diff options
Diffstat (limited to '')
| -rw-r--r-- | compiler/rustc_ty_utils/Cargo.toml | 2 | ||||
| -rw-r--r-- | compiler/rustc_ty_utils/src/consts.rs | 572 | ||||
| -rw-r--r-- | compiler/rustc_ty_utils/src/instance.rs | 10 | ||||
| -rw-r--r-- | compiler/rustc_ty_utils/src/layout.rs | 991 | ||||
| -rw-r--r-- | compiler/rustc_ty_utils/src/layout_sanity_check.rs | 536 | ||||
| -rw-r--r-- | compiler/rustc_ty_utils/src/lib.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_ty_utils/src/structural_match.rs | 44 | ||||
| -rw-r--r-- | compiler/rustc_ty_utils/src/ty.rs | 73 |
8 files changed, 640 insertions, 1590 deletions
diff --git a/compiler/rustc_ty_utils/Cargo.toml b/compiler/rustc_ty_utils/Cargo.toml index 5e4ba4730..52fbd3ae0 100644 --- a/compiler/rustc_ty_utils/Cargo.toml +++ b/compiler/rustc_ty_utils/Cargo.toml @@ -4,8 +4,6 @@ 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/consts.rs b/compiler/rustc_ty_utils/src/consts.rs index e057bb668..f8ff31f97 100644 --- a/compiler/rustc_ty_utils/src/consts.rs +++ b/compiler/rustc_ty_utils/src/consts.rs @@ -1,10 +1,11 @@ use rustc_errors::ErrorGuaranteed; use rustc_hir::def::DefKind; use rustc_hir::def_id::LocalDefId; -use rustc_index::vec::IndexVec; use rustc_middle::mir::interpret::{LitToConstError, LitToConstInput}; -use rustc_middle::ty::abstract_const::{CastKind, Node, NodeId}; -use rustc_middle::ty::{self, TyCtxt, TypeVisitable}; +use rustc_middle::thir::visit; +use rustc_middle::thir::visit::Visitor; +use rustc_middle::ty::abstract_const::CastKind; +use rustc_middle::ty::{self, Expr, TyCtxt, TypeVisitable}; use rustc_middle::{mir, thir}; use rustc_span::Span; use rustc_target::abi::VariantIdx; @@ -31,10 +32,8 @@ pub(crate) fn destructure_const<'tcx>( let (fields, variant) = match const_.ty().kind() { ty::Array(inner_ty, _) | ty::Slice(inner_ty) => { // construct the consts for the elements of the array/slice - let field_consts = branches - .iter() - .map(|b| tcx.mk_const(ty::ConstS { kind: ty::ConstKind::Value(*b), ty: *inner_ty })) - .collect::<Vec<_>>(); + let field_consts = + branches.iter().map(|b| tcx.mk_const(*b, *inner_ty)).collect::<Vec<_>>(); debug!(?field_consts); (field_consts, None) @@ -52,10 +51,7 @@ pub(crate) fn destructure_const<'tcx>( for (field, field_valtree) in iter::zip(fields, branches) { let field_ty = field.ty(tcx, substs); - let field_const = tcx.mk_const(ty::ConstS { - kind: ty::ConstKind::Value(*field_valtree), - ty: field_ty, - }); + let field_const = tcx.mk_const(*field_valtree, field_ty); field_consts.push(field_const); } debug!(?field_consts); @@ -64,12 +60,7 @@ pub(crate) fn destructure_const<'tcx>( } ty::Tuple(elem_tys) => { let fields = iter::zip(*elem_tys, branches) - .map(|(elem_ty, elem_valtree)| { - tcx.mk_const(ty::ConstS { - kind: ty::ConstKind::Value(*elem_valtree), - ty: elem_ty, - }) - }) + .map(|(elem_ty, elem_valtree)| tcx.mk_const(*elem_valtree, elem_ty)) .collect::<Vec<_>>(); (fields, None) @@ -82,328 +73,278 @@ pub(crate) fn destructure_const<'tcx>( ty::DestructuredConst { variant, fields } } -pub struct AbstractConstBuilder<'a, 'tcx> { - tcx: TyCtxt<'tcx>, - body_id: thir::ExprId, - body: &'a thir::Thir<'tcx>, - /// The current WIP node tree. - nodes: IndexVec<NodeId, Node<'tcx>>, -} - -impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> { - fn root_span(&self) -> Span { - self.body.exprs[self.body_id].span - } - - fn error(&mut self, sub: GenericConstantTooComplexSub) -> Result<!, ErrorGuaranteed> { - let reported = self.tcx.sess.emit_err(GenericConstantTooComplex { - span: self.root_span(), - maybe_supported: None, - sub, - }); - - Err(reported) +/// We do not allow all binary operations in abstract consts, so filter disallowed ones. +fn check_binop(op: mir::BinOp) -> bool { + use mir::BinOp::*; + match op { + Add | Sub | Mul | Div | Rem | BitXor | BitAnd | BitOr | Shl | Shr | Eq | Lt | Le | Ne + | Ge | Gt => true, + Offset => false, } +} - fn maybe_supported_error( - &mut self, - sub: GenericConstantTooComplexSub, - ) -> Result<!, ErrorGuaranteed> { - let reported = self.tcx.sess.emit_err(GenericConstantTooComplex { - span: self.root_span(), - maybe_supported: Some(()), - sub, - }); - - Err(reported) +/// While we currently allow all unary operations, we still want to explicitly guard against +/// future changes here. +fn check_unop(op: mir::UnOp) -> bool { + use mir::UnOp::*; + match op { + Not | Neg => true, } +} - #[instrument(skip(tcx, body, body_id), level = "debug")] - pub fn new( - tcx: TyCtxt<'tcx>, - (body, body_id): (&'a thir::Thir<'tcx>, thir::ExprId), - ) -> Result<Option<AbstractConstBuilder<'a, 'tcx>>, ErrorGuaranteed> { - let builder = AbstractConstBuilder { tcx, body_id, body, nodes: IndexVec::new() }; - - struct IsThirPolymorphic<'a, 'tcx> { - is_poly: bool, - thir: &'a thir::Thir<'tcx>, +fn recurse_build<'tcx>( + tcx: TyCtxt<'tcx>, + body: &thir::Thir<'tcx>, + node: thir::ExprId, + root_span: Span, +) -> Result<ty::Const<'tcx>, ErrorGuaranteed> { + use thir::ExprKind; + let node = &body.exprs[node]; + + let maybe_supported_error = |a| maybe_supported_error(tcx, a, root_span); + let error = |a| error(tcx, a, root_span); + + Ok(match &node.kind { + // I dont know if handling of these 3 is correct + &ExprKind::Scope { value, .. } => recurse_build(tcx, body, value, root_span)?, + &ExprKind::PlaceTypeAscription { source, .. } + | &ExprKind::ValueTypeAscription { source, .. } => { + recurse_build(tcx, body, source, root_span)? } - - use crate::rustc_middle::thir::visit::Visitor; - use thir::visit; - - impl<'a, 'tcx> IsThirPolymorphic<'a, 'tcx> { - fn expr_is_poly(&mut self, expr: &thir::Expr<'tcx>) -> bool { - if expr.ty.has_non_region_param() { - return true; + &ExprKind::Literal { lit, neg } => { + let sp = node.span; + match tcx.at(sp).lit_to_const(LitToConstInput { lit: &lit.node, ty: node.ty, neg }) { + Ok(c) => c, + Err(LitToConstError::Reported(guar)) => { + tcx.const_error_with_guaranteed(node.ty, guar) } - - match expr.kind { - 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_non_region_param() - } - _ => false, + Err(LitToConstError::TypeError) => { + bug!