https://gcc.gnu.org/g:8a3acd8cf449636079acb3d1dfcbcabb074b75af
commit r16-1548-g8a3acd8cf449636079acb3d1dfcbcabb074b75af
Author: Iain Sandoe <i...@sandoe.co.uk>
Date: Mon Jun 16 09:12:29 2025 +0300
c++, coroutines: Remove use of coroutine handle in the frame.
We have been keeping a copy of coroutine_handle<promise> in the state
frame, as it was expected to be efficient to use this to initialize the
argument to await_suspend. This does not turn out to be the case and
intializing the value is obstructive to CGW2563 fixes. This removes
the use.
gcc/cp/ChangeLog:
* coroutines.cc (struct coroutine_info): Update comments.
(struct coro_aw_data): Remove self_handle and add in
information to create the handle in lowering.
(expand_one_await_expression): Build a temporary coroutine
handle.
(build_actor_fn): Remove reference to the frame copy of the
coroutine handle.
(cp_coroutine_transform::wrap_original_function_body): Remove
reference to the frame copy of the coroutine handle.
Signed-off-by: Iain Sandoe <i...@sandoe.co.uk>
Diff:
---
gcc/cp/coroutines.cc | 62 +++++++++++++++++++++++-----------------------------
1 file changed, 27 insertions(+), 35 deletions(-)
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index f97bd9deae33..a0d155b2b8b9 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -206,11 +206,10 @@ struct GTY((for_user)) coroutine_info
tree traits_type; /* The cached traits type for this function. */
tree handle_type; /* The cached coroutine handle for this function. */
tree self_h_proxy; /* A handle instance that is used as the proxy for the
- one that will eventually be allocated in the coroutine
- frame. */
+ one that will eventually be built in lowering. */
tree promise_proxy; /* Likewise, a proxy promise instance. */
- tree from_address; /* handle_type from_address function. */
- tree return_void; /* The expression for p.return_void() if it exists. */
+ tree from_address; /* handle_type from_address() function. */
+ tree return_void; /* The expression for p.return_void(), if it exists. */
location_t first_coro_keyword; /* The location of the keyword that made this
function into a coroutine. */
@@ -1982,12 +1981,13 @@ struct coro_aw_data
tree coro_fp; /* Frame pointer var. */
tree resume_idx; /* This is the index var in the frame. */
tree i_a_r_c; /* initial suspend await_resume() was called if true. */
- tree self_h; /* This is a handle to the current coro (frame var). */
tree cleanup; /* This is where to go once we complete local destroy. */
tree cororet; /* This is where to go if we suspend. */
tree corocont; /* This is where to go if we continue. */
tree dispatch; /* This is where we go if we restart the dispatch. */
tree conthand; /* This is the handle for a continuation. */
+ tree handle_type; /* Handle type for this coroutine... */
+ tree hfa_m; /* ... and handle.from_address() for this. */
unsigned index; /* This is our current resume index. */
};
@@ -2105,6 +2105,18 @@ expand_one_await_expression (tree *expr, tree
*await_expr, void *d)
tree suspend = TREE_VEC_ELT (awaiter_calls, 1); /* await_suspend(). */
tree susp_type = TREE_TYPE (suspend);
+ tree susp_call = suspend;
+ if (TREE_CODE (suspend) == TARGET_EXPR)
+ susp_call = TARGET_EXPR_INITIAL (suspend);
+ gcc_checking_assert (TREE_CODE (susp_call) == CALL_EXPR);
+ tree dummy_ch = build_dummy_object (data->handle_type);
+ r = fold_convert (build_pointer_type (void_type_node), data->coro_fp);
+ vec<tree, va_gc> *args = make_tree_vector_single (r);
+ tree hfa = cp_fold_rvalue (
+ build_new_method_call (dummy_ch, data->hfa_m, &args, NULL_TREE,
+ LOOKUP_NORMAL, NULL, tf_warning_or_error));
+ release_tree_vector (args);
