[Bug c/52577] __builtin_shuffle -Wunused-but-set-* false positives

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52577

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-03-13
         AssignedTo|unassigned at gcc dot       |jakub at gcc dot gnu.org
                   |gnu.org                     |
   Target Milestone|---                         |4.7.1
     Ever Confirmed|0                           |1

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-03-13 08:35:58 UTC ---
Testcase for the false positive warnings:

/* PR c/52577 */
/* { dg-do compile } */
/* { dg-options "-Wall" } */

typedef int V __attribute__((vector_size (sizeof (int) * 4)));

void
f1 (V *p)
{
  V mask = { 1, 2, 3, 0 };
  *p = __builtin_shuffle (*p, mask);
}

void
f2 (V *p, V *q)
{
  V mask = { 1, 2, 3, 0 };
  *p = __builtin_shuffle (*p, *q, mask);
}

void
f3 (V *p, V *mask)
{
  V a = { 1, 2, 3, 0 };
  *p = __builtin_shuffle (a, *mask);
}

void
f4 (V *p, V *mask)
{
  V a = { 1, 2, 3, 0 };
  V b = { 2, 3, 4, 1 };
  *p = __builtin_shuffle (a, b, *mask);
}