[Bug sanitizer/99190] New: Undefined behaviour in libubsan

[zeccav at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99190

            Bug ID: 99190
           Summary: Undefined behaviour in libubsan
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zeccav at gmail dot com
                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, marxin at 
gcc dot gnu.org
  Target Milestone: ---

// gcc -fsanitize=shift -w
// ldd a.out produces
// libubsan.so.1 => /home/vitti/local/gcc-150221-undefined/lib64/libubsan.so.1
// ./a.out produces
// ../../../../gcc-150221/libsanitizer/ubsan/ubsan_value.cpp:77:25: runtime
error: left shift of 0x0000000000000000fffffffffffffffb by 96 places cannot be
represented in type '__int128'
// ubsan_value.cpp:77 -> "return SIntMax(Val) << ExtraBits >> ExtraBits;"
int main (void)
{

  1 << -5;

  return 0;
}