In the edge case of a coroutine not containing any locals, the ifcd/swch
temporaries would get added to the coroutine frame, corrupting its
layout. We can prevent this by ensuring that in cases where the scope of
the if/switch is the same as the coroutine frame one, we insert a
wrapping BIND_EXPR and try again.
PR c++/106188 - [coroutines] Incorrect frame layout after transforming
conditional statement without top-level bind expression
PR c++/106713 - [11/12/13 Regression] Coroutine regression in GCC 11.3.0: if
(co_await ...) crashes with a jump to ud2 since r12-3529-g70ee703c479081ac
gcc/cp/ChangeLog:
PR c++/106188
PR c++/106713
* coroutines.cc (struct susp_frame_data): Add fn_body for
informing the await_statement_walker of the coroutine body.
(maybe_add_bind): New function.
(await_statement_walker): Call maybe_add_bind when necessary.
(morph_fn_to_coro): Pass fnbody into susp_frame_data.
gcc/testsuite/ChangeLog:
* g++.dg/coroutines/pr106188.C: New test.
Signed-off-by: Arsen Arsenović <ar...@aarsen.me>
---
gcc/cp/coroutines.cc | 45 ++++++++++++++++++++--
gcc/testsuite/g++.dg/coroutines/pr106188.C | 35 +++++++++++++++++
2 files changed, 77 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/coroutines/pr106188.C
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index edb3b706ddc..2e88fb99d7d 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -2586,6 +2586,7 @@ struct susp_frame_data
bool captures_temporary; /* This expr captures temps by ref. */
bool needs_truth_if_exp; /* We must expand a truth_if expression. */
bool has_awaiter_init; /* We must handle initializing an awaiter. */
+ tree *fn_body; /* Original function body */
};
/* If this is an await expression, then count it (both uniquely within the
@@ -3326,6 +3327,33 @@ add_var_to_bind (tree& bind, tree var_type,
return newvar;
}
+/* Helper to ensure we have at least one bind to add vars to. */
+static bool
+maybe_add_bind(susp_frame_data *awpts, tree *stmt, location_t sloc)
+{
+ /* bind_stack is already asserted to be nonempty */
+ tree &bind = awpts->bind_stack->last();
+ gcc_checking_assert(TREE_CODE (*awpts->fn_body) == BIND_EXPR);
+ if (BIND_EXPR_VARS (bind) != BIND_EXPR_VARS (*awpts->fn_body))
+ {
+ /* Alright, we have a unique (enough) scope, bail early. */
+ return false;
+ }
+
+ /* In this case, we'd be pushing variables to the start of the coroutine
+ * unless we add a new BIND_EXPR here.
+ */
+ tree ifsw_bind = build3_loc (sloc, BIND_EXPR, void_type_node,
+ NULL, NULL, NULL);
+ BIND_EXPR_BODY (ifsw_bind) = *stmt;
+ *stmt = ifsw_bind;
+ /* We don't push this BIND_EXPR to the walkers bind stack, it will be handled
+ * by a call to cp_walk_tree, since we start the next walk off from this
+ * bind node.
+ */
+ return true;
+}
+
/* Helper to build and add if (!cond) break; */
static void
@@ -3456,6 +3484,12 @@ await_statement_walker (tree *stmt, int *do_subtree,
void *d)
return NULL_TREE; /* Nothing special to do here. */
gcc_checking_assert (!awpts->bind_stack->is_empty());
+ location_t sloc = EXPR_LOCATION (IF_COND (if_stmt));
+ if (maybe_add_bind (awpts, stmt, sloc))
+ {
+ *do_subtree = false; /* Done inside maybe_add_bind. */
+ return cp_walk_tree (stmt, await_statement_walker, awpts, NULL);
+ }
tree& bind_expr = awpts->bind_stack->last ();
tree newvar = add_var_to_bind (bind_expr, boolean_type_node,
"ifcd", awpts->cond_number++);
@@ -3464,7 +3498,6 @@ await_statement_walker (tree *stmt, int *do_subtree, void
*d)
if (TREE_CODE (cond_inner) == CLEANUP_POINT_EXPR)
cond_inner = TREE_OPERAND (cond_inner, 0);
add_decl_expr (newvar);
- location_t sloc = EXPR_LOCATION (IF_COND (if_stmt));
/* We want to initialize the new variable with the expression
that contains the await(s) and potentially also needs to
have truth_if expressions expanded. */
@@ -3640,6 +3673,12 @@ await_statement_walker (tree *stmt, int *do_subtree,
void *d)
return NULL_TREE; /* Nothing special to do here. */
gcc_checking_assert (!awpts->bind_stack->is_empty());
+ location_t sloc = EXPR_LOCATION (SWITCH_STMT_COND (sw_stmt));
+ if (maybe_add_bind (awpts, stmt, sloc))
+ {
+ *do_subtree = false; /* Done inside maybe_add_bind. */
+ return cp_walk_tree (stmt, await_statement_walker, awpts, NULL);
+ }
/* Build a variable to hold the condition, this will be
included in the frame as a local var. */
tree& bind_expr = awpts->bind_stack->last ();
@@ -3652,7 +3691,6 @@ await_statement_walker (tree *stmt, int *do_subtree, void
*d)
tree cond_inner = SWITCH_STMT_COND (sw_stmt);
if (TREE_CODE (cond_inner) == CLEANUP_POINT_EXPR)
cond_inner = TREE_OPERAND (cond_inner, 0);
- location_t sloc = EXPR_LOCATION (SWITCH_STMT_COND (sw_stmt));
tree new_s = build2_loc (sloc, INIT_EXPR, sw_type, newvar,
cond_inner);
finish_expr_stmt (new_s);
@@ -4477,7 +4515,8 @@ morph_fn_to_coro (tree orig, tree *resumer, tree
*destroyer)
vars) they will get added to the coro frame along with other locals. */
susp_frame_data body_aw_points
= {&field_list, handle_type, fs_label, NULL, NULL, 0, 0,
- hash_set<tree> (), NULL, NULL, 0, false, false, false};
+ hash_set<tree> (), NULL, NULL, 0, false, false, false,
+ &fnbody};
body_aw_points.block_stack = make_tree_vector ();
body_aw_points.bind_stack = make_tree_vector ();
body_aw_points.to_replace = make_tree_vector ();
diff --git a/gcc/testsuite/g++.dg/coroutines/pr106188.C
b/gcc/testsuite/g++.dg/coroutines/pr106188.C
new file mode 100644
index 00000000000..1de3d4cceca
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/pr106188.C
@@ -0,0 +1,35 @@
+// { dg-additional-options "-std=c++20 -w" }
+// { dg-do run }
+// test case from pr106188, w/o workaround
+#include <coroutine>
+
+struct task {
+ struct promise_type {
+ task get_return_object() { return task{}; }
+ void return_void() {}
+ void unhandled_exception() {}
+ auto initial_suspend() noexcept { return std::suspend_never{}; }
+ auto final_suspend() noexcept { return std::suspend_never{}; }
+ };
+};
+
+struct suspend_and_resume {
+ bool await_ready() const { return false; }
+ void await_suspend(std::coroutine_handle<> h) { h.resume(); }
+ void await_resume() {}
+};
+
+task f() {
+ if (co_await suspend_and_resume{}, false) {}
+}
+
+task g() {
+ switch (co_await suspend_and_resume{}, 0) {
+ default: break;
+ }
+}
+
+int main() {
+ f();
+ g();
+}
--
2.35.1
