[gcc r16-775] c++, coroutines: Clean up the ramp cleanups.
Iain D Sandoe
iains@gcc.gnu.org
Wed May 21 07:56:16 GMT 2025
https://gcc.gnu.org/g:18df4a10bc96946401218019ec566d867238b3e4
commit r16-775-g18df4a10bc96946401218019ec566d867238b3e4
Author: Iain Sandoe <iain@sandoe.co.uk>
Date: Mon May 12 20:38:48 2025 +0100
c++, coroutines: Clean up the ramp cleanups.
This replaces the cleanup try-catch block in the ramp with a series of
eh-only cleanup statements.
gcc/cp/ChangeLog:
* coroutines.cc
(cp_coroutine_transform::build_ramp_function): Replace ramp
cleanup try-catch block with eh-only cleanup statements.
Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
Diff:
---
gcc/cp/coroutines.cc | 199 ++++++++++++++++-----------------------------------
1 file changed, 62 insertions(+), 137 deletions(-)
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 5c4133a42b7e..a62099622288 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -4866,39 +4866,6 @@ cp_coroutine_transform::build_ramp_function ()
coro_fp = pushdecl (coro_fp);
add_decl_expr (coro_fp);
- tree coro_promise_live = NULL_TREE;
- if (flag_exceptions)
- {
- /* Signal that we need to clean up the promise object on exception. */
- coro_promise_live
- = coro_build_and_push_artificial_var (loc, "_Coro_promise_live",
- boolean_type_node, orig_fn_decl,
- boolean_false_node);
-
- /* To signal that we need to cleanup copied function args. */
- if (DECL_ARGUMENTS (orig_fn_decl))
- for (tree arg = DECL_ARGUMENTS (orig_fn_decl); arg != NULL;
- arg = DECL_CHAIN (arg))
- {
- param_info *parm_i = param_uses.get (arg);
- if (parm_i->trivial_dtor)
- continue;
- parm_i->guard_var = pushdecl (parm_i->guard_var);
- add_decl_expr (parm_i->guard_var);
- }
- }
-
- /* deref the frame pointer, to use in member access code. */
- tree deref_fp
- = cp_build_indirect_ref (loc, coro_fp, RO_UNARY_STAR,
- tf_warning_or_error);
- tree frame_needs_free
- = coro_build_and_push_artificial_var_with_dve (loc,
- coro_frame_needs_free_id,
- boolean_type_node,
- orig_fn_decl, NULL_TREE,
- deref_fp);
-
/* Build the frame. */
/* The CO_FRAME internal function is a mechanism to allow the middle end
@@ -4942,25 +4909,23 @@ cp_coroutine_transform::build_ramp_function ()
finish_if_stmt (if_stmt);
}
+ /* Dereference the frame pointer, to use in member access code. */
+ tree deref_fp
+ = cp_build_indirect_ref (loc, coro_fp, RO_UNARY_STAR, tf_warning_or_error);
+
/* For now, once allocation has succeeded we always assume that this needs
destruction, there's no impl. for frame allocation elision. */
- r = cp_build_init_expr (frame_needs_free, boolean_true_node);
- finish_expr_stmt (r);
-
- /* Set up the promise. */
- tree p
- = coro_build_and_push_artificial_var_with_dve (loc, coro_promise_id,
- promise_type, orig_fn_decl,
- NULL_TREE, deref_fp);
+ tree frame_needs_free
+ = coro_build_and_push_artificial_var_with_dve (loc,
+ coro_frame_needs_free_id,
+ boolean_type_node,
+ orig_fn_decl,
+ boolean_true_node,
+ deref_fp);
+ /* Although it appears to be unused here the frame entry is needed and we
+ just set it true. */
+ TREE_USED (frame_needs_free) = true;
- /* Up to now any exception thrown will propagate directly to the caller.
