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From: "zeccav at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug sanitizer/99190] New: Undefined behaviour in libubsan
Date: Mon, 22 Feb 2021 08:09:40 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99190

            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, marxi=
n at gcc dot gnu.org
  Target Milestone: ---

// gcc -fsanitize=3Dshift -w
// ldd a.out produces
// libubsan.so.1 =3D> /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;
}=