Fix version symbol problem

[akawashiro]

We fail to handle the default version symbol now. But not sure.

https://github.com/pfnet/sold/pull/6/files#diff-ea346e7232da277fcbfd75eb0102ceed1fca1e6c180b2bd4f64d40773c83717bR527

[xuzijian629]

I'm debugging this and I leave some memo here.

I temporarily revives the CHECKs disabled in #6 and ran ninja tests.
I got some errors and saw what (name, soname, version, versym) are actually caught by the checks.

In all failures, the symbols were __cxa_finalize. the corresponding soname and version are empty, but versym is neither 0 nor 1 (I observed 3, 6, and 9, in each failures).

In

sold/version_builder.cc

Line 32 in 8430ecd

CHECK(!soname.empty() && !version.empty()) << " versym=" << special_ver_ndx_to_str(versym);

, if the versym is not special (0 or 1), soname and version are expected to nonempty, and this check fails.

I tracked __cxa_finalize during AddSym

sold/symtab_builder.cc

Line 105 in 8430ecd

sym.index = AddSym(s);

At first, SymtabBuilder::Resolve was called with Resovle(__cxa_finalize, libc.so.6, GLIBC_2.2.5), adding symbol (name,soname,version,versym)=(__cxa_finalize,libc.so.6,GLIBC_2.2.5,6). this seems correct.
However, later it's also called with Resolve(__cxa_finalize, "", ""), generating symbol (__cxa_finalize,,,6)

the second versym 6 is copied from the first versym, but where did the first versym come from?
-> it was set by fallback

Other symbols processed by this line all had nonempty soname and version

So I changed

sold/symtab_builder.cc

Line 88 in 8430ecd

} else {

to

} else if (!soname.empty() && !version.empty()) {

and ninja succeeded (I don't know why)

[xuzijian629]

ctest --output-on-failure still fails, so this would not be the correct way

[akawashiro]

./tools/search-symbol.sh __cxa_finalize may work for you.

[akawashiro]

In my case, with this fix 5ac192f,

$ ./tools/search-symbol.sh __cxa_finalize
   711: 0003a4c0   540 FUNC    GLOBAL DEFAULT   15 __cxa_finalize@@GLIBC_2.1.3 in /lib32/libc.so.6
   223: 00000000000459a0   662 FUNC    GLOBAL DEFAULT   15 __cxa_finalize@@GLIBC_2.2.5 in /lib/x86_64-linux-gnu/libc.so.6

[xuzijian629]

thanks!
I confirmed that above change actually correctly resolves __cxa_finalize symbol.

(below is memo for myself)
but still I got error in CHECK(!soname.empty() && !version.empty()) when versym is not special (0 or 1).

the versym is 65535, which is NO_VERSION_INFO, set at

sold/elf_binary.cc

Line 198 in f7ea7ea

Elf_Versym v = versym_ ? versym_[idx] : NO_VERSION_INFO;

I updated is_special_ver_ndx as

bool is_special_ver_ndx(Elf64_Versym versym) {
    return (versym == VER_NDX_LOCAL || versym == VER_NDX_GLOBAL || versym == NO_VERSION_INFO);
}

and now feature_unit_tests passes in python3.8/ubuntu20.04.

Still, cuBLASLt and cuBLAS-related tests are failing in python3.8/ubuntu20.04 and I continue investigation