("encountered type error in lit_to_const") } } + } + &ExprKind::NonHirLiteral { lit, user_ty: _ } => { + let val = ty::ValTree::from_scalar_int(lit); + tcx.mk_const(val, node.ty) + } + &ExprKind::ZstLiteral { user_ty: _ } => { + let val = ty::ValTree::zst(); + tcx.mk_const(val, node.ty) + } + &ExprKind::NamedConst { def_id, substs, user_ty: _ } => { + let uneval = ty::UnevaluatedConst::new(ty::WithOptConstParam::unknown(def_id), substs); + tcx.mk_const(uneval, node.ty) + } + ExprKind::ConstParam { param, .. } => tcx.mk_const(*param, node.ty), - fn pat_is_poly(&mut self, pat: &thir::Pat<'tcx>) -> bool { - if pat.ty.has_non_region_param() { - return true; - } + ExprKind::Call { fun, args, .. } => { + let fun = recurse_build(tcx, body, *fun, root_span)?; - match pat.kind { - thir::PatKind::Constant { value } => value.has_non_region_param(), - thir::PatKind::Range(box thir::PatRange { lo, hi, .. }) => { - lo.has_non_region_param() || hi.has_non_region_param() - } - _ => false, - } + let mut new_args = Vec::<ty::Const<'tcx>>::with_capacity(args.len()); + for &id in args.iter() { + new_args.push(recurse_build(tcx, body, id, root_span)?); } + let new_args = tcx.mk_const_list(new_args.iter()); + tcx.mk_const(Expr::FunctionCall(fun, new_args), node.ty) } - - impl<'a, 'tcx> visit::Visitor<'a, 'tcx> for IsThirPolymorphic<'a, 'tcx> { - fn thir(&self) -> &'a thir::Thir<'tcx> { - &self.thir - } - - #[instrument(skip(self), level = "debug")] - fn visit_expr(&mut self, expr: &thir::Expr<'tcx>) { - self.is_poly |= self.expr_is_poly(expr); - if !self.is_poly { - visit::walk_expr(self, expr) - } + &ExprKind::Binary { op, lhs, rhs } if check_binop(op) => { + let lhs = recurse_build(tcx, body, lhs, root_span)?; + let rhs = recurse_build(tcx, body, rhs, root_span)?; + tcx.mk_const(Expr::Binop(op, lhs, rhs), node.ty) + } + &ExprKind::Unary { op, arg } if check_unop(op) => { + let arg = recurse_build(tcx, body, arg, root_span)?; + tcx.mk_const(Expr::UnOp(op, arg), node.ty) + } + // This is necessary so that the following compiles: + // + // ``` + // fn foo<const N: usize>(a: [(); N + 1]) { + // bar::<{ N + 1 }>(); + // } + // ``` + ExprKind::Block { block } => { + if let thir::Block { stmts: box [], expr: Some(e), .. } = &body.blocks[*block] { + recurse_build(tcx, body, *e, root_span)? + } else { + maybe_supported_error(GenericConstantTooComplexSub::BlockNotSupported(node.span))? } - - #[instrument(skip(self), level = "debug")] - fn visit_pat(&mut self, pat: &thir::Pat<'tcx>) { - self.is_poly |= self.pat_is_poly(pat); - if !self.is_poly { - visit::walk_pat(self, pat); - } + } + // `ExprKind::Use` happens when a `hir::ExprKind::Cast` is a + // "coercion cast" i.e. using a coercion or is a no-op. + // This is important so that `N as usize as usize` doesnt unify with `N as usize`. (untested) + &ExprKind::Use { source } => { + let arg = recurse_build(tcx, body, source, root_span)?; + tcx.mk_const(Expr::Cast(CastKind::Use, arg, node.ty), node.ty) + } + &ExprKind::Cast { source } => { + let arg = recurse_build(tcx, body, source, root_span)?; + tcx.mk_const(Expr::Cast(CastKind::As, arg, node.ty), node.ty) + } + ExprKind::Borrow { arg, .. } => { + let arg_node = &body.exprs[*arg]; + + // Skip reborrows for now until we allow Deref/Borrow/AddressOf + // expressions. + // FIXME(generic_const_exprs): Verify/explain why this is sound + if let ExprKind::Deref { arg } = arg_node.kind { + recurse_build(tcx, body, arg, root_span)? + } else { + maybe_supported_error(GenericConstantTooComplexSub::BorrowNotSupported(node.span))? } } - - let mut is_poly_vis = IsThirPolymorphic { is_poly: false, thir: body }; - visit::walk_expr(&mut is_poly_vis, &body[body_id]); - debug!("AbstractConstBuilder: is_poly={}", is_poly_vis.is_poly); - if !is_poly_vis.is_poly { - return Ok(None); + // FIXME(generic_const_exprs): We may want to support these. + ExprKind::AddressOf { .. } | ExprKind::Deref { .. } => maybe_supported_error( + GenericConstantTooComplexSub::AddressAndDerefNotSupported(node.span), + )?, + ExprKind::Repeat { .. } | ExprKind::Array { .. } => { + maybe_supported_error(GenericConstantTooComplexSub::ArrayNotSupported(node.span))? } + ExprKind::NeverToAny { .. } => { + maybe_supported_error(GenericConstantTooComplexSub::NeverToAnyNotSupported(node.span))? + } + ExprKind::Tuple { .. } => { + maybe_supported_error(GenericConstantTooComplexSub::TupleNotSupported(node.span))? + } + ExprKind::Index { .. } => { + maybe_supported_error(GenericConstantTooComplexSub::IndexNotSupported(node.span))? + } + ExprKind::Field { .. } => { + maybe_supported_error(GenericConstantTooComplexSub::FieldNotSupported(node.span))? + } + ExprKind::ConstBlock { .. } => { + maybe_supported_error(GenericConstantTooComplexSub::ConstBlockNotSupported(node.span))? + } + ExprKind::Adt(_) => { + maybe_supported_error(GenericConstantTooComplexSub::AdtNotSupported(node.span))? + } + // dont know if this is correct + ExprKind::Pointer { .. } => { + error(GenericConstantTooComplexSub::PointerNotSupported(node.span))? + } + ExprKind::Yield { .. } => { + error(GenericConstantTooComplexSub::YieldNotSupported(node.span))? + } + ExprKind::Continue { .. } | ExprKind::Break { .. } | ExprKind::Loop { .. } => { + error(GenericConstantTooComplexSub::LoopNotSupported(node.span))? + } + ExprKind::Box { .. } => error(GenericConstantTooComplexSub::BoxNotSupported(node.span))?, - Ok(Some(builder)) - } - - /// We do not allow all binary operations in abstract consts, so filter disallowed ones. - fn check_binop(op: mir::BinOp) -> bool { - use mir::BinOp::*; - match op { - Add | Sub | Mul | Div | Rem | BitXor | BitAnd | BitOr | Shl | Shr | Eq | Lt | Le - | Ne | Ge | Gt => true, - Offset => false, + ExprKind::Unary { .. } => unreachable!(), + // we handle valid unary/binary ops above + ExprKind::Binary { .. } => { + error(GenericConstantTooComplexSub::BinaryNotSupported(node.span))? + } + ExprKind::LogicalOp { .. } => { + error(GenericConstantTooComplexSub::LogicalOpNotSupported(node.span))? + } + ExprKind::Assign { .. } | ExprKind::AssignOp { .. } => { + error(GenericConstantTooComplexSub::AssignNotSupported(node.span))? + } + ExprKind::Closure { .. } | ExprKind::Return { .. } => { + error(GenericConstantTooComplexSub::ClosureAndReturnNotSupported(node.span))? + } + // let expressions imply control flow + ExprKind::Match { .. } | ExprKind::If { .. } | ExprKind::Let { .. } => { + error(GenericConstantTooComplexSub::ControlFlowNotSupported(node.span))? + } + ExprKind::InlineAsm { .. } => { + error(GenericConstantTooComplexSub::InlineAsmNotSupported(node.span))? } - } - /// While we currently allow all unary operations, we still want to explicitly guard against - /// future changes here. - fn check_unop(op: mir::UnOp) -> bool { - use mir::UnOp::*; - match op { - Not | Neg => true, + // we dont permit let stmts so `VarRef` and `UpvarRef` cant happen + ExprKind::VarRef { .. } + | ExprKind::UpvarRef { .. } + | ExprKind::StaticRef { .. } + | ExprKind::ThreadLocalRef(_) => { + error(GenericConstantTooComplexSub::OperationNotSupported(node.span))? } - } + }) +} - /// Builds the abstract const by walking the thir and bailing out when - /// encountering an unsupported operation. - pub fn build(mut self) -> Result<&'tcx [Node<'tcx>], ErrorGuaranteed> { - debug!