coroutines: Add cleanups, where required, to statements with captured references.

When we promote captured temporaries to local variables, we also
remove their initializers from the relevant call expression.  This
means that we should recompute the need for a cleanup expression
once the set of temporaries that remains becomes known.

gcc/cp/ChangeLog:

2020-04-08  Iain Sandoe  <iain@sandoe.co.uk>
	    Jun Ma  <JunMa@linux.alibaba.com>

	* coroutines.cc (maybe_promote_captured_temps): Add a
	cleanup expression, if needed, to any call from which
	we promoted temporaries captured by reference.

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 50f1857a3ec44b5ed3a8a858c74ed6e52ab9da52..e63f30bf3c1d44dc498178a8fe50a82705f91044 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,10 @@
+2020-04-08  Iain Sandoe  <iain@sandoe.co.uk>
+           Jun Ma <JunMa@linux.alibaba.com>
+
+       * coroutines.cc (maybe_promote_captured_temps): Add a cleanup
+       expression, if needed, to any call from which we promoted
+       temporaries captured by reference.
+
 2020-04-08  Marek Polacek  <polacek@redhat.com>
 
        PR c++/94507 - ICE-on-invalid with lambda template.

diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 983fa650b55e85f64ed301563dcc03b19a89572c..936be06c33629806a320b45c3676cb8f677b6dd1 100644 (file)
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -2798,11 +2798,13 @@ maybe_promote_captured_temps (tree *stmt, void *d)
       location_t sloc = EXPR_LOCATION (*stmt);
       tree aw_bind
        = build3_loc (sloc, BIND_EXPR, void_type_node, NULL, NULL, NULL);
-      tree aw_statement_current;
-      if (TREE_CODE (*stmt) == CLEANUP_POINT_EXPR)
-       aw_statement_current = TREE_OPERAND (*stmt, 0);
-      else
-       aw_statement_current = *stmt;
+
+      /* Any cleanup point expression might no longer be necessary, since we
+        are removing one or more temporaries.  */
+      tree aw_statement_current = *stmt;
+      if (TREE_CODE (aw_statement_current) == CLEANUP_POINT_EXPR)
+       aw_statement_current = TREE_OPERAND (aw_statement_current, 0);
+
       /* Collected the scope vars we need move the temps to regular. */
       tree aw_bind_body = push_stmt_list ();
       tree varlist = NULL_TREE;
@@ -2843,8 +2845,12 @@ maybe_promote_captured_temps (tree *stmt, void *d)
          /* Replace all instances of that temp in the original expr.  */
          cp_walk_tree (&aw_statement_current, replace_proxy, &pr, NULL);
        }
-      /* What's left should be the original statement with any temporaries
-        broken out.  */
+
+      /* What's left should be the original statement with any co_await
+        captured temporaries broken out.  Other temporaries might remain
+        so see if we need to wrap the revised statement in a cleanup.  */
+      aw_statement_current =
+       maybe_cleanup_point_expr_void (aw_statement_current);
       add_stmt (aw_statement_current);
       BIND_EXPR_BODY (aw_bind) = pop_stmt_list (aw_bind_body);
       awpts->captured_temps.empty ();