glsl: Do not vectorize vector array dereferences.

Array dereferences must have scalar indices, so we cannot vectorize
them.

Cc: "10.1" <mesa-stable@lists.freedesktop.org>
Reported-by: Andrew Guertin <lists@dolphinling.net>
Tested-by: Andrew Guertin <lists@dolphinling.net>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/glsl/opt_vectorize.cpp

@@ -82,6 +82,7 @@ public:
 
    virtual ir_visitor_status visit_enter(ir_assignment *);
    virtual ir_visitor_status visit_enter(ir_swizzle *);
+   virtual ir_visitor_status visit_enter(ir_dereference_array *);
    virtual ir_visitor_status visit_enter(ir_if *);
    virtual ir_visitor_status visit_enter(ir_loop *);
 
@@ -289,6 +290,19 @@ ir_vectorize_visitor::visit_enter(ir_swizzle *ir)
    return visit_continue;
 }
 
+/* Upon entering an ir_array_dereference, remove the current assignment from
+ * further consideration. Since the index of an array dereference must scalar,
+ * we are not able to vectorize it.
+ *
+ * FINISHME: If all of scalar indices are identical we could vectorize.
+ */
+ir_visitor_status
+ir_vectorize_visitor::visit_enter(ir_dereference_array *ir)
+{
+   this->current_assignment = NULL;
+   return visit_continue_with_parent;
+}
+
 /* Since there is no statement to visit between the "then" and "else"
  * instructions try to vectorize before, in between, and after them to avoid
  * combining statements from different basic blocks.