[PATCH] Fix unnecessary -Wmaybe-uninitialized false positive (PR target/65313)

[Jakub Jelinek]

Hi!

During profiledbootstrap on ppc64 I've noticed a -Wmaybe-uninitialized
warning in vect_schedule_slp_instance, when built with -fprofile-generate.
While it is clearly a false positive, IMHO it is completely unnecessary
to use here two variables, one uninitialized, another bool whether
it is initialized.  In valid code gimple_assign_rhs_code should not
return ERROR_MARK, so we can use ocode == ERROR_MARK for the allsame
case and ocode != ERROR_MARK for !allsame.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2016-02-10  Jakub Jelinek  <ja...@redhat.com>

        PR target/65313
        * tree-vect-slp.c (vect_schedule_slp_instance): Avoid
        -Wmaybe-uninitialized warning.

--- gcc/tree-vect-slp.c.jj      2016-01-21 13:54:19.000000000 +0100
+++ gcc/tree-vect-slp.c 2016-02-09 13:40:30.280769470 +0100
@@ -3568,20 +3568,18 @@ vect_schedule_slp_instance (slp_tree nod
   if (SLP_TREE_TWO_OPERATORS (node))
     {
       enum tree_code code0 = gimple_assign_rhs_code (stmt);
-      enum tree_code ocode;
+      enum tree_code ocode = ERROR_MARK;
       gimple *ostmt;
       unsigned char *mask = XALLOCAVEC (unsigned char, group_size);
-      bool allsame = true;
       FOR_EACH_VEC_ELT (SLP_TREE_SCALAR_STMTS (node), i, ostmt)
        if (gimple_assign_rhs_code (ostmt) != code0)
          {
            mask[i] = 1;
-           allsame = false;
            ocode = gimple_assign_rhs_code (ostmt);
          }
        else
          mask[i] = 0;
-      if (!allsame)
+      if (ocode != ERROR_MARK)
        {
          vec<gimple *> v0;
          vec<gimple *> v1;

        Jakub