[Bug sanitizer/104934] New: -fsanitize=undefined codegen err

[Bug sanitizer/104934] New: -fsanitize=undefined codegen err

[dimhen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104934

            Bug ID: 104934
           Summary: -fsanitize=undefined codegen err
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dimhen 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: ---

r12-7608 FAIL

Probably FAIL long ago: gcc-8 FAIL
gcc version 8.0.1 20180125 (experimental) [trunk revision 257061] (GCC)


$ g++ -fsanitize=undefined -c -o x.o x.ii && nm -u --reverse-sort x.o
                 U _ZTI1S
$ g++ -c -o x.o x.ii && nm -u --reverse-sort x.o

$ cat x.ii
struct a {};
struct b {
  a c;
};
struct S : a {
  virtual int d();
};
struct e : b {
  unsigned f();
};
unsigned e::f() { static_cast<S *>(&c); return 0; }

$ ~/arch-gcc/gcc_current/bin/g++ -v
Using built-in specs.
COLLECT_GCC=/home/dimhen/arch-gcc/gcc_current/bin/g++
COLLECT_LTO_WRAPPER=/home/dimhen/arch-gcc/gcc_current/libexec/gcc/x86_64-pc-linux-gnu/12.0.1/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
Target: x86_64-pc-linux-gnu
Configured with: /home/dimhen/src/gcc_current/configure
--prefix=/home/dimhen/arch-gcc/gcc_current
--enable-checking=yes,df,fold,rtl,extra --enable-languages=c,c++,lto
--disable-multilib --enable-shared --enable-threads=posix --enable-__cxa_atexit
--enable-gnu-unique-object --enable-linker-build-id
--with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl
--enable-offload-targets=nvptx-none --without-cuda-driver
--enable-gnu-indirect-function --enable-cet --with-tune=native
--enable-libstdcxx-debug
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.0.1 20220311 (experimental) [master r12-7608-g5e28be89665] (GCC)

[Bug sanitizer/104934] -fsanitize=undefined codegen err

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104934

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
And the bug is?
The S class doesn't have the key method defined, so some other TU needs to
define it and thus provide the vtable and rtti for it.
Without -fsanitize=vptr the typeinfo isn't needed on this particular testcase
and the vtable isn't needed either, which is why you don't get an undefined
symbol in that case and you get it with -fsanitize=vptr or -fsanitize=undefined
that implies that.

[Bug sanitizer/104934] -fsanitize=undefined codegen err

[dimhen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104934

--- Comment #2 from Dmitry G. Dyachenko <dimhen at gmail dot com> ---
(In reply to Jakub Jelinek from comment #1)
> And the bug is?
> The S class doesn't have the key method defined, so some other TU needs to
> define it and thus provide the vtable and rtti for it.
> Without -fsanitize=vptr the typeinfo isn't needed on this particular
> testcase and the vtable isn't needed either, which is why you don't get an
> undefined symbol in that case and you get it with -fsanitize=vptr or
> -fsanitize=undefined that implies that.

Thank you, Jakub.
So, close as 'INVALID'?

[Bug sanitizer/104934] -fsanitize=undefined codegen err

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104934

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
.