Fix off-by-one error in VEC_PERM_EXPR folder.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/wide-int@204329 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index ea5f17c..296b7ec 100644 (file)
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -14360,7 +14360,7 @@ fold_ternary_loc (location_t loc, enum tree_code code, tree type,
     case VEC_PERM_EXPR:
       if (TREE_CODE (arg2) == VECTOR_CST)
        {
-         unsigned int nelts = TYPE_VECTOR_SUBPARTS (type), i;
+         unsigned int nelts = TYPE_VECTOR_SUBPARTS (type), i, mask;
          unsigned char *sel = XALLOCAVEC (unsigned char, nelts);
          bool need_mask_canon = false;
          bool all_in_vec0 = true;
@@ -14368,23 +14368,22 @@ fold_ternary_loc (location_t loc, enum tree_code code, tree type,
          bool maybe_identity = true;
          bool single_arg = (op0 == op1);
          bool changed = false;
-         int nelts_cnt = single_arg ? nelts : nelts * 2;
 
+         mask = single_arg ? (nelts - 1) : (2 * nelts - 1);
          gcc_assert (nelts == VECTOR_CST_NELTS (arg2));
          for (i = 0; i < nelts; i++)
            {
              tree val = VECTOR_CST_ELT (arg2, i);
-
              if (TREE_CODE (val) != INTEGER_CST)
                return NULL_TREE;
 
              /* Make sure that the perm value is in an acceptable
                 range.  */
              wide_int t = val;
-             if (wi::gtu_p (t, nelts_cnt))
+             if (wi::gtu_p (t, mask))
                {
                  need_mask_canon = true;
-                 sel[i] = t.to_uhwi () & (nelts_cnt - 1);
+                 sel[i] = t.to_uhwi () & mask;
                }
              else
                sel[i] = t.to_uhwi ();