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.

Tested x86_64-pc-linux-gnu, applying to trunk.

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 982fca8983d..51c69957635 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 00000000000..e27563f4569
--- /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;
+}

base-commit: 62eb5308fe6c46f7eded3c9e06c53491515a6e63
-- 
2.27.0

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