[Bug rtl-optimization/70405] [6 Regression] -fcompare-debug failure with -mavx512f

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70405

--- Comment #1 from Uroš Bizjak <ubizjak at gmail dot com> ---
There is difference in _.optimized dump:

--- pr70405.c.211t.optimized    2016-03-25 13:54:01.942116037 +0100
+++ pr70405.c.gk.211t.optimized 2016-03-25 13:54:01.968115746 +0100
@@ -107,8 +107,10 @@
   _70 = (unsigned int) _68;
   _71 = _68 >> _70;
   v.1_2 = {_11, _15, _19, _23, _27, _31, _35, _39, _43, _47, _51, _55, _59,
_63, _67, _71};
-  _3 = VEC_PERM_EXPR <v.1_2, v.1_2, { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0 }>;
+  # DEBUG v => v.1_2
+  _3 = {_11, _11, _11, _11, _11, _11, _11, _11, _11, _11, _11, _11, _11, _11,
_11, _11};
   v.2_4 = v.1_2 - _3;
+  # DEBUG v => v.2_4
   _5 = BIT_FIELD_REF <v.2_4, 16, 48>;
   _6 = (int) _5;
   return _6;