[gcc r13-3165] c++: catch parm initialization tweak

[gcc r13-3165] c++: catch parm initialization tweak

[Jason Merrill]

https://gcc.gnu.org/g:f8ba88b6a811ca9bb4b8411d3f65c329fb480ee1

commit r13-3165-gf8ba88b6a811ca9bb4b8411d3f65c329fb480ee1
Author: Jason Merrill <jason@redhat.com>
Date:   Thu Oct 6 21:10:52 2022 -0400

    c++: catch parm initialization tweak
    
    We want to push the INIT_EXPR inside the CLEANUP_POINT_EXPR for the same
    reason we want to push it into the MUST_NOT_THROW_EXPR: any cleanups follow
    the initialization.
    
    gcc/cp/ChangeLog:
    
            * init.cc (expand_default_init): Also push the INIT_EXPR inside a
            CLEANUP_POINT_EXPR.

Diff:
---
 gcc/cp/init.cc | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index bf46578c08b..0ab0aaabb16 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -2124,19 +2124,20 @@ expand_default_init (tree binfo, tree true_exp, tree exp, tree init, int flags,
 	    return false;
 	}
 
-      if (TREE_CODE (init) == MUST_NOT_THROW_EXPR)
-	/* We need to protect the initialization of a catch parm with a
-	   call to terminate(), which shows up as a MUST_NOT_THROW_EXPR
-	   around the TARGET_EXPR for the copy constructor.  See
-	   initialize_handler_parm.  */
+      /* We need to protect the initialization of a catch parm with a
+	 call to terminate(), which shows up as a MUST_NOT_THROW_EXPR
+	 around the TARGET_EXPR for the copy constructor.  See
+	 initialize_handler_parm.  */
+      tree *p = &init;
+      while (TREE_CODE (*p) == MUST_NOT_THROW_EXPR
+	     || TREE_CODE (*p) == CLEANUP_POINT_EXPR)
 	{
-	  TREE_OPERAND (init, 0) = build2 (INIT_EXPR, TREE_TYPE (exp), exp,
-					   TREE_OPERAND (init, 0));
-	  TREE_TYPE (init) = void_type_node;
+	  /* Avoid voidify_wrapper_expr making a temporary.  */
+	  TREE_TYPE (*p) = void_type_node;
+	  p = &TREE_OPERAND (*p, 0);
 	}
-      else
-	init = build2 (INIT_EXPR, TREE_TYPE (exp), exp, init);
-      TREE_SIDE_EFFECTS (init) = 1;
+      *p = build2 (INIT_EXPR, TREE_TYPE (exp), exp, *p);
+      TREE_SIDE_EFFECTS (*p) = 1;
       finish_expr_stmt (init);
       return true;
     }