FYI: Unable to build -r501994 ports' devel/llvm60 on clang 8 based powerpc64 system: "BFD (GNU Binutils) 2.32 assertion fail elflink.c:2935"

[Mark Millard]

On 2019-May-19, at 11:06, Dimitry Andric <dim at FreeBSD.org> wrote:

> On 19 May 2019, at 16:56, Mark Millard via freebsd-toolchain <freebsd-toolchain at freebsd.org> wrote:
>> This was in a poudriere bulk build on a head -r347549 based powerpc64
>> system with system clang 8 for cc and c++ and base/binutils
>> for the likes of ld. (The system has the llvm libunwind patches
>> for powerpc64 so throwing c++ exceptions work.)
>> 
>> [4397/4552] : && /usr/bin/c++ -fPIC -O2 -pipe -DNDEBUG -fstack-protector-strong -isystem /usr/local/include -fno-strict-aliasing  -DNDEBUG -isystem /usr/local/include -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -std=c++11 -Wall -W -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wcovered-switch-default -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -fcolor-diagnostics -ffunction-sections -fdata-sections -O2 -pipe -DNDEBUG -fstack-protector-strong -isystem /usr/local/include -fno-strict-aliasing  -DNDEBUG -isystem /usr/local/include  -fstack-protector-strong   -Wl,-z,origin  -Wl,-O3 -Wl,--gc-sections  -Wl,--version-script,/wrkdirs/usr/ports/devel/llvm60/work/.build/tools/lto/LTO.exports -shared -Wl,-soname,libLTO.so.6 -o lib/libLTO.so.6.0.1 tools/lto/CMakeFiles/LTO.dir/LTODisassembler.cpp.o tools/lto/CMakeFiles/LTO.dir/lto.cpp.o -L/usr/local/lib -Wl,-rpath,"\$ORIGIN/../
>> lib:/usr/local/lib" lib/libLLVM-6.0.so && :
>> FAILED: lib/libLTO.so.6.0.1
>> : && /usr/bin/c++ -fPIC -O2 -pipe -DNDEBUG -fstack-protector-strong -isystem /usr/local/include -fno-strict-aliasing  -DNDEBUG -isystem /usr/local/include -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -std=c++11 -Wall -W -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wcovered-switch-default -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -fcolor-diagnostics -ffunction-sections -fdata-sections -O2 -pipe -DNDEBUG -fstack-protector-strong -isystem /usr/local/include -fno-strict-aliasing  -DNDEBUG -isystem /usr/local/include  -fstack-protector-strong   -Wl,-z,origin  -Wl,-O3 -Wl,--gc-sections  -Wl,--version-script,/wrkdirs/usr/ports/devel/llvm60/work/.build/tools/lto/LTO.exports -shared -Wl,-soname,libLTO.so.6 -o lib/libLTO.so.6.0.1 tools/lto/CMakeFiles/LTO.dir/LTODisassembler.cpp.o tools/lto/CMakeFiles/LTO.dir/lto.cpp.o -L/usr/local/lib -Wl,-rpath,"\$ORIGIN/../lib:/usr/loc
>> al/lib" lib/libLLVM-6.0.so && :
>> /usr/bin/powerpc64-unknown-freebsd13.0-ld: BFD (GNU Binutils) 2.32 assertion fail elflink.c:2935
>> /usr/bin/powerpc64-unknown-freebsd13.0-ld: BFD (GNU Binutils) 2.32 assertion fail elflink.c:2935
> 
> See <https://bugs.freebsd.org/237068>.  I think this is a BFD ld bug,
> but I still haven't been able to come up with a small test case.  Any
> help appreciated. :-)

I've put the evidence leading to the following in the
bugzilla report. The problem is tied to "seed" in:

/wrkdirs/usr/ports/devel/llvm60/work/llvm-6.0.1.src/include/llvm/ADT/Hashing.h 's:

. . .
namespace llvm {
. . .

// All of the implementation details of actually computing the various hash
// code values are held within this namespace. These routines are included in
// the header file mainly to allow inlining and constant propagation.
namespace hashing {
namespace detail {
. . .

/// \brief A global, fixed seed-override variable.
///
/// This variable can be set using the \see llvm::set_fixed_execution_seed
/// function. See that function for details. Do not, under any circumstances,
/// set or read this variable.
extern size_t fixed_seed_override;

inline size_t get_execution_seed() {
  // FIXME: This needs to be a per-execution seed. This is just a placeholder
  // implementation. Switching to a per-execution seed is likely to flush out
  // instability bugs and so will happen as its own commit.
  //
  // However, if there is a fixed seed override set the first time this is
  // called, return that instead of the per-execution seed.
  const uint64_t seed_prime = 0xff51afd7ed558ccdULL;
  static size_t seed = fixed_seed_override ? fixed_seed_override
                                           : (size_t)seed_prime;
  return seed;
}

It ends up with *h in the reported BFD_ASSERT failures having:

_ZZN4llvm7hashing6detail18get_execution_seedEvE4seed@@LLVM_6.0
root.type = bfd_link_hash_defweak
is_weakalias = 1

And *h->u.alias having:

__bss_start@@LLVM_6.0
root.type = bfd_link_hash_indirect
is_weakalias = 0

That means in the BFD_ASSERT:

def->root.type==bfd_link_hash_indirect

which fails the assert's: def->root.type == bfd_link_hash_defined


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)