[Bug tree-optimization/124034] New: [16 regression] systemd miscompiled with cleanup attribute

[sjames at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124034

            Bug ID: 124034
           Summary: [16 regression] systemd miscompiled with cleanup
                    attribute
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sjames at gcc dot gnu.org
  Target Milestone: ---

```
typedef struct
{
  void **parray;
  void *pfunc;
} ArrayCleanup;

__attribute__ ((noinline)) void
array_cleanup (ArrayCleanup *c)
{
  if (c->parray && !c->pfunc)
      __builtin_abort ();
  *c->parray = 0;
}

bool
memeqbyte (char byte, void *data, long length)
{
  char *p = data;
  for (long i = 0; i < 16; i++, length--)
    {
      if (length == 0)
        return true;
      if (p[i] != byte)
        return false;
    }
  return __builtin_memcmp (data, data + 6, length) == 0;
}

int
main ()
{
  int *iov;
  long n = 7;
  iov = __builtin_malloc (n * sizeof (int));
  __builtin_memset (iov, 'x', sizeof (int) * n);

  if (!memeqbyte ('x', iov, n))
    __builtin_abort ();

  __attribute__((__cleanup__(array_cleanup)_unused_ ) ArrayCleanup CONCATENATE
= {
      (void *)&iov, &n };

  if (!memeqbyte('x', iov, sizeof(int) * n))
   __builtin_abort();
}
```

```
$ gcc -O3 -march=x86-64-v2 -flto a.c -o a && ./a
Aborted                    (core dumped) ./a
```

```
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/16/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-pc-linux-gnu
Configured with:
/var/tmp/portage.notmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/configure
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr
--bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/16
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/16/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/16
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/16/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/16/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/g++-v16
--disable-silent-rules --disable-dependency-tracking
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/16/python
--enable-libphobos --enable-objc-gc
--enable-languages=c,c++,d,go,objc,obj-c++,fortran,ada,cobol,algol68,m2,rust,jit
--enable-obsolete --enable-secureplt --disable-werror --with-system-zlib
--enable-nls --without-included-gettext --disable-libunwind-exceptions
--enable-checking=yes,extra,rtl --with-bugurl=https://bugs.gentoo.org/
--with-pkgversion='Gentoo Hardened 16.0.9999 p, commit
160884cda0c273ff197b29a311dfaf6ae49a9663' --with-gcc-major-version-only
--enable-libstdcxx-time --enable-lto --disable-libstdcxx-pch --enable-shared
--enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu
--with-tls=gnu2 --enable-multilib --with-multilib-list=m32,mx32,m64
--disable-fixed-point --with-abi=m64 --enable-targets=all
--enable-offload-defaulted --enable-offload-targets=nvptx-none --enable-libgomp
--disable-libssp --enable-libada --disable-cet --enable-systemtap
--enable-valgrind-annotations --enable-valgrind-interop --disable-vtable-verify
--disable-libvtv --with-zstd --with-isl --disable-isl-version-check
--enable-default-pie --enable-host-pie --enable-host-bind-now
--enable-default-ssp --disable-fixincludes
--with-gxx-libcxx-include-dir=/usr/include/c++/v1 --enable-host-shared
--enable-libgdiagnostics --enable-linker-build-id --enable-linker-build-id
--enable-linker-build-id --enable-linker-build-id
--with-build-config='bootstrap-O3 bootstrap-lto'
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 16.0.1 20260207 (experimental)
7dda46111eb3ebc390c0287a00d97a69567b33f1 (Gentoo Hardened 16.0.9999 p, commit
160884cda0c273ff197b29a311dfaf6ae49a9663)
```