("AbstractConstBuilder::build: body={:?}", &*self.body); - self.recurse_build(self.body_id)?; +struct IsThirPolymorphic<'a, 'tcx> { + is_poly: bool, + thir: &'a thir::Thir<'tcx>, +} - Ok(self.tcx.arena.alloc_from_iter(self.nodes.into_iter())) - } +fn error<'tcx>( + tcx: TyCtxt<'tcx>, + sub: GenericConstantTooComplexSub, + root_span: Span, +) -> Result<!, ErrorGuaranteed> { + let reported = tcx.sess.emit_err(GenericConstantTooComplex { + span: root_span, + maybe_supported: None, + sub, + }); + + Err(reported) +} - fn recurse_build(&mut self, node: thir::ExprId) -> Result<NodeId, ErrorGuaranteed> { - use thir::ExprKind; - let node = &self.body.exprs[node]; - Ok(match &node.kind { - // I dont know if handling of these 3 is correct - &ExprKind::Scope { value, .. } => self.recurse_build(value)?, - &ExprKind::PlaceTypeAscription { source, .. } - | &ExprKind::ValueTypeAscription { source, .. } => self.recurse_build(source)?, - &ExprKind::Literal { lit, neg } => { - let sp = node.span; - let constant = match self.tcx.at(sp).lit_to_const(LitToConstInput { - lit: &lit.node, - ty: node.ty, - neg, - }) { - Ok(c) => c, - Err(LitToConstError::Reported) => self.tcx.const_error(node.ty), - Err(LitToConstError::TypeError) => { - bug!("encountered type error in lit_to_const") - } - }; - - self.nodes.push(Node::Leaf(constant)) - } - &ExprKind::NonHirLiteral { lit, user_ty: _ } => { - let val = ty::ValTree::from_scalar_int(lit); - self.nodes.push(Node::Leaf(ty::Const::from_value(self.tcx, val, node.ty))) - } - &ExprKind::ZstLiteral { user_ty: _ } => { - let val = ty::ValTree::zst(); - self.nodes.push(Node::Leaf(ty::Const::from_value(self.tcx, val, node.ty))) - } - &ExprKind::NamedConst { def_id, substs, user_ty: _ } => { - let uneval = - ty::UnevaluatedConst::new(ty::WithOptConstParam::unknown(def_id), substs); +fn maybe_supported_error<'tcx>( + tcx: TyCtxt<'tcx>, + sub: GenericConstantTooComplexSub, + root_span: Span, +) -> Result<!, ErrorGuaranteed> { + let reported = tcx.sess.emit_err(GenericConstantTooComplex { + span: root_span, + maybe_supported: Some(()), + sub, + }); + + Err(reported) +} - let constant = self - .tcx - .mk_const(ty::ConstS { kind: ty::ConstKind::Unevaluated(uneval), ty: node.ty }); +impl<'a, 'tcx> IsThirPolymorphic<'a, 'tcx> { + fn expr_is_poly(&mut self, expr: &thir::Expr<'tcx>) -> bool { + if expr.ty.has_non_region_param() { + return true; + } - self.nodes.push(Node::Leaf(constant)) + match expr.kind { + 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_non_region_param() } + _ => false, + } + } + fn pat_is_poly(&mut self, pat: &thir::Pat<'tcx>) -> bool { + if pat.ty.has_non_region_param() { + return true; + } - ExprKind::ConstParam { param, .. } => { - let const_param = self - .tcx - .mk_const(ty::ConstS { kind: ty::ConstKind::Param(*param), ty: node.ty }); - self.nodes.push(Node::Leaf(const_param)) + match pat.kind { + thir::PatKind::Constant { value } => value.has_non_region_param(), + thir::PatKind::Range(box thir::PatRange { lo, hi, .. }) => { + lo.has_non_region_param() || hi.has_non_region_param() } + _ => false, + } + } +} - ExprKind::Call { fun, args, .. } => { - let fun = self.recurse_build(*fun)?; - - let mut new_args = Vec::<NodeId>::with_capacity(args.len()); - for &id in args.iter() { - new_args.push(self.recurse_build(id)?); - } - let new_args = self.tcx.arena.alloc_slice(&new_args); - self.nodes.push(Node::FunctionCall(fun, new_args)) - } - &ExprKind::Binary { op, lhs, rhs } if Self::check_binop(op) => { - let lhs = self.recurse_build(lhs)?; - let rhs = self.recurse_build(rhs)?; - self.nodes.push(Node::Binop(op, lhs, rhs)) - } - &ExprKind::Unary { op, arg } if Self::check_unop(op) => { - let arg = self.recurse_build(arg)?; - self.nodes.push(Node::UnaryOp(op, arg)) - } - // This is necessary so that the following compiles: - // - // ``` - // fn foo<const N: usize>(a: [(); N + 1]) { - // bar::<{ N + 1 }>(); - // } - // ``` - ExprKind::Block { block } => { - if let thir::Block { stmts: box [], expr: Some(e), .. } = &self.body.blocks[*block] - { - self.recurse_build(*e)? - } else { - self.maybe_supported_error(GenericConstantTooComplexSub::BlockNotSupported( - node.span, - ))? - } - } - // `ExprKind::Use` happens when a `hir::ExprKind::Cast` is a - // "coercion cast" i.e. using a coercion or is a no-op. - // This is important so that `N as usize as usize` doesnt unify with `N as usize`. (untested) - &ExprKind::Use { source } => { - let arg = self.recurse_build(source)?; - self.nodes.push(Node::Cast(CastKind::Use, arg, node.ty)) - } - &ExprKind::Cast { source } => { - let arg = self.recurse_build(source)?; - self.nodes.push(Node::Cast(CastKind::As, arg, node.ty)) - } - ExprKind::Borrow { arg, .. } => { - let arg_node = &self.body.exprs[*arg]; - - // Skip reborrows for now until we allow Deref/Borrow/AddressOf - // expressions. - // FIXME(generic_const_exprs): Verify/explain why this is sound - if let ExprKind::Deref { arg } = arg_node.kind { - self.recurse_build(arg)? - } else { - self.maybe_supported_error(GenericConstantTooComplexSub::BorrowNotSupported( - node.span, - ))? - } - } - // FIXME(generic_const_exprs): We may want to support these. - ExprKind::AddressOf { .. } | ExprKind::Deref { .. } => self.maybe_supported_error( - GenericConstantTooComplexSub::AddressAndDerefNotSupported(node.span), - )?, - ExprKind::Repeat { .. } | ExprKind::Array { .. } => self.maybe_supported_error( - GenericConstantTooComplexSub::ArrayNotSupported(node.span), - )?, - ExprKind::NeverToAny { .. } => self.maybe_supported_error( - GenericConstantTooComplexSub::NeverToAnyNotSupported(node.span), - )?, - ExprKind::Tuple { .. } => self.maybe_supported_error( - GenericConstantTooComplexSub::TupleNotSupported(node.span), - )?, - ExprKind::Index { .. } => self.maybe_supported_error( - GenericConstantTooComplexSub::IndexNotSupported(node.span), - )?, - ExprKind::Field { .. } => self.maybe_supported_error( - GenericConstantTooComplexSub::FieldNotSupported(node.span), - )?, - ExprKind::ConstBlock { .. } => self.maybe_supported_error( - GenericConstantTooComplexSub::ConstBlockNotSupported(node.span), - )?, - ExprKind::Adt(_) => self - .maybe_supported_error(GenericConstantTooComplexSub::AdtNotSupported(node.span))?, - // dont know if this is correct - ExprKind::Pointer { .. } => { - self.error(GenericConstantTooComplexSub::PointerNotSupported(node.span))? - } - ExprKind::Yield { .. } => { - self.error(GenericConstantTooComplexSub::YieldNotSupported(node.span))? - } - ExprKind::Continue { .. } | ExprKind::Break { .. } | ExprKind::Loop { .. } => { - self.error(GenericConstantTooComplexSub::LoopNotSupported(node.span))? - } - ExprKind::Box { .. } => { - self.error(GenericConstantTooComplexSub::BoxNotSupported(node.span))? - } +impl<'a, 'tcx> visit::Visitor<'a, 'tcx> for IsThirPolymorphic<'a, 'tcx> { + fn thir(&self) -> &'a thir::Thir<'tcx> { + &self.thir + } - ExprKind::Unary { .. } => unreachable!