- This is OK since the only source of such exceptions would be in allocation
- of the coroutine frame, and therefore the ramp will not have initialized
- any further state. From here, we will track state that needs explicit
- destruction in the case that promise or g.r.o setup fails or an exception
- is thrown from the initial suspend expression. */
- tree ramp_try_block = NULL_TREE;
- tree ramp_try_stmts = NULL_TREE;
tree iarc_x = NULL_TREE;
tree coro_before_return = NULL_TREE;
if (flag_exceptions)
@@ -4976,8 +4941,15 @@ cp_coroutine_transform::build_ramp_function ()
orig_fn_decl,
boolean_false_node,
deref_fp);
- ramp_try_block = begin_try_block ();
- ramp_try_stmts = begin_compound_stmt (BCS_TRY_BLOCK);
+ tree frame_cleanup = push_stmt_list ();
+ tree do_fr_cleanup
+ = build1_loc (loc, TRUTH_NOT_EXPR, boolean_type_node, iarc_x);
+ do_fr_cleanup = build2_loc (loc, TRUTH_AND_EXPR, boolean_type_node,
+ coro_before_return, do_fr_cleanup);
+ r = build3 (COND_EXPR, void_type_node, do_fr_cleanup,
+ delete_frame_call, void_node);
+ finish_expr_stmt (r);
+ push_cleanup (coro_fp, pop_stmt_list (frame_cleanup), /*eh_only*/true);
}
/* Put the resumer and destroyer functions in. */
@@ -5050,24 +5022,38 @@ cp_coroutine_transform::build_ramp_function ()
tf_warning_or_error);
}
finish_expr_stmt (r);
- if (!parm.trivial_dtor)
+
+ /* Arrange for parm copies to be cleaned up when an exception is
+ thrown before initial await resume. */
+ if (flag_exceptions && !parm.trivial_dtor)
{
- param_dtor_list.safe_push (parm.field_id);
- /* Cleanup this frame copy on exception. */
parm.fr_copy_dtor
= cxx_maybe_build_cleanup (fld_idx, tf_warning_or_error);
- if (flag_exceptions)
+ if (parm.fr_copy_dtor && parm.fr_copy_dtor != error_mark_node)
{
- /* This var is now live. */
- r = build_modify_expr (loc, parm.guard_var,
- boolean_type_node, INIT_EXPR, loc,
- boolean_true_node, boolean_type_node);
+ param_dtor_list.safe_push (parm.field_id);
+ tree param_cleanup = push_stmt_list ();
+ tree do_cleanup
+ = build1_loc (loc, TRUTH_NOT_EXPR, boolean_type_node, iarc_x);
+ do_cleanup
+ = build2_loc (loc, TRUTH_AND_EXPR, boolean_type_node,
+ coro_before_return, do_cleanup);
+ r = build3_loc (loc, COND_EXPR, void_type_node, do_cleanup,
+ parm.fr_copy_dtor, void_node);
finish_expr_stmt (r);
+ push_cleanup (fld_idx, pop_stmt_list (param_cleanup),
+ /*eh_only*/true);
}
}
}
}
+ /* Set up the promise. */
+ tree p
+ = coro_build_and_push_artificial_var_with_dve (loc, coro_promise_id,
+ promise_type, orig_fn_decl,
+ NULL_TREE, deref_fp);
+
if (type_build_ctor_call (promise_type))
{
/* Construct the promise object [dcl.fct.def.coroutine] / 5.7.