+ CALL_EXPR_ARG (susp_call, call_expr_nargs (susp_call) - 1) = hfa;
bool is_cont = false;
/* NOTE: final suspend can't resume; the "resume" label in that case
@@ -2586,22 +2598,6 @@ build_actor_fn (location_t loc, tree coro_frame_type,
tree actor, tree fnbody,
/* Now we start building the rewritten function body. */
add_stmt (build_stmt (loc, LABEL_EXPR, actor_begin_label));
- /* actor's coroutine 'self handle'. */
- tree ash = coro_build_frame_access_expr (actor_frame, coro_self_handle_id,
- false, tf_warning_or_error);
- /* So construct the self-handle from the frame address. */
- tree hfa_m = get_coroutine_from_address (orig);
- /* Should have been set earlier by coro_promise_type_found_p. */
- gcc_assert (hfa_m);
-
- tree r = build1 (CONVERT_EXPR, build_pointer_type (void_type_node),
actor_fp);
- vec<tree, va_gc> *args = make_tree_vector_single (r);
- tree hfa = build_new_method_call (ash, hfa_m, &args, NULL_TREE,
LOOKUP_NORMAL,
- NULL, tf_warning_or_error);
- r = cp_build_init_expr (ash, hfa);
- finish_expr_stmt (r);
- release_tree_vector (args);
-
/* Now we know the real promise, and enough about the frame layout to
decide where to put things. */
@@ -2616,7 +2612,7 @@ build_actor_fn (location_t loc, tree coro_frame_type,
tree actor, tree fnbody,
add_stmt (fnbody);
/* Now do the tail of the function; first cleanups. */
- r = build_stmt (loc, LABEL_EXPR, del_promise_label);
+ tree r = build_stmt (loc, LABEL_EXPR, del_promise_label);
add_stmt (r);
/* Destructors for the things we built explicitly.
@@ -2684,6 +2680,12 @@ build_actor_fn (location_t loc, tree coro_frame_type,
tree actor, tree fnbody,
gcc_checking_assert (maybe_cleanup_point_expr_void (r) == r);
add_stmt (r);
+ /* How to construct the handle for this coroutine from the frame address. */
+ tree hfa_m = get_coroutine_from_address (orig);
+ /* Should have been set earlier by coro_promise_type_found_p. */
+ gcc_assert (hfa_m);
+ tree handle_type = TREE_TYPE (get_coroutine_self_handle_proxy (orig));
+
/* We've now rewritten the tree and added the initial and final
co_awaits. Now pass over the tree and expand the co_awaits. */
tree i_a_r_c = NULL_TREE;
@@ -2692,8 +2694,9 @@ build_actor_fn (location_t loc, tree coro_frame_type,
tree actor, tree fnbody,
false, tf_warning_or_error);
coro_aw_data data = {actor, actor_fp, resume_idx_var, i_a_r_c,
- ash, del_promise_label, ret_label,
- continue_label, restart_dispatch_label, continuation, 2};
+ del_promise_label, ret_label,
+ continue_label, restart_dispatch_label, continuation,
+ handle_type, hfa_m, 2};
cp_walk_tree (&actor_body, await_statement_expander, &data, NULL);
BIND_EXPR_BODY (actor_bind) = pop_stmt_list (actor_body);
@@ -4424,16 +4427,6 @@ cp_coroutine_transform::wrap_original_function_body ()
var_list = promise;
add_decl_expr (promise);
- /* We need a handle to this coroutine, which is passed to every
- await_suspend(). This was created on demand when parsing we now link it
- into our scope. */
- var = get_coroutine_self_handle_proxy (orig_fn_decl);
- DECL_CONTEXT (var) = orig_fn_decl;
- DECL_SOURCE_LOCATION (var) = loc;
- DECL_CHAIN (var) = var_list;
- var_list = var;
- add_decl_expr (var);
-
/* If we have function parms, then these will be copied to the coroutine
frame as per [dcl.fct.def.coroutine] / 13.
Here, we create a local (proxy) variable for each parm, since the original
@@ -5285,7 +5278,6 @@ cp_coroutine_transform::~cp_coroutine_transform ()
bool _Coro_frame_needs_free; free the coro frame mem if set.
bool _Coro_i_a_r_c; [dcl.fct.def.coroutine] / 5.3
short _Coro_resume_index;
- handle_type _Coro_self_handle;
parameter copies (were required).
local variables saved (including awaitables)
(maybe) trailing space.
