From 092e60f57adeccf98e876af6b7b5734337904812 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Thu, 30 Dec 2021 00:10:57 -0500
Subject: [PATCH] c++: don't wrap cleanups that can't throw
Since C++11, the vast majority of destructors are noexcept, so
wrap_temporary_cleanups adds a bunch of useless TRY_CATCH_EXPR to be removed
later in the optimizers. It's simple to avoid adding them in the first
place.
gcc/cp/ChangeLog:
* decl.c (wrap_cleanups_r): Don't wrap if noexcept.
gcc/testsuite/ChangeLog:
* g++.dg/eh/cleanup6.C: New test.
---
gcc/cp/decl.c | 14 ++++++++------
gcc/testsuite/g++.dg/eh/cleanup6.C | 13 +++++++++++++
2 files changed, 21 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/eh/cleanup6.C
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 982fca8983d4..51c69957635b 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -7428,12 +7428,14 @@ wrap_cleanups_r (tree *stmt_p, int *walk_subtrees, void *data)
tree guard = (tree)data;
tree tcleanup = TARGET_EXPR_CLEANUP (*stmt_p);
- tcleanup = build2 (TRY_CATCH_EXPR, void_type_node, tcleanup, guard);
- /* Tell honor_protect_cleanup_actions to handle this as a separate
- cleanup. */
- TRY_CATCH_IS_CLEANUP (tcleanup) = 1;
-
- TARGET_EXPR_CLEANUP (*stmt_p) = tcleanup;
+ if (tcleanup && !expr_noexcept_p (tcleanup, tf_none))
+ {
+ tcleanup = build2 (TRY_CATCH_EXPR, void_type_node, tcleanup, guard);
+ /* Tell honor_protect_cleanup_actions to handle this as a separate
+ cleanup. */
+ TRY_CATCH_IS_CLEANUP (tcleanup) = 1;
+ TARGET_EXPR_CLEANUP (*stmt_p) = tcleanup;
+ }
}
return NULL_TREE;
diff --git a/gcc/testsuite/g++.dg/eh/cleanup6.C b/gcc/testsuite/g++.dg/eh/cleanup6.C
new file mode 100644
index 000000000000..e27563f4569f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/eh/cleanup6.C
@@ -0,0 +1,13 @@
+// Test that we don't wrap the non-throwing A cleanup with a B cleanup.
+
+// { dg-do compile { target c++11 } }
+// { dg-additional-options -fdump-tree-gimple }
+// { dg-final { scan-tree-dump-times "B::~B" 1 "gimple" } }
+
+struct A { A(); ~A(); };
+struct B { B(const A& = A()); ~B(); };
+
+int main()
+{
+ B b;
+}
--
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