2016-06-29 Richard Biener <rguenther@suse.de>

	PR middle-end/71002
	* alias.c (component_uses_parent_alias_set_from): Handle
	type punning through union accesses by using the union alias set.
	* gimple.c (gimple_get_alias_set): Remove union type punning case.

	c-family/
	* c-common.c (c_common_get_alias_set): Remove union type punning case.
	
	fortran/
	* f95-lang.c (LANG_HOOKS_GET_ALIAS_SET): Remove (un-)define.
	(gfc_get_alias_set): Remove.

	* g++.dg/torture/pr71002.C: Adjust testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@237839 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 0 insertions, 15 deletions

diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 3301c313998..936ddfb87e5 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -4736,8 +4736,6 @@ static GTY(()) hash_table<c_type_hasher> *type_hash_table;
 alias_set_type
 c_common_get_alias_set (tree t)
 {
-  tree u;
-
   /* For VLAs, use the alias set of the element type rather than the
      default of alias set 0 for types compared structurally.  */
   if (TYPE_P (t) && TYPE_STRUCTURAL_EQUALITY_P (t))
@@ -4747,19 +4745,6 @@ c_common_get_alias_set (tree t)
       return -1;
     }
 
-  /* Permit type-punning when accessing a union, provided the access
-     is directly through the union.  For example, this code does not
-     permit taking the address of a union member and then storing
-     through it.  Even the type-punning allowed here is a GCC
-     extension, albeit a common and useful one; the C standard says
-     that such accesses have implementation-defined behavior.  */
-  for (u = t;
-       TREE_CODE (u) == COMPONENT_REF || TREE_CODE (u) == ARRAY_REF;
-       u = TREE_OPERAND (u, 0))
-    if (TREE_CODE (u) == COMPONENT_REF
-	&& TREE_CODE (TREE_TYPE (TREE_OPERAND (u, 0))) == UNION_TYPE)
-      return 0;
-
   /* That's all the expressions we handle specially.  */
   if (!TYPE_P (t))
     return -1;