PR tree-optimization/33723

	* c-gimplify.c (c_gimplify_expr): Optimize INIT_EXPR or
	MODIFY_EXPR with non-addressable COMPOUND_LITERAL_EXPR as source.

	* gcc.c-torture/execute/20071029-1.c: New test.
	* gcc.dg/tree-ssa/pr33723.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@129743 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 23 insertions, 0 deletions

diff --git a/gcc/c-gimplify.c b/gcc/c-gimplify.c
index 9721b67008b..a1ee27bfb70 100644
--- a/gcc/c-gimplify.c
+++ b/gcc/c-gimplify.c
@@ -233,6 +233,29 @@ c_gimplify_expr (tree *expr_p, tree *pre_p, tree *post_p ATTRIBUTE_UNUSED)
     case COMPOUND_LITERAL_EXPR:
       return gimplify_compound_literal_expr (expr_p, pre_p);
 
+    case INIT_EXPR:
+    case MODIFY_EXPR:
+      if (TREE_CODE (TREE_OPERAND (*expr_p, 1)) == COMPOUND_LITERAL_EXPR)
+	{
+	  tree complit = TREE_OPERAND (*expr_p, 1);
+	  tree decl_s = COMPOUND_LITERAL_EXPR_DECL_STMT (complit);
+	  tree decl = DECL_EXPR_DECL (decl_s);
+	  tree init = DECL_INITIAL (decl);
+
+	  /* struct T x = (struct T) { 0, 1, 2 } can be optimized
+	     into struct T x = { 0, 1, 2 } if the address of the
+	     compound literal has never been taken.  */
+	  if (!TREE_ADDRESSABLE (complit)
+	      && !TREE_ADDRESSABLE (decl)
+	      && init)
+	    {
+	      *expr_p = copy_node (*expr_p);
+	      TREE_OPERAND (*expr_p, 1) = init;
+	      return GS_OK;
+	    }
+	}
+      return GS_UNHANDLED;
+
     default:
       return GS_UNHANDLED;
     }