(), - // we handle valid unary/binary ops above - ExprKind::Binary { .. } => { - self.error(GenericConstantTooComplexSub::BinaryNotSupported(node.span))? - } - ExprKind::LogicalOp { .. } => { - self.error(GenericConstantTooComplexSub::LogicalOpNotSupported(node.span))? - } - ExprKind::Assign { .. } | ExprKind::AssignOp { .. } => { - self.error(GenericConstantTooComplexSub::AssignNotSupported(node.span))? - } - ExprKind::Closure { .. } | ExprKind::Return { .. } => { - self.error(GenericConstantTooComplexSub::ClosureAndReturnNotSupported(node.span))? - } - // let expressions imply control flow - ExprKind::Match { .. } | ExprKind::If { .. } | ExprKind::Let { .. } => { - self.error(GenericConstantTooComplexSub::ControlFlowNotSupported(node.span))? - } - ExprKind::InlineAsm { .. } => { - self.error(GenericConstantTooComplexSub::InlineAsmNotSupported(node.span))? - } + #[instrument(skip(self), level = "debug")] + fn visit_expr(&mut self, expr: &thir::Expr<'tcx>) { + self.is_poly |= self.expr_is_poly(expr); + if !self.is_poly { + visit::walk_expr(self, expr) + } + } - // we dont permit let stmts so `VarRef` and `UpvarRef` cant happen - ExprKind::VarRef { .. } - | ExprKind::UpvarRef { .. } - | ExprKind::StaticRef { .. } - | ExprKind::ThreadLocalRef(_) => { - self.error(GenericConstantTooComplexSub::OperationNotSupported(node.span))? - } - }) + #[instrument(skip(self), level = "debug")] + fn visit_pat(&mut self, pat: &thir::Pat<'tcx>) { + self.is_poly |= self.pat_is_poly(pat); + if !self.is_poly { + visit::walk_pat(self, pat); + } } } @@ -411,7 +352,7 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> { pub fn thir_abstract_const<'tcx>( tcx: TyCtxt<'tcx>, def: ty::WithOptConstParam<LocalDefId>, -) -> Result<Option<&'tcx [Node<'tcx>]>, ErrorGuaranteed> { +) -> Result<Option<ty::Const<'tcx>>, ErrorGuaranteed> { if tcx.features().generic_const_exprs { match tcx.def_kind(def.did) { // FIXME(generic_const_exprs): We currently only do this for anonymous constants, @@ -424,10 +365,17 @@ pub fn thir_abstract_const<'tcx>( } let body = tcx.thir_body(def)?; + let (body, body_id) = (&*body.0.borrow(), body.1); + + let mut is_poly_vis = IsThirPolymorphic { is_poly: false, thir: body }; + visit::walk_expr(&mut is_poly_vis, &body[body_id]); + if !is_poly_vis.is_poly { + return Ok(None); + } + + let root_span = body.exprs[body_id].span; - AbstractConstBuilder::new(tcx, (&*body.0.borrow(), body.1))? - .map(AbstractConstBuilder::build) - .transpose() + Some(recurse_build(tcx, body, body_id, root_span)).transpose() } else { Ok(None) } diff --git a/compiler/rustc_ty_utils/src/instance.rs b/compiler/rustc_ty_utils/src/instance.rs index 6436713b3..c6f2b16ca 100644 --- a/compiler/rustc_ty_utils/src/instance.rs +++ b/compiler/rustc_ty_utils/src/instance.rs @@ -202,8 +202,14 @@ fn resolve_associated_item<'tcx>( )), substs: generator_data.substs, }), + traits::ImplSource::Future(future_data) => Some(Instance { + def: ty::InstanceDef::Item(ty::WithOptConstParam::unknown( + future_data.generator_def_id, + )), + substs: future_data.substs, + }), traits::ImplSource::Closure(closure_data) => { - let trait_closure_kind = tcx.fn_trait_kind_from_lang_item(trait_id).unwrap(); + let trait_closure_kind = tcx.fn_trait_kind_from_def_id(trait_id).unwrap(); Instance::resolve_closure( tcx, closure_data.closure_def_id, @@ -264,8 +270,6 @@ fn resolve_associated_item<'tcx>( traits::ImplSource::AutoImpl(..) | traits::ImplSource::Param(..) | traits::ImplSource::TraitAlias(..) - | traits::ImplSource::DiscriminantKind(..) - | traits::ImplSource::Pointee(..) | traits::ImplSource::TraitUpcasting(_) | traits::ImplSource::ConstDestruct(_) => None, }) diff --git a/compiler/rustc_ty_utils/src/layout.rs b/compiler/rustc_ty_utils/src/layout.rs index 52ba0eee9..fbc055b5d 100644 --- a/compiler/rustc_ty_utils/src/layout.rs +++ b/compiler/rustc_ty_utils/src/layout.rs @@ -13,13 +13,8 @@ use rustc_span::symbol::Symbol; use rustc_span::DUMMY_SP; use rustc_target::abi::*; -use std::cmp::{self, Ordering}; +use std::fmt::Debug; 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; @@ -66,16 +61,6 @@ fn layout_of<'tcx>( 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). @@ -89,40 +74,13 @@ fn invert_mapping(map: &[u32]) -> Vec<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>> { +) -> Result<LayoutS<VariantIdx>, LayoutError<'tcx>> { let dl = cx.data_layout(); let pack = repr.pack; if pack.is_some() && repr.align.is_some() { @@ -130,208 +88,7 @@ fn univariant_uninterned<'tcx>( 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, - }) + cx.univariant(dl, fields, repr, kind).ok_or(LayoutError::SizeOverflow(ty)) } fn layout_of_uncached<'tcx>( @@ -382,14 +139,7 @@ fn layout_of_uncached<'tcx>( } // 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, - }), + ty::Never => tcx.intern_layout(cx.layout_of_never_type()), // Potentially-wide pointers. ty::Ref(_, pointee, _) | ty::RawPtr(ty::TypeAndMut { ty: pointee, .. }) => { @@ -418,7 +168,7 @@ fn layout_of_uncached<'tcx>( }; // Effectively a (ptr, meta) tuple. - tcx.intern_layout(scalar_pair(cx, data_ptr, metadata)) + tcx.intern_layout(cx.scalar_pair(data_ptr, metadata)) } ty::Dynamic(_, _, ty::DynStar) => { @@ -426,7 +176,7 @@ fn layout_of_uncached<'tcx>( 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)) + tcx.intern_layout(cx.scalar_pair(data, vtable)) } // Arrays and slices. @@ -442,8 +192,7 @@ fn layout_of_uncached<'tcx>( 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)) - { + let abi = if count != 0 && ty.is_privately_uninhabited(tcx, param_env) { Abi::Uninhabited } else { Abi::Aggregate { sized: true } @@ -576,8 +325,8 @@ fn layout_of_uncached<'tcx>( // 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)); - }; + return Err(LayoutError::Unknown(ty)); + }; (*e_ty, *count, true) } else { @@ -602,14 +351,14 @@ fn layout_of_uncached<'tcx>( // 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 - )) - }; + // 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))?; @@ -656,681 +405,41 @@ fn layout_of_uncached<'tcx>( 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>>, + return Ok(tcx.intern_layout( + cx.layout_of_union(&def.repr(), &variants).ok_or(LayoutError::Unknown(ty))?, + )); } - 