[Bug middle-end/71318] Can't disable ISAs via function attribute

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71318

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 38724
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38724&action=edit
A patch to show the problem