[BOLT] Gadget scanner: account for BRK when searching for auth oracles (#137975)

An authenticated pointer can be explicitly checked by the compiler via a
sequence of instructions that executes BRK on failure. It is important
to recognize such BRK instruction as checking every register (as it is
expected to immediately trigger an abnormal program termination) to
prevent false positive reports about authentication oracles:

      autia   x2, x3
      autia   x0, x1
      ; neither x0 nor x2 are checked at this point
      eor     x16, x0, x0, lsl #1
      tbz     x16, #62, on_success ; marks x0 as checked
      ; end of BB: for x2 to be checked here, it must be checked in both
      ; successor basic blocks
    on_failure:
      brk     0xc470
    on_success:
      ; x2 is checked
      ldr     x1, [x2] ; marks x2 as checked

0 files changed, 0 insertions, 0 deletions