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() + tcx.intern_layout( + cx.layout_of_struct_or_enum( + &def.repr(), + &variants, + def.is_enum(), + def.is_unsafe_cell(), + tcx.layout_scalar_valid_range(def.did()), + |min, max| Integer::repr_discr(tcx, ty, &def.repr(), min, max), + def.is_enum() + .then(|| def.discriminants(tcx).map(|(v, d)| (v, d.val as i128))) + .into_iter() + .flatten(), + 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)?))) + .any(|(i, v)| v.discr != ty::VariantDiscr::Relative(i.as_u32())), { - 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; + let param_env = tcx.param_env(def.did()); + def.is_struct() + && match def.variants().iter().next().and_then(|x| x.fields.last()) { + Some(last_field) => { + tcx.type_of(last_field.did).is_sized(tcx, param_env) } + None => false, } - // 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) + }, + ) + .ok_or(LayoutError::SizeOverflow(ty))?, + ) } // Types with no meaningful known layout. @@ -1488,8 +597,8 @@ fn generator_layout<'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)); - }; + return Err(LayoutError::Unknown(ty)); + }; let (ineligible_locals, assignments) = generator_saved_local_eligibility(&info); // Build a prefix layout, including "promoting" all ineligible @@ -1592,8 +701,8 @@ fn generator_layout<'tcx>( variant.variants = Variants::Single { index }; let FieldsShape::Arbitrary { offsets, memory_index } = variant.fields else { - bug!(); - }; + bug!(); + }; // Now, stitch the promoted and variant-only fields back together in // the order they are mentioned by our GeneratorLayout. @@ -1640,13 +749,13 @@ fn generator_layout<'tcx>( size = size.max(variant.size); align = align.max(variant.align); - Ok(tcx.intern_layout(variant)) + Ok(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()) { + let abi = if prefix.abi.is_uninhabited() || variants.iter().all(|v| v.abi.is_uninhabited()) { Abi::Uninhabited } else { Abi::Aggregate { sized: true } diff --git a/compiler/rustc_ty_utils/src/layout_sanity_check.rs b/compiler/rustc_ty_utils/src/layout_sanity_check.rs index 100926ad4..a5311dbd1 100644 --- a/compiler/rustc_ty_utils/src/layout_sanity_check.rs +++ b/compiler/rustc_ty_utils/src/layout_sanity_check.rs @@ -12,7 +12,7 @@ pub(super) fn sanity_check_layout<'tcx>( layout: &TyAndLayout<'tcx>, ) { // Type-level uninhabitedness should always imply ABI uninhabitedness. - if cx.tcx.conservative_is_privately_uninhabited(cx.param_env.and(layout.ty)) { + if layout.ty.is_privately_uninhabited(cx.tcx, cx.param_env) { assert!(layout.abi.is_uninhabited()); } @@ -20,283 +20,293 @@ pub(super) fn sanity_check_layout<'tcx>( bug!("size is not a multiple of align, in the following layout:\n{layout:#?}"); } - if cfg!(debug_assertions) { - /// Yields non-ZST fields of the type - fn non_zst_fields<'tcx, 'a>( - cx: &'a LayoutCx<'tcx, TyCtxt<'tcx>>, - layout: &'a TyAndLayout<'tcx>, - ) -> impl Iterator<Item = (Size, TyAndLayout<'tcx>)> + 'a { - (0..layout.layout.fields().count()).filter_map(|i| { - let field = layout.field(cx, i); - // Also checking `align == 1` here leads to test failures in - // `layout/zero-sized-array-union.rs`, where a type has a zero-size field with - // alignment 4 that still gets ignored during layout computation (which is okay - // since other fields already force alignment 4). - let zst = field.is_zst(); - (!zst).then(|| (layout.fields.offset(i), field)) - }) - } + if !cfg!(debug_assertions) { + // Stop here, the rest is kind of expensive. + return; + } - fn skip_newtypes<'tcx>( - cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, - layout: &TyAndLayout<'tcx>, - ) -> TyAndLayout<'tcx> { - if matches!(layout.layout.variants(), Variants::Multiple { .. }) { - // Definitely not a newtype of anything. - return *layout; - } - let mut fields = non_zst_fields(cx, layout); - let Some(first) = fields.next() else { - // No fields here, so this could be a primitive or enum -- either way it's not a newtype around a thing - return *layout - }; - if fields.next().is_none() { - let (offset, first) = first; - if offset == Size::ZERO && first.layout.size() == layout.size { - // This is a newtype, so keep recursing. - // FIXME(RalfJung): I don't think it would be correct to do any checks for - // alignment here, so we don't. Is that correct? - return skip_newtypes(cx, &first); - } + /// Yields non-ZST fields of the type + fn non_zst_fields<'tcx, 'a>( + cx: &'a LayoutCx<'tcx, TyCtxt<'tcx>>, + layout: &'a TyAndLayout<'tcx>, + ) -> impl Iterator<Item = (Size, TyAndLayout<'tcx>)> + 'a { + (0..layout.layout.fields().count()).filter_map(|i| { + let field = layout.field(cx, i); + // Also checking `align == 1` here leads to test failures in + // `layout/zero-sized-array-union.rs`, where a type has a zero-size field with + // alignment 4 that still gets ignored during layout computation (which is okay + // since other fields already force alignment 4). + let zst = field.is_zst(); + (!zst).then(|| (layout.fields.offset(i), field)) + }) + } + + fn skip_newtypes<'tcx>( + cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, + layout: &TyAndLayout<'tcx>, + ) -> TyAndLayout<'tcx> { + if matches!(layout.layout.variants(), Variants::Multiple { .. }) { + // Definitely not a newtype of anything. + return *layout; + } + let mut fields = non_zst_fields(cx, layout); + let Some(first) = fields.next() else { + // No fields here, so this could be a primitive or enum -- either way it's not a newtype around a thing + return *layout + }; + if fields.next().is_none() { + let (offset, first) = first; + if offset == Size::ZERO && first.layout.size() == layout.size { + // This is a newtype, so keep recursing. + // FIXME(RalfJung): I don't think it would be correct to do any checks for + // alignment here, so we don't. Is that correct? + return skip_newtypes(cx, &first); } - // No more newtypes here. - *layout } + // No more newtypes here. + *layout + } - fn check_layout_abi<'tcx>(cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, layout: &TyAndLayout<'tcx>) { - match layout.layout.abi() { - Abi::Scalar(scalar) => { - // No padding in scalars. - let size = scalar.size(cx); - let align = scalar.align(cx).abi; - assert_eq!( - layout.layout.size(), - size, - "size mismatch between ABI and layout in {layout:#?}" - ); - assert_eq!( - layout.layout.align().abi, - align, - "alignment mismatch between ABI and layout in {layout:#?}" - ); - // Check that this matches the underlying field. - let inner = skip_newtypes(cx, layout); - assert!( - matches!(inner.layout.abi(), Abi::Scalar(_)), - "`Scalar` type {} is newtype around non-`Scalar` type {}", - layout.ty, - inner.ty - ); - match inner.layout.fields() { - FieldsShape::Primitive => { - // Fine. - } - FieldsShape::Union(..) => { - // FIXME: I guess we could also check something here? Like, look at all fields? - return; - } - FieldsShape::Arbitrary { .. } => { - // Should be an enum, the only field is the discriminant. - assert!