rb_reg_match_pre  517 include/ruby/intern.h VALUE rb_reg_match_pre(VALUE);
rb_reg_match_pre 1503 re.c               return rb_reg_match_pre(rb_backref_get());
rb_reg_match_pre 3429 re.c               rb_define_method(rb_cMatch, "pre_match", rb_reg_match_pre, 0);
rb_reg_match_pre  982 vm_insnhelper.c 		val = rb_reg_match_pre(backref);