@@ -5101,11 +5087,22 @@ cp_coroutine_transform::build_ramp_function ()
finish_expr_stmt (r);
}
- tree promise_dtor = cxx_maybe_build_cleanup (p, tf_warning_or_error);;
- if (flag_exceptions && promise_dtor)
+ if (flag_exceptions)
{
- r = cp_build_init_expr (coro_promise_live, boolean_true_node);
- finish_expr_stmt (r);
+ tree promise_dtor = cxx_maybe_build_cleanup (p, tf_warning_or_error);
+ /* If the promise is live, then run its dtor if that's available. */
+ if (promise_dtor && promise_dtor != error_mark_node)
+ {
+ tree promise_cleanup = push_stmt_list ();
+ tree do_cleanup
+ = build1_loc (loc, TRUTH_NOT_EXPR, boolean_type_node, iarc_x);
+ do_cleanup = build2_loc (loc, TRUTH_AND_EXPR, boolean_type_node,
+ coro_before_return, do_cleanup);
+ r = build3 (COND_EXPR, void_type_node, do_cleanup,
+ promise_dtor, void_node);
+ finish_expr_stmt (r);
+ push_cleanup (p, pop_stmt_list (promise_cleanup), /*eh_only*/true);
+ }
}
tree get_ro
@@ -5180,85 +5177,13 @@ cp_coroutine_transform::build_ramp_function ()
boolean_false_node, tf_warning_or_error);
finish_expr_stmt (r);
}
-
+
/* The ramp is done, we just need the return statement, which we build from
- the return object we constructed before we called the function body. */
+ the return object we constructed before we called the actor. */
r = void_ramp_p ? NULL_TREE : convert_from_reference (coro_gro);
finish_return_stmt (r);
- if (flag_exceptions)
- {
- finish_compound_stmt (ramp_try_stmts);
- finish_try_block (ramp_try_block);
- tree handler = begin_handler ();
- finish_handler_parms (NULL_TREE, handler); /* catch (...) */
-
- /* Before initial resume is called, the responsibility for cleanup on
- exception falls to the ramp. After that, the coroutine body code
- should do the cleanup. This is signalled by the flag
- 'initial_await_resume_called'. */
-
- tree not_iarc
- = build1_loc (loc, TRUTH_NOT_EXPR, boolean_type_node, iarc_x);
- tree do_cleanup = build2_loc (loc, TRUTH_AND_EXPR, boolean_type_node,
- coro_before_return, not_iarc);
- tree cleanup_if = begin_if_stmt ();
- finish_if_stmt_cond (do_cleanup, cleanup_if);
-
- /* If the promise is live, then run its dtor if that's available. */
- if (promise_dtor && promise_dtor != error_mark_node)
- {
- tree promise_d_if = begin_if_stmt ();
- finish_if_stmt_cond (coro_promise_live, promise_d_if);
- finish_expr_stmt (promise_dtor);
- finish_then_clause (promise_d_if);
- finish_if_stmt (promise_d_if);
- }
-
- /* Clean up any frame copies of parms with non-trivial dtors.
- Do this in reverse order from their creation. */
- auto_vec<param_info *> worklist;
- if (DECL_ARGUMENTS (orig_fn_decl))
- for (tree arg = DECL_ARGUMENTS (orig_fn_decl); arg != NULL;
- arg = DECL_CHAIN (arg))
- {
- param_info *parm_i = param_uses.get (arg);
- if (parm_i->trivial_dtor)
- continue;
- worklist.safe_push (parm_i);
- }
- while (!worklist.is_empty ())
- {
- param_info *parm_i = worklist.pop ();
- if (parm_i->fr_copy_dtor && parm_i->fr_copy_dtor != error_mark_node)
- {
- tree dtor_if = begin_if_stmt ();
- finish_if_stmt_cond (parm_i->guard_var, dtor_if);
- finish_expr_stmt (parm_i->fr_copy_dtor);
- finish_then_clause (dtor_if);
- finish_if_stmt (dtor_if);
- }
- }
-
- /* No delete the frame if required. */
- tree fnf_if = begin_if_stmt ();
- finish_if_stmt_cond (frame_needs_free, fnf_if);
- finish_expr_stmt (delete_frame_call);
- finish_then_clause (fnf_if);
- finish_if_stmt (fnf_if);
-
- /* Finished cleanups conditional on "initial resume is not called". */
- finish_then_clause (cleanup_if);
- finish_if_stmt (cleanup_if);
-
- tree rethrow = build_throw (loc, NULL_TREE, tf_warning_or_error);
- suppress_warning (rethrow);
- finish_expr_stmt (rethrow);
- finish_handler (handler);
- finish_handler_sequence (ramp_try_block);
- }
-
finish_compound_stmt (ramp_fnbody);
return true;
}
More information about the Gcc-cvs
mailing list