@@ -, +, @@ 
  94e2418780f1d13235f3e2e6e5c09dbe821c1ce3 c++: Avoid unnecessary empty class copy [94175].
  "GOT IT GUYS!!!! Doing a handstand and singing the Italian national anthem
  during the compile fixes it."
    -- not a real example,
-gmt
--
--- gcc-11.1.0.orig/gcc/cp/call.c	2021-06-23 21:15:53.558557378 -0700
+++ gcc-11.1.0.orig/gcc/cp/call.c	2021-06-23 21:16:51.162744564 -0700
@@ -398,10 +398,6 @@ build_call_a (tree function, int n, tree
 	if (is_empty_class (TREE_TYPE (arg))
 	    && simple_empty_class_p (TREE_TYPE (arg), arg, INIT_EXPR))
 	  {
-	    while (TREE_CODE (arg) == TARGET_EXPR)
-	      /* We're disconnecting the initializer from its target,
-		 don't create a temporary.  */
-	      arg = TARGET_EXPR_INITIAL (arg);
 	    tree t = build0 (EMPTY_CLASS_EXPR, TREE_TYPE (arg));
 	    arg = build2 (COMPOUND_EXPR, TREE_TYPE (t), arg, t);
 	    CALL_EXPR_ARG (function, i) = arg;
--- gcc-11.1.0.orig/gcc/cp/cp-gimplify.c	2021-04-27 03:00:13.000000000 -0700
+++ gcc-11.1.0.orig/gcc/cp/cp-gimplify.c	2021-06-23 21:18:22.342622354 -0700
@@ -320,10 +320,6 @@ simple_empty_class_p (tree type, tree op
 {
   if (TREE_CODE (op) == COMPOUND_EXPR)
     return simple_empty_class_p (type, TREE_OPERAND (op, 1), code);
-  if (SIMPLE_TARGET_EXPR_P (op)
-      && TYPE_HAS_TRIVIAL_DESTRUCTOR (type))
-    /* The TARGET_EXPR is itself a simple copy, look through it.  */
-    return simple_empty_class_p (type, TARGET_EXPR_INITIAL (op), code);
 
   if (TREE_CODE (op) == PARM_DECL
       && TREE_ADDRESSABLE (TREE_TYPE (op)))
@@ -473,11 +469,6 @@ cp_gimplify_expr (tree *expr_p, gimple_s
 
 	else if (simple_empty_class_p (TREE_TYPE (op0), op1, code))
 	  {
-	    while (TREE_CODE (op1) == TARGET_EXPR)
-	      /* We're disconnecting the initializer from its target,
-		 don't create a temporary.  */
-	      op1 = TARGET_EXPR_INITIAL (op1);
-
 	    /* Remove any copies of empty classes.  Also drop volatile
 	       variables on the RHS to avoid infinite recursion from
 	       gimplify_expr trying to load the value.  */
@@ -492,9 +483,6 @@ cp_gimplify_expr (tree *expr_p, gimple_s
 	    gimplify_expr (&TREE_OPERAND (*expr_p, 0), pre_p, post_p,
 			   is_gimple_lvalue, fb_lvalue);
 	    *expr_p = TREE_OPERAND (*expr_p, 0);
-	    if (code == RETURN_EXPR && REFERENCE_CLASS_P (*expr_p))
-	      /* Avoid 'return *<retval>;'  */
-	      *expr_p = TREE_OPERAND (*expr_p, 0);
 	  }
 	/* P0145 says that the RHS is sequenced before the LHS.
 	   gimplify_modify_expr gimplifies the RHS before the LHS, but that
@@ -674,6 +662,7 @@ cp_gimplify_expr (tree *expr_p, gimple_s
 	      || TREE_CODE (TREE_OPERAND (*expr_p, 0)) == MODIFY_EXPR))
 	{
 	  expr_p = &TREE_OPERAND (*expr_p, 0);
+	  code = TREE_CODE (*expr_p);
 	  /* Avoid going through the INIT_EXPR case, which can
 	     degrade INIT_EXPRs into AGGR_INIT_EXPRs.  */
 	  goto modify_expr_case;
--- gcc-11.1.0.orig/gcc/cp/cp-tree.h	2021-04-27 03:00:13.000000000 -0700
+++ gcc-11.1.0.orig/gcc/cp/cp-tree.h	2021-06-23 21:16:51.163744585 -0700
@@ -5225,7 +5225,6 @@ more_aggr_init_expr_args_p (const aggr_i
    the initializer has void type, it's doing something more complicated.  */
 #define SIMPLE_TARGET_EXPR_P(NODE)				\
   (TREE_CODE (NODE) == TARGET_EXPR				\
-   && TARGET_EXPR_INITIAL (NODE)				\
    && !VOID_TYPE_P (TREE_TYPE (TARGET_EXPR_INITIAL (NODE))))
 
 /* True if EXPR expresses direct-initialization of a TYPE.  */
--- gcc-11.1.0.orig/gcc/testsuite/g++.dg/abi/empty30.C	2021-04-27 03:00:13.000000000 -0700
+++ gcc-11.1.0.orig/gcc/testsuite/g++.dg/abi/empty30.C	1969-12-31 16:00:00.000000000 -0800
@@ -1,14 +0,0 @@ 
-// PR c++/94175
-// { dg-do link }
-
-struct A {};
-extern A a;
-
-int i;
-__attribute ((noinline, noclone))
-void f(A) { ++i; }
-
-int main()
-{
-  f(a);
-}