[Bug sanitizer/60613] New: Invalid signed subtraction ubsan diagnostics

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60613

            Bug ID: 60613
           Summary: Invalid signed subtraction ubsan diagnostics
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: jakub at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
                CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
                    jakub at gcc dot gnu.org, kcc at gcc dot gnu.org

On x86_64-linux with -O2 -m32 -fsanitize=undefined on:
__attribute__((noinline, noclone)) long long
foo (long long y)
{
  asm ("");
  return 8LL - y;
}

int
main ()
{
  foo (1);
  return 0;
}

we get invalid diagnostics:
runtime error: signed integer overflow: 8 - 1 cannot be represented in type
'long long int'