( - inner.ty.is_enum(), - "`Scalar` layout for non-primitive non-enum type {}", - inner.ty - ); - assert_eq!( - inner.layout.fields().count(), - 1, - "`Scalar` layout for multiple-field type in {inner:#?}", - ); - let offset = inner.layout.fields().offset(0); - let field = inner.field(cx, 0); - // The field should be at the right offset, and match the `scalar` layout. - assert_eq!( - offset, - Size::ZERO, - "`Scalar` field at non-0 offset in {inner:#?}", - ); - assert_eq!( - field.size, size, - "`Scalar` field with bad size in {inner:#?}", - ); - assert_eq!( - field.align.abi, align, - "`Scalar` field with bad align in {inner:#?}", - ); - assert!( - matches!(field.abi, Abi::Scalar(_)), - "`Scalar` field with bad ABI in {inner:#?}", - ); - } - _ => { - panic!("`Scalar` layout for non-primitive non-enum type {}", inner.ty); - } + fn check_layout_abi<'tcx>(cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, layout: &TyAndLayout<'tcx>) { + match layout.layout.abi() { + Abi::Scalar(scalar) => { + // No padding in scalars. + let size = scalar.size(cx); + let align = scalar.align(cx).abi; + assert_eq!( + layout.layout.size(), + size, + "size mismatch between ABI and layout in {layout:#?}" + ); + assert_eq!( + layout.layout.align().abi, + align, + "alignment mismatch between ABI and layout in {layout:#?}" + ); + // Check that this matches the underlying field. + let inner = skip_newtypes(cx, layout); + assert!( + matches!(inner.layout.abi(), Abi::Scalar(_)), + "`Scalar` type {} is newtype around non-`Scalar` type {}", + layout.ty, + inner.ty + ); + match inner.layout.fields() { + FieldsShape::Primitive => { + // Fine. } - } - 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 size1 = scalar1.size(cx); - let align1 = scalar1.align(cx).abi; - let size2 = scalar2.size(cx); - let align2 = scalar2.align(cx).abi; - assert!( - layout.layout.align().abi >= cmp::max(align1, align2), - "alignment mismatch between ABI and layout in {layout:#?}", - ); - let field2_offset = size1.align_to(align2); - assert!( - layout.layout.size() >= field2_offset + size2, - "size mismatch between ABI and layout in {layout:#?}" - ); - // Check that the underlying pair of fields matches. - let inner = skip_newtypes(cx, layout); - assert!( - matches!(inner.layout.abi(), Abi::ScalarPair(..)), - "`ScalarPair` type {} is newtype around non-`ScalarPair` type {}", - layout.ty, - inner.ty - ); - if matches!(inner.layout.variants(), Variants::Multiple { .. }) { - // FIXME: ScalarPair for enums is enormously complicated and it is very hard - // to check anything about them. + FieldsShape::Union(..) => { + // FIXME: I guess we could also check something here? Like, look at all fields? return; } - match inner.layout.fields() { - FieldsShape::Arbitrary { .. } => { - // Checked below. - } - FieldsShape::Union(..) => { - // FIXME: I guess we could also check something here? Like, look at all fields? - return; - } - _ => { - panic!("`ScalarPair` layout with unexpected field shape in {inner:#?}"); - } + FieldsShape::Arbitrary { .. } => { + // Should be an enum, the only field is the discriminant. + assert!( + inner.ty.is_enum(), + "`Scalar` layout for non-primitive non-enum type {}", + inner.ty + ); + assert_eq!( + inner.layout.fields().count(), + 1, + "`Scalar` layout for multiple-field type in {inner:#?}", + ); + let offset = inner.layout.fields().offset(0); + let field = inner.field(cx, 0); + // The field should be at the right offset, and match the `scalar` layout. + assert_eq!( + offset, + Size::ZERO, + "`Scalar` field at non-0 offset in {inner:#?}", + ); + assert_eq!(field.size, size, "`Scalar` field with bad size in {inner:#?}",); + assert_eq!( + field.align.abi, align, + "`Scalar` field with bad align in {inner:#?}", + ); + assert!( + matches!(field.abi, Abi::Scalar(_)), + "`Scalar` field with bad ABI in {inner:#?}", + ); + } + _ => { + panic!("`Scalar` layout for non-primitive non-enum type {}", inner.ty); } - let mut fields = non_zst_fields(cx, &inner); - let (offset1, field1) = fields.next().unwrap_or_else(|| { - panic!("`ScalarPair` layout for type with not even one non-ZST field: {inner:#?}") - }); - let (offset2, field2) = fields.next().unwrap_or_else(|| { - panic!("`ScalarPair` layout for type with less than two non-ZST fields: {inner:#?}") - }); - assert!( - fields.next().is_none(), - "`ScalarPair` layout for type with at least three non-ZST fields: {inner:#?}" - ); - // The fields might be in opposite order. - let (offset1, field1, offset2, field2) = if offset1 <= offset2 { - (offset1, field1, offset2, field2) - } else { - (offset2, field2, offset1, field1) - }; - // The fields should be at the right offset, and match the `scalar` layout. - assert_eq!( - offset1, - Size::ZERO, - "`ScalarPair` first field at non-0 offset in {inner:#?}", - ); - assert_eq!( - field1.size, size1, - "`ScalarPair` first field with bad size in {inner:#?}", - ); - assert_eq!( - field1.align.abi, align1, - "`ScalarPair` first field with bad align in {inner:#?}", - ); - assert!( - matches!(field1.abi, Abi::Scalar(_)), - "`ScalarPair` first field with bad ABI in {inner:#?}", - ); - assert_eq!( - offset2, field2_offset, - "`ScalarPair` second field at bad offset in {inner:#?}", - ); - assert_eq!( - field2.size, size2, - "`ScalarPair` second field with bad size in {inner:#?}", - ); - assert_eq!( - field2.align.abi, align2, - "`ScalarPair` second field with bad align in {inner:#?}", - ); - assert!( - matches!(field2.abi, Abi::Scalar(_)), - "`ScalarPair` second field with bad ABI in {inner:#?}", - ); } - Abi::Vector { count, element } => { - // No padding in vectors. Alignment can be strengthened, though. - assert!( - layout.layout.align().abi >= element.align(cx).abi, - "alignment mismatch between ABI and layout in {layout:#?}" - ); - let size = element.size(cx) * count; - assert_eq!( - layout.layout.size(), - size.align_to(cx.data_layout().vector_align(size).abi), - "size mismatch between ABI and layout in {layout:#?}" - ); + } + Abi::ScalarPair(scalar1, scalar2) => { + // Sanity-check scalar pairs. Computing the expected size and alignment is a bit of work. + let size1 = scalar1.size(cx); + let align1 = scalar1.align(cx).abi; + let size2 = scalar2.size(cx); + let align2 = scalar2.align(cx).abi; + let align = cmp::max(align1, align2); + let field2_offset = size1.align_to(align2); + let size = (field2_offset + size2).align_to(align); + assert_eq!( + layout.layout.size(), + size, + "size mismatch between ABI and layout in {layout:#?}" + ); + assert_eq!