tree-ssa-alias.c (indirect_refs_may_alias_p): Do not treat arrays with same type…

tree-ssa-alias.c (indirect_refs_may_alias_p): Do not treat arrays with same type as objects that cannot overlap.

2016-12-01  Richard Biener  <rguenther@suse.de>

	* tree-ssa-alias.c (indirect_refs_may_alias_p): Do not
	treat arrays with same type as objects that cannot overlap.

	* gcc.dg/torture/alias-2.c: New testcase.

From-SVN: r243106

gcc/ChangeLog

+2016-12-01  Richard Biener  <rguenther@suse.de>
+
+	* tree-ssa-alias.c (indirect_refs_may_alias_p): Do not
+	treat arrays with same type as objects that cannot overlap.
+
 2016-12-01  Georg-Johann Lay  <avr@gjlay.de>
 
 	* config/avr/avr.c (avr_print_operand): Use SYMBOL_REF_P if possible.

gcc/testsuite/ChangeLog

+2016-12-01  Richard Biener  <rguenther@suse.de>
+
+	* gcc.dg/torture/alias-2.c: New testcase.
+
 2016-12-01  Georg-Johann Lay  <avr@gjlay.de>
 
 	* gcc.target/avr/tiny-memx.c: Only perform if target avr_tiny.

gcc/testsuite/gcc.dg/torture/alias-2.c

+/* { dg-do run } */
+
+/* We do not want to treat int[3] as an object that cannot overlap
+   itself but treat it as arbitrary sub-array of a larger array object.  */
+int ar1(int (*p)[3], int (*q)[3])
+{
+  (*p)[0] = 1;
+  (*q)[1] = 2;
+  return (*p)[0];
+}
+int main()
+{
+  int a[4];
+  if (ar1 ((int (*)[3])&a[1], (int (*)[3])&a[0]) != 2)
+    __builtin_abort ();
+  return 0;
+}