[Bug middle-end/69915] [6 Regression] ICE: SIGSEGV with -O -ftracer with broken backtrace

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69915

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 37768
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37768&action=edit
gcc6-pr69915.patch

Untested fix.