diff options
Diffstat (limited to 'compiler/rustc_ast_lowering/src/format.rs')
| -rw-r--r-- | compiler/rustc_ast_lowering/src/format.rs | 206 |
1 files changed, 77 insertions, 129 deletions
diff --git a/compiler/rustc_ast_lowering/src/format.rs b/compiler/rustc_ast_lowering/src/format.rs index 17b443b8ecc..12f0af75486 100644 --- a/compiler/rustc_ast_lowering/src/format.rs +++ b/compiler/rustc_ast_lowering/src/format.rs @@ -1,7 +1,5 @@ -use core::ops::ControlFlow; use std::borrow::Cow; -use rustc_ast::visit::Visitor; use rustc_ast::*; use rustc_data_structures::fx::FxIndexMap; use rustc_hir as hir; @@ -476,77 +474,52 @@ fn expand_format_args<'hir>( return hir::ExprKind::Call(new, new_args); } - // If the args array contains exactly all the original arguments once, - // in order, we can use a simple array instead of a `match` construction. - // However, if there's a yield point in any argument except the first one, - // we don't do this, because an Argument cannot be kept across yield points. - // - // This is an optimization, speeding up compilation about 1-2% in some cases. - // See https://github.com/rust-lang/rust/pull/106770#issuecomment-1380790609 - let use_simple_array = argmap.len() == arguments.len() - && argmap.iter().enumerate().all(|(i, (&(j, _), _))| i == j) - && arguments.iter().skip(1).all(|arg| !may_contain_yield_point(&arg.expr)); - - let args = if arguments.is_empty() { + let (let_statements, args) = if arguments.is_empty() { // Generate: - // &<core::fmt::Argument>::none() + // [] + (vec![], ctx.arena.alloc(ctx.expr(macsp, hir::ExprKind::Array(&[])))) + } else if argmap.len() == 1 && arguments.len() == 1 { + // Only one argument, so we don't need to make the `args` tuple. // - // Note: - // `none()` just returns `[]`. We use `none()` rather than `[]` to limit the lifetime. - // - // This makes sure that this still fails to compile, even when the argument is inlined: - // - // ``` - // let f = format_args!("{}", "a"); - // println!("{f}"); // error E0716 - // ``` - // - // Cases where keeping the object around is allowed, such as `format_args!("a")`, - // are handled above by the `allow_const` case. - let none_fn = ctx.arena.alloc(ctx.expr_lang_item_type_relative( - macsp, - hir::LangItem::FormatArgument, - sym::none, - )); - let none = ctx.expr_call(macsp, none_fn, &[]); - ctx.expr(macsp, hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, none)) - } else if use_simple_array { // Generate: - // &[ - // <core::fmt::Argument>::new_display(&arg0), - // <core::fmt::Argument>::new_lower_hex(&arg1), - // <core::fmt::Argument>::new_debug(&arg2), - // … - // ] - let elements = ctx.arena.alloc_from_iter(arguments.iter().zip(argmap).map( - |(arg, ((_, ty), placeholder_span))| { + // super let args = [<core::fmt::Argument>::new_display(&arg)]; + let args = ctx.arena.alloc_from_iter(argmap.iter().map( + |(&(arg_index, ty), &placeholder_span)| { + let arg = &arguments[arg_index]; let placeholder_span = placeholder_span.unwrap_or(arg.expr.span).with_ctxt(macsp.ctxt()); - let arg_span = match arg.kind { - FormatArgumentKind::Captured(_) => placeholder_span, - _ => arg.expr.span.with_ctxt(macsp.ctxt()), - }; let arg = ctx.lower_expr(&arg.expr); - let ref_arg = ctx.arena.alloc(ctx.expr( - arg_span, - hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, arg), - )); + let ref_arg = ctx.arena.alloc(ctx.expr_ref(arg.span.with_ctxt(macsp.ctxt()), arg)); make_argument(ctx, placeholder_span, ref_arg, ty) }, )); - ctx.expr_array_ref(macsp, elements) + let args = ctx.arena.alloc(ctx.expr(macsp, hir::ExprKind::Array(args))); + let args_ident = Ident::new(sym::args, macsp); + let (args_pat, args_hir_id) = ctx.pat_ident(macsp, args_ident); + let let_statement = ctx.stmt_super_let_pat(macsp, args_pat, Some(args)); + (vec![let_statement], ctx.arena.alloc(ctx.expr_ident_mut(macsp, args_ident, args_hir_id))) } else { // Generate: - // &match (&arg0, &arg1, &…) { - // args => [ - // <core::fmt::Argument>::new_display(args.0), - // <core::fmt::Argument>::new_lower_hex(args.1), - // <core::fmt::Argument>::new_debug(args.0), - // … - // ] - // } + // super let args = (&arg0, &arg1, &…); let args_ident = Ident::new(sym::args, macsp); let (args_pat, args_hir_id) = ctx.pat_ident(macsp, args_ident); + let elements = ctx.arena.alloc_from_iter(arguments.iter().map(|arg| { + let arg_expr = ctx.lower_expr(&arg.expr); + ctx.expr( + arg.expr.span.with_ctxt(macsp.ctxt()), + hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, arg_expr), + ) + })); + let args_tuple = ctx.arena.alloc(ctx.expr(macsp, hir::ExprKind::Tup(elements))); + let