[Bug c++/70272] [5/6 Regression] -flifetime-dse miscompilation starting with r217967

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70272

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 37997
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37997&action=edit
gcc6-pr70272.patch

Untested fix.