cmp_def = MethodDef { name: sym::partial_cmp, generics: Bounds::empty(), @@ -30,7 +51,7 @@ pub fn expand_deriving_partial_ord( attributes: attrs, fieldless_variants_strategy: FieldlessVariantsStrategy::Unify, combine_substructure: combine_substructure(Box::new(|cx, span, substr| { - cs_partial_cmp(cx, span, substr) + cs_partial_cmp(cx, span, substr, tag_then_data) })), }; @@ -38,6 +59,7 @@ pub fn expand_deriving_partial_ord( span, path: path_std!(cmp::PartialOrd), skip_path_as_bound: false, + needs_copy_as_bound_if_packed: true, additional_bounds: vec![], supports_unions: false, methods: vec![partial_cmp_def], @@ -47,7 +69,12 @@ pub fn expand_deriving_partial_ord( trait_def.expand(cx, mitem, item, push) } -pub fn cs_partial_cmp(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> BlockOrExpr { +fn cs_partial_cmp( + cx: &mut ExtCtxt<'_>, + span: Span, + substr: &Substructure<'_>, + tag_then_data: bool, +) -> BlockOrExpr { let test_id = Ident::new(sym::cmp, span); let equal_path = cx.path_global(span, cx.std_path(&[sym::cmp, sym::Ordering, sym::Equal])); let partial_cmp_path = cx.std_path(&[sym::cmp, sym::PartialOrd, sym::partial_cmp]); @@ -71,15 +98,53 @@ pub fn cs_partial_cmp(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_ let [other_expr] = &field.other_selflike_exprs[..] else { cx.span_bug(field.span, "not exactly 2 arguments in `derive(Ord)`"); }; - let args = vec![field.self_expr.clone(), other_expr.clone()]; + let args = thin_vec![field.self_expr.clone(), other_expr.clone()]; cx.expr_call_global(field.span, partial_cmp_path.clone(), args) } - CsFold::Combine(span, expr1, expr2) => { - let eq_arm = - cx.arm(span, cx.pat_some(span, cx.pat_path(span, equal_path.clone())), expr1); - let neq_arm = - cx.arm(span, cx.pat_ident(span, test_id), cx.expr_ident(span, test_id)); - cx.expr_match(span, expr2, vec![eq_arm, neq_arm]) + CsFold::Combine(span, mut expr1, expr2) => { + // When the item is an enum, this expands to + // ``` + // match (expr2) { + // Some(Ordering::Equal) => expr1, + // cmp => cmp + // } + // ``` + // where `expr2` is `partial_cmp(self_tag, other_tag)`, and `expr1` is a `match` + // against the enum variants. This means that we begin by comparing the enum tags, + // before either inspecting their contents (if they match), or returning + // the `cmp::Ordering` of comparing the enum tags. + // ``` + // match partial_cmp(self_tag, other_tag) { + // Some(Ordering::Equal) => match (self, other) { + // (Self::A(self_0), Self::A(other_0)) => partial_cmp(self_0, other_0), + // (Self::B(self_0), Self::B(other_0)) => partial_cmp(self_0, other_0), + // _ => Some(Ordering::Equal) + // } + // cmp => cmp + // } + // ``` + // If we have any certain enum layouts, flipping this results in better codegen + // ``` + // match (self, other) { + // (Self::A(self_0), Self::A(other_0)) => partial_cmp(self_0, other_0), + // _ => partial_cmp(self_tag, other_tag) + // } + // ``` + // Reference: https://github.com/rust-lang/rust/pull/103659#issuecomment-1328126354 + + if !tag_then_data + && let ExprKind::Match(_, arms) = &mut expr1.kind + && let Some(last) = arms.last_mut() + && let PatKind::Wild = last.pat.kind { + last.body = expr2; + expr1 + } else { + let eq_arm = + cx.arm(span, cx.pat_some(span, cx.pat_path(span, equal_path.clone())), expr1); + let neq_arm = + cx.arm(span, cx.pat_ident(span, test_id), cx.expr_ident(span, test_id)); + cx.expr_match(span, expr2, thin_vec![eq_arm, neq_arm]) + } } CsFold::Fieldless => cx.expr_some(span, cx.expr_path(equal_path.clone())), }, |