let_statement_1 = ctx.stmt_super_let_pat(macsp, args_pat, Some(args_tuple)); + + // Generate: + // super let args = [ + // <core::fmt::Argument>::new_display(args.0), + // <core::fmt::Argument>::new_lower_hex(args.1), + // <core::fmt::Argument>::new_debug(args.0), + // … + // ]; let args = ctx.arena.alloc_from_iter(argmap.iter().map( |(&(arg_index, ty), &placeholder_span)| { let arg = &arguments[arg_index]; @@ -567,58 +540,47 @@ fn expand_format_args<'hir>( make_argument(ctx, placeholder_span, arg, ty) }, )); - let elements = ctx.arena.alloc_from_iter(arguments.iter().map(|arg| { - let arg_expr = ctx.lower_expr(&arg.expr); - ctx.expr( - arg.expr.span.with_ctxt(macsp.ctxt()), - hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, arg_expr), - ) - })); - let args_tuple = ctx.arena.alloc(ctx.expr(macsp, hir::ExprKind::Tup(elements))); - let array = ctx.arena.alloc(ctx.expr(macsp, hir::ExprKind::Array(args))); - let match_arms = ctx.arena.alloc_from_iter([ctx.arm(args_pat, array)]); - let match_expr = ctx.arena.alloc(ctx.expr_match( - macsp, - args_tuple, - match_arms, - hir::MatchSource::FormatArgs, - )); - ctx.expr( - macsp, - hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, match_expr), + let args = ctx.arena.alloc(ctx.expr(macsp, hir::ExprKind::Array(args))); + let (args_pat, args_hir_id) = ctx.pat_ident(macsp, args_ident); + let let_statement_2 = ctx.stmt_super_let_pat(macsp, args_pat, Some(args)); + ( + vec![let_statement_1, let_statement_2], + ctx.arena.alloc(ctx.expr_ident_mut(macsp, args_ident, args_hir_id)), ) }; - if let Some(format_options) = format_options { + // Generate: + // &args + let args = ctx.expr_ref(macsp, args); + + let call = if let Some(format_options) = format_options { // Generate: - // <core::fmt::Arguments>::new_v1_formatted( - // lit_pieces, - // args, - // format_options, - // unsafe { ::core::fmt::UnsafeArg::new() } - // ) + // unsafe { + // <core::fmt::Arguments>::new_v1_formatted( + // lit_pieces, + // args, + // format_options, + // ) + // } let new_v1_formatted = ctx.arena.alloc(ctx.expr_lang_item_type_relative( macsp, hir::LangItem::FormatArguments, sym::new_v1_formatted, )); - let unsafe_arg_new = ctx.arena.alloc(ctx.expr_lang_item_type_relative( - macsp, - hir::LangItem::FormatUnsafeArg, - sym::new, - )); - let unsafe_arg_new_call = ctx.expr_call(macsp, unsafe_arg_new, &[]); + let args = ctx.arena.alloc_from_iter([lit_pieces, args, format_options]); + let call = ctx.expr_call(macsp, new_v1_formatted, args); let hir_id = ctx.next_id(); - let unsafe_arg = ctx.expr_block(ctx.arena.alloc(hir::Block { - stmts: &[], - expr: Some(unsafe_arg_new_call), - hir_id, - rules: hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::CompilerGenerated), - span: macsp, - targeted_by_break: false, - })); - let args = ctx.arena.alloc_from_iter([lit_pieces, args, format_options, unsafe_arg]); - hir::ExprKind::Call(new_v1_formatted, args) + hir::ExprKind::Block( + ctx.arena.alloc(hir::Block { + stmts: &[], + expr: Some(call), + hir_id, + rules: hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::CompilerGenerated), + span: macsp, + targeted_by_break: false, + }), + None, + ) } else { // Generate: // <core::fmt::Arguments>::new_v1( @@ -632,35 +594,21 @@ fn expand_format_args<'hir>( )); let new_args = ctx.arena.alloc_from_iter([lit_pieces, args]); hir::ExprKind::Call(new_v1, new_args) - } -} - -fn may_contain_yield_point(e: &ast::Expr) -> bool { - struct MayContainYieldPoint; - - impl Visitor<'_> for MayContainYieldPoint { - type Result = ControlFlow<()>; - - fn visit_expr(&mut self, e: &ast::Expr) -> ControlFlow<()> { - if let ast::ExprKind::Await(_, _) | ast::ExprKind::Yield(_) = e.kind { - ControlFlow::Break(()) - } else { - visit::walk_expr(self, e) - } - } - - fn visit_mac_call(&mut self, _: &ast::MacCall) -> ControlFlow<()> { - // Macros should be expanded at this point. - unreachable!("unexpanded macro in ast lowering"); - } + }; - fn visit_item(&mut self, _: &ast::Item) -> ControlFlow<()> { - // Do not recurse into nested items. - ControlFlow::Continue(()) - } + if !let_statements.is_empty() { + // Generate: + // { + // super let … + // super let … + // <core::fmt::Arguments>::new_…(…) + // } + let call = ctx.arena.alloc(ctx.expr(macsp, call)); + let block = ctx.block_all(macsp, ctx.arena.alloc_from_iter(let_statements), Some(call)); + hir::ExprKind::Block(block, None) + } else { + call } - - MayContainYieldPoint.visit_expr(e).is_break() } fn for_all_argument_indexes(template: &mut [FormatArgsPiece], mut f: impl FnMut(&mut usize)) { |