( + layout.layout.align().abi, + align, + "alignment mismatch between ABI and layout in {layout:#?}", + ); + // Check that the underlying pair of fields matches. + let inner = skip_newtypes(cx, layout); + assert!( + matches!(inner.layout.abi(), Abi::ScalarPair(..)), + "`ScalarPair` type {} is newtype around non-`ScalarPair` type {}", + layout.ty, + inner.ty + ); + if matches!(inner.layout.variants(), Variants::Multiple { .. }) { + // FIXME: ScalarPair for enums is enormously complicated and it is very hard + // to check anything about them. + return; + } + match inner.layout.fields() { + FieldsShape::Arbitrary { .. } => { + // Checked below. + } + FieldsShape::Union(..) => { + // FIXME: I guess we could also check something here? Like, look at all fields? + return; + } + _ => { + panic!("`ScalarPair` layout with unexpected field shape in {inner:#?}"); + } } - Abi::Uninhabited | Abi::Aggregate { .. } => {} // Nothing to check. + let mut fields = non_zst_fields(cx, &inner); + let (offset1, field1) = fields.next().unwrap_or_else(|| { + panic!( + "`ScalarPair` layout for type with not even one non-ZST field: {inner:#?}" + ) + }); + let (offset2, field2) = fields.next().unwrap_or_else(|| { + panic!( + "`ScalarPair` layout for type with less than two non-ZST fields: {inner:#?}" + ) + }); + assert!( + fields.next().is_none(), + "`ScalarPair` layout for type with at least three non-ZST fields: {inner:#?}" + ); + // The fields might be in opposite order. + let (offset1, field1, offset2, field2) = if offset1 <= offset2 { + (offset1, field1, offset2, field2) + } else { + (offset2, field2, offset1, field1) + }; + // The fields should be at the right offset, and match the `scalar` layout. + assert_eq!( + offset1, + Size::ZERO, + "`ScalarPair` first field at non-0 offset in {inner:#?}", + ); + assert_eq!( + field1.size, size1, + "`ScalarPair` first field with bad size in {inner:#?}", + ); + assert_eq!( + field1.align.abi, align1, + "`ScalarPair` first field with bad align in {inner:#?}", + ); + assert!( + matches!(field1.abi, Abi::Scalar(_)), + "`ScalarPair` first field with bad ABI in {inner:#?}", + ); + assert_eq!( + offset2, field2_offset, + "`ScalarPair` second field at bad offset in {inner:#?}", + ); + assert_eq!( + field2.size, size2, + "`ScalarPair` second field with bad size in {inner:#?}", + ); + assert_eq!( + field2.align.abi, align2, + "`ScalarPair` second field with bad align in {inner:#?}", + ); + assert!( + matches!(field2.abi, Abi::Scalar(_)), + "`ScalarPair` second field with bad ABI in {inner:#?}", + ); } + Abi::Vector { count, element } => { + // No padding in vectors, except possibly for trailing padding to make the size a multiple of align. + let size = element.size(cx) * count; + let align = cx.data_layout().vector_align(size).abi; + let size = size.align_to(align); // needed e.g. for vectors of size 3 + assert!(align >= element.align(cx).abi); // just sanity-checking `vector_align`. + assert_eq!( + layout.layout.size(), + size, + "size mismatch between ABI and layout in {layout:#?}" + ); + assert_eq!( + layout.layout.align().abi, + align, + "alignment mismatch between ABI and layout in {layout:#?}" + ); + // FIXME: Do some kind of check of the inner type, like for Scalar and ScalarPair. + } + Abi::Uninhabited | Abi::Aggregate { .. } => {} // Nothing to check. } + } - check_layout_abi(cx, layout); + check_layout_abi(cx, layout); - if let Variants::Multiple { variants, .. } = &layout.variants { - for variant in variants.iter() { - // No nested "multiple". - assert!(matches!(variant.variants(), Variants::Single { .. })); - // Variants should have the same or a smaller size as the full thing, - // and same for alignment. - if variant.size() > layout.size { - bug!( - "Type with size {} bytes has variant with size {} bytes: {layout:#?}", - layout.size.bytes(), - variant.size().bytes(), - ) - } - if variant.align().abi > layout.align.abi { - bug!( - "Type with alignment {} bytes has variant with alignment {} bytes: {layout:#?}", - layout.align.abi.bytes(), - variant.align().abi.bytes(), - ) - } - // 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 the coherence check - // for them. They also fail that check, since they have - // `Aggregate`/`Uninhbaited` ABI even when the main type is - // `Scalar`/`ScalarPair`. (Note that sometimes, variants with fields have size - // 0, and sometimes, variants without fields have non-0 size.) - continue; - } - // The top-level ABI and the ABI of the variants should be coherent. - let scalar_coherent = |s1: Scalar, s2: Scalar| { - s1.size(cx) == s2.size(cx) && s1.align(cx) == s2.align(cx) - }; - let abi_coherent = match (layout.abi, variant.abi()) { - (Abi::Scalar(s1), Abi::Scalar(s2)) => scalar_coherent(s1, s2), - (Abi::ScalarPair(a1, b1), Abi::ScalarPair(a2, b2)) => { - scalar_coherent(a1, a2) && scalar_coherent(b1, b2) - } - (Abi::Uninhabited, _) => true, - (Abi::Aggregate { .. }, _) => true, - _ => false, - }; - if !abi_coherent { - bug!( - "Variant ABI is incompatible with top-level ABI:\nvariant={:#?}\nTop-level: {layout:#?}", - variant - ); + if let Variants::Multiple { variants, .. } = &layout.variants { + for variant in variants.iter() { + // No nested "multiple". + assert!(matches!(variant.variants, Variants::Single { .. })); + // Variants should have the same or a smaller size as the full thing, + // and same for alignment. + if variant.size > layout.size { + bug!( + "Type with size {} bytes has variant with size {} bytes: {layout:#?}", + layout.size.bytes(), + variant.size.bytes(), + ) + } + if variant.align.abi > layout.align.abi { + bug!( + "Type with alignment {} bytes has variant with alignment {} bytes: {layout:#?}", + layout.align.abi.bytes(), + variant.align.abi.bytes(), + ) + } + // 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 the coherence check + // for them. They also fail that check, since they have + // `Aggregate`/`Uninhbaited` ABI even when the main type is + // `Scalar`/`ScalarPair`. (Note that sometimes, variants with fields have size + // 0, and sometimes, variants without fields have non-0 size.) + continue; + } + // The top-level ABI and the ABI of the variants should be coherent. + let scalar_coherent = + |s1: Scalar, s2: Scalar| s1.size(cx) == s2.size(cx) && s1.align(cx) == s2.align(cx); + let abi_coherent = match (layout.abi, variant.abi) { + (Abi::Scalar(s1), Abi::Scalar(s2)) => scalar_coherent(s1, s2), + (Abi::ScalarPair(a1, b1), Abi::ScalarPair(a2, b2)) => { + scalar_coherent(a1, a2) && scalar_coherent(b1, b2) } + (Abi::Uninhabited, _) => true, + (Abi::Aggregate { .. }, _) => true, + _ => false, + }; + if !abi_coherent { + bug!( + "Variant ABI is incompatible with top-level ABI:\nvariant={:#?