public inbox for gcc-cvs@sourceware.org
help / color / mirror / Atom feed
* [gcc(refs/users/marxin/heads/slp-function-v2)] coroutines: Fix missed ramp function return copy elision [PR95346].
@ 2020-06-11 9:53 Martin Liska
0 siblings, 0 replies; only message in thread
From: Martin Liska @ 2020-06-11 9:53 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:4f2d05ef0142d269964e165c14c6f7fe4bdfd5a3
commit 4f2d05ef0142d269964e165c14c6f7fe4bdfd5a3
Author: Iain Sandoe <iain@sandoe.co.uk>
Date: Thu Jun 4 17:14:37 2020 +0100
coroutines: Fix missed ramp function return copy elision [PR95346].
Confusingly, "get_return_object ()" can do two things:
- Firstly it can provide the return object for the ramp function (as
the name suggests).
- Secondly if the type of the ramp function is different from that
of the get_return_object call, this is used as a single parameter
to a CTOR for the ramp's return type.
In the first case we can rely on finish_return_stmt () to do the
necessary processing for copy elision.
In the second case, we should have passed a prvalue to the CTOR as
per the standard comment, but I had omitted the rvalue () call. Fixed
thus.
gcc/cp/ChangeLog:
PR c++/95346
* coroutines.cc (morph_fn_to_coro): Ensure that the get-
return-object is constructed correctly; When it is not the
final return value, pass it to the CTOR of the return type
as an rvalue, per the standard comment.
gcc/testsuite/ChangeLog:
PR c++/95346
* g++.dg/coroutines/pr95346.C: New test.
Diff:
---
gcc/cp/coroutines.cc | 72 ++++++++++++++++++++-----------
gcc/testsuite/g++.dg/coroutines/pr95346.C | 26 +++++++++++
2 files changed, 73 insertions(+), 25 deletions(-)
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 58102f51797..e86b3d42a7f 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -4284,7 +4284,8 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
}
tree gro_context_body = push_stmt_list ();
- bool gro_is_void_p = VOID_TYPE_P (TREE_TYPE (get_ro));
+ tree gro_type = TREE_TYPE (get_ro);
+ bool gro_is_void_p = VOID_TYPE_P (gro_type);
tree gro = NULL_TREE;
tree gro_bind_vars = NULL_TREE;
@@ -4294,17 +4295,23 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
finish_expr_stmt (get_ro);
else
{
- gro = build_lang_decl (VAR_DECL, get_identifier ("coro.gro"),
- TREE_TYPE (get_ro));
+ gro = build_lang_decl (VAR_DECL, get_identifier ("coro.gro"), gro_type);
DECL_CONTEXT (gro) = current_scope ();
DECL_ARTIFICIAL (gro) = true;
DECL_IGNORED_P (gro) = true;
add_decl_expr (gro);
gro_bind_vars = gro;
-
- r = build2_loc (fn_start, INIT_EXPR, TREE_TYPE (gro), gro, get_ro);
- r = coro_build_cvt_void_expr_stmt (r, fn_start);
- add_stmt (r);
+ if (TYPE_NEEDS_CONSTRUCTING (gro_type))
+ {
+ vec<tree, va_gc> *arg = make_tree_vector_single (get_ro);
+ r = build_special_member_call (gro, complete_ctor_identifier,
+ &arg, gro_type, LOOKUP_NORMAL,
+ tf_warning_or_error);
+ release_tree_vector (arg);
+ }
+ else
+ r = build2_loc (fn_start, INIT_EXPR, gro_type, gro, get_ro);
+ finish_expr_stmt (r);
}
/* Initialize the resume_idx_name to 0, meaning "not started". */
@@ -4338,28 +4345,43 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
/* Switch to using 'input_location' as the loc, since we're now more
logically doing things related to the end of the function. */
- /* The ramp is done, we just need the return value. */
- if (!same_type_p (TREE_TYPE (get_ro), fn_return_type))
+ /* The ramp is done, we just need the return value.
+ [dcl.fct.def.coroutine] / 7
+ The expression promise.get_return_object() is used to initialize the
+ glvalue result or prvalue result object of a call to a coroutine.
+
+ If the 'get return object' is non-void, then we built it before the
+ promise was constructed. We now supply a reference to that var,
+ either as the return value (if it's the same type) or to the CTOR
+ for an object of the return type. */
+ if (gro_is_void_p)
+ r = NULL_TREE;
+ else
+ r = rvalue (gro);
+
+ if (!same_type_p (gro_type, fn_return_type))
{
- /* construct the return value with a single GRO param, if it's not
- void. */
- vec<tree, va_gc> *args = NULL;
- vec<tree, va_gc> **arglist = NULL;
- if (!gro_is_void_p)
+ /* The return object is , even if the gro is void. */
+ if (CLASS_TYPE_P (fn_return_type))
{
- args = make_tree_vector_single (gro);
- arglist = &args;
+ vec<tree, va_gc> *args = NULL;
+ vec<tree, va_gc> **arglist = NULL;
+ if (!gro_is_void_p)
+ {
+ args = make_tree_vector_single (r);
+ arglist = &args;
+ }
+ r = build_special_member_call (NULL_TREE,
+ complete_ctor_identifier, arglist,
+ fn_return_type, LOOKUP_NORMAL,
+ tf_warning_or_error);
+ r = build_cplus_new (fn_return_type, r, tf_warning_or_error);
+ if (args)
+ release_tree_vector (args);
}
- r = build_special_member_call (NULL_TREE,
- complete_ctor_identifier, arglist,
- fn_return_type, LOOKUP_NORMAL,
- tf_warning_or_error);
- r = build_cplus_new (fn_return_type, r, tf_warning_or_error);
+ else /* ??? suppose we have non-class return and void gro? */
+ r = build1_loc (input_location, CONVERT_EXPR, fn_return_type, r);
}
- else if (!gro_is_void_p)
- r = rvalue (gro); /* The GRO is the return value. */
- else
- r = NULL_TREE;
finish_return_stmt (r);
diff --git a/gcc/testsuite/g++.dg/coroutines/pr95346.C b/gcc/testsuite/g++.dg/coroutines/pr95346.C
new file mode 100644
index 00000000000..8505a7322e1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/pr95346.C
@@ -0,0 +1,26 @@
+#if __has_include(<coroutine>)
+#include <coroutine>
+#elif defined (__clang__) && __has_include (<experimental/coroutine>)
+#include <experimental/coroutine>
+namespace std { using namespace experimental; }
+#endif
+#include <utility>
+
+struct task {
+ struct promise_type {
+ task get_return_object();
+ void return_void();
+ void unhandled_exception();
+ std::suspend_always initial_suspend() noexcept;
+ std::suspend_always final_suspend() noexcept;
+ };
+};
+
+struct wrapper {
+ using promise_type = task::promise_type;
+ wrapper(task&&);
+};
+
+wrapper f() {
+ co_return;
+}
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2020-06-11 9:53 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-11 9:53 [gcc(refs/users/marxin/heads/slp-function-v2)] coroutines: Fix missed ramp function return copy elision [PR95346] Martin Liska
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).