From 5dc8ec8dc3322b513bd55a1e824c36f085b67cb2 Mon Sep 17 00:00:00 2001 From: Steven Fackler Date: Sun, 5 Apr 2020 17:55:19 -0700 Subject: [PATCH] Remove a stack frame from .await calls --- src/libcore/future/mod.rs | 7 +-- src/librustc_ast_lowering/expr.rs | 45 ++++++++++++++----- src/librustc_span/symbol.rs | 3 +- src/test/ui/async-await/issue-70594.stderr | 5 +-- .../async-await/issues/issue-62009-1.stderr | 5 +-- 5 files changed, 40 insertions(+), 25 deletions(-) diff --git a/src/libcore/future/mod.rs b/src/libcore/future/mod.rs index 8dfda7a4a3236..a6b769147d068 100644 --- a/src/libcore/future/mod.rs +++ b/src/libcore/future/mod.rs @@ -77,9 +77,6 @@ where #[unstable(feature = "gen_future", issue = "50547")] #[cfg(not(bootstrap))] #[inline] -pub unsafe fn poll_with_context(f: Pin<&mut F>, mut cx: ResumeTy) -> Poll -where - F: Future, -{ - F::poll(f, cx.0.as_mut()) +pub unsafe fn get_context<'a, 'b>(cx: ResumeTy) -> &'a mut Context<'b> { + &mut *cx.0.as_ptr().cast() } diff --git a/src/librustc_ast_lowering/expr.rs b/src/librustc_ast_lowering/expr.rs index 9984eb4e2825f..1c057ddfb7f35 100644 --- a/src/librustc_ast_lowering/expr.rs +++ b/src/librustc_ast_lowering/expr.rs @@ -556,9 +556,9 @@ impl<'hir> LoweringContext<'_, 'hir> { /// ```rust /// match { /// mut pinned => loop { - /// match unsafe { ::std::future::poll_with_context( + /// match unsafe { ::std::future::Future::poll( /// <::std::pin::Pin>::new_unchecked(&mut pinned), - /// task_context, + /// ::std::future::get_context(task_context), /// ) } { /// ::std::task::Poll::Ready(result) => break result, /// ::std::task::Poll::Pending => {} @@ -598,9 +598,9 @@ impl<'hir> LoweringContext<'_, 'hir> { let task_context_ident = Ident::with_dummy_span(sym::_task_context); // unsafe { - // ::std::future::poll_with_context( + // ::std::future::Future::poll( // ::std::pin::Pin::new_unchecked(&mut pinned), - // task_context, + // ::std::future::get_context(task_context), // ) // } let poll_expr = { @@ -621,10 +621,15 @@ impl<'hir> LoweringContext<'_, 'hir> { arena_vec![self; ref_mut_pinned], ); let new_unchecked = self.expr(span, new_unchecked_expr_kind, ThinVec::new()); - let call = self.expr_call_std_path( + let get_context = self.expr_call_std_path_mut( gen_future_span, - &[sym::future, sym::poll_with_context], - arena_vec![self; new_unchecked, task_context], + &[sym::future, sym::get_context], + arena_vec![self; task_context], + ); + let call = self.expr_call_std_path( + span, + &[sym::future, sym::Future, sym::poll], + arena_vec![self; new_unchecked, get_context], ); self.arena.alloc(self.expr_unsafe(call)) }; @@ -1326,25 +1331,43 @@ impl<'hir> LoweringContext<'_, 'hir> { self.arena.alloc(self.expr(sp, hir::ExprKind::Tup(&[]), ThinVec::new())) } + fn expr_call_mut( + &mut self, + span: Span, + e: &'hir hir::Expr<'hir>, + args: &'hir [hir::Expr<'hir>], + ) -> hir::Expr<'hir> { + self.expr(span, hir::ExprKind::Call(e, args), ThinVec::new()) + } + fn expr_call( &mut self, span: Span, e: &'hir hir::Expr<'hir>, args: &'hir [hir::Expr<'hir>], ) -> &'hir hir::Expr<'hir> { - self.arena.alloc(self.expr(span, hir::ExprKind::Call(e, args), ThinVec::new())) + self.arena.alloc(self.expr_call_mut(span, e, args)) } // Note: associated functions must use `expr_call_std_path`. - fn expr_call_std_path( + fn expr_call_std_path_mut( &mut self, span: Span, path_components: &[Symbol], args: &'hir [hir::Expr<'hir>], - ) -> &'hir hir::Expr<'hir> { + ) -> hir::Expr<'hir> { let path = self.arena.alloc(self.expr_std_path(span, path_components, None, ThinVec::new())); - self.expr_call(span, path, args) + self.expr_call_mut(span, path, args) + } + + fn expr_call_std_path( + &mut self, + span: Span, + path_components: &[Symbol], + args: &'hir [hir::Expr<'hir>], + ) -> &'hir hir::Expr<'hir> { + self.arena.alloc(self.expr_call_std_path_mut(span, path_components, args)) } // Create an expression calling an associated function of an std type. diff --git a/src/librustc_span/symbol.rs b/src/librustc_span/symbol.rs index 54b404e1161b9..82caca17308bf 100644 --- a/src/librustc_span/symbol.rs +++ b/src/librustc_span/symbol.rs @@ -546,8 +546,9 @@ symbols! { plugin, plugin_registrar, plugins, + poll, Poll, - poll_with_context, + get_context, powerpc_target_feature, precise_pointer_size_matching, pref_align_of, diff --git a/src/test/ui/async-await/issue-70594.stderr b/src/test/ui/async-await/issue-70594.stderr index d2fa7e58f6a9b..496ca506c60f2 100644 --- a/src/test/ui/async-await/issue-70594.stderr +++ b/src/test/ui/async-await/issue-70594.stderr @@ -32,11 +32,8 @@ error[E0277]: the trait bound `(): std::future::Future` is not satisfied | LL | [1; ().await]; | ^^^^^^^^ the trait `std::future::Future` is not implemented for `()` - | - ::: $SRC_DIR/libcore/future/mod.rs:LL:COL | -LL | F: Future, - | ------ required by this bound in `std::future::poll_with_context` + = note: required by `std::future::Future::poll` error: aborting due to 5 previous errors diff --git a/src/test/ui/async-await/issues/issue-62009-1.stderr b/src/test/ui/async-await/issues/issue-62009-1.stderr index 2417b592c7dbd..ec4e9e397a81e 100644 --- a/src/test/ui/async-await/issues/issue-62009-1.stderr +++ b/src/test/ui/async-await/issues/issue-62009-1.stderr @@ -32,11 +32,8 @@ error[E0277]: the trait bound `[closure@$DIR/issue-62009-1.rs:12:5: 12:15]: std: | LL | (|_| 2333).await; | ^^^^^^^^^^^^^^^^ the trait `std::future::Future` is not implemented for `[closure@$DIR/issue-62009-1.rs:12:5: 12:15]` - | - ::: $SRC_DIR/libcore/future/mod.rs:LL:COL | -LL | F: Future, - | ------ required by this bound in `std::future::poll_with_context` + = note: required by `std::future::Future::poll` error: aborting due to 4 previous errors