}\nTop-level: {layout:#?}", + variant + ); } } } diff --git a/compiler/rustc_ty_utils/src/lib.rs b/compiler/rustc_ty_utils/src/lib.rs index cce5a79dd..7ad5cbc01 100644 --- a/compiler/rustc_ty_utils/src/lib.rs +++ b/compiler/rustc_ty_utils/src/lib.rs @@ -29,6 +29,7 @@ mod layout; mod layout_sanity_check; mod needs_drop; pub mod representability; +mod structural_match; mod ty; pub fn provide(providers: &mut Providers) { @@ -42,4 +43,5 @@ pub fn provide(providers: &mut Providers) { representability::provide(providers); ty::provide(providers); instance::provide(providers); + structural_match::provide(providers); } diff --git a/compiler/rustc_ty_utils/src/structural_match.rs b/compiler/rustc_ty_utils/src/structural_match.rs new file mode 100644 index 000000000..a55bb7e7e --- /dev/null +++ b/compiler/rustc_ty_utils/src/structural_match.rs @@ -0,0 +1,44 @@ +use rustc_hir::lang_items::LangItem; +use rustc_middle::ty::query::Providers; +use rustc_middle::ty::{self, Ty, TyCtxt}; + +use rustc_infer::infer::TyCtxtInferExt; +use rustc_trait_selection::traits::{ObligationCause, ObligationCtxt}; + +/// This method returns true if and only if `adt_ty` itself has been marked as +/// eligible for structural-match: namely, if it implements both +/// `StructuralPartialEq` and `StructuralEq` (which are respectively injected by +/// `#[derive(PartialEq)]` and `#[derive(Eq)]`). +/// +/// Note that this does *not* recursively check if the substructure of `adt_ty` +/// implements the traits. +fn has_structural_eq_impls<'tcx>(tcx: TyCtxt<'tcx>, adt_ty: Ty<'tcx>) -> bool { + let ref infcx = tcx.infer_ctxt().build(); + let cause = ObligationCause::dummy(); + + let ocx = ObligationCtxt::new(infcx); + // require `#[derive(PartialEq)]` + let structural_peq_def_id = + infcx.tcx.require_lang_item(LangItem::StructuralPeq, Some(cause.span)); + ocx.register_bound(cause.clone(), ty::ParamEnv::empty(), adt_ty, structural_peq_def_id); + // for now, require `#[derive(Eq)]`. (Doing so is a hack to work around + // the type `for<'a> fn(&'a ())` failing to implement `Eq` itself.) + let structural_teq_def_id = + infcx.tcx.require_lang_item(LangItem::StructuralTeq, Some(cause.span)); + ocx.register_bound(cause, ty::ParamEnv::empty(), adt_ty, structural_teq_def_id); + + // We deliberately skip *reporting* fulfillment errors (via + // `report_fulfillment_errors`), for two reasons: + // + // 1. The error messages would mention `std::marker::StructuralPartialEq` + // (a trait which is solely meant as an implementation detail + // for now), and + // + // 2. We are sometimes doing future-incompatibility lints for + // now, so we do not want unconditional errors here. + ocx.select_all_or_error().is_empty() +} + +pub fn provide(providers: &mut Providers) { + providers.has_structural_eq_impls = has_structural_eq_impls; +} diff --git a/compiler/rustc_ty_utils/src/ty.rs b/compiler/rustc_ty_utils/src/ty.rs index 3eebb4ace..5fc9bcac1 100644 --- a/compiler/rustc_ty_utils/src/ty.rs +++ b/compiler/rustc_ty_utils/src/ty.rs @@ -49,12 +49,9 @@ fn sized_constraint_for_ty<'tcx>( // it on the impl. let Some(sized_trait) = tcx.lang_items().sized_trait() else { return vec![ty] }; - let sized_predicate = ty::Binder::dummy(ty::TraitRef { - def_id: sized_trait, - substs: tcx.mk_substs_trait(ty, &[]), - }) - .without_const() - .to_predicate(tcx); + let sized_predicate = ty::Binder::dummy(tcx.mk_trait_ref(sized_trait, [ty])) + .without_const() + .to_predicate(tcx); let predicates = tcx.predicates_of(adtdef.did()).predicates; if predicates.iter().any(|(p, _)| *p == sized_predicate) { vec![] } else { vec![ty] } } @@ -108,12 +105,7 @@ fn adt_sized_constraint(tcx: TyCtxt<'_>, def_id: DefId) -> &[Ty<'_>] { /// See `ParamEnv` struct definition for details. fn param_env(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamEnv<'_> { - // The param_env of an impl Trait type is its defining function's param_env - if let Some(parent) = ty::is_impl_trait_defn(tcx, def_id) { - return param_env(tcx, parent.to_def_id()); - } // Compute the bounds on Self and the type parameters. - let ty::InstantiatedPredicates { mut predicates, .. } = tcx.predicates_of(def_id).instantiate_identity(tcx); @@ -413,63 +405,7 @@ fn issue33140_self_ty(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Ty<'_>> { /// Check if a function is async. fn asyncness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::IsAsync { let node = tcx.hir().get_by_def_id(def_id.expect_local()); - if let Some(fn_kind) = node.fn_kind() { fn_kind.asyncness() } else { hir::IsAsync::NotAsync } -} - -/// Don't call this directly: use ``tcx.conservative_is_privately_uninhabited`` instead. -pub fn conservative_is_privately_uninhabited_raw<'tcx>( - tcx: TyCtxt<'tcx>, - param_env_and: ty::ParamEnvAnd<'tcx, Ty<'tcx>>, -) -> bool { - let (param_env, ty) = param_env_and.into_parts(); - match ty.kind() { - ty::Never => { - debug!("ty::Never =>"); - true - } - ty::Adt(def, _) if def.is_union() => { - debug!("ty::Adt(def, _) if def.is_union() =>"); - // For now, `union`s are never considered uninhabited. - false - } - ty::Adt(def, substs) => { - debug!("ty::Adt(def, _) if def.is_not_union() =>"); - // Any ADT is uninhabited if either: - // (a) It has no variants (i.e. an empty `enum`); - // (b) Each of its variants (a single one in the case of a `struct`) has at least - // one uninhabited field. - def.variants().iter().all(|var| { - var.fields.iter().any(|field| { - let ty = tcx.bound_type_of(field.did).subst(tcx, substs); - tcx.conservative_is_privately_uninhabited(param_env.and(ty)) - }) - }) - } - ty::Tuple(fields) => { - debug!("ty::Tuple(..) =>"); - fields.iter().any(|ty| tcx.conservative_is_privately_uninhabited(param_env.and(ty))) - } - ty::Array(ty, len) => { - debug!("ty::Array(ty, len) =>"); - match len.try_eval_usize(tcx, param_env) { - Some(0) | None => false, - // If the array is definitely non-empty, it's uninhabited if - // the type of its elements is uninhabited. - Some(1..) => tcx.conservative_is_privately_uninhabited(param_env.and(*ty)), - } - } - ty::Ref(..) => { - debug!("ty::Ref(..) =>"); - // References to uninitialised memory is valid for any type, including - // uninhabited types, in unsafe code, so we treat all references as - // inhabited. - false - } - _ => { - debug!("_ =>"); - false - } - } + node.fn_sig().map_or(hir::IsAsync::NotAsync, |sig| sig.header.asyncness) } pub fn provide(providers: &mut ty::query::Providers) { @@ -481,7 +417,6 @@ pub fn provide(providers: &mut ty::query::Providers) { instance_def_size_estimate, issue33140_self_ty, impl_defaultness, - conservative_is_privately_uninhabited: conservative_is_privately_uninhabited_raw, ..*providers }; } |