[Bug tree-optimization/90610] [10 Regression] 526.blender_r miscompared on znver1 with -Ofast -march=native since r271463

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90610

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
Testing

Index: gcc/match.pd
===================================================================
--- gcc/match.pd        (revision 271644)
+++ gcc/match.pd        (working copy)
@@ -5453,8 +5453,8 @@ (define_operator_list COND_TERNARY
                   first vector we only can insert the first elt from
                   the first vector.  */
                at = 0;
-               ins = fold_read_from_vector (cop0, 0);
-               op0 = op1;
+               if ((ins = fold_read_from_vector (cop0, 0)))
+                 op0 = op1;
              }
            else
              {